Baseline serum carcinoembryonic antigen (CEA) is an independent prognostic biomarker for metastatic castration-resistant prostate cancer (mCRPC) patients receiving 177Lu-PSMA therapy.

PURPOSE: 177Lu-PSMA is currently approved for metastatic castration-resistant prostate cancer (mCRPC). However, only a subset of eligible patients derives a meaningful clinical benefit from treatment. To date, there is a lack of validated biomarkers that could help find the best candidates for this radioligand therapy (RLT). METHODS: 142 patients undergoing 177Lu-PSMA therapy were enrolled in a biological observational prospective study, with blood samples collected at baseline for analysis. Clinical characteristics and routinely available laboratory biomarkers - including hemoglobin, alkaline phosphatase, prostate-specific antigen (PSA), and carcinoembryonic antigen (CEA) - were evaluated by uni- and multivariable Cox regression analyses for their association with progression-free survival (PFS) and overall survival (OS). RESULTS: At a median follow-up of 44.0 months, median PFS and OS were 7.0 and 16.8 months, respectively. Elevated baseline CEA was independently associated with shorter PFS (p = 0.026) and OS (p = 0.003). Moreover, combining CEA with PSA improved prognostic discrimination compared with PSA alone. CONCLUSION: Baseline CEA was independently associated with shorter PFS and OS, supporting its role as a promising prognostic biomarker for patients with mCRPC undergoing 177Lu-PSMA therapy. Further studies are warranted to validate its prognostic value and determine whether it also has predictive utility.