Combining PSA density (PSAD) with prostate magnetic resonance imaging (MRI) may improve detection of clinically significant prostate cancer (csPCa) among men without a prior diagnosis of PCa, according to a new study.
Among men with a PI-RADS score of 3 or lower, a PSAD less than 0.15 predicted a low risk of harboring csPCa, investigators reported in Urologic Oncology.
When a PSAD threshold of 0.15 was applied, the frequency of csPCa in patients with a PI-RADS score of 3 or lower decreased from 9.8% to 5.6% among patients without known PCa and from 10.7% to 2.7% among men on active surveillance (AS).
“Our findings confirm that PSAD can be used as a safety net for cases in which the MRI did not find any suspicious or highly suspicious areas in the prostate,” corresponding author Andrei S. Purysko, MD, Clinical Assistant Professor of Radiology at the Glickman Urological and Kidney Institute at Cleveland Clinic, told Renal & Urology News. “This can increase the confidence of urologists and patients in making decisions when considering forgoing a biopsy in that circumstance.”
The findings emerged from a retrospective study that included 526 men without known PCa (initial diagnosis group) and 133 men with Grade Group 1 cancer on AS. All men underwent MRI-guided and/or systematic prostate biopsies. Dr Purysko and his collaborators found that the area under the curve (AUC) increased significantly when PSAD was added to PI-RADS in the initial diagnosis group (difference in AUC = 0.031), but they observed little benefit in the AS group (difference in AUC = 0.016).
“The improvement in accuracy for detection of clinically significant cancer detection by combining PSAD and PI-RADS scores was demonstrated in patients who did not have a previous diagnosis of prostate cancer,” Dr Purysko said. “For patients on AS, we probably need larger studies to confirm the benefit. Nevertheless, we still found that the PSAD threshold of 0.15 also applies to patients on AS with regards to a lower risk on harboring clinically significant cancer.”
Ahmad Shabsigh, MD, a urologic surgeon at The Ohio State University Comprehensive Cancer Center in Columbus, said the new study builds on previous data and confirms the value of using PSAD in conjunction with MRI for detecting clinically relevant disease. “We always knew MRI was not enough. MRI is good, but MRI still misses some prostate cancers. It depends on the quality of the MRI and the tumor itself. It misses small-volume tumors,” Dr Shabsigh said.
Ben Spilseth, MD, Associate Professor of Radiology at the University of Minnesota Medical School in Minneapolis, observed that the new study “shows what many suspect, that prostate MRI is useful in detection of cancer and that combined with PSA density can improve performance.” The findings add to existing literature suggesting that incorporating both PSAD and prostate MRI into diagnostic algorithms “will improve care by reducing unnecessary biopsies and still detect cancer at a very high rate,” Dr Spilseth said.
There is growing consensus among radiologists that combining PSAD and prostate MRI is the right approach in helping to decide which men with elevated PSA should be biopsied. “This [new study] adds further to that consensus opinion. There are still some who are reluctant to change and advocate for biopsy based on older PSA thresholds and risk models, though that is shifting,” he said.
Stevens E, Truong M, Bullen JA, et al. Clinical utility of PSAD combined with PI-RADS category for the detection of clinically significant prostate cancer [published online June 21, 2020]. Urol Oncol. doi: 10.1016/j.urolonc.2020.05.024