P-275 Evaluation of radical chemoradiation outcomes in stage II/III anal cancer: Real-world data population

Abstract

Squamous cell carcinoma of the anus (SCCA) is a rare disease accounting for 1%–2% of digestive tract tumours and 2%–4% of colon, rectal and anal tumours. The annual incidence is 1 in 100 000, is higher in women and is increasing. Five-year survival has changed little in the last two decades. In the United States, the overall 5-year survival rates for 1994–2000 were 60% for men and 78% for women (SEER data). In Europe, 5-year survival varied between 66% (Central Europe) and 44% (Eastern Europe). Combinations of 5-fluorouracil (5-FU)-based radical chemoradiation (CRT) and other cytotoxic agents [mainly mitomycin C (MMC)] have been established as the standard of care, leading to complete tumour regression in 80%–90% of patients, with locoregional failures of ∼15%. Approximately 10%–20% of patients suffer distant relapse. The aim of this study was to evaluate outcomes in stage II/III anal cancer submitted to CRT. A retrospective analysis evaluated stage II-III SCCA pts with PS ECOG 0-1 treated with CRT using fluoropyrimidine and MMC at a single Portuguese Oncology Unit between January 1st 2010 and October 30th 2020. Data cut-off was March 20th 2021. Data were obtained from pts´ clinical files and analysed with SPSSv26.0. Twenty-three pts were selected with a median (med) age of 66 years (y) [30-81], the majority being females (60.9%). Regarding initial staging, 21.7% had stage II, 17.4% stage IIIA, and 60.9% stage IIIB. 39.1% were active smokers; 56.5% were tested for HIV infection, of whom 3 were HIV positive. 78.3% had lymph node disease; 47.8% had tumours > 5 cm in size; 56.5% had ulcerated lesions (skin or endoscopically). Of the 23 pts, 2 (8.7%) were treated with capecitabine (CAP), while the others were treated with infusional 5-FU in addition to MMC. There was an imaging and endoscopic complete response (CR) in 78.3% of the pts (including both pts treated with CAP); 3 of the 5 pts without CR underwent salvage surgery. 13% had locoregional relapse and 4.3% had distant relapse. Med follow-up was 4y; the overall survival at 4y was about 75%, with an estimated med OS 8.09y [6.0-10.2]. In our cohort, CRT was associated with a higher CR rate in concordance with previous evidence. Distant relapse was slightly inferior in our population. Going forward, we will be studying prospective data on the use of CAP vs infusional 5-FU in CRT-treated patients. Given the rarity of this diagnosis and the lack of evidence on this subject, we believe our findings are of extreme importance to share.