The Challenges with Prostate Cancer Diagnosis
Prostate cancer is the most commonly diagnosed male cancer, yet the standards for diagnosis remain blurry. Based on elevated PSA level or abnormal digital rectal exam, men will typically undergo a standard 10-12 core transrectal ultrasound-guided (TRUS) biopsy. Although the idea is to systematically sample the whole prostate, the majority of cores are taken from the peripheral zone. Due to its distance from the rectum, the anterior is rarely sampled, while areas in the midline are undersampled to avoid the urethra. The transrectal route also makes it more difficult to target the apex.1 The TRUS biopsy is considered “blind” or “random” because the appearance of cancer is pretty ambiguous on the conventional, low-frequency ultrasound. This often leads to the underdetection of clinically significant cancer and the overdetection of low-grade (clinically insignificant) cancers.2 The high false negative rate and potential for infectious complications make matters even worse for men with suspected low grade cancer. Unfortunately, the current standard of care to monitor low grade prostate cancer relies on repeat TRUS biopsy every 6-24 months. Due to the random nature of systematic biopsies, pathology results can differ significantly, with up to 37%-48% of men with low grade cancer receiving a benign diagnosis on confirmatory biopsy.3 This form of active surveillance repeatedly subjects patients to the potential undergrading of disease, overuse of antibiotics, invasive surgery and risk of sepsis.
High Frequency Micro-Ultrasound
Multiparametric MRI (mpMRI)
1 Bosaily, A. E., Parker, C., Brown, L., Gabe, R., Hindley, R., Kaplan, R., . . . Ahmed, H. (2015). PROMIS — Prostate MR imaging study: A paired validating cohort study evaluating the role of multi-parametric MRI in men with clinical suspicion of prostate cancer. Contemporary Clinical Trials, 4226-40. doi:10.1016/j.cct.2015.02.008
2 Kasivisvanathan, V., Rannikko, A. S., Borghi, M., Panebianco, V., Mynderse, L. A., Vaarala, M. H., . . . Moore, C. M. (2018). MRI-Targeted or Standard Biopsy for Prostate-Cancer Diagnosis. New England Journal of Medicine, 378(19), 1767-1777. doi:10.1056/nejmoa1801993
3 Eure, G., Fanney, D., Lin, J., Wodlinger, B., & Ghai, S. (2018). Comparison of conventional transrectal ultrasound, magnetic resonance imaging, and micro-ultrasound for visualizing prostate cancer in an active surveillance population: A feasibility study. Canadian Urological Association Journal, 13(3). doi:10.5489/cuaj.5361
4 Wallis, C. J. (2019, May). AUA 2019: Diagnostic Accuracy of Targeted Prostate Biopsies: Comparing Micro-Ultrasound with Multiparametric MRI for the Detection of Prostate Cancer. UroToday.
5 Kim, M., Choi, S., Park, M., Shim, M., Song, C., Jeong, I. G., . . . Ahn, H. (2016). Characteristics of Anteriorly Located Prostate Cancer and the Usefulness of Multiparametric Magnetic Resonance Imaging for Diagnosis. Journal of Urology, 196(2), 367-373. doi:10.1016/j.juro.2016.03.075
6 Bott, S., Young, M., Kellett, M., & Parkinson, M. (2002). Anterior prostate cancer: Is it more difficult to diagnose?. BJU International, 89(9), 886-889. doi:10.1046/j.1464-410x.2002.02796.x
7 Goldberg, H., MD. (2020, June). AUA 2020: Reviewing the Current Indispensable Role of Prostate MRI. UroToday.
8 Moosavi, B., Flood, T., Al-Dandan, O., Breau, R., Cagiannos, I., Morash, C., . . . Schieda, N. (2016). Multiparametric MRI of the anterior prostate gland: Clinical–radiological–histopathological correlation. Clinical Radiology, 71(5), 405-417. doi:10.1016/j.crad.2016.01.002