Use of adjuvant chemotherapy in patients with stage III colon cancer in Puerto Rico: A population-based study

OBJECTIVE: This study aims to examine factors associated with the use of adjuvant chemotherapy and the use of oxaliplatin after curative resection in stage III colon cancer patients and assesses the effect of their use in three-year survival. METHODS: This retrospective cohort study was conducted using Puerto Rico Central Cancer Registry-Health Insurance Linkage Database. The study cohort consisted of stage III colon cancer patients with a curative surgery in the period 2008–2012. Multivariate logistic regression was used to estimate adjusted odds ratios. Kaplan-Meier methods and Cox proportional hazards models were used to assess the association between adjuvant chemotherapy and oxaliplatin use and overall survival and risk of death, respectively. RESULTS: Overall, 75% of the study population received adjuvant chemotherapy during the study period. Factors statistically associated with receiving adjuvant chemotherapy within four months after resection included being married (adjusted odds ratio [AOR] 1.64; 95% CI 1.18–2.28; p = 0.003), and being enrolled in Medicare (AOR 1.68; 95% CI: 1.03–2.75; p = 0.039) or Medicaid and Medicare dual eligible (AOR 1.66; 95% CI: 1.06–2.60; p = 0.028). However, patients aged ≥70 years were less likely to receive adjuvant chemotherapy (AOR 0.22; 95%CI 0.14–0.36; p<0.001). DISCUSSION: We observed a significant reduction in mortality in adjuvant chemotherapy treated patients. Similarly, patients <70 years treated with oxaliplatin had significantly lower risk of death than those who did not, although for patients ≥70 years no statistical significance was achieved. Future studies should assess effective interventions to reduce barriers to access guideline-based recommended colon cancer treatment.