Newly diagnosed high-risk localized prostate cancer after multiple [177Lu]Lu-PSMA radioligand therapy in the context of metastatic parotid carcinoma: a case report

Background Prostate-specific membrane antigen-direct radioligand therapy (PSMA RLT) is primarily used to treat castration-resistant metastatic prostate cancer (PCa) after prior treatment options have been exhausted. Occasionally, other tumor entities, such as parotid carcinoma in this case, also express prostate-specific membrane antigen (PSMA) on their cell surface. Case description We present the case of a white 67-year-old patient newly diagnosed with locally advanced PCa despite multiple cycles of Lutetium-177-labeled prostate-specific membrane antigen radioligand therapy ([177Lu]Lu-PSMA-RLT), which he had received for metastatic parotid carcinoma. Interestingly, no regressive histopathological changes were found in the prostate biopsy specimen, despite given PSMA-expression in the prostate. Conclusion The potential selection of high-grade disease, which appears to have occurred in this patient, underscores the need for further large-scale histopathological examination and thorough follow-up of the current investigational approaches using [177Lu]Lu-PSMA-RLT in high-risk prostate cancer (PCa).