Prognostic factors of colostomy free survival in patients presenting with locally advanced anal canal carcinoma: A pooled analysis of two prospective trials (KANAL 2 and ACCORD 03)

Abstract

BackgroundTo carry out a prognosis study of the prospective studies KANAL 2 and ACCORD 03 in order to highlight new prognostic factors of colostomy-free survival in patients with locally advanced anal canal carcinoma. Patients and methodsKANAL 2 and ACCORD 03 were phase 2 and phase 3 multicenter trials with same inclusion criteria: anal canal squamous cell carcinoma of ≥4 cm or pelvic node involvement treated with conformal radiotherapy (45 Gy/25 fractions plus a boost) and concomitant fluorouracyl and cisplatin at weeks 1 and 5. A multivariate analysis of potential factors (patients, tumors, and treatments) was carried out through Cox proportional hazard model. Results were presented as hazard ratio (HR). Results387 patients were included. In multivariate analysis, age over 55 years (HR = 0.62, p = 0.013), the increase of circumferential tumor spread (between 1/3 and 2/3 and more than 2/3 compared to less than 1/3) (respectively 1.97, p = 0.015 and 2.94, p < 0.001), the skin ulceration (1.57, p = 0.03), the inguinal node involvement (1,98, p < 0.001) and the total radiotherapy dose above 60 Gy (between 60 and 65 Gy (HR = 0.37, p < 0.001) and >65 Gy (HR = 0.61, p = 0.028)) were associated with colostomy-free survival. ConclusionOur study highlights new favorable prognostic factors such as circumferential tumor damage of less than two thirds, age over 55 years, dose escalation boost irradiation and possibly a total radiation dose between 60 and 65 Gy (but the BED dose depends on the overall treatment time). These results could be considered for better selection or stratification of the target population in future trials.