Abstract P067: Evaluating the risk of clinically significant prostate cancer in lesions detected on multiparametric MRI of the prostate

Abstract

Introduction: Multiparametric Magnetic Resonance Imaging (mpMRI) is a valuable tool in the prostate cancer diagnostic pathway. mpMRI has a negative predictive value (NPV) of approximately 90% for detecting clinically significant prostate cancer (csPCa), defined as the presence of any Gleason Grade (GG) 4 or 5. Lesions detected on mpMRI are scored using the PIRADS scoring system from 1 to 5. PIRADS-3, 4 and 5 lesions are recommended for biopsy. The use of mpMRI to guide prostate biopsy has been shown to be superior to systematic biopsy alone for detecting early csPCa as small lesions can be identified and accurately targeted. We analysed the outcome of targeted biopsy of prostate lesions detected on mpMRI, and systematic biopsy when no lesions were detected, to determine the risk of csPCa based on mpMRI findings. Methods: Men attending our prostate diagnostic pathway were offered mpMRI before biopsy. The criteria for pre-biopsy mpMRI were any man suitable for radical surgery or radiotherapy, plus one or more of PSA > 3, palpable lesion on digital rectal examination, or family history of PCa in a first degree relative (father or brother). mpMRI was performed with a 1.5-Tesla magnet and included T2, DWI and DCE sequences. Men with PIRADS 3, 4, and 5 lesions were offered targeted biopsy with 2-4 biopsy cores per lesion, and men with no lesion on MRI were offered systematic prostate biopsy with 8-16 biopsy cores. Results: 546 targeted lesions were biopsied in 349 men. 159 lesions were PIRADS-3, 226 were PIRADS-4, and 161 were PIRADS-5. 141 men with negative mpMRI had systematic prostate biopsy. Of the PIRADS-3 lesions, 84% were benign, 5% had GG 3, 11% had GG 4 and none had GG 5. Of the PIRADS-4 lesions, 44% were benign, 12% had GG 3, 42% had GG 4, and 2% had GG 5. Of the PIRADS-5 lesions, 23% were benign, 2% had GG 3, 62% had GG 4, and 13% had GG 5. Of the men with no lesion on mpMRI, 9% had GG 3, 4% had GG 4, and none had GG 5. Conclusion: Most men with negative mpMRI or PIRADS-3 lesions have benign tissue on biopsy or early PCa and are unlikely to have csPCa. A decision for biopsy vs PSA monitoring in these men should weigh the risks and benefits of biopsy and should be a shared decision taking into consideration individual risk factors for PCa, age and co-morbidities. Citation Format: Chidi N. Molokwu, Christos Gkikas, Nicola Lee, Joanna Lesniak-Buzon, Faisal Ali, Harry Bardgett. Evaluating the risk of clinically significant prostate cancer in lesions detected on multiparametric MRI of the prostate. [abstract]. In: Proceedings of the AACR Special Conference: Precision Prevention, Early Detection, and Interception of Cancer; 2022 Nov 17-19; Austin, TX. Philadelphia (PA): AACR; Can Prev Res 2023;16(1 Suppl): Abstract nr P067.