Abstract only e15116 Background: Fluorouracil-based adjuvant chemotherapy has been shown to improve survival of patients with early-stage colon cancer. Suboptimal adherence to oral chemotherapy, such as capecitabine, remains a serious issue and reduces treatment efficacy. Patient barriers to adherence include adverse effects and high medical costs. This study assesses the completion rates and associated factors in patients on capecitabine monotherapy (Cape) and capecitabine with oxaliplatin (CAPOX) for adjuvant treatment of early-stage colon cancer. Methods: Patients with a primary/secondary diagnosis of early-stage colon cancer between April 2013-March 2017, and 1+ claim of Cape or CAPOX within 60 days of colectomy were identified from the MarketScan Commercial/Medicare Database. Therapy completion rates (treatment ≥7 cycles) were calculated. Multivariate logistic regressions analyses were used to assess the factors (patients’ age, gender, payer type, geography, comorbidities, healthcare costs, etc.) associated with treatment completion. Results: A total of 679 patients met the eligibility criteria (mean age ± SD: 57.3 ± 11.5 years, 54% male), of which 382 (56%) were on Cape (mean age ± SD: 60.2±12.4) and 297 (44%) on CAPOX (mean age ± SD: 53.6±9.0). Completion rates were 43% in Cape and 42% in CAPOX. The baseline overall mean monthly healthcare cost was significantly higher in non-completers vs. completers (Cape: $9,870 vs $7,169, P=0.003; CAPOX: $10,009 vs $8,068, P=0.01). Multivariate logistic regression showed that patients <65 years of age on CAPOX were more likely to complete treatment than patients ≥65 years on CAPOX (Odds Ratio=5.1, P=0.03). Conclusions: Cape and CAPOX completion rates are suboptimal in patients with early-stage colon cancer. Non-completion of therapy is associated with significantly higher baseline healthcare costs for both Cape and CAPOX, as is older age for CAPOX. The low completion rates highlight the unmet need for more effective strategies to optimize oral chemotherapy for the adjuvant treatment of early-stage colon cancer. Table: see text