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.