Assessing Early Treatment Response in mCSPC Using KELIM PSA Score: Implications for Survival.

PURPOSE: The prognostic value of the PSA ELIMination rate constant K (KELIM PSA) score was investigated in patients with metastatic castration-sensitive prostate cancer (mCSPC) treated with docetaxel in combination with ADT. METHODS: This multicenter retrospective study included 105 patients diagnosed with prostate adenocarcinoma who received first line docetaxel in combination with ADT for mCSPC. The KELIM score was calculated using PSA kinetics modeled with a nonlinear mixed-effects model. Patients with KELIM PSA<1 were categorized as unfavorable, whereas those with KELIM PSA≥1 were considered favorable. RESULTS: A total of 105 patients were included in the study. There were 53 and 52 patients in the favorable KELIM PSA and unfavorable KELIM PSA groups, respectively. Favorable KELIM PSA patients having a median OS of 44 months compared to 24 months for those with unfavorable KELIM PSA. One-, three-, and five-year OS rates were higher in the favorable KELIM PSA group. In the univariate analysis, ECOG≥2, older age, liver metastasis, and unfavorable KELIM score were associated with worse OS. However, in the multivariable analysis, only definitive treatment and advanced age remained independent prognostic factors for OS. CONCLUSION: The KELIM PSA score may serve as a simple, effective, and inexpensive prognostic tool for assessing early treatment responses and predicting disease progression in patients with mCSPC treated with docetaxel.