Baseline CTC Count as a Predictor of Long-Term Outcomes in High-Risk Prostate Cancer

The aim of the present study was to verify whether the baseline circulating tumor cell (CTC) count might serve as a predictor of overall survival (OS) and metastasis-free survival (MFS) in patients with high-risk prostate cancer (PCa) during a follow-up period of at least 5 years. CTCs were enumerated using three different assay formats in 104 patients: the CellSearch((R)) system, EPISPOT assay and GILUPI CellCollector. A total of 57 (55%) patients survived until the end of the follow-up period, with a 5 year OS of 66% (95% CI: 56-74%). The analysis of univariate Cox proportional hazard models identified a baseline CTC count >= 1, which was determined with the CellSearch((R)) system, a Gleason sum >= 8, cT >= 2c and metastases at initial diagnosis as significant predictors of a worse OS in the entire cohort. The CTC count >= 1 was also the only significant predictor of a worse OS in a subset of 85 patients who presented with localized PCa at the baseline. The baseline CTC number did not affect the MFS. In conclusion, the baseline CTC count can be considered a determinant of survival in high-risk PCa and also in patients with a localized disease. However, determining the prognostic value of the CTC count in patients with localized PCa would optimally require longitudinal monitoring of this parameter.

Automated summary

The aim of this study was to determine if baseline circulating tumor cell (CTC) count could predict overall survival (OS) and metastasis-free survival (MFS) in high-risk prostate cancer (PCa) patients during a follow-up of 5 years or more. Three different assay formats were used to enumerate CTCs in 104 patients, including the CellSearch((R)) system, EPISPOT assay, and GILUPI CellCollector. The results showed that a baseline CTC count of >=1, determined by the CellSearch((R)) system, Gleason sum >=8, cT >=2c, and initial diagnosis with metastases were significant predictors of worse OS in the entire cohort. In a subset of 85 patients with localized PCa at baseline, only baseline CTC count of >=1 was a significant predictor of worse OS. The MFS was not affected by the baseline CTC number. In conclusion, baseline CTC count can be considered a determinant of survival in high-risk PCa and patients with localized disease. However, longitudinal monitoring is necessary to fully understand the prognostic value of CTC count in localized PCa.