The number of cores taken at initial biopsy in patients diagnosed with a single microfocus of prostate cancer is an independent predictor of having pathologically confirmed insignificant prostate cancer, according to a study published in the March issue of the Journal of Urology.

In addition to the number of cores, age and prostate specific antigen density were also predictors of insignificant prostate cancer, according to Luca Villa, MD, of University Vita-Salute San Raffaele, Milan, Italy, and colleagues.

“An accurate preoperative definition of potential [pathologically confirmed insignificant prostate cancer] might be a starting point for identifying patients who are eligible for [active surveillance], reducing the proportion of patients subjected to overtreatment and the rate of complications related to radical treatments,” wrote the authors.

Villa and colleagues analyzed data from 233 patient with a single focus of prostate cancer—Gleason 6 involving 5 percent or less of the core—at initial transrectal prostate biopsy. All patients were subsequently treated with radical prostatectomy and the authors analyzed the relationship between the number of cores taken and the probability of confirming the presence of indolent disease.

Sixty-five patients (27.9 percent) showed pathologically confirmed insignificant prostate cancer at prostatectomy, according to Villa and colleagues. The rate of insignificant prostate cancer increased along with the number of cores. Insignificant cancer rates were 3.8 percent, 29.6 percent and 39.4 percent in patients who underwent biopsies of 12 or fewer cores, 13 to 18 cores and 19 or more cores, respectively.

The authors added that cubic spline adjusted linear correlation analysis showed that for each core added to the sampling scheme, the probability of having pathologically confirmed insignificant prostate cancer at prostatectomy increases without any plateau effect.

“Although not included in previously published predictive models, our findings demonstrated that the number of cores taken should be considered in the evaluation of patients who are potentially affected by [pathologically confirmed insignificant prostate cancer], especially in those diagnosed with a single [microfocus of prostate],” wrote the authors.

They also found that elderly men have a lower probability of having indolent disease and are more likely to harbor aggressive disease. Even in patients at low risk for prostate cancer who are suitable for active surveillance, age of 70 years and older is an independent predictor of upstaging at radical prostatectomy.

For more about prostate cancer, please read "Prostate Cancer: In the Eye of the Storm" from Health Imaging magazine.