Article Abstract

Outcomes of patients in the national cancer database treated non-surgically for localized rectal cancer

Authors: Emma B. Holliday, Pamela K. Allen, Hesham Elhalawani, Omar Abdel-Rahman

Abstract

Background: Some patients undergo a non-operative approach to localized rectal adenocarcinoma either because they decline surgery or because their medical comorbidities preclude surgical intervention. Published studies reporting excellent outcomes with a “wait-and-see” approach have been small and highly-selected. We aimed to analyze survival outcomes and prognostic factors for patients with localized rectal adenocarcinoma in the National Cancer Database (NCDB) undergoing definitive radiation without surgical intervention.
Methods: The NCDB was queried for patients with non-metastatic rectal adenocarcinoma treated with definitive radiotherapy who did not undergo a surgical resection either because the patient refused surgery, surgery was medically contraindicated, or surgery was otherwise unplanned. Patient, tumor and treatment-related characteristics were compared between those treated with 45–50.3 Gray (Gy), 50.4–54 Gy and >54 Gy. Survivals were compared using the Log-Rank test. Univariate and multivariate Cox regression analyses were performed. Survivals were then compared utilizing a robust inverse-probability-weighted regression adjustment method with nearest-neighbor matching.
Results: Eight thousand four hundred and eight patients were included for analysis. After case-matching and adjusting for significant prognostic factors, patients receiving 50.4–54 Gy had a significantly longer median, 1- and 5-year overall survival (OS) (49.4 months, 85.8%, 44.7%) compared with patients receiving 45–50.3 or >54 Gy (37.2 months, 79.2%, 38.4% and 34.2 months, 84.5%, 35.3%, respectively; Log rank P value <0.0001).
Conclusions: In an unselected group of patients treated at NCDB-participating institutions, survival rates with a non-surgical approach to non-metastatic rectal adenocarcinoma are much lower than those reported in well-selected single-institutional studies. Moderate dose escalation from 50.4–54 Gy was associated with better OS compared with doses <50.4 Gy or >54 Gy after adjusting for significant covariant.