PTU-213 Oncological outcomes following local excision with and without (chemo)-radiotherapy for anal margin squamous cell carcinoma

Abstract

Introduction The mainstay of treatment for anal squamous cell carcinoma (ASCC) is chemo-radiotherapy (CRT). Less than 5% of initial presentations are confined to the anal margin and amenable to local excision (LE) with or without post-operative (C)RT. However, treatment is poorly defined and outcome is understudied. Method PLATO is the next UK anal cancer trial; a three-part umbrella trial where the first stream (ACT 3) is a phase II study to assess the use of LE, for T1N0 anal margin tumours, combined with low-dose post-operative CRT (41.4Gy in 23 fractions) for close margins (≤ 1 mm), evaluated against a minimally tolerated loco-regional actuarial relapse rate of 10%. To inform this trial, we report the characteristics, treatment and outcomes of patients treated through a large anal cancer MDT (2004 to 2013), supplemented by a literature review. Results From 446 patients with new ASSC, there were 20 (4%) anal margin tumours treated by LE. Thirteen (65%) were T1; 7 (35%) were T2. All were N0 and M0. The lateral and deep margins were close (≤ 1 mm) in seven patients (35%). Five patients had additional therapy: 2 RT; 3 CRT. With a median follow-up of 38.6 months, there were no primary site recurrences; 3 patients developed nodal relapses (3-year loco-regional relapse = 11%). Three patients died attributed to their disease – the 3-year disease-free survival rate was 89%. The literature search identified six studies – there was a near total paucity of data on tumour characteristics, excision margin status, and the impact of these on subsequent treatment or outcome. Conclusion There is a need for a contemporaneous prospective study of this sub-population of patients with anal cancer, through centralisation of patients to anal cancer MDTs with pro-active identification and recruitment of these patients for the ACT3 trial. Disclosure of interest None Declared.