Background: Utilization of evidence-based treatments for patients with colorectal liver metastasis (CRC-LM) outside high-volume centers is not well-characterized. We sought to describe trends in treatment and outcomes, and identify predictors of therapy within a nationwide integrated health system. Methods: Observational cohort study of patients with CRC-LM treated within the Veterans Affairs (VA) health system (1998–2012). Secular trends and outcomes were compared on the basis of treatment type. Multivariate regression was used to identify predictors of no treatment (chemotherapy or surgery). Results: Among 3270 patients, 57.3 % received treatment (chemotherapy and/or surgery) during the study period. The proportion receiving treatment doubled (38 % in 1998 vs. 68 % in 2012; trend test, p < 0.001), primarily driven by increased use of chemotherapy (26 vs. 57 %; trend test, p < 0.001). Among patients having surgery (16 %), the proportion having ablation (10 vs. 61.9 %; trend test, p < 0.001) and multimodality therapy (15 vs. 67 %; trend test, p < 0.001) increased significantly over time. Older patients [65–75 years: odds ratio (OR) 1.65, 95 % confidence interval (CI) 1.39–1.97; >75 years: OR 3.84, 95 % CI 3.13–4.69] and those with high comorbidity index (Charlson ≥3: OR 1.47, 95 % CI 1.16–1.85) were more likely to be untreated. Overall survival was significantly different based on treatment strategy (log-rank p < 0.001). Conclusions: The proportion of CRC-LM patients receiving treatment within the largest integrated health system in the US (VA health system) has increased substantially over time; however, one in three patients still does not receive any treatment. Future initiatives should focus on increasing treatment among older patients as well as on evaluating reasons leading to the no-treatment approach and increased use of ablation procedures.
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