CRYOSURGICAL ABLATION OF PROSTATE CANCER: PATTERNS OF CANCER RECURRENCE

Purpose

We determined the rate of biochemical and biopsy failure in relation to the prostate specific antigen (PSA) nadir, the effect of neoadjuvant androgen blockade and the pattern of residual tumor after cryosurgical ablation of prostate cancer.

Materials and Methods

From July 1993 to April 1996, 134 patients underwent 147 cryosurgical ablation procedures. Of those patients, 110 had adequate followup and did not receive post-treatment androgen deprivation. Followup included PSA determination at 3, 6 and 12 months, and every 6 months thereafter. Biopsies were performed at 6 months or with biochemical failure defined as 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 had careful ultrasound guided mapping biopsy preoperatively and postoperatively to define the sites of disease. The likelihood of residual disease was correlated with the initial site(s) of the cancer in an attempt to identify if areas of the prostate and/or seminal vesicles were more likely to be sites of treatment failure.

Results

At a mean followup 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 between 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 biochemical failures (43%) or extremely high PSA nadirs (greater than 30 ng./ml.) necessitating hormonal therapy (11%). Biopsy failure was lowest in 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 values 0.5 ng./ml. or greater had biopsy failure. Biochemical and biopsy failure tended to occur within the first 18 months after treatment. Neoadjuvant androgen blockade appeared to reduce subsequent biochemical 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 cancers. Recurrence was more common in cancers at the apex (9.5%) and seminal 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 should be achieved following cryotherapy. Higher values are associated with 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 blockade reduces the risk of biochemical failure in patients with stages T1 and T2 cancers.