Bagshaw HP, et al. - In this retrospective review, researchers examined the impact of definitive chemotherapy and intensity-modulated radiation therapy (IMRT) on localregional control (LRC), distant metastasis free survival, disease-free survival, overall survival (OS), and toxicity in patients treated for squamous cell carcinoma of the anus at their institution since 2005. Using the Kaplan-Meier curves, LRC and OS were assessed. The overall cohort showed limited recurrence rates. Two vulvar recurrences were identified within the avoided external genitalia in patients treated with IMRT-based chemoradiation. The risk for subclinical involvement of in-transit vulvar dermal lymphatics and subsequent recurrence may exist for patients with a locally advanced primary tumor and bulky bilateral inguinal or pelvic disease. If proved by a similar pattern of recurrence at other institutions, the external genitalia may need to be reclassified from an avoidance structure to a clinical treatment volume in patients with locally advanced anal cancer.