A Systematic Review Defining Early Anal Squamous Cell Carcinoma and Identifying Treatment

Background: Anal cancer screening has allowed for the diagnosis of early-stage anal cancers; however, guidelines for the treatment of early anal cancers remain mixed given the scarcity of clinical trials and data. Management ranges from chemoradiation therapy to local surgical excision. Methods: This paper’s objective is to clarify the definition of early anal cancer and its management. Approval for this systematic review was obtained through PROSPERO [CRD42022304327]. Three independent reviewers screened the studies and performed data analysis, with conflicts resolved by a fourth reviewer. All information is presented according to the Preferred Reporting Item for Systematic Reviews and Meta-Analysis (PRISMA). The Grades of Recommendation, Assessment, Development, and Evaluation (GRADE) criteria were used to assess the certainty of the evidence. Results: The MEDLINE, EMBASE and Cochrane databases were queried with 628 articles screened. A total of 15 articles were selected for inclusion. Early anal cancer was most often defined as T1-2N0M0 anal cancer but also included Superficially Invasive Squamous Cell Carcinoma (SISCCA). There were various treatments assessed for outcomes including local excision, chemoradiation, and radiation. The studies reported overall survival, cancer-specific survival, recurrence-free survival, and/or colostomy-free survival, leading to significant heterogeneity amongst the studies. No meta-analysis was possible. Conclusions: Poor-quality studies exist for the evaluation of the most effective treatment modality for early anal cancer. Surgical excision alone with adequate margins has equivocal results, but data is poor. Chemoradiation is successful but may be overtreatment. Randomized controlled studies are needed, as screening will result in earlier anal cancer diagnoses.