Predictive factors of early and late local toxicities in anal cancer treated by radiotherapy in combination with or without chemotherapy.

Abstract

667 Background: Treatment of anal cancer is based on combined radiotherapy and chemotherapy (CT). Some patients present early (<2 months) and late (>2 months) toxicities of grade 3 or greater which can strongly impair quality of life. We aimed to identify predictive factors of toxicities in 106 patients treated in a single center between January 2000 and February 2010. Methods: Retrospective analysis of our databases reported severe local toxicities (grade 3 or higher) during treatment of proven localized epidermoid carcinoma of the anal cancer. The following factors were screened as potential predictive factors: gender, age, irradiation dose, HIV status, type of boost (external vs brachytherapy), circumferential extension, type of chemotherapy, invasion of anal margin, clinical T and N stage, and clinical stage. Results: With a median follow-up of 54.1 months (46.8-61.4) early severe local toxicities occurred in 42 patients (pts) (39.6%) whereas late severe toxicities happened in 21 pts (19.8%). Both early and late toxicities were dominated by proctitis (diarrhea and/or rectal bleeding) (7 pts, 6.6% and 6 pts, 5.6% respectively) and recto-anal epithelial toxicities (27 pts, 25.4% and 17 pts, 16% respectively). Two patients got colostomia because of treatment toxicities (1,8%). Predictive factors of increased early toxicities were as follows: clinical stage III/IV (p=0.04), no brachytherapy boost (p=0.008) and type of CT (no CT, 5.9%, CT, 48.8% p=0.001). Brachytherapy boost and presence of CT retained their independency in multivariate analysis (respectively, p=0.001 and p=0.05). Only HIV positivity (p=0.02) was identified as a predictive factor of late toxicities. HIV positivity (p=0.02), invasion of anal margin (p=0.01) and circumferential extension > 33% (p=0.007) correlated with epithelial ulcer. Invasion of anal margin (p<0.001) and circumferential extension (p=0.02) were identified as independent factors in multivariate analysis. Conclusions: In this cohort absence of brachytherapy boost and CT correlated with more severe early local toxicities whereas HIV positivity was the only predictor of local late toxicities.