Postoperative chemotherapy use after neoadjuvant chemoradiotherapy for rectal cancer: Analysis of Surveillance, Epidemiology, and End Results-Medicare data, 1998-2007

BACKGROUND Neoadjuvant chemoradiotherapy followed by tumor resection and postoperative chemotherapy is the standard of care for patients with clinical stage II or III adenocarcinoma of the rectum. Significant variation exists in the receipt of postoperative chemotherapy after resection in this population. The objective of this study was to determine the demographic and clinicopathologic factors associated with the initiation of postoperative chemotherapy in elderly patients with rectal cancer and to identify potential targets for reducing treatment variation. METHODS A retrospective cohort study was performed of patients with rectal cancer ages 66 to 80 years who received neoadjuvant chemoradiotherapy and underwent radical resection in the Surveillance, Epidemiology, and End Results-linked Medicare database (1998-2007). Multivariate logistic regression was used to assess chemotherapy use in relation to patient, tumor, and treatment response characteristics. RESULTS Among 1492 patients who met the study criteria, 61.5% received adjuvant therapy with 5-fluorouracil. Pathologic stage was the strongest determinant of whether patients received postoperative chemotherapy (48.3% of patients with stage I disease, 59.6% of patients with stage II disease, and 77.6% of patients with stage III disease). Increasing age and postoperative readmission also were associated significantly with a decreased rate of adjuvant therapy initiation. CONCLUSIONS Although standard treatment guidelines for locally advanced rectal cancer include postoperative chemotherapy for all patients after neoadjuvant chemoradiotherapy and radical resection, greater than 1 in 3 patients failed to receive adjuvant therapy. Despite the absence of established evidence, treatment decisions appear to be influenced by the findings at surgical pathology. Cancer 2014;120:1162–1170. © 2014 American Cancer Society.