TREATMENT OF COLON CARCINOMASHASWATA SAHA10.03.2017 MALDA MEDICAL COLLEGE

Objectives •Removal of the primary cancer with adequate margins •Regional lymphadenectomy •Restoration of the continuity of the GI tract by anastomosis•En block removal of adjacent organ if involved

THE EXTENT OF RESECTION IS DETERMINED BY •location of the cancer

•its blood supply and draining lymphatic system

•presence or absence of direct extension into adjacent organs

So a detailed knowledge of blood supply and lymphatic drainage is important for the surgery.

BLOOD SUPPLY OF THE COLONThe colic branches of the superior mesentric artery i.e. iliocolic right colic and middle colic artery and The inferior mesentric artery i.e left colic and sigmoidal branches supply the colon .

They anastomoses circumferentially from iliocoecal junction to rectosigmoidal junction and located close to inner margin of colon (within 3cm ) and called the marginal arcade or artery of Drummond.

LYMPHATIC DRAINAGE FOLLOWS THE ARTERIAL SUPPLYThe Colic lymph node are distributed in following four groups

1.Epicolic nodes : lie on the wall of the colon.

2.Paracolic nodes : lie very close to the marginal artery (of Drummond)

3.Intermediate colic nodes :lie along the ileocolic, right colic, middle colic and left colic, arteries, and drain into terminal nodes.

4.Preterminal nodes : lie along trunks of superior and inferior mesenteric arteries.

PREOPERATIVE WORKUP AND PLANNING

For elective Surgery preoperative workup is to be done depending upon the patients comorbidities.The additional workup in preoperative period to be done are Nutritional status evaluation Preoperative bowel preparation Thromboembolic prophylaxis Catheterization Optional nasogastric tube Preoperative epidural anaesthesia

NUTRITIONAL STATUS EVALUATIONTwo parameters to be checked for are Serum albumin indicates long term

nutrition(21 days) Serum prealbumin indicates short

term nutrition(3-5 days)

They are important as –A low prealbumin (<3.5g/dl ) is a risk

factor for anastomoses leak.They assessment determines the

patients who would be benefitted by the parenteral nutrition postoperatively.

Preoperative Bowel Preparation

Purging the foecal matter Administration of antibiotics

• Previously it was thought to reduce chances of post operative infectionand anastomoses leakage.

• But as the colonocytes get the nutrition from free fatty acids produced by fermentation of lipids by commensal bacteria (109 /ml)

• Nowadays the purging though done in practice the advantages are debatable.

•To prevent surgical site infection the role of antibiotics has been proven through randomized controlled trials.

•It is given as prophylactic doses 30 minutes before surgery and if surgery is proloned it should be given in 4 hourly doses.

•Postoperative antibiotics are not advisable as they increase chances of Clostridium difficile colitis , candida infection, bacterial resistance.

Period

Agents used Adverse effects

Before 1980 Bisacodyl , castor oil,

senna with whole bowel nasogastric irrigation +mannitol irrigation +repeated enemas

Dehydration Electrolyte imbalanceSevere abdominal crampsLow tolerance

1980 Polythene glycol

+ large volume of fluid infusion(used in case of renal insufficiency , liver diseases , CHF)

Abdominal cramps

Nausea

vomiting

1990 Oral Sodium Phosphate Impaired renal functionHypernatrimiaHyperphosphatemiaHypokalemiaHypocalcemia

Mechanical Preparation agents

ANTIBIOTICSRegimens used preoperatively are 1. Single antibiotics (IV Etrapenem / Piperacillin

/tazobactam)

2. Combination of 2nd /3rd generation cephalosporin + Metronidazole

3. Combination of Fluoroquinolone +Metronidazole + Clindamycin

4. Triple combinations of Amoxicillin- clavulinic acid + Metronidzole + Aminoglycosides

Thromboembolic prophylaxis is given by Subcuteneous or IV Low

Molecular weight heparin and/or with intermittent pneumatic calf stockings to prevent chances of

a. Deep vein thrombosis b. Pulmonary embolism

LMWH is given from 2 hours before surgery until patient achieve full ambulation post operatively.

GENERAL TECHNICAL PRINCIPALS

The length of bowel and mesentery resected is dictated by tumor location and distribution of the primary artery but a radical resection of a colonic tumor should achieve at least a 5-cm clearance at the proximal and distal margin also.

Right hemicolectomy is done

For lesions in Cecum , Ascending colon , or proximal 1/3 of Transverse colon

This involves removal of the from 4 to 6 cm proximal to the ileocecal valve to theportion of the transverse colon supplied by the right branch of the middle colic artery .

An anastomosis is fashioned between the terminal ileum and transverse colon.

An extended right hemicolectomy

is the procedure of choice for most transverse colon lesions

This involves division of the right and middle colic arteries at their origin, with removal of the right and transverse colon supplied by these vessels. The anastomosis is fashioned between the terminal ileum and proximal left colon.

Post-Operative Management

Adjuvant Chemotherapy Monitoring

ADJUVANT CHEMOTHERAPYIn post operative period can be administered

by following regimens

•5-Fluorouracil (5-FU) and Leucovorin(LV) in Mayo-clinic , Rosewell park, De gramont regimens with toxicity causing myelosuppression and GI side effects

• Oral Fluoropyrimidine therapy can be given using 2 prodrug Capecitabine and Uracil/Tegafur with less side effects than 5-FU/LV regimen with more or less same efficacy

•Though most widely Used Regimen is modified FOLFOX 6 using 5-FU/LV with Oxaliplatin

FOR STAGE I DISEASE

After operation proper1. Colonoscopic

examination should be done annually and if any polyp is found it is removed. Then Examination can be done 5 yearly. If familial association is present colonoscopy should be more frequently done.

2. CEA level is assesed 3 monthly in first 2 years. If value is high MRI or PET scan is done for detection of metastasis.

For Stage II disease

After operation properAdjuvant chemotherapy with 5-Fluorouracil & Leucovorin regimen is advised in stage 2 diseaseif associated with any of the poor prognostic factors like

a. T4 lesions b. Insufficient lymph node

samplingc. Poorly differentiated lesionsd. Bowel perforation

These should be associated with CEA level assesment 3 monthly for 2 year and 6 monthly for 5 years

And annual CT scan.

FOR STAGE III OR IV DISEASE•Adjuvent chemotherapy is advised with both 5-FU +Leucovorin regimen and Oxaliplatin .

•If associated with metastasis asymptomatic cases should be treated with Adjuvant chemotherapy without delay in post operative period

•And if associated with symptomatic involvement of lung or hepatic segment the segment is amenable to resection

•Monoclonal antibodies like Bevacizumab , Cetuximab, Panitimumab can be added with 5-FU Oxaipaltin regimen.

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