Genomic Test May Reveal Which Prostate Cancer Patients Gain Most From Hormone Therapy

A new molecular analysis of a major radiation oncology clinical trial suggests that the biology of a prostate tumor, read through a genomic classifier originally developed for breast cancer, could help clinicians decide which men with rising prostate-specific antigen levels after prostate surgery stand to gain the most from adding hormone therapy to salvage radiation. The findings, drawn from the NRG Oncology-led NRG-RTOG 0534 trial known as SPPORT, were presented during the Clinical Trials Session of the 2026 American Society for Radiation Oncology Annual Meeting in Boston, Massachusetts, and they point toward a future in which treatment intensification after prostatectomy is guided less by one-size-fits-all rules and more by the molecular fingerprint of each patient’s cancer.

The analysis centered on the Luminal B, or LumB, molecular subtype, identified using the PAM50 genomic classifier. PAM50 measures the activity of fifty genes to assign tumors to biologically defined subgroups, an approach with a long track record in breast cancer management, where it helps determine who benefits from chemotherapy and endocrine therapy. Applying the same classifier to prostate tumors represents an effort to bring that level of biological stratification into a disease that has, until recently, been managed largely on clinical parameters such as PSA levels, Gleason grade, surgical margin status, and imaging findings.

Luminal B prostate cancers are generally associated with more aggressive disease behavior and increased androgen receptor signaling. That characteristic is central to why researchers hypothesized that these tumors might be particularly vulnerable to androgen deprivation therapy, the hormone-based treatment that suppresses the signaling pathway prostate cancer cells rely on for growth. If a tumor is driven hard by androgen receptor activity, starving that pathway pharmacologically could, in principle, deliver a disproportionate benefit compared with tumors whose growth is less dependent on the same axis.

The SPPORT trial itself compared three treatment strategies in men who required salvage radiation therapy following a detectable or rising PSA after radical prostatectomy. Participants were assigned to radiation to the prostate bed alone, radiation plus short-term androgen deprivation therapy, or radiation plus short-term androgen deprivation therapy together with pelvic lymph-node radiation. The trial has previously shaped practice by clarifying when hormone therapy and nodal treatment add value to salvage radiotherapy, and the new molecular analysis revisits those results through the lens of tumor biology.

For the subtype analysis, researchers obtained prostate tissue from 709 patients and used PAM50 to classify each tumor as either Luminal B or non-LumB. After adjusting for other factors that could influence outcomes, LumB tumors were associated with a higher risk of disease progression and distant metastases, confirming that the subtype carries prognostic weight in the post-prostatectomy salvage setting. More striking, however, was what happened when the researchers examined whether the benefits of treatment intensification differed between the two biological groups.

The answer was a clear interaction between subtype and therapy. Adding short-term androgen deprivation therapy, with or without pelvic lymph-node radiation, to prostate-bed radiation provided a greater benefit for patients with LumB tumors than for those whose tumors were classified as non-LumB. At five years, the absolute improvement in freedom from progression was 31 percent for LumB patients compared with 10 percent for non-LumB patients, a difference that reached statistical significance with a p-value of 0.01. The pattern extended to longer-term control of metastatic disease: at ten years, the absolute improvement in metastasis-free survival was 20 percent for LumB patients, while non-LumB patients showed an improvement of negative 3 percent, with a p-value of 0.05.

Those numbers carry substantial clinical implications. A 31 percent absolute gain in freedom from progression at five years is a large treatment effect by the standards of oncology, and the contrast with the much smaller benefit observed in non-LumB tumors suggests that a meaningful fraction of men currently receiving hormone therapy with salvage radiation may be exposed to its side effects without a commensurate reduction in their risk of progression or metastasis. Androgen deprivation therapy, even when limited to a short course, can cause hot flashes, fatigue, sexual dysfunction, and metabolic changes, so identifying patients unlikely to benefit would allow clinicians to spare them those burdens while concentrating intensified therapy where it does the most good.

Phuoc T. Tran, MD, PhD, of the University of Texas MD Anderson Cancer Center and lead author of the SPPORT analysis, framed the results as a step toward biologically informed personalization. According to Tran, the findings suggest that the biology of a patient’s prostate cancer may help determine who is most likely to benefit from adding hormone therapy to salvage radiation, and he emphasized that future research should focus on validating PAM50 as a predictive biomarker and determining whether molecular testing can help personalize treatment by identifying patients who may benefit from more intensive therapy while sparing others from treatment and its potential side effects when it is unlikely to provide meaningful benefit.

The distinction between a prognostic and a predictive biomarker is important for interpreting the work. A prognostic marker, such as the association between LumB status and higher risk of progression observed here, tells clinicians something about the likely natural course of a disease regardless of treatment. A predictive marker, by contrast, identifies patients whose outcomes will change in response to a specific therapy. The SPPORT subtype analysis provides evidence pointing in the predictive direction, because the benefit of androgen deprivation therapy differed by subtype, but the investigators themselves stress that formal validation is required before PAM50 testing can be recommended as a standard tool for treatment selection in the salvage setting.

Several questions will need to be answered before molecular testing changes routine practice. The analysis was conducted within a single large cooperative-group trial, and its findings will need replication in independent cohorts and, ideally, in prospectively designed studies that assign therapy based on PAM50 results. Questions also remain about the optimal assay workflow, the cost-effectiveness of molecular testing in the salvage population, and whether the classifier retains its value in patients with different clinical risk profiles or in the era of advanced prostate-specific membrane antigen PET imaging, which is reshaping how recurrent disease is detected and targeted after prostatectomy.

Even so, the analysis adds momentum to a broader movement in genitourinary oncology toward biology-driven treatment decisions. Genomic classifiers are already used to guide surveillance and adjuvant decisions in other contexts of prostate cancer care, and the SPPORT results extend that logic to one of the most common clinical dilemmas in the field: what to do, and how intensively to treat, when PSA rises after surgery. The work was supported by grants U10CA180868, U10CA180822, and U24CA196067 from the National Cancer Institute, part of the National Institutes of Health, and the content is the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. If validation studies confirm the signal, a fifty-gene test performed on routinely collected prostate tissue could become the tool that separates men who need hormone therapy from those who can safely be spared it, turning a decades-old treatment decision into a precisely targeted one.

Subject of Research: PAM50 Luminal B molecular subtyping to predict benefit from androgen deprivation therapy in post-prostatectomy salvage radiotherapy

Article Title: NRG Oncology SPPORT analysis highlights potential role of genetic testing in identifying prostate cancer patients who may benefit most from hormone therapy

Article References: NRG Oncology SPPORT analysis highlights potential role of genetic testing in identifying prostate cancer patients who may benefit most from hormone therapy. (n.d.). Original publication

Image Credits: AI Generated

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Keywords: prostate cancer, PAM50, Luminal B, androgen deprivation therapy, salvage radiation, NRG Oncology, SPPORT trial, biomarker, genomic classifier, metastasis-free survival, ASTRO 2026, personalized medicine