Receipt of Adjuvant Chemotherapy in Stage II Colon Cancer and Overall Survival: A National Cancer Database Study

Background: There are variations in the use of adjuvant chemotherapy (AC) in stage II colon cancer (CRC). We sought to determine which patients received chemotherapy, what factors were associated with receipt of AC, and how this impacted overall survival. Methods: Using the National Cancer Database, patients with stage II CRC who underwent surgical resection were selected; patients who received radiation or neoadjuvant chemotherapy were excluded. High-risk features (HRFs) were defined as pathological tumor stage IV, positive surgical margins, and perineural or lymphovascular invasion. Multivariable and subgroup analysis with eight subgroups stratified in the presence of HRFs, age, and the Charlson-Deyo score was performed. Results: Of 77,739 patients identified with stage II CRC, 18.3% received AC. Younger, healthier patients with HRFs had the highest chemotherapy receipt rate (46.7%), whereas patients without HRFs, ≥ 75 y, and with the Charlson-Deyo score of 2+ had the lowest rate (2.1%). Community cancer centers were more likely to initiate AC (odds ratio = 1.24 P < 0.01) especially among healthy HRF-negative patients and younger patients. No significant racial differences in AC use were observed. AC was associated with improved overall survival in subgroups with HRFs (hazard ratio [HR]: 0.81 P < 0.001; HR: 0.75 P < 0.001; HR: 0.65 P = 0.03; HR: 0.55, P < 0.001) but not in patients without HRFs. Conclusions: AC receipt rates differed depending on patient age and type of institution delivering care. AC was associated with survival benefits only in patients with HRFs regardless of age. These findings are clinically relevant to inform appropriate use of AC in stage II CRC.