Assessing IMPT Outcomes Across Localized Prostate Cancer Risk Groups

In an interview with CancerNetwork®, at the 2026 American Society for Radiation Oncology (ASTRO) Annual Meeting, Marcio A. Fagundes, MD, discussed disease control outcomes by risk group from his institution’s experience with intensity-modulated proton therapy (IMPT) in localized prostate cancer. Fagundes is vice chair of Radiation Oncology, director of International Outreach, and a radiation oncologist at Baptist Health Herbert Wertheim Cancer Institute (WCI) in Miami, Florida.

The study included 404 patients with prostate cancer treated with IMPT at the institution between 2018 and December 2023. With a median follow-up of more than 4 years, recurrences were rare among patients with intermediate-risk disease and somewhat more frequent among those with high- and very high–risk disease. Most patients in the high- and very high–risk groups also received pelvic nodal irradiation.

Transcript:

CancerNetwork: How did biochemical relapse-free survival and overall disease control compare across the intermediate-, high-, and very high–risk cohorts in your study of intensity-modulated proton therapy?

Fagundes: When we talk about biochemical disease control, we are talking about patients with prostate cancer whom we treat and whose [prostate-specific antigen (PSA)] goes down and does not come back up. Biochemical recurrence is defined as a rise in PSA that may be caused by recurrence of cancer. In a patient who is treated successfully, we expect the PSA to remain low. In patients with favorable intermediate- or unfavorable intermediate-risk [disease], the results are generally better, with a better than 90% chance of remaining free of disease recurrence. In patients with high-risk or very high–risk disease, the recurrence risk may be in the range of 10% to 20%.

This is not a comparative study [against patients who did not receive protons]. This study reports on WCI’s experience treating patients with prostate cancer with proton therapy between 2018 and December 2023. This is the first report of the initial 404 patients, all of whom were treated with proton therapy.

What is interesting is that in patients with high-risk and very high–risk [disease], a substantial number, the majority, also received pelvic nodal radiation as part of their treatment. That is because these patients have an increased risk of cancer spreading to the lymph nodes. Proton therapy can treat the pelvic lymph nodes without increasing the risk of [adverse] effects like diarrhea. The treatment is safer in that sense, and we are giving the same effective dose as you would with conventional radiation, which is intensity-modulated photon radiation.

Reference

Fagundes MA, Hassan H, Rodrigues M-A, et al. Intensity modulated proton therapy (IMPT) for localized prostate cancer: disease control outcomes in intermediate to very-high risk patients. Presented at: 2026 ASTRO Annual Meeting; September 26-30, 2026; Boston, MA. Abstract PQA 06.