In Dr. Vickers’ opinion, we have made a quantum leap in data on MRI for prostate biopsy decision making over the past 12 months. However, he qualified the review of recent trials by emphasizing the need for the analysis to address a clinical question. For example, is the point of MRI to improve the specificity of PSA? Or to improve the sensitivity of biopsy? Or is the role of MRI to guide the need for repeat biopsy?
The PROMIS study considered the role of MRI in biopsy-naïve men. The take-home message was that MRI predicted clinically significant cancer on template biopsy with 93% sensitivity and 89% negative predictive value. However, it is important to understand that clinically significant cancer was defined as 4+3=7 disease. When 3+4=7 disease is added to the realm of clinical significant, the sensitivity and negative predictive value decline to 88% and 76%, respectively. Thus, while MRI finds cancers that TRUS-biopsy would have missed, it is not reliable in and of itself when 3+4=7 cancers are considered as clinically significant.
The PICTURE study considered the role of MRI in men with a previous negative biopsy. Unfortunately, many significant cancers were missed as the MRI threshold for biopsy was increased to PIRADS 4 or higher. Therefore, the recommendation remains to include PIRADS 3-5 for targeting. The conclusions, then, for MRI are that the negative predictive value is not consistently high enough and is not a reliable reflex test. However, MRI-guided biopsy does find cancers that are missed by TRUS biopsy.
A few collaborative efforts on the epidemiology of prostate cancer were included as well. A pooled analysis of 15 prospective cohort studies on eating fruits and vegetables on prostate cancer risk demonstrated no significant reduction in prostate cancer incidence with greater fruit and vegetable intake (RR 0.92, 95% CI 0.81-1.04 p > 0.05). Further, an analysis of 1.44 million adults demonstrated increased risk of prostate cancer with exercise (RR 1.05, 95% CI 1.03-1.08 p < 0.001). Of course, this result is likely due to confounders (men who exercise are more likely to go the doctor and receive a PSA test). Finally, selenium and prostate cancer has been extensively studies. Despite having a randomized trial which showed no benefit of selenium in reducing prostate cancer risk, an analysis of 15 prospective studies suggested that high risk cancers may be reduced with selenium.
Lastly, Dr. Vickers considered a model-based study estimating harms and benefits of prostate cancer screening as used in common practice versus recommended best practice. Screening done using an ERSPC-based model generated 56 QALY per 1000 men screened compared to 19 QALYs per 1000 based on current US practice and 74 QUALY per 1000 based on guideline best practices. Therefore, how screening is performed has a clear and differential impact on patient quality of life.
Presented By: Andrew Vickers, PhD
Written By: Benjamin T. Ristau, MD, Fox Chase Cancer Center, Philadelphia, PA
at the 2017 AUA Annual Meeting - May 12 - 16, 2017 – Boston, Massachusetts, USA