Propensity‐score matched analysis of the pathologic outcomes and survival benefits of neoadjuvant therapy in stage II–III anal adenocarcinoma

Abstract

AbstractBackgroundAnal adenocarcinomas are a rare condition which account for less than 10% of anal cancers. The present study aimed to assess the impact of neoadjuvant therapy on the clinical and pathologic outcomes and overall survival (OS) of patients with stage II–III anal adenocarcinomas after abdominoperineal resection (APR).MethodsA retrospective cohort study of patients with anal adenocarcinoma in the US National Cancer Database (NCDB) (2010–2020) was conducted. Propensity‐score matching was used to compare patients who received neoadjuvant therapy (neoadjuvant therapy group) to the no‐neoadjuvant group. The primary outcome was 5‐year OS whereas secondary outcomes included conversion to open surgery, hospital stay, surgical margins, 30‐day mortality, 90‐day mortality, and 30‐day readmission.ResultsA total of 742 patients (56% male) with a mean age of 63.6 ± 12.4 years were included. A total of 214 patients in the neoadjuvant group were matched with 107 in the no‐neoadjuvant group. The mean OS was similar between the two groups (47.5 vs. 44.8 months, p = 0.253). Patients who received neoadjuvant therapy had a longer median time between diagnosis and surgery (151 vs. 54 days, p < 0.001), lower 90‐day mortality (1.9% vs. 6.7%, p = 0.046), more pT0 tumors (15.7% vs. 0%), less pT3‐4 tumors (28.4% vs. 36.4%, p = 0.001), less pN1‐2 tumors (22.9% vs. 34.7%, p < 0.001), and less lymphovascular invasion (16.2% vs. 40%, p < 0.001) than the no‐neoadjuvant group. Both groups had similar conversion rates, hospital stay, 30‐day mortality, 30‐day readmission, and positive surgical margins.ConclusionsNeoadjuvant therapy before APR was associated with significant downstaging of anal adenocarcinomas and lower 90‐day mortality, yet similar OS to patients who were surgically treated without neoadjuvant treatment.