When Insurance Says No: How Patients Can Fight Back Against Cancer Treatment Denials

For patients already navigating a cancer diagnosis, an insurance denial can feel like a second blow. Yet denials — particularly for newer, more targeted therapies — are increasingly common, and the consequences are measurable. According to research presented at the 2025 ASCO Quality Care Symposium, three out of four people with cancer had to go through at least one prior authorization process between 2022 and 2024. In half of those cases, patients and families weren’t just bystanders — they had to actively get involved on top of their doctors’ efforts, resulting in more treatment delays, financial strain and stress.

Oncologists and patient advocates say the appeals process is far more winnable than most patients realize — if they know how to use it.

Why Denials Happen

Insurance companies deny cancer treatment claims for several reasons: a therapy may be deemed experimental or not yet guideline-concordant, a prior authorization wasn’t obtained, or the plan’s internal medical policy doesn’t align with what a treating physician has recommended.

That last scenario is especially fraught for Medicare Advantage enrollees. Medicare Advantage plans typically require prior authorization for imaging tests, radiation therapy, inpatient hospital stays, outpatient oncology services, certain types of chemotherapy and many other cancer medicines — and this process can cause treatment delays, denials and inferior care as the insurance company dictates treatment timing and options.

According to KFF, in 2024 Medicare Advantage insurers required providers to submit nearly 53 million prior authorization requests — far more than traditional Medicare.

A report from the U.S. Department of Health and Human Services Office of Inspector General found the problem goes beyond administrative friction. The HHS OIG found that 13% of prior authorization denials in Medicare Advantage were for service requests that actually met Medicare fee-for-service coverage rules — meaning they were likely delaying or preventing care patients were entitled to receive.

The burden falls particularly hard on radiation oncology. Despite its high cost-effectiveness, radiation oncology faces the greatest prior authorization burden of any medical specialty, according to a January 2025 review published in Advances in Radiation Oncology. A peer-reviewed study published in the International Journal of Radiation Oncology found that radiation therapy services were inappropriately denied in roughly 15 to 19% of Medicare Advantage cases reviewed between 2022 and 2024 — compared to an inappropriate denial rate of just 3 to 5% for all other health services combined.

The First Step: Peer-to-Peer Review

One of the most underutilized tools available is the peer-to-peer review — a direct conversation between the treating oncologist and the insurance company’s medical reviewer. Patients can request that their physician initiate this process, and research shows it works.

In one large radiation oncology department, of 123 treatment courses denied and sent to peer-to-peer review, nearly 70% had the denial overturned without any change to the treatment plan. A key factor in successful reviews is grounding the argument in established clinical guidelines. In one oncology clinical trial, a peer-to-peer strategy focused on NCCN guidelines and supporting Level 1 clinical evidence resulted in the reversal of all insurance denials for eligible patients.

However, the quality of these reviews is inconsistent. According to ASTRO’s 2024 survey, only two-thirds of peer-to-peer consultations for radiation therapy are actually conducted by radiation oncologists, raising questions about whether reviewers always have the relevant specialty expertise to evaluate complex oncology cases.

The Formal Appeals Process

If a peer-to-peer doesn’t resolve the denial, patients have the right to file a formal internal appeal. The data here is encouraging — though largely unknown to patients. ASTRO’s 2024 survey found that for denied radiation oncology requests, 73% of denials were ultimately overturned on appeal. A strong appeal should include a detailed letter of medical necessity from the treating oncologist, the patient’s relevant medical records, and supporting clinical evidence — published guidelines from the NCCN or ASCO carry particular weight with reviewers.

The human cost of not appealing is real. The same ASCO research found that prior authorization delays had serious consequences, with 30% of radiation oncologists reporting major patient complications, and 7% linking prior authorization directly to patient deaths.

External Appeals and the Medicare Process

If the internal appeal is denied, patients can escalate to an external independent review — and this is where the playing field often levels. An independent review organization evaluates whether the denial was medically appropriate, and in many states plans are legally bound by the outcome.

For Medicare Advantage patients specifically, the appeals process has five formal levels established by CMS. These include redetermination by a Medicare Administrative Contractor, reconsideration by a Qualified Independent Contractor, a hearing before an Administrative Law Judge through the Office of Medicare Hearings and Appeals, review by the Medicare Appeals Council, and finally judicial review in federal district court. For calendar year 2025, the amount in controversy threshold to reach the federal court level is $1,900.

Patients should also know that among the Medicare Advantage denials that were actually appealed, plans overturned 75% of their own denials at the first level — data the American Cancer Society Cancer Action Network says suggests that plans’ default is to deny claims regardless of medical necessity.

Patient Advocates and Legal Support

Navigating this process alone is difficult. Hospital-based patient navigators are an underused resource — many cancer centers employ staff specifically trained to interface with insurers on a patient’s behalf. Disease-specific patient advocacy organizations often provide case managers who can guide patients through the process at no cost, and some health insurance attorneys work on contingency for wrongful denial cases.

A cross-sectional study published in JAMA Network Open found that among patients with prior authorization experience, most delays lasted two weeks or longer, and the process was rated “bad or horrible” by the majority of respondents — with the experience associated with decreased trust in the health care system overall.

The Bottom Line

A denial is not a final answer. The data consistently shows that patients who appeal — especially with strong physician support and thorough clinical documentation — have a meaningful chance of reversal. “Prior authorization isn’t just an administrative hurdle for clinicians — it’s a hidden second job for patients,” said Dr. Marcin Chwistek, director of Supportive Oncology and Palliative Care at Fox Chase Cancer Center, in an ASCO news release. The tools to push back exist, and knowing how to use them can make a critical difference in care.

References

1. “Prior Authorization Often Places Burden on Patients With Cancer, Delays Care.” American Society of Clinical Oncology. Oct. 6, 2025.
2. “Are Medicare Advantage Plans Bad for People with Cancer?” Breastcancer.org. April 28, 2026.
3. “Prior Authorization Causes Significant Care Delays in Medicare Advantage, Federal Agency Report Says.” American Society of Clinical Oncology. June 3, 2022.
4. “The Burden of Insurance Prior Authorization on Cancer Care: A Review of Evidence From Radiation Oncology.” Gracie, Jayden, et al. Advances in Radiation Oncology, Elsevier/American Society for Radiation Oncology. Jan. 2025.
5. “Inappropriate Denials for Radiation Therapy in Medicare Advantage Plans.” Pasetsky, Jared, et al. International Journal of Radiation Oncology. March 15, 2025.
6. “New ASTRO Survey Finds That Prior Authorization Delays Lead to Serious Harm for People With Cancer.” American Society for Radiation Oncology. Dec. 4, 2024.
7. “Peer-to-Peer Phone Calls and Letters Appealing Insurance Denials of Service: Practical Tips and Resources.” Yu, James B., et al. Advances in Radiation Oncology, ScienceDirect. July 30, 2024.
8. “Insurance Denial of Care for Randomized Controlled Trial-Eligible Patients: Incidence and Success Rate of Peer-to-Peer Authorization in Allowing Patients to Remain Trial-Eligible.” McClelland, S., et al. American Journal of Clinical Oncology. Oct. 10, 2023.
9. “Original Medicare (Fee-for-Service) Appeals.” Centers for Medicare & Medicaid Services, CMS.gov. Updated Feb. 10, 2025.
10. “Fifth Level of Appeal: Judicial Review in Federal District Court.” Centers for Medicare & Medicaid Services, CMS.gov. Jan. 7, 2025.
11. “The Medicare Appeals Process: Reforms Needed to Ensure Beneficiary Access.” American Cancer Society Cancer Action Network, fightcancer.org. Jan. 28, 2026.
12. “The Patient Experience of Prior Authorization for Cancer Care.” JAMA Network Open, NIH/PubMed Central. Oct. 2023.

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