The high sensitivity of MRI has led to its incorporation into the diagnostic pathway as an initial test prior to biopsy. A systematic review on mpMRI detection of prostate cancer reported a sensitivity of 93%, a negative predictive value of 89%, and a specificity of 41%1. With the introduction of MRI, prostate biopsy techniques have evolved to further improve the diagnostic uncertainty of previous random biopsies. Targeted prostate biopsy utilizing MRI for guiding tissue sampling has been reported to improve the detection rate of csPCa while lowering the detection of clinically insignificant prostate cancer2. However, targeted biopsy alone is not recommended in most reports owing to the undetected csPCa on mpMRI in up to 16–28% of the cases and the multifocality of prostate cancer, which is known to be present in 60–90% of cases9,10,11. Therefore, current guidelines suggest that targeted prostate biopsies should be performed in combination with a systematic biopsy for a more accurate risk stratification that could further impact treatment decisions. However, the high detection rate of targeted biopsy for PI-RADS 5 lesions suggest that the detection rate of a targeted biopsy could be further increased and potentially warrant the omission of systematic biopsies in more specifically selected patients. Therefore, patients with a PIRADS-5 lesion on MRI with additional high-risk features (with an extracapsular extension or PSA level > 20 ng/mL) may benefit from a frozen section biopsy because these subgroup of patients need only a histologic diagnosis without further risk assessment with a systematic biopsy. Frozen section biopsy provides immediate results to omit systematic biopsy in cases of a positive result for cancer; however, a 16-core systematic biopsy can be performed in cases of a negative result to mitigate the potential risk of missing prostate cancer.
The cancer detection rate for high-risk patients with frozen section-targeted biopsy alone was 97.0% (63/65 patients). There were three cases where an additional systematic biopsy was performed owing to the negative results of a targeted biopsy using frozen sections. In one case, an additional systematic biopsy was performed, and the pathology was reported to be a prostate abscess. If we were to have performed a routine systematic biopsy in combination with targeted biopsy for these high-risk patients with PI-RADS 5 lesions, 95.5% (63/66) of these patients would have undergone an additional systematic biopsy without any benefit.
Regarding treatment course, 31 (51.7%) patients underwent whole-gland treatment initially with radical prostatectomy or radiation therapy. Twenty-nine (48.3%) patients underwent systemic therapy with hormonal therapy alone or in combination with chemotherapy. An additional systematic biopsy would not have deviated the course of treatment for these patients.
The most commonly reported minor complications related to transrectal biopsies were hematospermia (36.3%), hematuria (14.5%), and rectal bleeding (2.3%). Rectal bleeding requiring intervention was reported in 0.6% of the patients. Other reported complications include urinary tract infection (0.8%) and urinary retention (0.2%)14. Additionally, the risks of antimicrobial resistance and urosepsis have been reported to increase with the number of cores sampled15. Though the biopsy technique adopted in this study utilizes a transperineal approach, it is speculated that frozen sections utilized in a transrectal approach for target biopsy may provide similar benefits of a significant reduction in the number of biopsy cores. No complications associated with the procedures were noted in any of the 66 patients in this study.
The major advantage of incorporating a frozen section biopsy is that the total biopsy cores obtained can be significantly reduced by omitting a systematic biopsy without compromising the risk of missing diagnoses of prostate cancer. Reducing the number of cores sampled may lower the risk of antimicrobial resistance and urosepsis, as they have been reported to increase with the number of cores sampled15. Furthermore, the time from suspicion to diagnosis and eventually to treatment is shortened, and the anxiety experienced by patients in these intervals is lowered. However, when an accurate risk assessment is required, a systematic biopsy should be added to targeted biopsy cores to improve the local staging in order to plan the optimal therapeutic strategy16.
The procedure presented in this study has limitations. Obtaining frozen section biopsy results requires a pathologist to be readily able to assess the specimen, which may not be possible in local practices. However, by omitting a routine systematic biopsy, the total number of biopsy cores that need to be reviewed by the pathologist can be significantly reduced, leading to a decrease in the burden on pathologists as well. In addition, time for a pathologic report for frozen section can be time consuming and may exceed performing a systematic biopsy. The total operation time consumed in this study was a mean 25.3 ± 5.7 min which is similar to MRI–US fusion-targeted transperineal prostate biopsies with systematic biopsies that are performed in our institute. However, a reduction in biopsy cores may enable this method to be performed in an out-patient setting under local anesthesia where the patient can wait in the waiting room until the pathology result is reported. Another limitation is that MRI must be performed preoperatively to perform an MRI fusion biopsy, which can be expensive in certain countries. However, owing to the national health insurance policy in Korea, the patients are not economically burdened. Lastly, the number of cases included in this study was small; a larger trial is required to make any definitive conclusions.