Hypoxia Scan Cuts Radiation Dose for 3 in 4 HPV Throat Cancer Patients
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- In a Memorial Sloan Kettering analysis of 430 patients presented at ASCO 2026, 323 patients (75%) had no tumor hypoxia on an FMISO PET scan and received 30 Gy of radiation instead of the standard 70 Gy.
- The investigators reported 5-year overall survival of 97% in both the 30 Gy and 70 Gy groups, with median follow-up of about 4 years.
- In an earlier 152-patient report on FMISO-guided treatment, severe acute side effects occurred in 32% of the 30 Gy group and 58.3% of the 70 Gy group, according to the authors.
- Patients whose tumors stayed hypoxic on the FMISO PET scan had more cancer spread to distant organs (7.5% vs 1.3%), the investigators reported, so they may need more treatment.
- A randomized phase 3 trial at Memorial Sloan Kettering, NCT06563479, is enrolling 291 patients to test the approach, with completion listed for August 2027.
Table of Contents
- Why HPV Throat Cancer Radiation De-escalation Makes Sense
- What the Five-Year Results Show
- Research Gap: What a Single-Center Analysis Cannot Settle
- Closing Thoughts
Why HPV Throat Cancer Radiation De-escalation Makes Sense
HPV-positive oropharyngeal cancer, a head and neck cancer of the tonsils and base of the tongue caused by the human papillomavirus, responds unusually well to treatment. Standard care is 70 Gy of radiation, given over 7 weeks, with 3 cycles of chemotherapy [5].
That dose cures most patients, and the cost of the cure is mouth sores, painful swallowing, dry mouth, lost taste and nausea. Memorial Sloan Kettering says patients often lose 20 to 30 pounds and cannot work for months [5].
Because most of these patients survive for decades, the side effects last for decades too. That is why HPV throat cancer radiation de-escalation, meaning giving less radiation to the patients who do not need the full dose, has been a research goal for years. The hard part has been working out which patients are safe to treat with less.
Earlier attempts show the risk. Two randomized phase 3 trials published in 2019, RTOG 1016 and De-ESCALaTE, replaced the chemotherapy drug cisplatin with cetuximab to reduce side effects, and patients on cetuximab had worse survival and more cancer recurrence. Both trials concluded that radiation with cisplatin remains the standard of care [6, 7].
Other groups are testing different routes to lower doses. NRG Oncology’s HN005 trial, for example, compares standard 70 Gy treatment with a moderately lower 60 Gy dose given with either cisplatin or the immunotherapy drug nivolumab, without a scan to choose who gets less [8].
How an FMISO PET Scan Decides the Dose
The Memorial Sloan Kettering program uses a tumor’s oxygen level to decide. Tumor hypoxia, meaning low oxygen inside a tumor, makes cancer cells more resistant to radiation, because radiation damages DNA largely through oxygen-dependent chemistry.
18F-fluoromisonidazole, or FMISO, is a radioactive tracer that builds up in hypoxic tissue and lights up on a PET scan, one of several imaging tools that guide cancer care. Patients in the program were scanned before treatment and again 1 to 2 weeks into it [2].
Patients whose tumors showed no hypoxia on the scan during treatment stopped at 30 Gy, given over 3 weeks, with 2 cycles of chemotherapy. Patients whose tumors stayed hypoxic went on to the full 70 Gy [1, 5].
What the Five-Year Results Show
The new analysis, presented at the 2026 ASCO Annual Meeting, pooled 3 consecutive phase II trials, including NCT03323463, that enrolled 430 patients from October 2015 to November 2023 [1, 4]. Of those, 323 patients (75%) qualified for 30 Gy and 107 (25%) received 70 Gy, with a median follow-up of 4.05 years and a longest follow-up of just over 10 years [1].
Five-year overall survival was 97% in both groups. Local failure, meaning cancer returning at the original tumor site, was 2.2% at 30 Gy and 1.9% at 70 Gy [1].
Regional failure in nearby lymph nodes was 6.2% and 3.9%. Progression-free survival was 91% and 89%. None of these differences were statistically significant [1].
The authors concluded that the approach “results in durable long-term outcomes, benefiting ~75% of the patients.” Treatment ran over 3 weeks for most patients instead of 7.
Side Effects at 30 Gy Versus 70 Gy
The 2026 abstract did not report the full cohort’s side-effect data, which the authors said would be presented at the meeting. The clearest published safety data come from the program’s earlier 152-patient report in the Journal of Clinical Oncology [2].
In that report, severe acute side effects (grade 3 or 4) occurred in 32% of the 30 Gy group and 58.3% of the 70 Gy group. Late severe side effects appeared only in the 70 Gy group, where 4.5% of patients had lasting swallowing problems [2].
Nancy Y. Lee, MD, vice chair of radiation oncology at Memorial Sloan Kettering and the program’s lead investigator, described the gap in a statement published by the center [5]. “The difference in toxicity is dramatic,” Lee said.
The 25% Whose Tumors Stayed Hypoxic
The 107 patients who did not qualify for the lower dose produced a separate finding.
Patients whose tumors stayed hypoxic received the full 70 Gy. They still had more distant metastasis (cancer spreading to organs such as the lungs): 7.5%, compared with 1.3% in the 30 Gy group. The difference was statistically significant (p=0.004) [1].
That means the same scan that spares most patients radiation also points to a smaller group at higher risk of spread, much as liquid biopsy tests aim to flag risk from a blood sample. The authors wrote that additional therapy for this group “can be considered in future trials.” The abstract does not name a specific added treatment.
Research Gap: What a Single-Center Analysis Cannot Settle
The pooled data come from nonrandomized trials at one institution. Patients were assigned a dose by their scan result, so the 30 Gy and 70 Gy groups were different kinds of patients from the start, and the comparison cannot show what 30 Gy would have done for a hypoxic tumor.
Median follow-up was about 4 years. That is long enough to judge 5-year survival but short for late radiation effects, which can appear years after treatment. Only 22.3% of patients had more than 10 pack-years of smoking history, so the results say little about heavier smokers [1].
Access is narrow for now. FMISO scanning also depends on specialists who read PET scans. All sites that treat patients on the phase 3 trial are Memorial Sloan Kettering locations; two partner hospitals collect data only [3].
The Phase 3 Trial and FDA Review
The randomized test is NCT06563479, a double-blinded phase 3 trial that compares FMISO-guided treatment with standard chemoradiation in patients who were not selected by scan. It opened in August 2024, plans to enroll 291 patients, uses 2-year overall survival as its primary endpoint and lists August 2027 for completion [3].
The ASCO abstract says more than a third of patients have been randomized [1]. Trials like this one depend on the kind of precision oncology programs that match patients to treatment by test results.
Memorial Sloan Kettering says the FDA gave FMISO a designation that speeds its review, for use in selecting patients for reduced-dose radiation [5]. The tracer is licensed from the center to Juniper Biosciences, according to the same page, which gives the institution a commercial interest in the approach.
Patients with HPV-positive throat cancer who want to know whether reduced-dose radiation applies to them can ask their radiation oncologist about FMISO scanning and about trial eligibility. The phase 3 trial is open to adults with small tumors (T2 or smaller, including cancers with an unknown primary site) that have spread to lymph nodes [3].
Closing Thoughts
The FMISO results are the largest body of evidence so far that a tumor’s oxygen level can pick which HPV throat cancer patients do well on less than half the standard radiation. Survival held at five years in a program that treated 430 patients.
What remains unsettled is whether the approach holds up under randomization and outside a single center, and what to do for the quarter of patients whose tumors stay hypoxic. The phase 3 trial is set to answer the first question by the end of 2027.
References
1. Lee, N. Y., Sherman, E. J., Schöder, H., Wray, R., Dee, E. C., McBride, S. M., Yu, Y., Gelblum, D. Y., Shamseddine, A., Rutter, C., Kalman, N., Wong, W., Dunn, L., Ganly, I., Morris, L., Cracchiolo, J. R., Ho, A. L., Wong, R. J., & Riaz, N. (2026). Long-term outcomes of 18F-fluoromisonidazole positron emission tomography (FMISO PET)–guided major radiation dose de-escalation in HPV-associated oropharyngeal cancer: The 30 ROC approach [Abstract]. Journal of Clinical Oncology, 44(16_suppl), 103. https://doi.org/10.1200/JCO.2026.44.16_suppl.103
2. Lee, N. Y., Sherman, E. J., Schöder, H., Wray, R., Boyle, J. O., Singh, B., Grkovski, M., Paudyal, R., Cunningham, L., Zhang, Z., Hatzoglou, V., Katabi, N., Diplas, B. H., Han, J., Imber, B. S., Pham, K., Yu, Y., Zakeri, K., McBride, S. M., . . . Riaz, N. (2024). Hypoxia-directed treatment of human papillomavirus–related oropharyngeal carcinoma. Journal of Clinical Oncology, 42(8), 940–950. https://doi.org/10.1200/JCO.23.01308
3. Memorial Sloan Kettering Cancer Center. (2024). Phase III randomized and double-blinded trial of de-escalated radiation in FMISO PET-selected good risk versus standard of care radiation in unselected HPV positive oropharyngeal cancer (ClinicalTrials.gov Identifier NCT06563479). https://clinicaltrials.gov/study/NCT06563479
4. Memorial Sloan Kettering Cancer Center. (2017). Major de-escalation to 30 Gy for select human papillomavirus associated oropharyngeal carcinoma (ClinicalTrials.gov Identifier NCT03323463). https://clinicaltrials.gov/study/NCT03323463
5. Memorial Sloan Kettering Cancer Center. (2026, September 3). FDA reviewing low-dose radiation to treat HPV throat cancer with fewer side effects. https://www.mskcc.org/news/low-dose-radiation-possible-game-changer-treating-hpv-positive-head-and-neck
6. Gillison, M. L., Trotti, A. M., Harris, J., Eisbruch, A., Harari, P. M., Adelstein, D. J., Jordan, R. C. K., Zhao, W., Sturgis, E. M., Burtness, B., Ridge, J. A., Ringash, J., Galvin, J., Yao, M., Koyfman, S. A., Blakaj, D. M., Razaq, M. A., Colevas, A. D., Beitler, J. J., . . . Le, Q.-T. (2019). Radiotherapy plus cetuximab or cisplatin in human papillomavirus-positive oropharyngeal cancer (NRG Oncology RTOG 1016): A randomised, multicentre, non-inferiority trial. The Lancet, 393(10166), 40–50. https://doi.org/10.1016/S0140-6736(18)32779-X
7. Mehanna, H., Robinson, M., Hartley, A., Kong, A., Foran, B., Fulton-Lieuw, T., Dalby, M., Mistry, P., Sen, M., O’Toole, L., Al Booz, H., Dyker, K., Moleron, R., Whitaker, S., Brennan, S., Cook, A., Griffin, M., Aynsley, E., Rolles, M., . . . Dunn, J. (2019). Radiotherapy plus cisplatin or cetuximab in low-risk human papillomavirus-positive oropharyngeal cancer (De-ESCALaTE HPV): An open-label randomised controlled phase 3 trial. The Lancet, 393(10166), 51–60. https://doi.org/10.1016/S0140-6736(18)32752-1
8. National Cancer Institute. (2019). A randomized phase II/III trial of de-intensified radiation therapy for patients with early-stage, p16-positive, non-smoking associated oropharyngeal cancer (ClinicalTrials.gov Identifier NCT03952585). https://clinicaltrials.gov/study/NCT03952585
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