Medicare Coverage for Breast Cancer: Screening, Surgery, Drugs, and Reconstruction

Breast cancer is the most commonly diagnosed cancer in women, and the majority of new cases occur in women over 65—squarely in the Medicare population. A breast cancer diagnosis sets off a long, multi-stage treatment journey: screening, diagnostic imaging, surgery, reconstruction, radiation, chemotherapy, targeted drugs, and years of hormone therapy and surveillance. Each stage touches a different part of Medicare with different cost-sharing. This guide maps the entire path, so you know what Medicare pays, where your out-of-pocket exposure is largest, and how supplemental coverage protects you.

Screening: Mammograms Are Free

Medicare covers breast cancer screening at no cost when you use a provider who accepts assignment:

• Annual screening mammograms for women 40 and older are covered at 100 percent—no deductible, no coinsurance. (Medicare also covers a one-time baseline mammogram for women 35–39.)
• The screening must be billed as a screening mammogram (preventive). This is one of the most valuable preventive benefits in Medicare and you should use it every year.

The free benefit applies only to screening. The moment imaging shifts from screening to diagnostic—because a lump was felt or the screening mammogram found something suspicious—cost-sharing begins.

Diagnostic Workup Under Part B

Once a finding needs investigation, services move to diagnostic status and are covered under Part B at 80 percent after the $257 deductible (2026), leaving you 20 percent coinsurance:

• Diagnostic mammogram — 20 percent coinsurance (unlike the free screening version)
• Breast ultrasound and breast MRI — 20 percent coinsurance
• Biopsy (core needle, stereotactic, or surgical) and pathology — 20 percent coinsurance
• Genetic and tumor testing — BRCA testing for qualifying patients, and tumor genomic assays like Oncotype DX and MammaPrint that guide chemotherapy decisions, are covered under Part B when criteria are met
• Staging scans — CT, PET-CT, and bone scans for staging are covered at 20 percent coinsurance

The 20 percent coinsurance on a diagnostic workup—multiple imaging studies, biopsy, pathology, genomic testing—can total several thousand dollars before treatment even begins. This is the first point where supplemental coverage matters.

Surgery and Reconstruction

Breast cancer surgery is covered under Medicare, with the part depending on inpatient versus outpatient status:

• Lumpectomy (breast-conserving surgery) — usually outpatient, covered under Part B at 20 percent coinsurance for the surgeon and facility.
• Mastectomy — may be inpatient (Part A, subject to the $1,676 hospital deductible per benefit period in 2026) or outpatient (Part B), governed by the two-midnight rule. Whether you are admitted as an inpatient or kept under observation affects your costs and any later skilled nursing eligibility.
• Sentinel lymph node biopsy and axillary dissection — covered as part of the surgical procedure.
• Breast reconstruction — federal law (the Women’s Health and Cancer Rights Act) requires Medicare to cover reconstruction after a mastectomy, including implants or autologous (flap) reconstruction, surgery on the opposite breast to produce symmetry, and external breast prostheses and post-surgical bras. Reconstruction is covered under Part A or Part B depending on setting. External breast prostheses are covered as durable medical equipment under Part B.

For how inpatient cost-sharing and the two-midnight rule work, see Medicare Part A Coverage.

Radiation Therapy

Most breast cancer patients who have a lumpectomy, and many who have a mastectomy, undergo radiation. Radiation therapy is covered under Part B at 20 percent coinsurance, whether delivered as:

• Whole-breast external beam radiation (typically 3–6 weeks of daily treatments)
• Hypofractionated or accelerated partial breast irradiation
• Brachytherapy (internal radiation)

Because a course of radiation involves many individual treatment sessions, the cumulative 20 percent coinsurance can reach a few thousand dollars. There is no annual cap under Part B alone.

Chemotherapy and Targeted Drugs: The Part B vs. Part D Split

This is where breast cancer costs become large, and where the Part B vs. Part D distinction—covered in depth in Medicare Part B vs. Part D Drugs—drives your exposure.

Infused Drugs Covered Under Part B (20%, No Cap)

Drugs infused or injected by a clinician are Part B physician-administered drugs, covered at 20 percent coinsurance with no annual out-of-pocket maximum:

• Traditional IV chemotherapy — doxorubicin, cyclophosphamide, paclitaxel, docetaxel, carboplatin
• HER2-targeted antibodies — trastuzumab (Herceptin and biosimilars), pertuzumab (Perjeta), the fixed-dose combination Phesgo (subcutaneous), and ado-trastuzumab emtansine (Kadcyla) and trastuzumab deruxtecan (Enhertu)
• Immunotherapy — pembrolizumab (Keytruda) for triple-negative breast cancer
• Sacituzumab govitecan (Trodelvy) — for metastatic triple-negative disease
• Fulvestrant (Faslodex) — an injected hormonal agent given by a clinician
• Bone-protective agents — zoledronic acid (Zometa) and denosumab (Xgeva) for bone metastases

HER2-positive treatment is illustrative of the cost. A standard year of Herceptin plus Perjeta runs well over $100,000 in drug cost; 20 percent coinsurance with no cap can exceed $20,000 in a single year for a beneficiary without supplemental coverage. This uncapped Part B exposure is the single largest financial risk in breast cancer treatment.

Oral Drugs Covered Under Part D ($2,000 Cap)

Pills you take at home are Part D, where out-of-pocket spending is capped at $2,000 per year (2025 onward):

• CDK4/6 inhibitors — palbociclib (Ibrance), ribociclib (Kisqali), abemaciclib (Verzenio)—oral drugs for HR-positive metastatic disease with list prices around $15,000/month, now capped at $2,000/year out of pocket
• Hormone (endocrine) therapy — tamoxifen and aromatase inhibitors (anastrozole, letrozole, exemestane), taken daily for 5–10 years; these are inexpensive Tier 1 generics, typically $5–$15/month
• PARP inhibitors — olaparib (Lynparza), talazoparib (Talzenna) for BRCA-mutated cancer—oral, capped at $2,000/year
• Elacestrant (Orserdu) and alpelisib (Piqray) — oral targeted agents, Part D

The $2,000 Part D cap is a profound improvement for breast cancer patients on oral targeted therapy. A CDK4/6 inhibitor that once cost a beneficiary $10,000+ per year out of pocket is now bounded at $2,000. See Medicare Part D Explained for how the cap and the Medicare Prescription Payment Plan (spreading the $2,000 across monthly installments) work.

Why Medigap Is the Decisive Factor

Notice the asymmetry: oral drugs are capped at $2,000, but infused HER2 therapy and IV chemo under Part B have no cap—and that is exactly where the biggest dollars are. The protection against that uncapped exposure is Medigap Plan G, which pays the 20 percent Part B coinsurance.

For a HER2-positive patient on a year of Herceptin and Perjeta:

• Original Medicare, no Medigap: roughly $20,000+ in Part B coinsurance, no ceiling
• Original Medicare + Plan G: $0 beyond the Part B deductible for the entire course

That single difference can exceed $20,000 in one treatment year. For anyone facing breast cancer, comprehensive supplemental coverage is the most important financial decision they can make. To compare options, see Medigap Plans Compared and Medicare Supplement vs. Advantage Costs.

Medicare Advantage Considerations

Medicare Advantage plans cover the same cancer treatment and—unlike original Medicare alone—cap your annual medical out-of-pocket spending, which protects against uncapped Part B drug coinsurance. But for cancer, the trade-offs are real:

• Prior authorization on chemotherapy, targeted drugs, scans, and surgery can delay treatment
• Network restrictions may limit which cancer center and oncologist you can use—an issue if you want an NCI-designated comprehensive cancer center
• Out-of-pocket maximums still run several thousand dollars before protection kicks in

If you are already in MA at diagnosis, you generally cannot switch to original Medicare plus Medigap mid-treatment without medical underwriting (outside your enrollment windows). Choosing the right structure before a diagnosis is far better than scrambling after. See Medicare Advantage vs. Original Medicare.

Survivorship, Surveillance, and Supportive Care

Breast cancer care continues for years after active treatment:

• Surveillance — follow-up visits, annual mammograms (screening mammograms remain free; diagnostic imaging is 20 percent), and tumor marker labs (clinical lab tests at $0).
• Lymphedema treatment — Medicare covers lymphedema therapy and, under a 2024 benefit expansion, lymphedema compression garments as a covered item.
• Bone health — aromatase inhibitors accelerate bone loss; DEXA scans and osteoporosis drugs are covered as described in Medicare Coverage for Osteoporosis.
• Supportive drugs — anti-nausea medications and G-CSF (white-blood-cell support) are covered (injectable forms under Part B, oral under Part D).
• Mental health — counseling and psychiatry during and after treatment are covered under Part B. See Medicare Mental Health Coverage.
• Home health and skilled nursing — covered for homebound patients or after a qualifying inpatient stay.

Low-Income Assistance

Cancer drug costs should never go unmanaged. Extra Help (Part D Low-Income Subsidy) reduces oral cancer and hormone-therapy copays to a few dollars; Medicare Savings Programs (QMB, SLMB, QI) can cover Part B premiums and the 20 percent coinsurance on infused chemo and HER2 drugs—the exact exposure that is otherwise uncapped. Cancer-specific charities (CancerCare, the Patient Advocate Foundation, the Pink Fund) provide additional help. See Medicare Savings Programs.

Cost Comparison: A Year of HER2-Positive Treatment

Key Takeaways

• Screening mammograms are free every year for women 40+; diagnostic imaging after a finding shifts to 20 percent coinsurance.
• Surgery, reconstruction, and radiation are covered (reconstruction is guaranteed by federal law), with cost-sharing under Part A or Part B depending on setting.
• Infused chemo and HER2 drugs (Herceptin, Perjeta, Enhertu, Keytruda) are Part B at 20 percent with no annual cap—the largest financial risk, potentially $20,000+/year without supplemental coverage.
• Oral targeted and hormone drugs (Ibrance, Verzenio, Lynparza, aromatase inhibitors) are Part D, capped at $2,000/year.
• Medigap Plan G eliminates the uncapped Part B coinsurance—the single most valuable protection for a cancer patient.
• Extra Help and Medicare Savings Programs dramatically lower costs for low-income beneficiaries.

For the overarching guide to cancer coverage across all tumor types, see Medicare Cancer Treatment Coverage. For budgeting a major diagnosis, see Healthcare Costs in Retirement.