A nomogram for predicting low-volume/low-grade prostate cancer: a tool in selecting patients for active surveillance

The authors reported previously that assessment of the number of positive biopsy cores, maximum tumor length in a core, Gleason score, and prostate volume in an extended biopsy enhanced the accuracy of predicting low-volume/low-grade prostate cancer. On the basis of those findings, they developed a nomogram to predict the probability of low-volume/low-grade prostate cancer specifically for men with a single positive biopsy core.

The study cohort comprised 258 men who underwent radical prostatectomy without neoadjuvant therapy. Prostate cancer was diagnosed in only 1 core of an extended biopsy scheme. Low-volume/low-grade cancer was defined as pathologic organ-confined disease and a tumor volume<0.5 cc with no Gleason grade 4 or 5 cancer. Patient age, prostate-specific antigen (PSA) level, prostate volume, PSA density (PSAD), and tumor length in a biopsy core were examined as variables. A fitted multiple logistic regression model was used to establish the nomogram.

One hundred thirty-three patients (51.6%) had low-volume/low-grade cancer. To establish the nomogram, age, PSAD, and tumor length were adopted as variables. The fitted model suggested that older age, higher PSAD values, and greater tumor length would reduce the probability of low-volume/low-grade cancer. The nomogram predicted low-volume/low-grade cancer with good discrimination (an area under the receiver operating characteristic curve of 0.727). Calibration of this nomogram showed good predicted probability.

The authors established a nomogram with which to predict low-volume/low-grade cancer in men with 1 positive biopsy core in an extended biopsy scheme, and they recommend this nomogram for use in selecting men for active surveillance.