Palliative Care for Advanced Cancer in Medicare Advantage and Physician Networks.

Importance: Palliative care (PC) is guideline recommended to improve symptoms and quality of life concurrent with cancer-directed therapy for patients with advanced cancer, yet utilization remains low among Medicare beneficiaries. While Medicare Advantage (MA) enrollment has surpassed traditional Medicare (TM), how PC and other health care utilization differs between MA and TM for beneficiaries with advanced cancer is unknown. Objective: To compare PC, systemic therapy, and hospice utilization among patients with advanced cancer covered by MA vs TM and evaluate whether differences are associated with physician network composition. Design, Setting, and Participants: This retrospective cohort study used linked Surveillance, Epidemiology, and End Results (SEER) and Medicare data for beneficiaries aged 66 years or older diagnosed with distant-stage breast, colorectal, lung, pancreatic, or prostate cancer from January 1, 2016, to December 31, 2021, who had continuous MA or TM enrollment and at least 2 months' survival. Beneficiaries were followed up from diagnosis until the earlier of death or December 31, 2021. Each beneficiary was assigned a treating oncologist; MA beneficiaries within each plan were matched 1:1 to TM beneficiaries based on treating oncologists. Data were analyzed from November 18, 2025, to July 26, 2026. Exposure: Medicare plan type. Main Outcomes and Measures: Time to first PC, systemic therapy, and hospice utilization. Multivariable models estimated the associations between MA enrollment and outcomes before and after matching on treating oncologist, adjusting for sociodemographic and clinical characteristics. Results: Among 135 402 eligible beneficiaries, 32.3% were enrolled in MA and 67.7% in TM; mean (SD) age was 76.2 (6.7) years, and 53.3% were male. Medicare Advantage beneficiaries had higher 6-month cumulative incidence of PC compared with TM beneficiaries (13.3% vs 9.3%; adjusted hazard ratio [AHR], 1.39 [95% CI, 1.35-1.44]; P < .001), particularly those in a health maintenance organization (HMO) plan (AHR, 1.66 [95% CI, 1.60-1.73]; P < .001). After matching, there were no overall differences between MA and TM in PC receipt (AHR, 1.05 [95% CI, 0.98-1.12]; P = .19), and the AHR was attenuated for HMO plans vs TM (AHR, 1.16 [95% CI, 1.08-1.24]; P < .001). Medicare Advantage beneficiaries had lower systemic therapy receipt (adjusted probability difference, -5.38 percentage points [pp]; 95% CI, -6.02 to -4.74 pp; P < .001) and higher hospice enrollment (3.42 pp; 95% CI, 2.82-4.03 pp; P < .001) than TM beneficiaries; differences persisted after matching (systemic therapy: -5.70 pp [95% CI, -6.89 to -4.52 pp]; P < .001; hospice enrollment: 1.68 pp [95% CI, 0.56-2.80 pp]; P = .003). Conclusions and Relevance: In this retrospective cohort study of Medicare beneficiaries with advanced cancer, MA enrollment was associated with increased PC utilization, primarily attributable to differential oncologist network composition. Persistent differences in systemic therapy use and hospice enrollment after matching by treating oncologists suggest that MA plan-level features beyond physician networks and patient characteristics may be associated with these outcomes.