Objective:To investigate the efficacy of the biopsy strategy combining 6-core systematic and 3-core MRI-targeted biopsy on prostate cancer (PCa) detection in biopsy-na?ve patients.Methods:The clinical data of 121 biopsy-na?ve patients who underwent transperineal prostate biopsy in West China Hospital of Sichuan University from July 2018 to January 2020 were retrospectively analyzed. The average age was (64.7±9.1) years old. Pre-biopsy prostate-specific antigen (PSA) was (12.4±7.5)ng/ml, f/t PSA was 0.13±0.05. Prostate volume was (43.1±26.1) ml and PASD was (0.35±0.27) ng/ml 2. The prostate-imaging and data system (PI-RADS) score of MRI before biopsy was reported to be 3 for 29 patients (24.0%), 4 for 54 patients (44.6%) and 5 for 38 patients (31.8%). All 121 patients underwent 12-core systematic biopsy combined with a 3-core or 5-core MRI-targeted biopsy, of which 61 patients underwent 3-core targeted biopsy and 60 underwent 5-core targeted biopsy. There was no significant difference in the pre-biopsy clinical data between the two groups ( P>0.05). A 6-core systematic biopsy was redefined as the results of 6 cores among the 12-core systematic biopsy. We compared the detection rates among the single 12-core systematic biopsy, 6-core systematic biopsy, MRI-targeted biopsy (3-core or 5-core), and different systematic biopsy combing with targeted biopsy for any PCa and clinically significant PCa, and we also analyzed the cumulative cancer detection rates for MRI-targeted biopsy of different cores. Results:Of the 121 patients in this study, the biopsy results were negative for 43 patients (35.5%) and positive for 78 (64.5%). The detection rate of clinically significant PCa was 55.4% (67/121). The detection rate of the 6-core systematic biopsy combined with MRI-targeted biopsy was 62.0% (75/121) for PCa and 55.4% (67/121) for clinically significant PCa, which was of no difference compared with that for the 12-core systematic biopsy combined with MRI-targeted biopsy ( P>0.05), but the 6-core systematic biopsy combined with MRI-targeted biopsy avoided the overdiagnosis of 3 patients with Gleason score 3+ 3. The detection rate of PCa for MRI-targeted biopsy was 57.9% (70/121), including 42.1% (51/121) for the first core, 55.4% (67/121) for the first two cores, and 57.9% (70/121) for the first three cores. Compared with the single-core targeted biopsy for suspicious lesions, the first 2-core targeted biopsy ( OR=1.7, 95% CI 1.0-2.8) and 3-core targeted biopsy ( OR=1.9, 95% CI 1.1-3.1) can significantly increase the detection rate of PCa, while the fourth or fifth core of targeted biopsy can not increase the detection rate additionally (60%, 36/60). Conclusion:For patients with suspected PCa, the prostate biopsy strategy combing 6-core systematic and 3-core MRI-targeted biopsy performs no inferior than the current 12-core systematic biopsy combined with MRI-targeted biopsy.