DISCUSSION
The result of the analyses undertaken in our study showed that PCa aggressiveness increased clinically and histopathologically in the patients with an index lesion size over 10 mm and the increase in lesion size was able to predict the aggressiveness of the disease. We took 10 mm as the threshold lesion size since a sphere of 0.5 cc corresponds to 1 cm, which is the standard limit for cisPCa according to the Epstein criteria (2). Lee et al. determined that lesion size detected in mpMRI was an independent predictive factor for the presence of cisPCa (8).
The role of mpMRI in PCa management has been continuously increasing over the last decade. The European Urology Association guidelines recommend the use of mpMRI in various indications in patients who have not yet been diagnosed with PCa or before treatment in those who have been diagnosed with this cancer (9). In addition, the use of mpMRI has become more popular in the last decade to increase the detection of csPCa and reduce the number of complications associated with biopsy procedures (10, 11). In recent years, the PI-RADS scoring system, which was developed to standardize mpMRI findings among radiologists and clinicians, has been revised and updated to PI-RADS version 2 that involves diffusion-weighted imaging (DWI), T2-weighted imaging, and apparent diffusion coefficient (ADC) in high b-value (>1400) images (5). In addition, in this scoring system, 15 mm lesion size was determined as the cut-off value in T2-weighted imaging and DWI in distinguishing between category 4 and 5 lesions (5). Rosenkrantz et al. reported that when they reduced the 15 mm size criterion to 10 mm, resulting in increasing PI-RADS score 4 to 5, they detected PCa in 33 (79%) of 42 cases and csPCa in 26 (62%) and suggested that the size limit in score 5 should be reduced to 10 mm for PI-RADS versions (12). In a study by Lee et al. including 188 patients, when the index lesion size cut-off value was taken as 10 mm, no difference was found between the groups in terms of the number of positive biopsy cores and clinical T-stage (8). However, in our study with a higher number of patients, we determined that the rate of positive cores, clinical T-stage, biopsy-ISUP grade, and PI-RADS scores were higher among the patients in Group B.
An mpMRI-targeted fusion biopsy is known to have a higher rate of detecting csPCa compared to the standard systematic TRUS biopsy, and the former also has higher upgrade rates in the Gleason score obtained from RP (13, 14). In our study, an mpMRI fusion biopsy was performed in all patients, and it was observed that the patients in both groups had similar rates (38.5 vs 37%) in terms of Gleason upgrade, and these rates were consistent with the literature (15).
According to the PCa risk classification models, the pathological stage in the RP specimen can be predicted by examining tumor size, localization and extension in mpMRI images. Studies on this subject have revealed that mpMRI not only provides anatomical tumor localization but also predicts pathological stage in the RP specimen (16, 17). In our study, when we took the lesion size cut-off value as 10 mm in the preoperative mpMRI in the patients who underwent RALP, there was no difference in the clinical T-stage of the patients, but we observed higher pathological T-stage in Group B. In contrast, Lee et al. determined no difference in pathological T-stage between the patients with a lesion size of less than or more than 10 mm (8).
In studies investigating the relationship between the PI-RADS index lesion size determined in mpMRI and the ISUP-Gleason grade, it has been reported that the ISUP grade was more advanced and the tumor progressed more aggressively in larger lesions. It has also been shown that increased lesion size and other factors had prognostic value for the course of the disease (18-20). Considering these factors, it has been suggested that mpMRI has a potential role in risk classification before definitive treatment in patients with PCa (21). EPE, SVI, LNM, and SM are important oncological prognostic markers in histopathological evaluation after RP (22, 23). Considering these oncological prognostic markers, mpMRI can help plan surgical treatment, preserve the neurovascular bundle, and reduce the rate of positive SMs (24). Drovak et al. showed that when the maximal tumor lesion size was 13 mm and above, the positivity of SM was significantly higher (25). Tonttila et al., investigating the relationship between lesion size in mpMRI and the pathology of the RP specimen, found higher EPE, SVI and LNM rates and higher ISUP grades in patients with lesions larger than 15 mm (26). In our study, we observed that the index lesion size being >10 mm was an independent predictive factor for EPE and SM positivity.
In the PAIREDCAP study, the PCa detection rates based on PI-RADS scores determined according to the index lesion size were evaluated and the effect of lesion size on PCa detection was emphasized. That study provided guidance in determining the treatment protocol according to lesion size (27). Related to this, Lee et al. stated that if the lesion size measured in mpMRI was over 10 mm, there was a much higher possibility of csPCa, and these patients were not suitable for active surveillance (AS). They found that among the patients with PCa who were suitable for AS, there was a significant rate of Gleason upgrade according to the prostatectomy pathology those with a MRI-DWI lesion diameter of >10 mm. Thus, the authors suggested that patients with a lesion larger than 10 mm were not suitable for AS (8). Similarly, in our study, we found an increased probability of having csPCa among the patients with a lesion size of over 10 mm. Ă–zden et al. reported that the rate of csPCa detection increased in patients with an mpMRI lesion size of >10 mm among those who underwent a cognitive-targeted biopsy (7). Considering these findings, our study supports the literature and can shed light on future studies to revise the 15 mm criterion used for the differentiation of PI-RADS 4 and 5 categories. This study has several strengths, including all biopsies being in the form of fusion biopsies performed by a single experienced radiologist, RALP being performed by two specialist urologists, and histopathological evaluation being undertaken by a single uropathologist. The use of fusion biopsy combined with systematic biopsy in all patients reduced the possibility of overlooking csPCa in patients with large prostate volumes. The limitations of the study include the retrospective design and the low rate of RALP in our cohort.