Nodal Elective Volume Selection and Definition during Radiation Therapy for Early Stage (T1–T2 N0 M0) Perianal Squamous Cell Carcinoma: A Narrative Clinical Review and Critical Appraisal.

Simple Summary: Early-stage (T1–T2 N0 M0) true perianal tumors are very uncommon, and the scientific literature is scant. Based on common features with anal canal carcinomas (aCCs), perianal skin cancers and aCCs are included in the same tumor classification and treated similarly. In fact, contouring radiation therapy guidelines do not differentiate between the two subsites. However, anal canal tumors and perianal skin cancers have different lymphatic drainage patterns. Modulation of radiotherapy treatment volumes can be considered for the latter. We performed a literature review to analyze the sites at higher risk of microscopic spread in patients with early-stage perianal cancer to tailor the selection of radiation therapy elective volumes. Distinction between anal canal and perianal squamous cell carcinomas (pSCCs) is essential, as these two subgroups have different anatomical, histological, and lymphatic drainage features. Early-stage true perianal tumors are very uncommon and have been rarely included in clinical trials. Perianal skin cancers and aCCs are included in the same tumor classification, even though they have different lymphatic drainage features. Furthermore, pSCCs are treated similarly to carcinomas originating from the anal canal. Radiation therapy (RT) is an essential treatment for anal canal tumors. Guidelines do not differentiate between treatment volumes for perianal tumors and anal cancers. So far, in pSCC, no study has considered modulating treatment volume selection according to the stage of the disease. We conducted a narrative literature review to describe the sites at higher risk for microscopic disease in patients with early-stage perianal cancers (T1–T2 N0 M0) to propose a well-thought selection of RT elective volumes. [ABSTRACT FROM AUTHOR]