Estimation of prostate size in community-dwelling men

Low suspicion lesions on multiparametric magnetic resonance imaging predict for the absence of high-risk prostate cancer

What's known on the subject? and What does the study add? Over-treatment of indolent prostate cancer lesions is a problem which can result in increased human and medical costs. Lesions with a low suspician level at mpMRI of the prostate have low risk of including high risk prostate cancer.

OBJECTIVE

To determine whether multiparametric magnetic resonance imaging (mpMRI) has the potential to identify patients at low risk for cancer, thus obviating the need for biopsy. Prostate cancer is currently diagnosed by random biopsies, resulting in the discovery of multiple low-risk cancers that often lead to overtreatment.

PATIENTS AND METHODS

We reviewed 800 consecutive patients who underwent a 3 Tesla mpMRI of the prostate with an endorectal coil from March 2007 to November 2011. All suspicious lesions were independently reviewed by two radiologists using T2-weighted, diffusion-weighted, spectroscopic and dynamic contrast-enhanced MRI sequences. Patients with only low suspicion lesions (maximum of two positive parameters on mpMRI) who subsequently underwent transrectal ultrasonography (TRUS)/MRI fusion targeted biopsy were selected for analysis.

RESULTS

In total, 125 patients with only low suspicion prostatic lesions on mpMRI were identified. On TRUS/MRI fusion biopsy, 77 (62%) of these patients had no cancer detected, 38 patients had Gleason 6 disease and 10 patients had Gleason 7 (3+4) disease. There were 30 patients with cancer detected on biopsy who qualified for active surveillance using 2011 National Comprehensive Cancer Network guidelines. No cases of high-risk (≥ Gleason 4+3) cancer were identified on biopsy and, of the fifteen patients who underwent radical prostatectomy at our institution, none were pathologically upgraded to high-risk cancer. Thus, for patients with only low suspicion lesions, 107 (88%) patients either had no cancer or clinically insignificant disease.

CONCLUSIONS

The results obtained in the present study show that low suspicion lesions on mpMRI are associated with either negative biopsies or low-grade tumours suitable for active surveillance. Such patients have a low risk of harbouring high-risk prostate cancers.

A novel equation and nomogram including body weight for estimating prostate volumes in men with biopsy-proven benign prostatic hyperplasia

Anthropometric measurements, e.g., body weight (BW), body mass index (BMI), as well as serum prostate-specific antigen (PSA) and percent-free PSA (%fPSA) have been shown to have positive correlations with total prostate volume (TPV). We developed an equation and nomogram for estimating TPV, incorporating these predictors in men with benign prostatic hyperplasia (BPH). A total of 1852 men, including 1113 at Tokyo Medical and Dental University (TMDU) Hospital as a training set and 739 at Cancer Institute Hospital (CIH) as a validation set, with PSA levels of up to 20 ng ml(-1), who underwent extended prostate biopsy and were proved to have BPH, were enrolled in this study. We developed an equation for continuously coded TPV and a logistic regression-based nomogram for estimating a TPV greater than 40 ml. Predictive accuracy and performance characteristics were assessed using an area under the receiver operating characteristics curve (AUC) and calibration plots. The final linear regression model indicated age, PSA, %fPSA and BW as independent predictors of continuously coded TPV. For predictions in the training set, the multiple correlation coefficient was increased from 0.38 for PSA alone to 0.60 in the final model. We developed a novel nomogram incorporating age, PSA, %fPSA and BW for estimating TPV greater than 40 ml. External validation confirmed its predictive accuracy, with AUC value of 0.764. Calibration plots showed good agreement between predicted probability and observed proportion. In conclusion, TPV can be easily estimated using these four independent predictors.

Performance of prostate-specific antigen mass in estimation of prostate volume in Japanese men with benign prostate hyperplasia

OBJECTIVES

Obese men with benign prostate hyperplasia might have lower serum prostate-specific antigen because of hemodilution, resulting in underestimation of total prostate volume by serum prostate-specific antigen. The aim of this study was to compare the performance of prostate-specific antigen mass as the absolute amount of prostate-specific antigen protein secreted into circulation with that of serum prostate-specific antigen in the prediction of total prostate volume.

METHODS

A total of 1517 men with serum prostate-specific antigen up to 10 ng/mL, including 1425 with biopsy-proven benign prostate hyperplasia, were enrolled in this study. Height and weight were used to estimate body mass index, body surface area and plasma volume. Prostate-specific antigen mass was calculated as serum prostate-specific antigen multiplied by plasma volume. The association between serum prostate-specific antigen or prostate-specific antigen mass and transrectal ultrasound-measured total prostate volume were evaluated by Pearson's correlation coefficient (Υ), linear regression analyses and receiver operating characteristic curves.

RESULTS

Serum prostate-specific antigen had an inverse relationship with plasma volume, decreasing as plasma volume increased, after adjustment of total prostate volume. Larger total prostate volume per serum prostate-specific antigen was found in men with higher body mass index or plasma volume. Among all participants, the correlation (Υ = 0.456) between prostate-specific antigen mass and total prostate volume was apparently stronger than that (Υ = 0.442) between serum prostate-specific antigen and total prostate volume. Prostate-specific antigen mass outperformed serum prostate-specific antigen at estimating total prostate volume cut-off values of 30 and 40 mL. These findings were more significant in men aged ≥60 years.

CONCLUSIONS

Prostate-specific antigen mass performs better than serum prostate-specific antigen in estimating TPV, especially in men aged ≥60 years.