Out-of-pocket cost modeling of EUROPA trial arms for adjuvant breast cancer therapy: Five days of radiation versus five years of antiestrogen therapy.

519 Background: Optimal adjuvant therapy following breast-conserving surgery in adults with low-risk, early-stage breast cancer remains uncertain. Cost and financial toxicity remain significant concerns for breast cancer patients. There is limited granular analysis of the role of insurance in the aggregate cost of five fractions of adjuvant radiotherapy (RT) versus adjuvant endocrine therapy (ET), as is being explored in the EUROPA Phase III trial. This study aims to disaggregate costs, estimate out-of-pocket (OOP) expenses by insurance plan, and increase transparency to better inform treatment decisions. Methods: Treatment protocols were aligned with the EUROPA trial arms. For our financial model, we used five-fraction RT and ET prescribed over 5 years, with follow-up after two years (consistent with EUROPA trial results) and five years (full duration of prescribed antiestrogen therapy). OOP costs, deductibles, and copays/coinsurance were calculated using Medicaid, Original Medicare, Medigap Plan G, and Medicare Part D plans. Data sources included medicare.gov, medicaid.oh.gov, aarpmedicareplans.com, and the CMS physician fee schedule. Price estimates reflect actual insurance plan costs rather than claims data. The model assumes a Medicare- and/or Medicaid-eligible patient aged ≥ 70 years with early-stage estrogen-receptor positive breast cancer after breast-conserving surgery. Results: Original Medicare beneficiaries face estimated OOP treatment costs of $1,049.06 for adjuvant ET at 24 months and $2,130.25 at five years. For five-fraction RT, the estimated OOP costs are $1,490.93 at 24 months and $2,320.12 at five years. Medigap Plan G beneficiaries incur lower OOP expenses: $682 for adjuvant ET at 24 months and $1,705 at five years, and $514 at 24 months and $1,285 at five years for five-fraction RT. In contrast, Medicaid beneficiaries have no OOP expenses for either treatment option, as Medicaid fully covers all treatments. Conclusions: The EUROPA trial highlights HRQOL outcomes at 24 months for endocrine therapy versus radiotherapy in women aged 70+ with luminal A-like early breast cancer. This cost analysis, based on actual cost estimates, provides a clear comparison of OOP expenses across Medicaid and Medicare plans. While RT has higher upfront OOP costs at 24 months under Original Medicare, the cost difference narrows over five years, with RT incurring slightly higher cumulative costs. This reflects RT’s one-time nature versus the ongoing costs of ET, which more than doubles over the same period. Medigap Plan G beneficiaries experience significantly reduced OOP costs, favoring RT further at five years, while Medicaid eliminates OOP costs entirely for either treatment, ensuring equitable access to both options. These findings support the initial EUROPA trial results favoring RT over ET for HRQOL and treatment-related toxicity.