Combining radiotherapy with a drug delays prostate cancer recurrence

Researchers from UCLA Health have shown that combining a second therapeutic agent with radiotherapy keeps prostate cancer recurrence under control for longer, according to updated results from the LUNAR trial published in October 2026 in European Urology. This approach is particularly useful when the disease has returned in a small number of foci, a situation where the challenge is to control visible tumors while delaying hormone therapy.

Radiotherapy targets visible tumors but misses hidden cells

When prostate cancer recurs, doctors can sometimes identify between one and five tumor foci. A stereotactic radiotherapy allows them to be targeted with great precision. However, some cancer cells still escape treatment and remain invisible to examinations. Even PSMA PET imaging, which is particularly sensitive, does not always manage to detect these tiny foci.

Radioactive drug reaches undetectable tumor foci

To reach these hidden cells, researchers are relying on 177Lu-PNT2002, a radioactive compound administered by injection. Transported by the bloodstream, it can reach tumor foci too small to be detected by imaging. Its mechanism relies on the PSMA protein, present on the surface of most prostate cancer cells. By binding to it, the molecule delivers direct radiation to the targeted cells, including in areas inaccessible to localized treatments.

Invisible cancer cells remain a challenge

When prostate cancer recurs, it often reappears in only a few visible spots. The problem is that microscopic cells, too small to be detected, are already circulating elsewhere. A radioactive drug, dispersed in the blood, is precisely hunting these invisible foci.