Rurality and Use of Metastasis-Directed Therapies for Medicare Beneficiaries with Metastatic Colon Cancer: A Retrospective Cohort Study.

Abstract

Liver- and lung-directed local therapies can eradicate metastatic disease and prolong survival for selected patients with oligometastatic colon cancer. Evidence about the association of rurality with access to metastasis-directed therapies and survival outcomes is limited. A retrospective study analyzed fee-for-service Medicare beneficiaries with colon cancer metastatic to liver and/or lung using claims from 2016-2019. The exposure of interest was residential rurality, categorized as metropolitan versus non-metropolitan (i.e., rural). The study evaluated the association of rurality with use of metastasis-directed therapies (surgery, stereotactic radiation, and ablation) via multivariable logistic regression. Survival analyses used proportional hazards regression and treated receipt of metastasis-directed therapy as a time-varying covariate. The study identified 11,796 beneficiaries with colon cancer metastatic to liver and/or lung, 26.6% of whom lived in rural areas. Overall, 7.3% of the beneficiaries received any metastasis-directed therapy. Rural residence was not significantly associated with metastasis-directed therapy (adjusted odds ratio [OR], 1.11; 95% confidence interval [CI], 0.93-1.31). However, Medicare-Medicaid dual eligibility and greater area deprivation were significantly associated with lower odds of metastasis-directed therapy. Metastasis-directed therapy was associated with a decreased hazard of death (adjusted hazard ratio [HR], 0.41 for beneficiaries receiving metastasis-directed therapy within 90 days after cancer diagnosis; 95% CI, 0.35-0.49). Rural residence was not independently associated with mortality (adjusted HR, 1.00; 95% CI, 0.96-1.06). Metastasis-directed therapy was associated with decreased mortality from metastatic colon cancer. Medicare-Medicaid dual eligibility and greater area deprivation both were associated with lower use of metastasis-directed therapy, but residential rurality was not. New care delivery approaches are needed to extend equitable access to metastasis-directed therapies.