Medicare covers proton beam therapy, but only for specific cancers and only when your doctor documents that it offers a real advantage over standard radiation

Medicare Part B covers proton beam therapy as a form of radiation treatment, but the coverage comes with conditions. Your doctor must show that proton therapy is medically necessary for your particular cancer — not just that it exists as an option. For some cancers, Medicare considers proton therapy standard treatment. For others, it requires prior approval from Medicare before you start.

The cost to you depends on whether you have Original Medicare alone, a Medigap plan, or a Medicare Advantage plan. With Original Medicare, you pay 20 percent of the approved amount after you meet your Part B deductible. The approved amount varies by facility and region, so your out-of-pocket cost is not the same everywhere.

Key Takeaways

  • Medicare covers proton beam therapy for certain cancers including eye melanoma, some brain tumors, and pediatric cancers, without requiring prior approval.
  • For other cancers, your doctor must request prior approval from Medicare and explain why proton therapy is medically necessary for your specific case.
  • You pay 20 percent of Medicare's approved amount after meeting your Part B deductible, unless you have Medigap or Medicare Advantage coverage.
  • Proton therapy facilities are limited in number, so you may need to travel, and Medicare covers travel costs only under specific circumstances.

Which cancers Medicare covers without prior approval

Medicare automatically covers proton beam therapy for eye melanoma (melanoma of the uvea), certain brain and spinal cord tumors, and cancers in children and young adults. For these diagnoses, your doctor does not need to request permission before starting treatment — Medicare considers the therapy medically necessary based on the diagnosis alone.

Pediatric cancers receive automatic coverage because proton therapy reduces radiation exposure to growing tissue and organs around the tumor. This matters more in children because they have decades of life ahead and are at higher risk of developing secondary cancers from radiation. Medicare recognizes this benefit and covers the treatment without requiring your doctor to make a case for it.

Cancers that require prior approval

For breast cancer, lung cancer, prostate cancer, and other solid tumors, Medicare requires your radiation oncologist to request prior approval before treatment begins. Your doctor submits documentation showing your specific tumor location, size, and why proton therapy offers an advantage over conventional photon radiation for your case.

Medicare's medical review process typically takes 5 to 10 business days. Your doctor's office handles the request, so you do not submit it yourself. If Medicare denies the request, your doctor can appeal with additional clinical information, or you can pursue an appeal through Medicare's formal process — though this adds time before treatment can start.

What you pay out of pocket

With Original Medicare, you are responsible for 20 percent of the approved amount after you meet your Part B deductible (which is $240 in 2024, though this amount changes yearly). Proton therapy typically involves 15 to 40 treatment sessions, so your total out-of-pocket cost depends on how many sessions you receive and the approved amount at your facility.

If you have a Medigap plan (supplemental insurance), your plan may cover some or all of the 20 percent coinsurance, depending on which Medigap plan you hold. If you have a Medicare Advantage plan, your costs depend on your plan's copay structure and whether the proton facility is in your plan's network. Always check with your plan before starting treatment, because out-of-network facilities may cost you significantly more.

Finding a proton therapy facility covered by Medicare

Proton beam therapy centers are not in every city. The United States has roughly 30 to 35 proton facilities, concentrated in major medical centers and cancer hospitals. Your oncologist will refer you to a facility that treats your cancer type and accepts Medicare.

Before scheduling treatment, confirm that the facility is Medicare-approved and that your specific treatment plan is covered. Facilities can tell you the approved amount Medicare will pay, which helps you calculate your 20 percent share. If the nearest facility is far from home, ask your social worker or patient advocate whether Medicare covers travel costs — coverage is limited and depends on your specific situation and the facility's distance from your home.

How proton therapy differs from standard radiation

Proton beam therapy uses protons instead of X-rays to target tumors. Protons deposit most of their energy at the tumor site and then stop, releasing less radiation to surrounding healthy tissue. Standard radiation (photon therapy) releases energy both before and after the tumor, exposing more of the body to radiation.

This difference matters most when the tumor is near critical structures — the eye, the brain, the heart, or organs in children. For some cancers in less sensitive locations, the benefit of proton therapy over standard radiation is smaller, which is why Medicare requires prior approval for those cases. Your doctor weighs the benefit against the added cost and logistics of traveling to a proton facility.

Appealing a Medicare denial

If Medicare denies prior approval for proton therapy, your doctor can appeal by submitting additional clinical evidence. This might include imaging showing tumor location, pathology reports, or published studies supporting proton therapy for your specific situation. The appeal process takes another 5 to 10 business days.

You also have the right to request a peer-to-peer review, where your doctor speaks directly with a Medicare medical reviewer. This conversation sometimes resolves disagreements faster than a written appeal. Your doctor's office can request this review on your behalf. If Medicare denies the appeal, you can pursue a formal appeal through Medicare's independent review process, though this delays treatment further.

Frequently Asked Questions

Does Medicare cover proton therapy for all cancers?

No. Medicare covers it automatically for eye melanoma, certain brain tumors, and pediatric cancers. For other cancers, your doctor must request prior approval and show that proton therapy is medically necessary for your specific case. Medicare may deny approval if standard radiation is considered adequate treatment.

How long does prior approval take?

Medicare typically reviews prior approval requests within 5 to 10 business days. Your doctor's office submits the request, so you do not need to do anything. If Medicare denies it, your doctor can appeal, which takes another 5 to 10 days. Plan ahead so treatment is not delayed.

What if the nearest proton facility is hours away?

Medicare does not routinely cover travel costs, though some programs at major cancer centers offer lodging information. Ask your social worker or the proton facility's patient advocate about local resources. Some patients use grants from cancer organizations or negotiate payment plans with the facility.

Will my Medicare Advantage plan cover proton therapy?

Coverage varies by plan. Some Medicare Advantage plans cover proton therapy the same way Original Medicare does; others have different rules or require the facility to be in-network. Contact your plan before your doctor requests prior approval so you know what your plan will cover.

Can I switch to Original Medicare to get proton therapy covered?

You can switch from Medicare Advantage to Original Medicare during the Annual Enrollment Period (October 15 to December 7) or if you have a may have access to life event. However, treatment cannot wait months for enrollment to open. Talk to your doctor and your current plan about coverage options now, rather than waiting to switch plans.