Prostate cancer in a large prostate is associated with a decreased prostate specific antigen failure rate after brachytherapy

PSA Rising, July 31, 2005. A large prostate has previously been found to go along with improved prostate cancer survival in men undergoing radical prostatectomy. A team at Mount Sinai Medical Center, New York, in a recent study, analyzed the relationship of prostate size and prostate specific antigen (PSA) failure in men undergoing brachytherapy for localized prostate cancer.

They studied data on 613 men who had undergone I radioactive seed implantation. Average patient age was 65 (plus orminus 7 years). Average prostate volume ultrasonically measured at seed insertion was 40 ml. All patients had a minimum of 2 years of followup.

Results

Men with a large prostate had increased freedom from failure compared to men with a small prostate. Failure time in men with an intermediate size prostate was between that for large and small prostates. This difference in failure rates was statistically significant.

Large prostate size significantly correlated with time to PSA failure and it was independent of the significant effects of Gleason score, PSA, disease stage, minimal radiation dose covering 90% of prostate volume and hormone treatment, including androgen ablation.

Conclusions

Some researchers theorize that paracrine signals, which regulate tissue growth in benign prostatic hypertrophy, have beneficial influences on coexistent prostate cancer.

The Mount Sinai team say, "Our finding that the effect of prostate size is independent of Gleason score, PSA and disease stage supports the paracrine signal mechanism."

"If a circulating substance," they go on, "such as a cytokine, might be responsible for improved survival, this substance might be useful for treating prostate cancer. Moreover, since we found that prostate size is independent of PSA, Gleason score and tumor stage for predicting outcome, we hypothesize that patients with a small prostate treated with brachytherapy might benefit from hormone treatment and larger radiation doses. These measures are now generally reserved for men with more advanced tumors, higher PSA and increased Gleason scores."

In an editorial comment, Dr. Andreas Bohle, Professor of Urology at HELIOS Agnes Karll Hospital, Germany notes that this paper "bears outcome data of one of the largest cohorts of permanent interstitial seed (LDR) brachytherapy treated patients with a long term follow up of 140 months," and should be read carefully.

"In low-risk patients," Bohle says, "around 95% had no progression after 140 months. For intermediate risk patients roughly 12% and for high-risk patients roughly 45% had biochemical progression after 140 months. Interestingly, the curves do not show any further decrease and remain linear 75 months after treatment." Brachytherapy, he concludes, "can no longer be considered an inferior therapeutic option to radical prostatectomy in men with localized prostate cancer."

Reference: UROLOGICAL ONCOLOGY

Prostate cancer in a large prostate is associated with a decreased prostate specific antigen failure rate after brachytherapy
Lehrer S, Stone NN, Stock RG. Department of Radiation Oncology and Urology, Mount Sinai Medical Center, New York, NY 10029, USA
J Urol. 2005; 173: 79-81

Editorial Comment in Int Braz J Urol. 2005 Jan-Feb;31(1):87-8. Bohle A.