Two-year outcomes of RTOG 0529: A phase II evaluation of dose-painted IMRT in combination with 5-fluorouracil and mitomycin-C for the reduction of acute morbidity in carcinoma of the anal canal.

Abstract

368 Background: 5-Fluorouracil (5FU) and mitomycin-C (MMC) chemoradiation for anal cancer is associated with high rates of acute morbidity. We have previously shown that dose-painted IMRT (DP-IMRT) significantly reduces grade 3+ GI and dermatologic acute toxicity, as compared to the RTOG 9811 5FU/MMC arm, which used non-conformal radiation techniques. We now report on the two-year outcomes of this DP-IMRT approach. Methods: T2-4N0-3M0 anal canal cancers received 5FU (1,000 mg/m2/day 96 hour infusion) and MMC (10 mg/m2 bolus) days 1 and 29 of DP-IMRT prescribed as follows - T2N0: 42 Gy elective nodal and 50.4 Gy anal tumor planning target volumes (PTVs), 28 fractions; T3-4N0-3: 45 Gy elective nodal, 50.4 Gy ≤ 3 cm and 54 Gy > 3 cm metastatic nodal and 54 Gy anal tumor PTVs, 30 fractions. The following two-year outcomes were assessed: local-regional (LRF) and colostomy failures (CF) using the cumulative incidence method, and disease-free (DFS), overall (OS) and colostomy-free survivals (CFS) using the Kaplan-Meier method. Results: Of 63 accrued patients, 52 were analyzable. Median age was 58 years; 81% female; 54% stage II; 25% IIIA; 21% IIIB. Median follow-up was 23.2 months (0.2-33). Two-year LRF, CF, DFS and 95% confidence intervals are 20% (9%, 31%), 8% (0.4%, 15%) and 77% (62%, 86%), respectively. The causes of death for the 7 patients that died are: anal cancer in 5, morbidity in one and second primary outside the radiation field in one. Two-year comparison data from the RTOG 9811 5FU/MMC arm are shown in the table below. Conclusions: DP-IMRT with 5FU/MMC for the treatment of anal canal cancer yields similar two-year outcomes as the RTOG 9811 conventional radiation, 5FU/MMC arm. Because of the associated acute toxicity sparing, DP-IMRT will be used as the platform, and may allow for radiation dose escalation, in future RTOG anal canal trials. Supported by RTOG U10 CA21661, CCOP U10 CA3742 and ATC U24 CA 81647 NCI grants. [Table: see text] No significant financial relationships to disclose.