60 Pre-Treatment Nomogram for Grade > 2 Acute GI Toxicity (RTOG/EORTC) for Prostate Cancer 3DCRT

R. Valdagni1, T. Rancati1, C. Fiorino2, P. Franzone3, F. Mauro4, F. Munoz5, E. Cagna6, G. Fellin7, C. Greco8,V. Vavassori9

1Istituto Nazionale per lo Studio e la Ricerca sui Tumori, Italy, 2Ospedale San Raffaele, Milan, Italy, 3Ospedale diAlessandria, Alessandria, Italy, 4Ospedale Villa Maria Cecilia, Lugo, Italy, 5Institute for Cancer Research and Treatment,Candiolo, Italy, 6Ospedale S. Anna, Como, Italy, 7Ospedale S. Chiara, Trento, Italy, 8REM Radioterapia, Catania, Italy,9Ospedale di Circolo, Varese, Italy

Purpose/Objective(s): To develop a nomogram to predict grade� 2 acute GI toxicity (tox) (RTOG/EORTC) following prostatecancer CRT.

Materials/Methods: Between July 2002 and March 2004, 1132 patients (pts) entered a prospective cooperative study on rectaltox in 3DCRT for prostate cancer (AIROPROS01-02). All pts were treated with doses � 70Gy (ICRU dose: median 74Gy;range: 70-81.6Gy) at 1.8-2Gy/fr. All pts received a questionnaire before treatment and at its end to monitor the rectal symptomprofile and to question drug prescription during and just after the end of therapy. Acute rectal tox was scored followingRTOG/EORTC scale and by considering the changes (after-before treatment) of the questionnaire scores. In the present workonly grade 2 and 3 tox were considered. The correlation between mean and maximum rectal doses, ICRU dose, pre-treatmentmorbidities, hormonal therapy, drug prescription, presence of diabetes or hypertension, pelvic node irradiation and rectaltoxicity was assessed by univariate and multivariate (MVA) logistic analyses. Based on MVA a nomogram to predict grade �2 acute tox was created (using the R-project software).

Results: Pts with grade 2 and 3 tox were 265 and 28, respectively. Mean rectal dose was the most predictive variable in MVA(p�0.0004, OR�1.03). Haemorrhoids (p�0.06, OR�1.33), diabetes (p�0.08, OR�1.25) and pelvic node irradiation (p�0.06,OR�1.67) were significant variables to adjust tox prediction. The use of anticoagulants/antiaggregants was found to beprotective (p�0.002, OR�0.62). The nomogram, developed considering as risk factors the use of anticoagulants/antiag-gregants, diabetes, haemorrhoids, pelvic node irradiation and mean rectal dose, is presented in the figure.

Conclusions: Using MVA, a nomogram to predict grade� 2 acute tox (RTOG/EORTC) following prostate cancer CRT wasdeveloped. The prediction capability of this tool, which represents the first nomogram for acute tox available in the literature,will be soon studied and validated on a independent set of pts.

The AIROPROS01-02 trial is partially supported by a grant from Fondazione Italo Monzino.

Author Disclosure: R. Valdagni, None; T. Rancati, None; C. Fiorino, None; P. Franzone, None; F. Mauro, None; F. Munoz,None; E. Cagna, None; G. Fellin, None; C. Greco, None; V. Vavassori, None.

61 A Prospective Study of Hypofractionated Radiotherapy for Localized Prostate Cancer

J. M. Martin, A. Bayley, R. Bristow, P. Chung, J. Crook, M. Gospodarowicz, M. Milosevic, M. McLean, P. Warde,C. Catton

Princess Margaret Hospital, Toronto, ON, Canada

Background: Prostate cancer appears to exhibit a more pronounced response to treatment with larger doses per fraction ofradiotherapy (hypofractionation: HypoRT), offering the potential to enhance the therapeutic index.

Purpose/Objective(s): Primary study objectives of this prospective phase 2 trial were to assess HypoRT feasibility and toxicityvia RTOG scoring. A secondary endpoint was biochemical failure.

Materials/Methods: Eligible patients had clinical stage T1c-2cNXM0 disease. They received 60Gy in 20 fractions given overfour weeks using intensity modulated radiotherapy including daily on-line image guidance with intraprostatic fiducial markers.

Results: 92 patients were treated with HypoRT between June 2001 and March 2004. Seven additional patients were excludedbecause they exceeded dose constraints for bladder or rectum. The cohort had a median PSA of 7.06 (range 2-25.4). Themajority had Gleason grade 5-6 (38%) or 7 (59%) disease, and 82 patients had T1c-T2a clinical staging. Overall, 29 patientshad low risk disease, 56 intermediate risk and 7 high risk disease. Severe acute toxicity (grade 3-4) was rare (table). Median

S35Proceedings of the 48th Annual ASTRO Meeting

follow-up is 32 months (range 15-56). For the 88 patients not treated with adjuvant hormones, median PSA nadir was 0.69 aftera median of 22 months. Using the current ASTRO definition for biochemical failure, the rate of biochemical control at 2.5 yearsis 82%. By an alternative definition (absolute nadir plus 2 at call), the corresponding figure is 92% (graph). The incidence oflate toxicity is very low, with no severe (grade 3) toxicity at the time of most recent assessment.

Conclusions: Hypofractionated RT using 60Gy/20f/4 weeks using image guidance is feasible, and is associated with very lowrates of late bladder and rectal toxicity. At early follow-up, biochemical outcome is comparable to published conventionallyfractionated controls. The findings will be tested in a multicentre phase 3 trial comparing 60Gy in 20 fractions with 78Gy in39 fractions.

Author Disclosure: J.M. Martin, None; A. Bayley, None; R. Bristow, None; P. Chung, None; J. Crook, None; M. Gospoda-rowicz, None; M. Milosevic, None; M. McLean, None; P. Warde, None; C. Catton, None.

62 Hypofractionated Stereotactic Radiotherapy, 33.5Gy in Five Fractions, for Low Risk Prostate Cancer;Clinical Results

B. L. Madsen1, R. A. Hsi1, H. T. Pham1, J. F. Fowler2, L. Esagui1, J. Corman1

1Virginia Mason Medical Center, Seattle, WA, 2University of Wisconsin, Madison, WI

Purpose/Objective(s): To evaluate the feasibility and toxicity of hypofractionated stereotactic radiation therapy (SRT) inpatients with low risk prostate cancer.

Materials/Methods: A phase I trial of SRT was undertaken for low risk prostate cancer patients (PSA �10 ng/ml, Gleasonscore � 6, and clinical stage T1c-T2b). Five fractions of 6.7 Gy were delivered over 5 days, calculated to be biologicallyequivalent to 78 Gy in 2 Gy fractions using an �/� ratio of 1.5 Gy. Fused CT and MRI of the prostate with 3-4 mm marginwere used to define the clinical target volume. Treatment was in a flex-prone position with non-coplanar conformal fields anddaily stereotactic localization of implanted fiducials. Genitourinary (GU) and gastrointestinal (GI) toxicity were evaluated byAUA/RTOG toxicity criteria. PSA values and self reported sexual function were recorded at specified follow-up intervals.

Results: Forty patients completed protocol treatment and were available for follow-up assessment. The median follow-up is 41months (range 21 - 67). Acute GU toxicity was grade 0 in 19 patients (49%); grade 1- 2 in 19 patients (48.5%); and grade 3

RTOG toxicity due to hypofractionated prostate radiotherapy

RTOGGrade 0

RTOGGrade 1

RTOGGrade 2

RTOGGrade 3

RTOGGrade 4

Acute (Worst) GI (%) 66 22 11 1 0GU (%) 32 43 25 0 0

Late (at lastassessment) GI (%) 89 9 2 0 0

GU (%) 90 8 2 0 0

80% of patients had no late toxicity at the time of their most recent assessment

S36 I. J. Radiation Oncology ● Biology ● Physics Volume 66, Number 3, Supplement, 2006