Analysis of circulating tumor cells (CTCs) in blood samples prior to definitive therapy for prostate cancer (PCa) may provide another way to risk stratify patients with high-risk disease, according to study findings presented at the Society of Urologic Oncology 17th annual meeting in San Antonio, Texas.
If the findings are confirmed in a larger independent cohort with longer follow-up, use of CTCs prior to therapy may help predict biochemical recurrence (BCR) and potentially identify patients who might require multimodal therapy, a research team led by Simpa Salami, MD, MPH, of the University of Michigan in Ann Arbor concluded.
Dr Salami and colleagues collected blood samples from 45 men with high-risk localized PCa prior to undergoing treatment with either radiotherapy (with or without androgen-deprivation therapy) or radical prostatectomy (RP). Using the Epic Sciences platform, investigators analyzed the blood samples, characterizing them for traditional CTCs (CK+, intact nuclei) and CTC subtypes (CK-, CTCs, CTC clusters, and apoptotic CTCs (fragmented nuclei). They correlated CTC counts with biochemical recurrence (BCR), defined as a 0.2 ng/mL or greater PSA level.
Of the 45 patients, 26 underwent RP and 19 underwent radiotherapy with or without ADT. The median follow-up was 301 days (range 20–657). Twenty-eight patients (62%) had more than 1 CTC/mL, and 14 (31%) of patients had more than 3 CTC/mL. BCR occurred in 14 (53.8%) of the 26 RP patients compared with 1 (5.2%) of 19 radiotherapy patients. Subsequent metastases developed in 4 RP patients (15.3%) compared with 1 radiotherapy patient (5.2%). Among RP patients, the presence of more than 2.5 CTC/mL was associated with nearly 7-fold increased odds of BCR, although this increased risk was of borderline statistical significance.
Use of CTCs for phenotypic and genomic characterization may provide an additional means of risk stratifying patients with newly diagnosed high-risk PCa, according to the researchers.
1. Salami S, Singhal U, Spratt DE, et al. Prevalence and prognostic significance of circulating tumor cells (CTC) in clinically localized prostate cancer. Presented at the Society of Urologic Oncology 17th annual meeting in San Antonio, Texas.