Smaller prostate gland associated with high-grade PCa

Atlanta-Men with smaller prostate glands appear to be more likely to develop prostate cancer and have higher Gleason sum disease than are men with larger prostates, according to the results of a new prospective analysis.

"We have previously published findings regarding a relationship between prostate cancer diagnosis (ie, positive transrectal ultrasound) and low AUA symptom score [Urology 2004; 63:90-4]," Dr. Porter told Urology Times. "In this analysis, we wanted to evaluate the relationship of Gleason sum to gland volume more closely."

Median and mean PSA levels of the patients were 5.4 ng/mL and 10.4 ng/mL, respectively. Thirty-eight percent had an abnormal TRUS, and 52% had an abnormal DRE. The mean AUA symptom score was 10.4, with 47% of the men having a score of <7 (mild) and 14% having scores of 20 to 35 (severe). The positive biopsy rate was 38%.

Unseen danger?

Multivariate analysis of 790 patients who had not undergone prior biopsy indicated that low prostate volume, high PSA levels, positive DRE, and advanced age were independent predictors for prostate cancer (p<.0001). In addition, multivariate analysis found that Gleason sum ≥7 on biopsy was independently associated with both abnormal DRE and low prostate volume (p=.001 for both), and that for every cubic centimeter increase in gland volume, the risk of prostate cancer with Gleason sum ≥7 decreased by 2.2%.

According to Dr. Porter, these results may be explained by the fact that men are more likely to see their urologist and to be screened for prostate cancer if they are experiencing voiding symptoms.

"Therefore, men with smaller glands may be postulated to be less likely to see their urologist and to undergo screening," he said. "It is entirely possible that we are missing a large body of men in the population who may be more likely to have prostate cancer, primarily because they are less likely to be seen by their urologist."

The biologic rationale for men with smaller prostates having increased likelihood of cancer and significant disease has been illustrated in findings from the Prostate Cancer Prevention Trial, in which it was demonstrated that men with smaller glands were more likely to have higher-grade prostate cancer (N Engl J Med 2003; 349:215-24).

Another hypothesis may involve the relationship between BPH and prostate cancer, Dr. Porter said.

"It is possible that BPH exerts a protective effect on the prostate cells, and that benign cellular growth, either through substrate use or through the release of an unknown factor, may protect the cell from molecular changes that could spurn malignant change," he said.