Objectives: Combined modality therapy (CMT) consisting of chemotherapy and radiation is the standard of care for anal cancer treatment, with recurrence rates reported to be > 16%. Identification of high-grade anal intraepithelial neoplasia (HGAIN) precursor lesions through high resolution anoscopy (HRA)-guided biopsy followed by ablation may prevent recurrent anal cancer in CMT- treated patients and early-stage recurrent cancer may possibly be treated with local excision. Follow-up of patients’ post-CMT may therefore be important. This study sought to determine prevalence of HGAIN and cancer following completion of CMT for anal cancer.

Methods: Retrospective chart review of anal cancer patients diagnosed since 1999 and treated with CMT, referred to the University of California San Francisco for post-CMT follow-up.

Results: 52 men and 14 women completed CMT for anal cancer and were evaluated with HRA post-treatment. The average age at cancer diagnosis was 53.2 years (range 37-66). Nineteen (29%) patients returned for one visit and 47 (71%) returned for on-going HRA every 4-6 months (Figure). HGAIN was diagnosed in 14 (21%) patients (average 29 months post-CMT) and cancer in 9 (14%) patients (average 28 months post-CMT). 54% of HGAIN and 78% of cancers were diagnosed at the first post-CMT evaluation (range 7-47 months). Twelve of 14 HGAIN were treated; 5 of the 12 treated lesions progressed to cancer despite treatment. Seven of 9 patients with recurrent cancers were treated surgically, half with colostomy-sparing local resection; one was lost to follow-up and one died with the cause of death unknown.

Conclusions: One-third of patients had HGAIN or cancer post-CMT treatment. These were more common in men suggesting they be targeted for post-CMT HRA evaluation. It is unclear if detection and treatment of HGAIN will prevent cancer recurrence. Early follow-up and intervention may lead to better outcomes, including the possibility of curative local colostomy-sparing resection.