Significance of minute focus of adenocarcinoma on prostate needle biopsy

To assess the radical prostatectomy findings in patients with a minute focus of adenocarcinoma on prostate needle biopsy in current practice in Australia.

A total of 58 patients with a 0.5-mm focus or less of Gleason score 6 adenocarcinoma on needle biopsy who had been treated by radical prostatectomy were selected. At each biopsy, 6 to 20 cores (mean 11, median 13) were taken. Significant tumors were those with a Gleason score of 6 or more and tumor volume of 0.5 cm3 or larger.

The 58 patients (mean age 50 years, median 58, range 44 to 69) had a mean prostate-specific antigen (PSA) level of 6.9 ng/mL (range 0.7 to 16, median 6). Of the 58 men, 48 (82.75%) had pathologically significant tumor, with 8 (13.8%) showing extraprostatic extension. No statistically significant association was found between significant carcinoma and age, mean PSA level, PSA density greater than 0.15, prior negative biopsy, coexistent atypical glands, or the number of tissue cores per biopsy. A prostate weight greater than 40 g correlated significantly with insignificant cancer on both univariate (P = 0.03) and multivariate (P = 0.02) analyses. In 14 (29.2%) of 48 patients with significant tumor, the largest cancer focus in the radical prostatectomy was anterior, lateral, or anterolateral. In patients without atypical glands, 37 (78.72%) of 47 had significant carcinoma, a risk not significantly lower than that of the entire group.

The results of our study have shown that in populations without PSA screening, a minute focus of prostate cancer on needle biopsy, even with extended biopsy cores, does not mean insignificant carcinoma in most cases. Patients with larger glands had a greater chance of insignificant cancer.