Jennifer K. Logan, Kathryn E. Huber, Thomas A. DiPetrillo, David E. Wazer and Kara L. Leonard Abstract Background: According to the 2013 National Comprehensive Cancer Network guidelines, pelvic radiation therapy (RT) is one of the preferred regimens for patients with metastatic rectal cancer (mRC). The objective of this study was to analyze patterns of care and outcomes data for the receipt of RT among patients with mRC using the Surveillance, Epidemiology, and End Results (SEER) database. Methods: Patients with stage IV rectal or rectosigmoid cancer were identified in the SEER database (2004–2009). Patients were stratified according to their primary disease site (rectum vs rectosigmoid), tumor (T) classification, and lymph node (N) classification. Treatment regimens (with or without surgical resection, with or without RT) were recorded. The Fisher exact test was used to compare RT rates based on stratified factors. Two and five–year survival rates were compared among treatment groups. Results: In total, 6873 patients with stage IV rectal cancer and 3417 patients with rectosigmoid cancer were identified. Overall, 20.5% of patients with rectal cancer underwent surgery alone, whereas 38.7% received RT with or without surgery. Within the rectosigmoid group, 51.4% of patients underwent surgery alone, and 15.1% received RT with or without surgery. The use of RT differed significantly between patients with in situ (Tis) through T2 tumors versus T3/T4 tumors (P < .001) and between those with N0 disease versus N1/N2 disease (P < .001). The 2–year and 5–year survival rates differed between treatment groups, with the highest survival rates observed among those who received combined surgery and RT. Conclusions: The primary treatments for patients with mRC include RT with or without surgery. RT is used more commonly in patients with primary rectal (vs rectosigmoid) tumors, N0 disease, or Tis–T2 tumors. Treatment with combination surgery and RT is associated with prolonged survival. Cancer 2014;120:731–737. © 2013 American Cancer Society.