Objective: Nowadays, active surveillance (AS) for prostate cancer (PCa) is accepted as therapeutic option for low risk and very low risk PCa patients, alternative to surgery or radiation therapy. Recently, multiparametric Magnetic Resonance Imaging (mpMRI) has joined increasing enthusiasm as a diagnostic tool for detection of clinical significant PCa. However, the role and the potential advantages of mpMRI into AS protocols is still a matter of debate. Therefore, the aim of our study was to evaluate the impact of mpMRI in the early reclassification of patients with clinically significant PCa.
Material and methods: From May 2015 to March 2018, 71 very low and low risk PCa patients were included in our AS protocol. The inclusion criteria were: 35-75 year-old men; diagnosis of PCa within 8 weeks; PSA≤10 ng/ml; Clinical T1c or T2 assessed with DRE and TRUS; Gleason Score=6; < 3 positive cores; at least 12 biopsy cores taken; PSA density less or equal to 0.2; ASA score ≤ 3; central revision of the biopsy core confirming the presence of indolent PCa. Patients were randomized (1:1) in two groups: Group 1 (n=38) received a mpMRI at 3 months from the beginning of AS, and then were scheduled for AS according to the PRIAS criteria; Group 2 (control group, n= 33) did not receive mpMRI, and were scheduled for traditional PRIAS AS. Patients in both groups had a PSA dosage every 3 months and underwent digital rectal examination (DRE) every 6 months. In group 1, patients with at least one PIRADS ≥3 lesion at mpMRI underwent a Fusion biopsy (FB); patients with negative mpMRI (namely PIRADS≤2 lesion at mpMRI) in group 1 and patients included in group 2 underwent a confirmation biopsy 12 months after the beginning of the protocol and subsequent prostate biopsy at 48 and 72 months. In case of reclassification (both due to upgrading and to upsizing) patients were scheduled for radical treatments (including radical prostatectomy or primary radiotherapy).
Results: Table 1 shows the clinical characteristics of the entire patient population. No significant differences between the two groups were found. Table 2 reports the percentage of reclassified patients at 3 and 12 months. Of the 36 patients who underwent mpMRI at 3 months, 10 (28%) had at least one significant lesions (7 men had PIRADS=3 and 3 men had PIRADS=4). Those individuals underwent a subsequent targeted FB. Eight of these patients (22.2%) were reclassified: 7 (87.5%) men due to upgrading (2 with Gleason score 4+4, 4 with Gleason score 4+3 and 1 with Gleason score 3+4) and 1 patient due to upsizing (>2 positive cores with Gleason score 3+3). At 12-month random re-biopsy, 2 out of 18 patients in Group 1 (11%) and 7 out of 24 patients in Group 2 (29%) were reclassified. At a median (IQR) follow up of 12 months (6-18), 5 (14%) patients in group 1 underwent surgery after reclassification due to mpMRI performed at 3 months while only 1 (2.8%) men was referred to surgery due to reclassification at re-biopsy at 12 months; in control group, 5 (21.8%) men were scheduled for surgery after reclassification at 12 months re-biopsy.
Conclusion: Our study showed promising preliminary data: despite no statistical differences between the two groups in terms of rates of reclassification at 12 months due to limited number of patients included, mpMRI seems to be able to achieve a higher early reclassification rate of patients who can no longer stay in AS because of clinically significant PCa. A larger study population and longer follow up may help to achieve more accurate results.
