journal of medical science and clinical research | 2019
Chemoradiotherapy of Locally-Advanced Anal Canal Squamous Cell Carcinoma: A Brief Review of Outcomes of Randomized Clinical Trials
Abstract
First-line treatment of locally advanced anal canal squamous cell carcinomas (AC-SCC) has evolved from the abdominoperineal resection resulting in permanent colostomies to definitive concurrent chemoradiotherapy, with surgery reserved for salvage. Publication of small but practice-changing chemoradiotherapy studies in the second half of the 1970s prompted the conduction of large phase III randomized controlled trials consequences of which increased our ability to deliver systemic chemotherapy more effectively and reduce treatment-related toxicity rates by utilizing more sophisticated radiotherapy techniques. This article aims to review the design and outcomes of currently accessible phase III randomized controlled chemoradiotherapy trials of AC-SCC. Introduction Anal canal squamous cell carcinoma (AC-SCC) is a relatively rare tumor which constitutes only 2% of all gastrointestinal tumors (1,2) . However, the incidence of AC-SCC has been increasing over the past three 30 years, which is assumed to be associated with increased exposure to the human papillomavirus and human immunodeficiency virus infections, for the most part, due to changes in sexual practices (2) . Abdominoperineal resection (APR) with resultant permanent colostomy was the standard of care for all stages of AC-SCC (3) until the publication of seminal work by Nigro 1974 (4) . In this small yet admirable study, the authors exhibited the superiority of neoadjuvant concurrent chemoradiotherapy (C-CRT) over surgery alone with utilizing 30 Gy (15 fractions) radiotherapy (RT) and concurrently administered 5-fluorouracil (5-FU) and mitomycin-C (MMC). Opening another treatment window for AC-SCC, the authors reported that the pathologic complete response (CR) was achieved in 80% of patients following this regimen. Albeit initially the practice-changing Nigro’s C-CRT protocol was developed as a neoadjuvant therapy preceding surgical resection, the exhibition that 80% of patients were rendered free of cancer by C-CRT on clinical and histopathological examinations prompted the conduction of many prospective http://jmscr.igmpublication.org/home/ ISSN (e)-2347-176x ISSN (p) 2455-0450 DOI: https://dx.doi.org/10.18535/jmscr/v7i8.164