CRYOSURGICAL ABLATION OF PROSTATE-CANCER - PATTERNS OF CANCER RECURRENCE

Purpose: We determined the rate of biochemical and biopsy failure in r elation to the prostate specific antigen (PSA) nadir, the effect of ne oadjuvant androgen blockade and the pattern of residual tumor after cr yosurgical ablation of prostate cancer. Materials and Methods: From Ju ly 1993 to April 1996, 134 patients underwent 147 cryosurgical ablatio n procedures. Of those patients, 110 had adequate followup and did not receive post-treatment androgen deprivation. Follow up included PSA d etermination at 3, 6 and 12 months, and every 6 months thereafter. Bio psies were performed at 6 months or with biochemical failure defined a s PSA nadir 0.5 ng./ml. or greater or subsequent biochemical failure ( PSA increase 0.2 ng./ml. or greater). Biochemical and biopsy failures were correlated with PSA nadir values following cryosurgery (less than 0.1 ng./ml., 0.1 to 0.4 and or greater 0.5). A total of 68 patients h ad careful ultrasound guided mapping biopsy preoperatively and postope ratively to define the sites of disease. The Likelihood of residual di sease was correlated with the initial site(s) of the cancer in an atte mpt to identify if areas of the prostate and/or seminal vesicles were more likely to be sites of treatment failure. Results: At a mean follo wup of 17.6 months biochemical failure (subsequent rise in PSA 0.2 ng. /ml. or greater) was lowest in those who achieved PSA nadirs less than 0.1 ng./ml. (21%) but it was noted in 48% of patients with nadirs bet ween 0.1 and 0.4 ng./ml. Those patients with PSA nadirs 0.5 or greater had either immediate local failure (46%), subsequent local or biochem ical failures (43%) or extremely high PSA nadirs (greater than 30 ng./ ml.) necessitating hormonal therapy (11%). Biopsy failure was lowest i n those with nadirs less than 0.1 ng./ml. (7%) and those with nadirs 0 .1 to 0.4 ng./ml. (22%). In contrast, 60% of the patients with nadir v alues 0.5 ng./ml. or greater had biopsy failure. Biochemical and biops y failure tended to occur within the first 18 months after treatment. Neoadjuvant androgen blockade appeared to reduce subsequent biochemica l failure in patients with stages T1 and T2 cancers (11% versus 50% in those without androgen deprivation) but not in those with T3 and T4 c ancers. Recurrence was more common in cancers at the apex (9.5%) and s eminal vesicles (44%), in contrast to those located in the mid gland ( 4%) and base (0%). Conclusions: A PSA nadir of 0.4 ng./ml. or less sho uld be achieved following cryotherapy. Higher values are associated wi th a significant risk of continued PSA elevation and a high likelihood of residual disease detected on prostatic biopsy. Local failure tends to occur at the apex and seminal vesicles. Neoadjuvant androgen block ade reduces the risk of biochemical failure in patients with stages T1 and T2 cancers.