Prognostic factors of overall survival and cancer-specific survival in patients with resected early-stage rectal adenocarcinoma: a SEER-based study

The benefits of radiotherapy for colorectal cancer are well documented, but the impact of adjuvant radiotherapy on early-stage rectal adenocarcinoma remains unclear. This study aimed to identify predictors of overall survival (OS) and cancer-specific survival (CSS) in patients with stage II rectal adenocarcinoma treated with preoperative or postoperative radiation therapy. Patients with early-stage rectal adenocarcinoma in the postoperative state were identified using the Surveillance, Epidemiology, and End Results database. The primary endpoints were OS and overall CSS. Stage IIA patients without radiotherapy had significantly lower OS and CSS compared with those who received radiation before or after surgery. Stage IIB patients with radiotherapy before surgery had significantly higher OS and CSS compared with patients in the postoperative or no radiotherapy groups. Patients with signet ring cell carcinoma had the poorest OS among all the groups. Multivariable analysis showed that ethnicity (HR, 0.388, p=0.006) and radiation before surgery (HR, 0.614, p=0.006) were favorable prognostic factors for OS, while age (HR, 1.064, p<0.001), race (HR, 1.599, p=0.041), stage IIB (HR, 3.011, p=0.011), and more than one tumor deposit (TD) (HR, 2.300, p=0.001) were unfavorable prognostic factors for OS. Old age (HR, 1.047, p<0.00L), stage IIB (HR, 8.619, p=0.005), circumferential resection margin between 0.1mm and 10mm (HR, 1.529, p=0.039), and more than one TD (HR, 2.688, p=0.001) were unfavorable prognostic factors for CSS. This population-based study identified predictors of OS and CSS in patients with early-stage resected rectal adenocarcinoma, which may help to guide future management of this patient population.