Outcomes following local excision of early anal squamous cell carcinomas of the anal canal and perianal margin.

Aim: There is a paucity of data on outcomes from local excision (LE) of early anal squamous cell carcinomas (ASCCs). This study aimed to assess survival outcomes according to tumour location, perianal (PAT) or anal canal (ACT), and to determine factors associated with R1 excision and outcomes according to T-category.

Methods: This was a retrospective cohort study of consecutive patients with early ASCC treated by LE from 2007 to 2019. Data were collected on baseline demographics, tumour location, staging, excision histology, adjuvant treatment, site and timing of recurrence. The main outcome measures were R1 resection, locoregional recurrence (LRR), disease-free survival and overall survival.

Results: Of 367 patients treated for ASCC, 39 (10.6%) patients with complete follow-up data underwent LE: 15 ACTs and 24 PATs. R1 resections were obtained in 27 patients (69.2%) and occurred more frequently in ACTs than PATs (93.3% vs. 54.2%, P = 0.006). Eighteen of 27 patients (66.7%) received adjuvant therapy (chemoradiotherapy [n = 11], radiotherapy alone [n = 7]) for R1 excision or re-excision, following which LRR developed in one of 10 (10.0%) patients in the ACT cohort and one of eight (12.5%) patients in the PAT cohort. There was no difference in 5-year LRR-free survival (82.0% vs. 70.1%, P = 0.252), disease-free survival (58.2% vs. 78.4%, P = 0.200) or overall survival (86.2% vs. 95.7%, P = 0.607) between the ACT and PAT cohorts.

Conclusions: LE is a feasible treatment option for early ASCCs of the perianal margin but not the anal canal. Acceptable long-term outcomes can still be achieved with adjuvant therapy in the presence of a positive margin. Larger prospective studies to assess LE as a treatment strategy, such as the ACT3 trial, are warranted.