10 Year Biochemical Failure Free Survival of Men with CD82 Positive Primary Circulating Prostate Cells Treated by Radical Prostatectomy

Objective: The biological characteristics of circulating prostate cells (CPCs) are probably more important than their mere presence. CD82 is a tumor suppressor, we present the outcome of radical prostatectomy (RP) in men with CD82 positive CPCs. Methods and Patients: consecutive men treated with RP were studied, age, total PSA, Gleason, stage, the presence of extra-capsular extension, positive surgical margens and infiltration of the seminal vesicles and lymph nodes were registered. Biochemical failure was defined as a PSA >0.2ng/ml. Immediately before the RP, 8ml of venous blood was taken to detect CPCs. Mononuclear cells were separated using differential gel centrifugation and CPCs identified using immunocytochemistry with anti-PSA and anti-CD82. The men were divided into three groups; 1) CPC (-), 2) CPC (+) CD82 (+) and 3) CPC (+) CD82 (-). The groups were compared with respect to clinical-pathological findings and biochemical free survival using Kaplan Meier and Cox regression models. Results: 285 men, mean age 65.9 years participated, 61 (21%) were CPC (-); 57 (20%) were CPC (+) CD82 (+) and 167 (59%) were CPC (+) CD82 (-). Group 1 had low grade small volume cancer, in Group 2, low grade but a larger volume than Group 1 and Group 3 high grade cancer. Kaplan Meier biochemical free survival curves at 36, 60 and 120 months were; Group 1 98%, 96% and 90%; for Group 2 93%, 93% and 69% and for Group 3 62%, 44% and 16% respectively. Conclusions: Kaplan Meier survival curves for Group 1 and Group 2 were similar, although Group 2 men had higher PSA values, more advanced staging but a similar Gleason score. Group 3 men had a worse prognosis. The results support that biological characteristics of CPCs are more important than their mere presence identifying men with a high risk of biochemical failure.