Management of anal intraepithelial neoplasia and anal squamous cell carcinoma at a tertiary referral centre with a dedicated infectious diseases unit: an 18-year review.

INTRODUCTION Anal squamous cell carcinoma (ASCC) is a rare malignancy with rising incidence rates. Risk factors include human immunodeficiency virus (HIV) infection, high-risk sexual activity and HPV-related genitourinary dysplasia/neoplasia. There is an overlap between high-risk patients and those attending HIV Medicine/Sexual Health (HMSH) services. We hypothesised that HMSH involvement may facilitate earlier referral to colorectal surgeons, with better outcomes. METHODS Retrospective review of all ASCC and anal intraepithelial neoplasia (AIN) treated at a tertiary-referral hospital with a dedicated HMSH clinic between 2000 and 2018. Comparative analysis was performed of demographics, management and outcomes between HMSH and non-HMSH patients. RESULTS One hundred and nine patients had anal pathology, eighty-five with ASCC (78%) and twenty-four with AIN (22%). Seventy (64%) were male. Median (range) age at ASCC diagnosis was 51 years (26-88). Thirty-six percent of all patients attended HMSH services, 28% were HIV positive, and 41% of males were men-who-have-sex-with-men (MSM). Eighty-one ASCC patients (97.5%) were treated with curative intent. Sixty-seven (80%) had primary chemoradiation therapy. Fifteen (17.5%) had primary surgical excision. Twelve (14%) developed recurrent disease. Ultimately, seven required salvage APR. Overall 3-year survival (3YS) was 76%. HMSH patients were significantly younger at ASCC diagnosis (p < 0.001), with a higher prevalence of HIV, HPV and MSM. HMSH attenders also tended to be diagnosed at earlier stages, were less likely to develop recurrence and achieved better overall outcomes, with a superior overall 3YS than non-HMSH patients (92% vs 72%, p = 0.037). CONCLUSION ASCC incidence is increasing worldwide. The HMSH cohort has emerged as a distinct subpopulation of younger, high-risk, male patients. Collaboration between HMSH and colorectal surgeons offers an opportunity for risk reduction strategies and earlier intervention.