Patterns of Care and Oncologic Outcomes after Pelvic Exenteration for Locally Advanced Rectal Cancer in the United States

Background: Pelvic exenterations (PEs) are technically demanding procedures performed with curative intent for advanced malignancies to improve patient survival while balancing morbidity and functional outcomes. The majority of United States (US) data regarding PE for rectal cancers originate from single-center series. Objective: We aimed to investigate patterns of care and oncologic outcomes for primary rectal cancer patients undergoing PE in a national registry. Methods: The National Cancer Database (2004–2019) was queried for adults with a pT4 rectal adenocarcinoma. Logistic regression identified factors associated with positive margins. Multivariable Cox regression estimated treatment effects on overall survival (OS). Results: Of 673 patients (73% <65 years of age, 39% male, 82% White), median follow-up was 39 months. The majority received neoadjuvant chemotherapy (76%) and radiation (75%), while adjuvant chemotherapy (37%) and radiation (13%) were less common. Twenty-four percent had positive margins (R1 = 98, R2 = 11, R + NOS = 48). Univariable analysis demonstrated that only nodal involvement was associated with higher positive margin rates (odds ratio 1.75, 95% confidence interval [CI] 1.22–2.51). Five-year OS for R0 and R+ resections were 55% and 33%, respectively. On multivariable analysis, age <65 years (hazard ratio [HR] 0.73, 95% CI 0.53–0.99) and adjuvant chemotherapy (HR 0.62, 95% CI 0.47–0.82) were associated with improved OS, while N+ status (HR 2.13, 95% CI 1.67–2.70) and positive margins (HR 1.82, 95% CI 1.41–2.35) portended worse prognosis. No significant associations were observed between outcomes and institutional volume. Conclusion: One in four US patients undergoing PE for locally advanced rectal cancer had an R+ resection regardless of center volume. Quality of surgical resection to achieve negative margins remains the most relevant prognostic factor.