title: Vulvar Recurrences After Intensity-modulated Radiation Therapy for Squamous Cell Carcinoma of the Anus.
abstract: The objective is to determine localregional control (LRC), distant metastasis free survival, disease-free survival, overall survival (OS), and toxicity for patients with squamous cell carcinoma of the anus treated with definitive chemotherapy and intensity-modulated radiation therapy (IMRT).
  
  
  
  We conducted a retrospective review of patients treated using IMRT for squamous cell carcinoma of the anus at our institution since 2005. Patients with local recurrences were identified and reviewed. The Kaplan-Meier curves were used for LRC and OS.
  
  
  
  From 2005 to 2014, 52 patients were treated with IMRT-based chemoradiation for squamous cell carcinoma of the anus. Median dose to the primary tumor was 54 Gy. LRC, distant metastasis free survival, OS, and disease-free survival were 92.3%, 88.5%, 86.5%, and 84.6%, respectively, with a median follow-up of 20 months. Two local failures occurred at the anal primary site and 2 in the vulva. Despite subsequent palliative radiotherapy and chemotherapy, neither patient with a vulvar recurrence achieved disease control.
  
  
  
  In a cohort of patients treated with IMRT-based chemoradiation, 2 vulvar recurrences were identified within the avoided external genitalia despite limited recurrence rates within the cohort overall. This experience suggests that for patients with a locally advanced primary tumor and bulky bilateral inguinal or pelvic disease, the in-transit vulvar dermal lymphatics may be at risk for subclinical involvement and subsequent recurrence. If substantiated 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.
authors.affiliation: Stanford University Hospital and Clinics, Stanford, CA.
authors.forename: Hilary P
authors.initials: HP
authors.lastname: Bagshaw
authors.affiliation: Intermountain Healthcare Radiation Oncology.
authors.forename: William T
authors.initials: WT
authors.lastname: Sause
authors.affiliation: Intermountain Colon & Rectal Surgery.
authors.forename: Ute
authors.initials: U
authors.lastname: Gawlick
authors.affiliation: Intermountain Colon & Rectal Surgery.
authors.forename: H Tae
authors.initials: HT
authors.lastname: Kim
authors.affiliation: Huntsman Cancer Institute, Salt Lake City, UT.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Whisenant
authors.affiliation: Intermountain Healthcare Radiation Oncology.
authors.forename: George M
authors.initials: GM
authors.lastname: Cannon
mesh_terms: D001005:Anus Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D002294:Carcinoma, Squamous Cell / Q000473:pathology / Q000532:radiotherapy*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008875:Middle Aged; D011379:Prognosis; D011879:Radiotherapy Dosage; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects*; D012008:Recurrence; D012189:Retrospective Studies; D015996:Survival Rate; D014846:Vulvar Neoplasms / Q000175:diagnosis* / Q000556:secondary