Discussion
In this study, the incidental PCa rate and predictive factors in patients who underwent OP with a pre-diagnosis of BPH were evaluated and significant findings emerged. The multivariate analysis showed that only pathological DRE findings and presence of MeTS were significantly associated with the incidental PCa risk after OP surgery. To our knowledge, this study evaluated the highest number of parameters in the prediction of incidental PCa detection after OP.
PCa can be detected by DRE when the prostate volume is ≥0.2 mL. PCa is detected by a suspicious DRE finding alone in 18% cases.12 In a multicentric study (11 centers, 1613 patients) Yoo et al. reported that the DRE finding was an independent predictive factor for diagnosing incidental PCa in tissue-ablative surgery for BPH, such as transurethral resection of the prostate and OP. The rate of an abnormal DRE finding was 12.7% in the BPH group and 36.6% in the incidental PCa group, and the incidental PCa rate was 4.8% in all cases.13 Similarly, another retrospective study including 218 patients showed that DRE and elderly age were predictive factors for incidental PCa after BPH surgery (TURP and OP) (14). In our study, we also found that the rate of an abnormal DRE finding was significantly higher in the incidental PCa group (3.6% vs 45.8%, respectively). In light of all these results, in case of an abnormal DRE finding prior to OP, the risk of PCa should always be considered, and additional diagnostic tests, such as multiparametric MRI and target biopsies can be added to the algorithm.
Although the association between MetS and PCa is not clear, there are many studies that have revealed the higher risk of PCa development in patients with MetS. In Finland, Laukkanen et al. followed up 1880 patients for 13 years and found that the risk of PCa development was 1.9-fold higher in patients with MetS.15 Similarly, in a study evaluating the relationship between PCa and MetS and late-onset hypogonadism, Kayali et al. showed a higher risk of PCa in the MetS group compared to the patients without MetS (32.7% and 21.2%, respectively).16 On the other hand, according to a meta-analysis including 19 studies, no correlation was found between MetS and PCa development; however, a significant correlation was present between MetS and aggressive PCa development. The authors determined that MetS increased the risk of high-grade (GS 7) and advanced-stage ( T3) PCa at a rate of 36 and 37%, respectively.17 In the current study, we showed that MetS was significantly higher in the incidental PCa group. This is the first study that evaluated the presence of MetS and incidental PCa after OP.
PSA is organ-specific but it is not specific to cancer. It may be elevated in BPH, prostatitis, and other non-malignant conditions. As an independent variable, PSA is a better predictor of cancer than DRE or TRUS.18 In a multicentric study, the authors reported that the PSA level was significantly higher in the incidental PCa group than in the BPH group (6.9 ng/mL and 4.7 ng/mL, respectively). In the current study, the PSA levels were similar in the incidental PCa and BPH groups (7.63 ng/mL and 7.47 ng/mL, respectively). Similarly, Antunes et al. reported that the presence of a high PSA level was not associated with incidental PCa detection after BPH surgery. They referred to the possibility of other reasons, such as the use of urinary catheters and presence of urinary retention increasing PSA levels.14Abedi et al. reported that the cut-off value of PSA in incidental PCa detection was 3.8 ng/mL.7 We consider that high prostate volume can be another possible factor that can change the PSA level.
Many researchers have shown that PCa is associated with increasing age. In autopsy reports, the prevalence of PCa has been reported as 29% in men aged 30 to 40 years and 64% in those aged 60-70 years.7 A previous study showed that advanced age was statistically significantly related to the findings of the surgical specimen analysis. The mean age of patients with incidental PCa was approximately six years greater than those with BPH.14In another study, Sakamoto et al. determined that at a cut-off value of 75 years, age was an independent predictive factor for incidental PCa in TURP.19 Similarly, in the current study, the incidental PCa group was older than the BPH group (73.6 and 69.2 years, respectively), but age was not found to be a statistically significant variable in the multivariate analysis.
AST/ALT ratio can predict several malignant tumors, such as pancreatic cancer and breast cancer. Zhou et al. showed that the AST/ALT ratio was significantly higher in PCa than in BPH, but they noted that this ratio was not a good predictor of high-risk PCa detection.20In our study, we also evaluated the AST/ALT ratio and found it to be higher in the incidental PCa group. Although this parameter was statistically significant in the univariate analysis, it was not significant in the multivariate analysis. NLR is common predictor factor for many cancer types. Wang et al. evaluated this ratio in patients with PCa by dividing them into two GS groups as ≤6 and ≥7 and reported that NLR was significantly higher in the high GS group.21We also found that NLR was higher in the incidental PCa group (2.57 vs 3); however, the difference between the two groups was not statistically significant. To our knowledge, none of the studies in the literature evaluated inflammatory hematological parameters for incidental PCa after OP. Our study has certain limitations. It had a retrospective design and included the data of 430 patients. Some parameters that could be associated with incidental PCa, such as a family history of PCa and smoking and alcohol habits were not evaluated due to the retrospective design. Despite these limitations, we consider our study to be important because it included the evaluation of the highest number of parameters in the prediction of incidental PCa detection after OP.