Medicare Insurance Type and Broad Genomic Profiling in Metastatic Cancer

Importance: Broad genomic profiling (BGP) is recommended for several types of metastatic cancer but remains underused. Over half of Medicare beneficiaries are enrolled in Medicare Advantage (MA), where cost-containment strategies may limit access to BGP. Whether Medicare payer type and geographic region are associated with BGP use is not well established. Objectives: To evaluate whether BGP use differs by Medicare payer type (MA vs fee-for-service Medicare [FFS]) and to characterize geographic variation in BGP use across hospital referral regions (HRRs). Design, Setting, and Participants: This nationwide retrospective cohort study used Medicare Chronic Conditions Data Warehouse claims and service records to identify beneficiaries aged 66 years or older with a new diagnosis of metastatic cancer, including bladder, breast, colorectal, endometrial, kidney, lung, melanoma, pancreatic, prostate, or thyroid, from January 1, 2020, to June 30, 2022. Data analysis was conducted from October 2024 to March 2026. Exposures: Medicare type (FFS vs MA) and HRR. Main Outcomes and Measures: The primary outcome was receipt of BGP within 2 months before through 6 months after diagnosis. Mixed-effects logistic regression models were used to estimate adjusted odds ratios (AORs) for the association between Medicare type and BGP use, controlling for demographic, clinical, and geographic factors. HRR-level variation was summarized using the median odds ratio (MOR). Subgroup analyses stratified cancers by the strength of guideline recommendations for BGP. Results: Of 254 720 Medicare beneficiaries with metastatic cancer (median age, 74 years [IQR, 70-79 years]; 141 964 female [55.7%]), 112 637 (44.2%) were enrolled in MA and 142 083 (55.8%) in FFS. Overall, 64 351 (25.3%) received BGP. FFS beneficiaries had higher BGP use than MA beneficiaries (36 633 of 142 083 [25.8%] vs 27 718 of 112 637 [24.6%]; AOR, 1.08 [95% CI, 1.06-1.10]). BGP use was more frequent among FFS vs MA beneficiaries for cancers with equivocal BGP recommendations (AOR, 1.15 [95% CI, 1.11-1.19]) and, to a lesser extent, cancers with explicit recommendations (AOR, 1.04 [95% CI, 1.02-1.07]). Adjusted BGP use varied widely across HRRs (range, 13.8%-35.9%; median, 24.5% [IQR, 21.8%-27.6%]; MOR, 1.28 [95% CI, 1.25-1.31]). Conclusions and Relevance: In this cohort study of Medicare beneficiaries with metastatic cancer, BGP use differed by Medicare payer type and showed substantial regional variation. These findings highlight opportunities to improve guideline-concordant molecular testing.