Overtreatment of young adults with colon cancer: More intense treatments with unmatched survival gains

IMPORTANCE: Colon cancer is increasing among adults younger than 50 years. However, the prognosis of young-onset colon cancer remains poorly defined given significant age-related demographic, disease, and treatment differences. OBJECTIVE: To define stage-specific treatments and prognosis of colon cancer diagnosed in young adults (ages 18-49 years) vs older adults (ages 65-75 years) outside of the clinical trial setting while accounting for real-world age-related variations in patient, tumor, and treatment factors. DESIGN, SETTING, AND PARTICIPANTS: A nationwide cohort study was conducted among US hospitals accredited by the American College of Surgeons Commission on Cancer. Participants were 13 102 patients diagnosed as having young-onset colon adenocarcinoma aged 18 to 49 years and 37 007 patients diagnosed as having later-onset colon adenocarcinoma aged 65 to 75 years treated between January 1, 2003, and December 31, 2005, and reported to the National Cancer Data Base. EXPOSURES: Patients who underwent surgical resection and postoperative systemic chemotherapy of curative intent. MAIN OUTCOMES AND MEASURES: The primary end point was stage-specific relative survival, an objective measure of survival among patients with cancer, adjusting for baseline mortality rates and independent of the data on cause of death. The secondary end point was stage-specific likelihood of receiving postoperative systemic chemotherapy. RESULTS: Most young-onset colon cancer was initially seen at advanced stages (61.8% had stage III or IV). After adjusting for patient-related and tumor-related factors, young patients were more likely to receive systemic chemotherapy, particularly multiagent regimens, at all stages relative to those with later-onset disease. These odds ratios were 2.88 (95% CI, 2.21-3.77) for stage I, 3.93 (95% CI, 3.58-4.31) for stage II, 2.42 (95% CI, 2.18-2.68) for stage III, and 2.74 (95% CI, 2.44-3.07) for stage IV. The significantly more intense treatments received by younger patients were unmatched by any survival gain, which was nil for stage II (relative risk, 0.90; 95% CI, 0.69-1.17) and marginal for stage III (relative risk, 0.89; 95% CI, 0.81-0.97) and stage IV (relative risk, 0.84; 95% CI, 0.79-0.90). CONCLUSIONS AND RELEVANCE: Young adults with colon cancer received significantly more postoperative systemic chemotherapy at all stages, but they experienced only minimal gain in adjusted survival compared with their older counterparts who received less treatment. This mismatch suggests that attention should be given to long-term cancer survivorship in young adults with colon cancer because they likely face survivorship needs that are distinct from those of their older counterparts.