Salvage Treatment of Recurrent or Persistent Anal Squamous Cell Carcinoma: The Role of Multi-modality Therapy

Background: The standard treatment for recurrent or persistent anal squamous cell carcinoma is surgical salvage, but disease control and survival are suboptimal. Patients/Methods: Patients treated for recurrent or persistent anal squamous cell carcinoma at our institution from 2002 to 2022 were included. Patients were classified by type of salvage treatment received: surgery alone vs. reirradiation followed by surgery and by whether they received intraoperative radiation at the time of surgery. Clinical and pathologic variables were collected and assessed for association with risk of second local recurrence and death from any cause. Results: Sixty four patients were included; 55(85.9%) were treated with surgery alone and 9 (14.1%) were treated with reirradiation followed by surgery. Median (IQR) follow up from the time of salvage treatment was 40.0 (20.3-68.0) months. The 3-year cumulative incidence of second local recurrence (95% CI) after salvage surgery was 36% (24%-48%); 39% (26%-52%) for patients treated with surgery alone and 15% (0.46%-51%) for patients treated with reirradiation followed by surgery. Factors associated with increased second local recurrence after salvage surgery included a locoregional recurrence, lymphovascular space invasion and positive surgical margins. The 3-year overall survival (95% CI) after salvage surgery was 70% (59%-83%); 68% (7%-56%) after surgery alone and 89% (10.5%-70.6%) after reirradiation followed by surgery. Factors associated with worse overall survival included male sex, a larger recurrent tumor and positive surgical margins. Conclusions: Approximately 60% of patients achieved pelvic control after salvage therapy for recurrent or persistent anal squamous cell carcinoma. Although receipt of reirradiation and intraoperative radiation were not associated with improved second local recurrence or overall survival in our cohort, patients with positive surgical margins and lymphovascular space invasion on surgical pathology had higher rates of pelvic recurrence after salvage surgery and may benefit from escalated salvage therapy.