Prostate cancer risk assessment by the primary care physician and urologist: transabdominal- versus transrectal ultrasound prostate volume-based use of the Rotterdam Prostate Cancer Risk Calculator.

Background: Our objective was to assess the accuracy of transabdominal ultrasound (TAUS) measured prostate volume in the primary care setting with transrectal ultrasound (TRUS) measured prostate volume by the urologist as the reference test. Furthermore, our objective was to assess whether risk-stratification using TAUS prostate volume by the primary care physician could reduce unnecessary referrals to the urologist. Methods: Men in two Dutch primary care offices with a prostate cancer (PCa) screening request received a digital rectal examination (DRE), prostate specific-antigen (PSA), and TAUS prostate volume measurement by the general practitioner, followed by Rotterdam Prostate Cancer Risk Calculator (RPCRC) risk assessment. The examination was repeated by a urologist using TRUS. A prostate biopsy was performed in case of a RPCRC positive biopsy advice. A non-inferiority analysis was performed comparing TAUS and TRUS prostate volume differences. A risk-based referral strategy using TAUS and the RPCRC in the primary care setting was compared with the standard referral strategy based on PSA (≥3 ng/mL) and DRE. Results: A total of 105 men were included with a median PSA of 1.9 ng/mL. The mean prostate volumes measured by TAUS and TRUS were 55 and 45 mL, respectively. The mean overestimation of the prostate volume by TAUS as compared to the reference test was 9.9 mL (95% CI: 5.9-13.8). According to Dutch standard practice, 41 out of 105 (39%) men would have been referred to the urologist. Stratification in primary care based on the RPCRC using TAUS prostate volume would have avoided 29 out of the 41 (71%) referrals, at the expense of non-referral of 5 out of 11 (45%) men with a biopsy indication, according to the urologist. Conclusions: RPCRC-based risk stratification in primary care using TAUS prostate volume measurement is feasible and may prevent unnecessary referrals to the urologist and reduce costs. The accuracy of the risk assessment with TAUS might be improved by sufficient training and centralization to achieve a higher volume of consultations in primary care facilities.