Radiation Therapy in carcinoma breast

Made by:Dr. Isha JaiswalGuided by: Dr. Sandeep Barik

Date: 31st march 2014

Aim of radiation therapy

improve loco regional controlimprove overall survival

EVIDENCES FOR POST-OP RADIOTHERAPY

Investigated the role of radiation in breast cancer. Information was available on 42 000 women in 78 randomised treatment comparisons

RESULTS: In these trials, avoidance of a local recurrence after BCS and mastectomy led to decrease 15-year breast cancer

mortality.

CONCLUSION

Adequate local treatment will avoid about one breast cancer death over the next 15years for every four local recurrences avoided, and should reduce 15-year overall mortality.

EBCTCG Lancet 2005; 366: 2087-2106 5

Effect of radiotherapy after breast-conserving surgery (10 trials of BCS RT) on local recurrence and on breast cancer mortality

1214 women with node-positive disease

Effect of radiotherapy after breast-conserving surgery (10 trials of BCS RT) on local recurrence and on breast cancer mortality

6097 women with node-negative disease

There were 7300 women with BCS in trials of RT

5-year local recurrence risks (mainly in the conserved breast):7% vs 26% (reduction 19%)

15-year breast cancer mortality risks:30.5% vs 35.9% (reduction 5.4%, SE 1.7, 2p=0.002)

15-year overall mortality risks:35.2% vs 40.5% (reduction 5.3%, SE 1.8, 2p=0.005)

EBCTCG Lancet 2005; 366: 2087-2106 6

Mastectomy and axillary clearance: N-ve

5-year local recurrence risks:• 2% vs 6%• (reduction 4%)

15-year breast cancer mortality risks:

• 31.3% vs 27.7% • (increase 3.6%, SE 3.6,

2p=0.01)

15-year overall mortality risks:• 42.4% vs 38.2% • (increase 4.2%, SE 2.7,

2p=0.0002)

Effect of radiotherapy after mastectomy and axillary clearance (25 trials of Mast+AC RT) on local recurrence and on breast cancer mortality

1428 women with node-negative disease

EBCTCG Lancet 2005; 366: 2087-2106 7

Mastectomy and axillary clearance: N+ve

5-year local recurrence risks:• 6% vs 23% • (reduction 17%)

15-year breast cancer mortality risks:

• 54.7% vs 60.1% • (reduction 5.4%, SE 1.3,

2p=0.0002)

15-year overall mortality risks:• 59.8% vs 64.2 %• (reduction 4.4%, SE 1.2,

2p=0.0009)

Effect of radiotherapy after mastectomy and axillary clearance (25 trials of Mast+AC RT) on local recurrence and on breast cancer mortality

8505 women with node-positive disease

10801 women17 RCTsRole of RT after BCS67% were pathologically node negative disease

In women with pN0 disease 67% (n=7287),radiotherapy reduced

10 year Recurrence risks from 31·0% to 15·6% (absolute recurrence reduction 15·4%, 13·2–17·6, 2p<0·00001)

15 year Mortality reduction from 20·5% to 17·2% (absolute mortality reduction 3·3%, 0·8–5·8, 2p=0·005)

In women with pN+ disease (n=1050), radiotherapy reduced

10-year recurrence risk from 63·7% to 42·5% (absolute reduction 21·2%, 95% CI 14·5–27·9, 2p<0·00001

15-year risk of breast cancer death from 51·3% to 42·8% (absolute reduction 8·5%,1·8–15·2, 2p=0·01).

Overall, radiotherapy reduced

10-year risk of any (ie, locoregional or distant) first recurrence from 35·0% to 19·3% (absolute reduction 15·7%, 95% CI 13·7–17·7, 2p<0·00001)

reduced the 15-year risk of breast cancer death from 25·2% to 21·4% (absolute reduction 3·8%, 1·6–6·0, 2p=0·00005).

aimed to assess the effect of radiotherapy in women with only one to three lymph nodes positive after mastectomy and axillary dissection.

For 700 women with Mastectomy + ANDRT had no significant effect on locoregional recurrence overall recurrence breast cancer mortality

For 1772 women with axillary dissection and four or more positive nodes,radiotherapy reduced locoregional recurrence (2p<0·00001), overall recurrence (RR 0·79, 95% CI 0·69–0·90, 2p=0·0003), breast cancer mortality (RR 0·87, 95% CI 0·77–0·99, 2p=0·04).

For 1314 women with axillary dissection and one to three positive nodes, radiotherapy reduced locoregional recurrence (2p<0·00001), overall recurrence (RR 0·68, 95% CI 0·57–0·82, 2p=0·00006), breast cancer mortality (RR 0·80, 95% CI 0·67–0·95,2p=0·01).

Indications of adj. RT• All cases of BCS.

• Cases of MRM wherein i. ≥1 positive axillary LN/s ii. T3iii. T4 disease

Treatment Planning

OBJECTIVE : • Deliver uniform dose distribution throughout target volume• ensure adequate tumor coverage• minimize doses to normal tissue

TECHNIQUE FOR RADIOTHERAPY

PositioningImmobilizationSimulationTarget VolumeTreatment Planning Dose & FractionationSet Up VerificationSequelae Of Radiotherapy

Positioning & Immobilizationmost crucial parts of RT treatment for accurate delivery of a prescribed radiation dose sparing surrounding critical tissues

primary goal:

other benefits :

1) can reduce time for daily set up.2) make patient feel more secure & less apprehensive.3) help to stabilize relationship between external skin marks & internal structures

1) reproducibility of position2) reduce positioning errors

TREATMENT POSITION

SupineProne

Older techniques Lateral erect

• Most important aspect of positioning - patient comfort & reproducibility.

Positioning devices

• Breast board• Wing board

Breast Board

breast board is an inclined plane with fixed angle positions

the ant. chest wall slopes downward from mid chest to neck

brings the chest wall parallel to treatment couch

the inclination is limited to a 10–15° angle for 70 cm, and 17.5–20° for larger 85 cm aperture ct scanners

• Several adjustable features to allow for the manipulation of patients arms, wrists, head & shoulders.

• make chest wall surface horizontal, • brings arms out of the way of lateral beams..

• Thermoplastic breast support can be added for

immobilization of large pendulous breast

• Constructed of carbon fiber which has lower attenuation

levels permitting maximum beam penetration.

Advantages of breast board

Wing board

Simpler positioning device Can be used in narrow bore gantry Chest wall slope cannot be corrected Need other techniques for reducing dose to heart and field

matching

Other treatment positions

• Prone• Requires patient to climb onto a

prone board, lie on the stomach & rest the arms over the head.

• The i/l breast gravitates through a hole in the breast board & c/l breast is pushed away against an angled platform to avoid the radiation beams

Prone breast boardSystem includes:Prone boardFace cushion15 Degree Contralateral WedgeHandles

advantages

A systematic review of methods to immobilise breast tissue during adjuvant breast irradiationSheffield Hallam University Research Archive

Immobilization devicesThermoplastic shellsAdhesive tapeVac lockAlpha cradle Wireless braBreast ringBreast cupStockingVacuum L-shaped breast plate

For large pendulous breast• Patients with large or pendulous breasts treated supine require a breast support, either

with a thermoplastic shell, or breast cup which can be used to bring the lateral and inferior part of the breast anteriorly away from the heart, lung and abdomen.

ring device

Breast ring with valecro

The ring consisted of a hollow PVC tube wrapped around the base of the breast and supported by a Velcro strap

Vac-lock

Alpha cradle

Simulation

• Where available, CT scanning has become standard for planning breast radiotherapy

• Scar & drain sites identified with radiopaque markers.• field borders are chosen & radiopaque wires are placed • Radiopaque wires is also placed encircling breast tissue

• CT data are acquired superiorly from neck and inferiorly up to diaphragm• Slice thickness should be sufficient (usually 5 mm) but dependent on agreed local

CT protocols• Three reference tattoos are placed on the central slice and in right & left sides so

that measurements can be made to subsequent beam centres

Supine:• Most patients are treated in the supine position, with the arm/s abducted and face turned

to the C/L side• breast tilt boards with armrests used for positioning• immobilization devices (e.g., Alpha cradle, plastic moulds) can be used

patient immobilized for breast irradiation on a slant board with custom mold

POSITION OF ARMS• The preferred arm position is bilateral arms to be abducted 90 degrees or greater & externally

rotated • Arm elevation required to facilitate tangential fields across the chest wall without irradiating the

arm.

• Advantages of raising both arms vs only the I/L arm

• Factors deciding the angle of arm elevation i) Ability to elevate without discomfort. ii) No/Minimal skin folds in the Supraclavicular region. iii) Ability to move the patient through the CT aperture.

i. patient is more comfortable and relaxedii. position is more symmetrical and easily reproducible with lesser chances of rotation of the torsoiii. more precise matching of the previously irradiated field if c/l breast requires radiation in future

Position of head:

• rigid head holder or a neck rest can be used to stabilize & position head

• also elevate the chin to minimize neck skin folds within the SCF field

Treatment planning• Conventional• Three-Dimensional Conformal• Intensity-Modulated Radiation

Therapy

Treatment volumes

• AFTER BCS• Whole breast radiotherapy + lumpectomy

boost • Regional nodes• Accelerated Partial breast irradiation

• AFTER MASTECTOMY• chest wall, • mastectomy scar, • regional nodes

2D based planning

Conventional planning• positioning & immobilization• Technique• field borders • simulation: fluoroscopy or ct based• Setting medial & lateral tangential beams • beam modification• field matching

POSITIONING• Breast board• Supine with anterior chest wall

parallel to couch• Arms overhead and comfortable• If 2 field: patient looks straight• If 3- field technique: turn the

head to the opposite side to be treated.

TECHNIQUE for WBRT• Two tangential fields are used.• Additional fields for SCF, IMC, & post. Axillary may be used

Field borders For tangential fields

• Upper border –• when supra clavicular field used - 2nd ICS (angle of Louis) When SCF not irradiated – head of clavicle

• Medial border – at or 1cm away from midline

• Lateral border – 2-3cm beyond all palpable breast tissue – mid axillary line

• Lower border – 2cm below inframammary fold

• Borders can be modified in order to • cover entire breast tissue, • to include nodal volumes and scar marks DO NOT MISS THE TARGET VOLUME

• Lead wire placed on lateral border• Field opened at 0 rotation on chest wall and central axis placed along medial border of ⁰

marked field• Gantry rotated , until on fluoroscopy, central axis & lead wire intersect – angle of gantry at

that point is noted – medial tangent angle• Lateral tangential angle is 180 °opposite to medial tangent• Simulation film is taken

Deciding angle of rotation of gantry for tangential fields

• After setting simulator at the isocentre, the gantry is rotated medially till the field light corresponds to the medial border drawn.

• A simulation film is then taken in this position.

• A wire is placed over the lateral border so that it can be identified on fluoroscopy/X-ray. This represents intended posterior border of exit of the medial tangential beam.

• Check whether the entire breast is covered in portal.

• Whether there is a margin of 1.5-2 cms beyond the breast for respiratory excursion

• Whether there is 1 to 3 cm of lung visible on the simulation film in the field anterior to the posterior field edge.

• Whether the lead wire coincides with the posterior edge of the portal.

Beam Modification Devices in breast radiotherapy

Wedges Compensators Bolus

WBRT uses tangential field technique; however, dose distribution is complicated because of irregularities in the chest-wall contour varying thickness of the underlying lung tissue.

Therefore beam modification is required to improve dose

planning target volume (PTV) should be within the 95% and 107% isodose for homogenous dose distribution

Wedge Filters• beam modifying device• causes progressive decrease in intensity across the beam, resulting in

tilting the isodose curves from their normal positions.• Degree of the tilt depends upon the slope of the wedge filter.

• Wedges Are Used As Compensators In Breast Radiotherapy.• Dose uniformity within the breast tissue can be improved• Preferred in the lateral tangential field than the medial

.

Higher dose to the

apex without wedges

Wedges alter dose distribution only in the transverse direction and not in the sagittal direction of the bitangential fields.

Compensators• Wedges cannot compensate for a change in breast

shape in the cranio-caudal direction

• Compensators are used to allow normal dose distribution data to be applied to the treated zone, when the beam enters obliquely through the body

• advantages• evens out the skin surface contours, while

retaining the skin-sparing advantage.

reduction in the hot spot

Bolus• A tissue equivalent material used to reduce the depth of the maximum dose (Dmax).• Better called a “build-up bolus”.• In MV radiation bolus is used to bring up the buildup zone near the skin

Increases dose to skin & scar after mastectomy

In PMRT 3- to 5-mm bolus is used over the chest wall every other day or every day for 2

weeks (20 Gy total dose) and then as needed to ensure that a brisk radiation dermatitis develops

Cosmetic results may be inferior

Universal wax bolus used

Alignment of the Tangential Beam with the Chest Wall Contour

• following can be used to make the posterior edge of tangential beam follow chest contour

Rotating Collimators, Breast Board: Multileaf Collimation.

Sloping surface of chest wall • Due to the obliquity of the anterior chest wall, the tangential fields require collimation so as to reduce the amount of lung irradiated.

Rotating Collimators: collimator of the tangential beam may be rotated

The need for collimation can be eliminated if the upper torso is elevated so as to make the chest wall horizontal. This is done by BREAST BOARD

However in a collimated field, junction matching between the bitangential fields and the anterior SCF field becomes problematic resulting in hot/cold spots.

consists of two banks of tungsten leaves, situated within the path of the treatment beam, which individually move under computer control

Can be moved automatically independent of each other to generate a field of any shape

multileaf collimator (MLC)

Selection of appropriate energy

X-ray energies of 4 to 6 MV are preferred Photon energies >6 MV underdose superficial tissues beneath the skin surface

If tangential field separation is >22 cm :significant dose inhomogeneity in the breast

So higher-energy photons (10 to 18 MV) can be used to deliver a portion of the breast radiation (approximately 50%) as determined with treatment planning to maintain the inhomogeneity throughout the entire breast to between 93 and 105%.

IMRT techniques such as field-in-field or dynamic multileaf collimators (MLCs) may be utilized to reduce dose inhomogeneity

Dose of radiation

Perez & Brady's Principles and Practice of Radiation Oncology, chapter 56, p1089

Whole breast radiotherapy/chest wall irradiation• Conventional Dose• 50 Gy in 25 daily fractions given in 5 weeks• Hypofractionated dose schedule • 40 Gy in 15 daily fractions of 2.67 Gy given in 3 weeks.• 42.5 Gy in 16 daily fractions of 2.66 Gy given in 31⁄2 weeks.Breast boost irradiation to Tumour bed• 16 Gy in 8 daily fractions given in 1.5 weeks.• 10 Gy in 5 daily fractions given in 1 weekLymph node irradiation• 50 Gy in 25 daily fractions given in 5 weeks• 40 Gy in 15 daily fractions of 2.67 Gy given in 3 weeks.

Doses To Heart & Lung By Tangential Fields

• The amount of lung included in the irradiated volume is greatly influenced by the portals used.

• Various parameters are used to determine he amount of lung & heart in tangential field

• CLD: perpendicular distance from the posterior tangential field edge to the posterior part of the anterior chest wall at the center of the field

• MLD: maximum perpendicular distance from the posterior tangential field edge to the posterior part of the anterior chest wall

Central lung distance marked on the digitally reconstructed radiograph (a) and on the central axial slice (b)

Central lung distance• Best predictor of %age of ipsilateral lung vol.

treated by tangential fields

CLD (cm) % of lung irradiated

1.5 cm 6%2.5 cm 16%3.5 cm 26%

Usually up to 2 to 3 cm of underlying lung may be included in the tangential portals

Radiation pneumonitis risk <2% with CLD<3 cm.Risk upto 10% with CLD 4-4.5 cm.

To prevent excess volume of lung irradiated, the divergence of the deep margins is matched.2 ways - angle the central axes slightly more than 180⁰ - half beam block technique.

In very large breasts, bitangentials are unable to cover the target volume without significantly increasing the volume of OARs irradiated.

MATCHING DIVERGENCE OF PHOTON BEAM

angle the central axes slightly more than 180⁰

half beam block technique.

 By moving one of the independent jaws to midline, a half beam block can be created. This forms a non-divergent field edge centrally.

The half beam block functions is easier to set up (less movements of the couch/gantry)

Dose to heart can be minimized byMedian tangential breast portCardiac block & electron fieldbreath holdgating

When the CLD is >3 cm, in treatment of the left breast, a significant volume of heart will also be irradiated

MAXIMUM HEART DISTANCE: maximum perpendicular distance from the posterior tangential field edge to the heart border

A and B: Left tangential breast field with heart block to shield left ventricle from radiation port. Projection of heart block on breast shields minimal amount of breast tissue. If necessary, a shadow electron field may be added to cover the portion of breast tissue shielded by heart block

HEART BLOCK

Irradiation Dose to the Contralateral Breast• radiation dose to the contralateral breast is of concern due to potential long-term

carcinogenic effect of scattered radiation.

• this risk appears to be minimal with modern techniques,.

• Use of tangential fields only resulted in more dose delivered to the surface of the opposite breast,

• whereas use of the internal mammary field in addition to the tangential portals gave more dose deeper in the breast.  

Following are helpful in decreasing the dose to the contralateral breast.

• The use of half-field blocks (beam splitter), • independent jaws • MLC following the contour of the chest wall of the patient• wedges on the lateral tangential fields rather than on the medial• 2.5-cm-thick lead shield over the contralateral breast during treatment with a

medial tangential field

Irradiation of Regional Lymphatic

• Supraclavicular Lymph Nodes • Axillary Lymph Nodes • Posterior Axillary Boost • Internal Mammary Lymph Nodes

SCF L.N IRRADIATIONIndications of RT to Supraclavicular group:• N2 or N3 disease• >4 positive lymph nodes after axillary dissection• 1-3 positive lymph nodes with high risk features• Node positive sentinel lymph node with no dissection• High risk with no dissection

Perez & Brady's Principles and Practice of Radiation Oncology, chapter 56, p1091

SCF field • Single anterior field is used.Field borders – • Upper border : thyrocricoid groove• Medial border : at or 1cm across midline extending

upward following medial border of SCM ms to thyrocricoid groove

• Lateral border: just medial to the humeral head, insertion of deltoid muscle

• Lower border : matched with upper border of tangential fields usually just below clavicle head

field is angled approximately 10 to 15 degrees laterally to spare the cervical spine dose: calculated at a depth of 3 cmFor obese patients target is deeper than 3 cm, higher energy or AP-PA field can be used

• Images of a radiation treatment field used to treat the axillary apex/ SCF. • The level III region of the axillary and the upper internal mammary vessels have been

contoured • These contours are used to determine depth of dose prescription

Humeral head shielding

• A hot spot caused by divergence of the tangential & the SCF field at the junction

• This may result in severe match line fibrosis or even rib fracture.

• There are numerous methods to adjust for divergence

• The divergence of fields can be eliminated byangling the foot of the treatment couch away from the radiation Collimator rotationHanging blockHalf beam block

Matching SCF & chest wall fields

Angulation: angling the foot of the treatment couch away from the radiation source direct the tangential beams inferiorly so that the superior edges of these beams line up perfectly with the inferior border of the supraclavicular field

Half beam block technique: Blocking the supraclav field’s inferior half, eliminating its divergence inferiorly .

Hanging block technique: Superior edge of tangential beam made

vertical by vertical hanging block.

Matching SCF & chest wall fields

Monoisocentric matching technique.

Single isocenter is set at the match between the supraclavicular and tangential fields.

inferior portion of the beam is blocked for SCF treatment & superior blocked for tangential field, with no movement of the isocenter

Blocks are drawn as indicated to shield lung and heart.

The field should be viewed clinically to ensure that the blocks drawn not block target tissue on the breast–chest wall.

AXILLARY L.N IRRADIATION

High risk with no dissection Sentinel lymph node positive with no dissection Inadequate axillary dissection Node positive with extensive extra capsular extension 1-3 positive nodes with unfavorable histology

Indications of RT to axilla

Perez & Brady's Principles and Practice of Radiation Oncology, chapter 56, p1091

Level I & portion of level II nodes included in tangential field; level III nodes are covered in SCF field

Modifications in the tangential & axillary field can be done for better coverage of axillary nodes

Depending on the dose distribution and patient’s anatomy, a posterior axillary boost may be considered

MODIFICATION IN TANGENTIAL FIELD: HIGH TANGENT

Field border:Cranial edge:2 cm below humeral headDeep edge: 2 cm lung from chest wall interfaceCovers 80% of level I/II node

• Usually the lateral border of SCF field is just medial to the humeral head

• when the axilla is treated supraclavicular field is extended laterally

to cover at least two-thirds of the humeral head,Insertion of deltoid or up to surgical head of humerus

MODIFICATION IN SCF FIELD

POSTERIOR AXILLARY BOOST

• Field border• Medial border – allow 1.5-2cm of lung on

portal film• Inferior border – inferior border of s.c field• Lateral border – just blocks fall off post

axillary fold• Superior border – splits the clavicle• Superolaterally – shields or splits humeral

head• Centre – at acromial process of scapula

• The posterior axillary boost has been employed to supplement axillary dose.

• At the end of the treatments to SCF field, the dose to the midplane of the axilla may be supplemented by a posterior axillary field

• When indicated, a boost of 10 to 15 Gy is delivered with reduced portals

INTERNAL MAMMARY NODAL IRRADIATION

Indications of RT to Internal Mammary nodes

• Positive axillary lymph nodes with central & medial lesions• Stage III breast cancer• Positive sentinel lymph nodes in IM chain• Positive SLN in axilla with drainage to IM on lymphoscintigraphy

Perez & Brady's Principles and Practice of Radiation Oncology, chapter 56, p1091

IMC field• Several techniques used• wide or deep tangents:• direct anterior field matched to tangential fields

wide tangential fields• The nodes in the first three intercostal spaces are thought to be

most clinically significant.

• The medial border of the tangential field is moved 3 to 5 cm across the midline to cover the internal mammary nodes in the first three intercostal spaces

• To minimize lung and cardiac exposure, block can be used

More normal tissue is being irradaited. (lung, heart and contralateral breast Field matching not required

Wide tangential fields

SEPARATE IMC FIELD4 field technique

• Anterior field

Medial border – midline Lateral border – 5-6cm from midlineSuperior border – inferior border of SCF -lower border of clavicleInferior border – at xiphoid or higher if 1st three ICS coveredDepth:4-5 cm

Issues with direct anterior field (large breasted women)When an internal mammary field is required, the match between it and the medial tangential field can be a problem if there is a significant amount of breast tissue beneath the match line.

Diagrams showing several relationships between internal mammary and tangential fields. A: cold region exists if internal mammary (IM)- tangential matchline overlies large amount of breast tissue. B: The cold area may be negligible if the breast tissue beneath the matchline is thin. C:  it can be avoided by including the internal mammary nodes in the tangential field. but can result in irradiation of an excessive volume of lung

oblique incidence of IMC portal match the orientation of the adjacent medial tangential portal; this results in a more homogeneous dose distribution at the junction of the two fields

FIGURE:A: An obliquely incident electron beam matched to the usual tangential beams.

 B: Isodose presentation of optimal matching of an obliquely incident electron beam to the tangential beams.The target volume is enclosed by the 90% isodose line Electron beam 16 MeV; photon beam, 6 MV..

OBLIQUE IMC FIELDS

• Photon-Electron Combination:• To spare underlying lung, mediastinum,

and spinal cord, electrons in the range of 12 to 16 MeV are preferred for a portion of the treatment,

• for example 14.4 to 16.2Gy delivered with 6MV photons and 30.6 to 32.4 Gy with electrons

two medial electron fields were angled 15 degrees toward a matched pair of photon fields.

energy of upper electron field is higher than that of the lower electron field in order to achieve coverage of the contoured internal mammary target while minimizing the dose to the heart

Skin surface rendering of the fields. Lower axial image in region of heart.Upper axial image.

: Electron -Electron Combination IMC field in PMRT

Images of radiation treatment fields to treat the chest wall and IMC

Junctional electron field techniqueparticularly of benefit for patients with very little tissue between the lung and skinuse three electron fields. These fields are then match to a supraclavicular/axillary apex field

 Three medial electron fields are matched on the skin. The junction between the middle and lateral fields is shifted weekly due to the differences in gantry angle. A: Skin surface rendering of the fields. B: Axial image of the fields

Boost to Tumor Site after WBRT in BCS • Rationale : Local recurrences tend to be primarily in and around the primary

tumor site – boost risk of marginal recurrence. • More advantageous when margins unknown & young women less than 40

yrs but benefit seen in all age gp• Given by either EBRT or Brachytherapy• EBRT : Photon, Electrons • Brachytherapy• ISBT : Rigid / Catheter• IC Lumpectomy cavity : Mammosite etc

Localization of lumpectomy cavityVarious techniques of localizing the tumour bed

include: CT scan MRI USG pre op MMG Surgical scar/ pT size

Localization of lumpectomy cavityThe combination of surgical clips with a treatment planning CT is most ideal.

In the absence of surgical clips, CT scan of biopsy cavity or postsurgical changes, in combination with clinical information including mammography, scar location, operative reports, and patient input, provide accurate information regarding placement of the field and energy of the electron boost.

•lumpectomy cavity + a margin of 2 cm in all directions = approximate size of boost field.

•The margins of this field are marked on the skin with the centre of the scar as the centre of field

Boost-electrons• the accelerator head point straight down onto the target volume• Electron energy selected –• 90% isodose should cover tumor bed.(usual range is 9 to 16 MeV electrons).• the approximate energy of electron required to reach a depth of x cm will be

(4*x) MeV.

• Dose – 10-20Gy @ 2Gy/#

• electron beam boost preferred because of• its relative ease in setup, • outpatient setting, • lower cost, • decreased time demands on the physician, • excellent results compared with 192Ir implants

Boost photon • mini tangential fields used to boost target volume

Interstitial boost:• 1 or 2 planes of needles are usually needed

to cover the PTV depending upon size

• Needles are implanted parallel and equidistance from each other (Paris system).

• In most cases inserted in a mediolateral direction. • In very medially or laterally located tumor sites, needles should be implanted in a

craniocaudal direction .to enable separate target area from skin points. • In some rare cases, the upper outer quadrant has to be implanted with needles

orientated in a 45° angle to avoid overlap of source positions and skin

beam matching can be difficultDosimetry performed only on in the midplane of the target volume.Dose distribution can be inhomogenous away from the central axis (superoinferiorly), especially in large breasts.Doses to the OARs (Heart and lung) cannot be determined accurately. Shielding of heart while treating the left breast, won’t ensure whether a part of the target volume is being missed.

DISADVANTAGES OF 2D PLANNING

Three-Dimensional Conformal Radiation Therapy

• Standard opposed tangential fields with appropriate use of wedges to optimize dose homogeneity remains the most commonly employed method for delivery of whole-breast irradiation

• 3DCRT may improve dose to target volume & reduction in dose to normal tissues & critical organs

• Better cosmetic results• Less dose to heart and lung

3-Dimensional planning• Simulation• Plain CT scan of 5mm

slice thickness is taken from the neck to just below diaphragm.

• Contouring

• Field set up

Breast contouring guidelines for conformal CT based planning

• The RTOG has come up with a Breast Cancer Atlas.

LABC: after NACT & BCS

after mastectomy

after BCS

Breast-superior Breast-inferior

Breast CTV after lumpectomy

Chest wall CTV after MRM

Regional nodal contouring

SCF begins SCF ends

SCF LEVEL III

LEVEL II

LEVEL I

IMC node

Lumpectomy GTV: Surgical cavity from lumpectomy. Contour using all available clinical and radiographic information including the cavity volume, lumpectomy scar, seroma and surgical clips

Lumpectomy CTV: GTV +1 cm margin 3D expansion Lumpectomy PTV: CTV+ 7 mm 3D expansion exclude heart

Lumpectomy PTV eval :

Breast CTV: Includes all palpable breast tissue. Takes into account clinical borders at the time of CT simulation. Limited anteriorly within 5 mm from skin & posteriorly to the anterior surface of the chest wall

Breast PTV: Breast CTV + 7 mm expansion–Used for beam aperture generation Breast PTV-EVAL: Clipped 5 mm into skin anteriorly and no deeper than the anterior surface of the ribs

posteriorly (excludes bony thorax and lung)–Used for DVH analysis

Role of IMRT in breast radiotherapy

IMRT Breast:• Dosimetric advantages:

(1) better dose homogeneity for whole breast RT(2) better coverage of tumor cavity(3) feasibility of SIB(4) Decrease dose to the critical organs(5) Left sided tumors- decrease heart dose

Disadvantages:may increase the volume of tissue exposed to lower doses of radiation. may increase the risk of second malignancies

• Reduces the hotspots specially in the superior and inframammary portions of the breast.

Increases homogenity

Manifests clinically into decrease in moist desqumation in these areas.

INVERSE PLANNINGInverse planning is a technique using a computer program to automatically achieve a treatment plan which has an optimal merit. target doses & OAR constraints are setThen, an optimisation program is run to find the treatment plan which best matches all the input criteria.

IMRT PLANNING: forward vs inverse

Forward planning IMRT: field within field

• Advancement to conventional 3DCRT• In this technique a pair of conventional open tangential fields is produced first • MLCs are used to shape the fields & spare OARs• Wedge angle & relative weight of beams optimized to produce plan• To ovoid hotspots and large doses to OAR & to obtain a homogenous dose distribution

(range 95-107%) the dose delivered with open fields is reduced to 90-93% of total dose• new tangential beam with same gantry & wedge angles are designed for remaining dose• The new reduced field are shaped to exclude areas receiving more than 105% of dose.• The other approach is to delineate regions of non uniform dose by contouring isodose

lines

Forward planned IMRT (field-in-field) is preferred• Breast dosimetry can be significantly improved• Better cosmetic outcomes• simple method• Less MU• Less scatter• Decreased planning time• Decreased treatment time

Forward plan IMRT

ACCELERATED PARTIAL BREAST IRRADIATION

PARRIAL BREAST IRRADIATION: The target

volume irradiated is only the post lumpectomy tumor bed

with 1-2cm margin around

ACCELERATED DOSE DELIVERY: the dose is

delivered in a shorter interval than the standard 5 – 6 weeks

Treatments delivered twice daily (with treatments separated

by six hours) for 10 treatments delivered in 5 treatment days.

RATIONALE OF APBI

(1) Most breast cancer recurrences occur in the index quadrant: higher dose of RT can be given than by conventional RT

(2) Many patients cannot come for prolonged 5-6 week adjuvant radiotherapy for logistic reasons:

reduces overall treatment period considerablyPatient convenience may increase acceptance of radiation treatment after breast-

conservation surgery

INDICATIONS OF APBI:ASTRO APBI CONSENSUS STATEMENT

APBI: modalities

HDR interstitial brachytherapyIntracavitary brachytherapy :Mammosite3DCRT/IMRTIntra-operative electrons (ELIOT) or orthovoltage X rays (TARGIT)

Accelerated Partial Breast Irradiation

Benefits:Larger dose can be delivered to small areaLimited radiation exposure to normal tissueTreatments completed in one week instead of six weeks

Limitations:May require additional surgical procedure Requires twice daily treatmentNewer modality with far fewer patients treated and much shorter follow-up

APBI: Interstitial Brachytherapy

Target should be small (less than 2 cm size with 2 mm margins & at least 7mm. of tissue between the catheter surface and the skin)

multiple catheters are generally positioned at 1- to 1.5-cm intervals, total number and planes dependent on the size, extent, and shape of the target.

Post BCS the catheters are implanted immediately or after 2 – 3 weeks in the lumpectomy site

Simulation is done with CT imaging and transferred to the TPS

Loading of source, position and dose distribution is decided in the TPS

Dose – 34 Gy in 10 # , 3.4 Gy per # / two # per day / 5 days.

catheter with expandable balloon at end Balloon filled with saline mixed with contrast for verify positioning expands to fill the lumpectomy cavity Radiation dose prescribed to 1 cm beyond balloon surface Prescription:34 Gy in 10 fractions over 5 -7days Advantage: simple, minimally invasive, offers acceptable cosmetic results, and induces mild side effects Disadvantages: Balloon must conform to cavity shape without air gaps.Ideal is to have 7 mm b/w balloon and

skin to decrease risk of erythema.Very dependent on surgical placement

MammoSite PBI

Four-field beam arrangement and conformal, homogeneous dose coverage of the target.

This APBI technique with conformal EBRT is attractive to both physician and patient alike because it is (1) noninvasive, (2) delivers a homogeneous dose with decreased procedural trauma to the breast(3) offers a potential reduction in normal breast tissue toxicity

APBI:3DCRT

Intraoperative Radiation Therapy (IORT) for PBI

• TARGIT trial is comparing whole breast irradiation to IORT delivering a single dose of 20 Gy..

• Using the Intrabeam Photon Radiosurgery System, 50 kV xrays

• Intraoperative electrons can also be used with mobile linear accelerators & cylindrical applicators for electron beam collimation

TARGIT

ELIOT

Partial breast irradiation techniquesInterstitialBrachyther.

IntracavitaryBrachyther

Intraop.RT

3DConformal RT

Dose 34 Gy in 10 frIn 5 days

34Gy in 10 frIn 5 days

20-21Gy in single fraction

38.5 Gy in 5 fr. In 10 days

Target 1.5 cm margin around WLE cavity

1cm aroundWLE cavity

Visual by surgeon and rad oncologist perop

2.5cm margin around WLE cavity

Pros Many dwell positions for Irreg. cavity

Ease of placement and planning

Single doseSpares skin

Fits with standard RTmachines

Cons Operatordependent

High costFewer dwellpositions

RT before pathology knownSpecialised centres only

Larger fields(respiration) and more normal tissue

Sequelae of irradiation in breast cancer• Lymphedema and Breast Edema• Skin and Breast Complications• Brachial Plexopathy• Pulmonary Sequelae• Cardiac Sequelae• Contralateral Breast Cancer and Irradiation• Incidence of Other Second Malignancies• Post irradiation Angiosarcoma of the Breast

Skin toxicities

• Erythema / Hyperpigmentation (after 20-26Gy total dose at 2Gy/#)• Dry desquamation till the basal layers can just replace the normal cell

turnover• Moist desquamation (first patchy and then confluent) later especially

in the regions of folds/ large breasts/ hotspots.• Hemorrhage, ulceration• Significantly less with modern radiotherapy• Treated symptomatically: good aeration, avoid friction, wear loose

fitting cotton clothes

Arm Lymphedema

• risk of arm edema increases with axillary dissection and RT• Sentinel node sampling has much lower degree of lymphedema• The ALMANAC randomized trial also confirms lower morbidity and

improved quality of life following sentinel node biopsy compared with axillary dissection.

• Associated with swelling,weakness, limitation in range of movement, stiffness pain & numbness 

Treatment of lymphedema

• it is mandatory to differentiate between treatment-associated complications and tumor recurrence in regional lymphatics

• Various treatment regimens have been used to treat lymphedema.• The compression pump, along with skin care, exercise, and

compression garments, • complex decongestive physiotherapy or complex physical therapy.:

Arm care, therapeutic exercises, manual lymph node drainage, and compression bandages or garments comprise this treatment regime..

Breast Complications

Includes• Breast edema – due to lymphatic obstruction.• Persistent breast edema- chronic disruption of lymphatics.• Subcutaneous fibrosis and telangiectasias – d/t late effects of dermal

fibrocytes and vessels• Increased breast stiffness seen with doses more than 1.8-2 Gy &

concurrent use of tamoxifen• Affects cosmesis the most.

Brachial plexopathyIncidence:1-2%possible complication of regional nodal radiation therapypain, loss of sensation, muscle weakness ,paralysis muscles of the shoulder and upper

limbRisk factors includes axillary dose was >50 Gy concomitant chemotherapy

important to distinguish between metastatic and radiation-induced brachial plexopathy.

Treatment for radiation brachial plexopathy consists of transdermal electrical nerve stimulation, dorsal column stimulators, Physical therapy, tricyclics, antiarrhythmics, anticonvulsives, nonsteroidal anti-inflammatory drugs, and steroids

Pulmonary sequalae• Rate of symptomatic pneumonitis 1-2% after WBRT• Patients present with dry cough, shortness of breath, rales, pleuritic chest pain or fever and on radiographic

studies a pulmonary infiltrate is observed in the irradiated volume.

• Responds well to steroids

• The risk for development of radiation pneumonitis related to age>60 yrs previous lung dsRT dose, fractionationvolume of lung irradiated.regional nodal radiation therapyConcurrent chemo (taxanes) or hormonal therapy

• Apical pulmonary fibrosis is noted when the regional lymph nodes are irradiated.• Rib fracture also seen in some cases

Cardiac sequalae• may be acute or chronic • Pericarditis is acute transient but may be chronic• Late injury includes CHF ,ischemia, CAD,MI• risk of cardiac toxicity greater inleft-sided breast cancerspatients receiving other cardiotoxic therapies, including adriamycin, epirubicin, and

trastuzumab.Old RT techniquesIMC irradiation

• Although clinical evidence of cardiac morbidity has decreased with modern techniques, care should be taken to exclude heart from the tangential radiation field

Contralateral Breast Cancer• Although all patients with a diagnosis of breast cancer are at increased risk for

developing a contralateral breast cancer, the additional risk contributed by radiation treatment appears to be minimal, with modern techniques

• EBCTCG 2005 overview analysis does suggest an elevated incidence of contralateral breast cancer in patients receiving radiation compared with those who did not receive radiation.RR=1.18 (p=.002).

• Although the excess risk appears to be driven primarily by older trials using antiquated techniques, these data highlight the need to maintain dose to the contralateral breast as low as possible.

EBCTCG Lancet 2005; 366: 2087-2106 148

Effect of radiotherapy on contralateral breast cancer incidence and on non-breast-cancer mortality (46 trials of adding radiotherapy, and 17 trials of radiotherapy vs more surgery) (29 623 women)

Incidence of Other Second Malignancies• Although more prevalent with older techniques, it is an important component

of treatment planning to minimize dose to nontarget normal tissues.• EBCTCG overview analysis did demonstrate an excess risk of secondary

cancers of the lung and esophagus as well as leukemia and sarcoma in all randomized trials of breast cancer that compared patients treated with and without radiation.

• The total relative risk for all secondary nonbreast malignancies was 1.20 (± 0.06; P = .001).

• Although the increased risk of secondary malignancies may be driven primarily by trials using older techniques, they highlight the importance of limiting dose to nontarget tissues.

Post irradiation Angiosarcoma of the Breast

rare but severe long-term complication of pts. treated with radiotherapydevelopment has been linked to radiotherapy and lymphedema.Special attention should be paid to uncommon skin changes of the treated breast The primary therapy is simple mastectomy if wide tumor-free margins can be achieved.

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