Age Determines Adjuvant Chemotherapy Use in Resected Stage II Colon Cancer

BACKGROUND: The role of adjuvant chemotherapy in resected stage II colon cancer remains controversial. Treatment recommendations rely largely on the presence of certain high-risk features for recurrence. OBJECTIVE: We sought to define patient and clinicopathologic differences between early-onset and late-onset colorectal cancer and determine whether these differences impact treatment. We hypothesized that high-risk features in stage II colorectal cancer differed between age groups and would most strongly influence administration of adjuvant chemotherapy. DESIGN: This was a retrospective cohort study. SETTING: The study was conducted at a Commission on Cancer designated hospital as well as the National Cancer Institute Intramural Research Program. PATIENTS: Patients with resected stage II colon cancer were identified in the National Cancer Database, and clinicopathologic characteristics were recorded. Patients were stratified into young (5_45), middle-aged (50-75), and older (>75) age groups. MAIN OUTCOME MEASURES: Incidence of high-risk clinicopathologic features and receipt of adjuvant chemotherapy were measured. RESULTS: A total of 14,966 patients met inclusion criteria. Young patients were found to have had at least one high-risk feature (n = 489, 44%) slightly more often than both middle-aged (n = 3734, 40%) and older patients (n = 1890, 42%). A total of 332 (7%) older patients received adjuvant chemotherapy compared to 627 (56%) young patients and 2854 (30%) middle-aged patients. Age group was independently associated with receipt of adjuvant chemotherapy when controlling for relevant clinicopathologic factors. LIMITATIONS: This was a retrospective study without granular detail on treatment decisions. CONCLUSIONS: Young patients are frequently prescribed adjuvant chemotherapy for both high- and low-risk tumors despite questionable benefit in the latter. Older patients rarely receive adjuvant therapy. Both medical and surgical oncologists should be aware of disparities in cancer treatment and remain conscientious about making treatment decisions solely based on age.