Compliance to chemoradiation (CRT) using mitomycin (MMC) or cisplatin (CisP), with or without maintenance 5FU/CisP chemotherapy (CT) in squamous cell carcinoma of the anus (SCCA) according to radiotherapy (RT) dose, overall treatment time (OTT) and chemotherapy (CT) and their impact on long-term outcome: Results of ACT II.

3518 Background: Concurrent CRT is standard treatment for patients with SCCA. We explored CRT compliance in ACT II, which compared 5FU/CisP with 5FU/MMC (wks 1 & 5) of a uniform RT dose (50.4Gy, 28 daily fractions (F) of 1.8Gy). Methods: We investigated the association between poor compliance and baseline factors (age, sex, site, T & N stage), type of CT (MMC/CisP) with progression free survival (PFS). Compliance was categorized as follows: RT, 5 groups: A = per protocol (50.4Gy in 28F in 38-42 days), B = ≤ 40Gy, C = 40-48.6Gy in 23-27F, D = 50.4Gy in > 42 days, E > 52.2Gy. CT, 2 groups: 1 = wks1 & 5 & 2 = wk1 only. Results: 933 and 862 of 940 pts were evaluable for RT & CT compliance respectively. Median follow-up was 5.1 yrs. Baseline characteristics of evaluable patients were similar to all 940 ACT II patients. Canal tumors, CisP, GFR<60 & WBC < 11 were borderline significant predictors of poor wk5 CT compliance (p 0.09, 0.07, 0.06 & 0.08 respectively). Poor CT compliance at wk5 impacted significantly ...