Low-risk Prostate Cancer Patients Without Visible Tumor (T1c) On Multiparametric MRI Could Qualify for Active Surveillance Candidate Even If They Did Not Meet Inclusion Criteria of Active Surveillance Protocol

We compared the pathologic outcomes of prostate cancer patients who did not qualify for active surveillance according to the tumor visibility on multiparametric magnetic resonance imaging. We retrospectively analyzed 464 prostate cancer patients who underwent multiparametric magnetic resonance imaging before radical prostatectomy between 2006 and 2012. All the patients had clinically localized prostate cancer with Gleason score 6 and prostate-specific antigen 10 ng/ml. Of these patients, 238 were eligible for active surveillance (group A) and 226 were not. We divided these 226 patients into two groups according to the result of multiparametric magnetic resonance imaging: 59 (26.1) patients without visible tumor (group B) and 167 (73.9) patients with visible tumor (group C). We evaluated the pathologic outcomes of organ-confined Gleason 6 disease and unfavorable disease in each group. The proportions of organ-confined Gleason 6 disease and unfavorable disease were 63.9 and 11.3 in group A, 59.3 and 10.2 in group B, and 38.9 and 22.8 in Group C. Comparing group A and B, these proportions were not statistically different (P 0.549 and P 1.000, respectively). However, comparing group A and C, those were significantly different (P 0.001 and P 0.002, respectively). In multivariate logistic regression analysis, no visible tumor on multiparametric magnetic resonance imaging was an independent predictor of organ-confined Gleason score 6 disease (odds ratio 0.426, P 0.007) but there was no statistically independent predictor for unfavorable disease. The tumor visibility on multiparametric magnetic resonance imaging could be a predictor of favorable disease for the prostate cancer patients who did not meet active surveillance criteria. Multiparametric magnetic resonance imaging could help to determine treatment modality for the low-risk prostate cancer patients who consider active surveillance even if they did not meet active surveillance criteria.