THE IMPACT OF TREATMENT FACTORS ON LOCAL-CONTROL IN T2-T3 ANAL CARCINOMAS TREATED BY RADIOTHERAPY WITH OR WITHOUT CHEMOTHERAPY

BACKGROUND, This study was conducted to investigate the influence of t herapeutic parameters on local control (LC) in the sphincter-conservin g treatment of T2-T3 anal carcinoma. METHODS, From 1976 to 1993, 137 p atients with anal carcinoma classified as T2 (85 patients) or T3 (52 p atients) were treated curatively by radiotherapy (RT) alone (54 patien ts) or by concomitant chemotherapy and RT (83 patients). RT was delive red in two sequences, with a median gap of 46 days between the sequenc es. The first sequence was delivered at a median dose of 39.6 gray (Gy ) using megavoltage photon beams. Boost treatment consisted of either Ir-192 implantation or external beam RT (median dose, 20 Gy). Chemothe rapy started on Day 1 and generally consisted of 1 cycle of mitomycin C (10 mg/m(2)) and a 5-day infusion of 5-fluorouracil (600-800 mg/m(2) /day). For surviving patients, median follow-up was 83 months. Univari ate and multivariate analyses were performed to determine therapeutic parameters affecting LC after adjustment for clinical factors. RESULTS , The 5-year actuarial LC was 76%. Factors associated with poorer LC ( univariate) were as follows: age < 66 years (LC was 67% with the facto r vs. 85% without), male gender (65% vs. 81%), tumor extent > 1/3 cana l circumference (67% vs. 90%), lymph node involvement (64% vs. 81%), u se of external beam boost (62% vs. 79%), and overall treatment time (O TT) greater than or equal to 75 days (69% vs. 85%). In multivariate an alysis, no therapeutic parameters remained significant when adjusted f or significant clinical factors, although OTT was of borderline signif icance (P = 0.09). CONCLUSIONS, The results of this multivariate analy sis suggest that therapeutic factors have a less marked effect on LC c ompared with clinical parameters; the only factor that appeared to hav e some effect was OTT. Efforts to improve LC in patients with poor pro gnoses should concentrate on optimizing OTT and the chemotherapeutic a spects of treatment (in other words, attempts should be made to provid e more effective agents and optimize scheduling). (C) 1997 American Ca ncer Society.