Abstract
IMPORTANCE: Enrollment in Medicare Advantage (MA) accounts for more than half of Medicare beneficiaries. Despite this growth, its impact on access to high-quality cancer surgery remains unclear. OBJECTIVE: To evaluate the association between MA enrollment and receipt of surgery at high-quality hospitals among Medicare beneficiaries undergoing major cancer surgery. DESIGN, SETTING, AND PARTICIPANTS: This national retrospective cohort study uses Medicare Provider Analysis and Review (MedPAR) data from January 1, 2016, to November 30, 2022. The study included 567 770 Medicare beneficiaries undergoing elective surgery for esophageal, pancreatic, liver, gastric, bladder, colon, kidney, or prostate cancer at hospitals across the United States. Data analysis was performed from August 2024 to July 2025. EXPOSURE: Enrollment in Medicare Advantage plan. MAIN OUTCOMES AND MEASURES: The primary outcome was surgery at a high-quality hospital, defined by procedure-specific mortality, risk-adjusted for patient characteristics and reliability-adjusted for differences in case volume using mixed-effects logistic regression models. Adjusted hospital mortality was rank ordered and sorted into quintiles. High quality was defined as hospitals in the quintile with the lowest mortality rates. The secondary outcome was likelihood of bypassing the nearest hospital of lower quality to undergo surgery at a high-quality hospital. RESULTS: Among 567 770 beneficiaries undergoing surgery, 351 447 were enrolled in traditional Medicare (TM; 231 104 [65.8%] male, 120 343 [34.2%] female; mean [SD] age, 72.5 [8.0] years) and 216 323 in MA (138 554 [64.0%] male, 77 769 [36.0%] female; mean [SD] age, 72.7 [7.6] years). MA enrollment increased from 32% in 2016 to 46% in 2022. Compared with beneficiaries in TM, MA enrollees were more likely to be from socially vulnerable areas, have more comorbidities, and undergo surgery at nonteaching hospitals across all cancer types. Compared with those in TM, MA beneficiaries were less likely to undergo surgery at a high-quality hospital. For example, 21.7% (95% CI, 20.7%-22.8%) of patients enrolled in TA had an esophagectomy at a high-quality hospital vs 17.3% (95% CI, 16.1%-18.5%) of MA beneficiaries, and 22.6% (95% CI, 22.1%-23.2%) of patients enrolled in TA had a pancreatectomy at a high-quality hospital vs 16.2% (95% CI, 15.6%-16.8%) of those in MA. TM beneficiaries were more likely to bypass a lower-quality hospital to receive surgery at a high-quality hospital for all procedures. CONCLUSIONS AND RELEVANCE: This study found that MA enrollees were less likely to receive cancer surgery at high-quality hospitals and less likely to bypass lower-quality hospitals. These findings suggest that current MA plan networks may limit access to optimal surgical care, raising concerns about the adequacy of cancer care delivery under privatized Medicare.