SURVIVAL AND PROGNOSTIC FACTORS OF ANAL CANCER: A STUDY BASED ON DATA FROM THE HOSPITAL-BASED CANCER REGISTRY OF A HIGH-COMPLEXITY ONCOLOGY CARE CENTER.

Background: Anal cancer is a relatively rare disease, and there is a lack of survival data from low- and middle-income countries.

Aims: The aim of this study was to investigate the survival rates and prognostic factors of anal cancer cases treated at a High-Complexity Oncology Care Center in Rio de Janeiro, Brazil.

Methods: A retrospective cohort study was conducted involving 665 cases of squamous cell carcinoma of the anus/anal canal treated from 2000 to 2016. To estimate the 5-year overall survival probability and survival according to selected variables, the Kaplan-Meier method and the log-rank test were applied. To identify factors associated with survival, the Cox proportional hazards model, stratified by staging, was used to estimate hazard ratios (HR). Ninety-five percent confidence intervals (95%CI) were also calculated.

Results: The overall survival probability was 62.20% (95%CI 57.90-66.20). Higher survival rates were observed in female cases, those with non-advanced staging, and those treated with chemoradiotherapy (p<0.001). Among cases with advanced staging, being female was a protective factor against death (HR=0.52; 95%CI 0.28-0.93). Compared to chemoradiotherapy, at least one type of treatment was identified as a risk factor: chemoradiotherapy + surgery among cases with non-advanced staging (HR=22.65; 95%CI 5.65-90.81), radiotherapy among cases with advanced staging (HR=2.71; 95%CI 1.39-5.30), and among cases with unknown staging, no treatment (HR=3.36; 95%CI 1.73-6.50), radiotherapy (HR=2.38; 95%CI 1.46-3.88), and radiotherapy + surgery (HR=3.99; 95%CI 1.20-13.27).

Conclusions: The findings support the superiority of chemoradiotherapy over other therapeutic modalities for anal cancer, resulting in increased survival and a better prognosis.