Trends in Adjuvant Chemotherapy Use Among Stage III Colon Cancer in Non-Elderly and Low Comorbidity Patients

Background: Adjuvant chemotherapy for stage III colon cancer is underutilized in the United States. The aim of this study was to assess the use of adjuvant chemotherapy in younger and medically fit patients and analyze the socioeconomic factors associated with its utilization.

Methods: Using the National Cancer Database from 2004 to 2015, we selected stage III colon cancer patients between age 18 to 65, Charlson-Deyo Comorbidity Index (CDCI) of 0 or 1, and those that survived at least 12 months after surgery. We then compared patients that underwent surgery only with those that received adjuvant chemotherapy. Multivariable logistic regression analysis was performed to identify variables associated with adjuvant chemotherapy use in the population. Overall survival was estimated by Kaplan-Meier curves.

Results: Of the 48,336 patients that met inclusion criteria, 43,315 (90%) received adjuvant chemotherapy. The utilization of adjuvant chemotherapy increased from 87% in 2004 to 91% in 2015. On multivariable regression analysis, the use of adjuvant chemotherapy was lower among males, Non-Hispanic Blacks and Hispanics, low-grade cancer, left-sided tumors, CDCI 1, those who travel ≥ 50 miles, yearly income < $40,227, and uninsured patients. The most common reason for the omission of adjuvant chemotherapy was the patient or caregiver's choice (40% between 2013 and 2015). The 5-year and 10-year overall survival rates were 76.7% and 63.8% respectively, in those who received adjuvant chemotherapy as compared to 65.1% and 49.3% in those who underwent surgery only (P < .001).

Conclusion: In young and medically fit stage III colon cancer patients, most patients received guideline-compliant care in the United States. However, socioeconomic disparities adversely impacted the use of adjuvant chemotherapy. The patient or caregiver's decision was the most common reason for non-adherence to adjuvant chemotherapy and lead to poor survival outcomes. Emphasis should be placed on developing patient-centered strategies to improve adherence to chemotherapy in all patients.