Prostate cancer (PCa) is among the most common male cancers worldwide, and its incidence is gradually increasing.¹ Several treatment modalities, including active surveillance (AS), radical prostatectomy (RP), radiation therapy, and an-drogen deprivation therapy, have been established for patients with clinically localized PCa. Generally, RP has been considered as the gold standard definitive treatment for clin-ically localized PCa. However, RP can cause surgical com-plications, including urinary incontinence and erectile dys-function, which can adversely influence quality of life.^2,3 To mitigate such complications, nerve-sparing radical prostatec-tomy (NSRP), which preserves the neurovascular bundles, can apply to patients with selected criteria based on pre-operative evaluations, such as prostate-specific antigen (PSA), clinical stage, and biopsy grade.^3,4

Although NSRP is currently acceptable for selected patients with PCa, it can sometimes cause incomplete tumor excision, depending on the tumor stage.⁵ Additionally, re-cent studies have shown that pathological stage and Gleason grade after RP are often inconsistent with clinical stage and biopsy Gleason grade.⁶ The discrepancy between pre-operative parameters and pathological results is usually ob-served as upstaging or upgrading.^6-11 Therefore, it is neces-sary to determine predictive factors for worse pathological outcomes, such as upgrading and upstaging, relative to pre-operative findings among patients with PCa amenable to NSRP.

Several studies have revealed that preoperative serum tes-tosterone level is associated with aggressive features of PCa, such as high stage and high grade.^12-16 Additionally, a recent study showed that low serum testosterone (<300 ng/dL) was associated with a high rate of upgrading and upstaging after RP.⁸ Another study also reported that low serum testosterone was associated with a positive surgical margin in RP specimens.¹⁷

In this study, we evaluated factors, including preoperative serum testosterone, to predict upstaging and upgrading after NSRP for PCa.

We retrospectively reviewed PCa patients who underwent NSRP, performed by a single experienced surgeon between January 2015 and May 2018 at Kyungpook National University Chilgok Hospital. Patients with biopsy Gleason grade group 1 or 2, PSA<10 ng/mL, and clinical/radiologic stage≤ T2 (using the 2009 TNM staging system) on pre-operative evaluations were included in this study. We ex-cluded patients who underwent neoadjuvant therapy, such as radiotherapy or hormonal therapy, and those with known medical problems that might affect testosterone status, such as thyroid disease, liver disease, and hypoalbuminemia. Patients with a history of 5 RI medication administration or testosterone replacement therapy were also excluded.

All patients were diagnosed with PCa by 12-core trans-rectal needle prostatic biopsies at our institution and under-went multiparametric magnetic resonance imaging for pre-operative radiologic staging.

All patients underwent open RP or robot-assisted RP ac-cording to preoperative counseling. Open RP or robot-as-sisted RP were conducted in an ante-grade fashion using a nerve-sparing technique and a continuous urethrovesical anastomosis suture in the manner previously reported.¹⁸ Gleason grade was assessed according to the 2014 International Society of Urological Pathology Modified Gleason System.¹⁹ Prostate volume was measured by standard meth-ods using transrectal ultrasonography, and PSA density (PSAD) was calculated by dividing PSA with prostate volume. Using an immunoassay at our institution's labo-ratory, the preoperative serum testosterone level (ng/dL) was measured. Considering diurnal fluctuations of the tes-tosterone level, serum samples were collected in the morning between 8 AM and 10 AM when testosterone levels are high and stable.

The upstaging and upgrading were defined as nonorgan confined disease (pathological stage≥ T3a) and pathological Gleason grade group≥3 after RP, respectively. We eval-uated the incidence of upstaging and upgrading after RP in patients with biopsy Gleason grade group 1 or 2, PSA<10 ng/mL, and clinical/radiologic stage≤ T2 on preoperative evaluation.

We also compared the patients’ characteristics according to upstaging and upgrading using Student t-test and the chi-square test. Predictive factors for upstaging and upgrading after RP were analyzed using a multivariate logistic re-gression model. Statistical analyses were performed using IBM SPSS Statistics ver. 23.0 (IBM Co., Armonk, NY, USA), and statistical significance was established with p-value of <0.05.

The present study protocol was reviewed and approved by the Institutional Review Board of Kyungpook National University Chilgok Hospital (Reg. No. KNUMC 2019-12-0 21). Informed consent was submitted by all subjects when they were enrolled.

A total of 108 patients were included in the study. The mean age was 65.5±6.2 years, mean preoperative PSA was 6.3±1.8 ng/mL, and mean preoperative serum testosterone was 347.2±154.1 ng/dL. Clinical/radiologic T stage was cT1c for 18 patients (16.7%) and cT2 for 90 patients (83.3%). Sixty-nine patients (63.9%) were classified as Gleason grade group 1, and 39 patients (36.1%) were classi-fied as grade group 2. Table 1 shows the clinical and patho-logical characteristics of patients included in this study. Upstaging and upgrading after surgery were observed in 22.2% (24 of 108) and 33.3% (36 of 108) patients, respectively. Among the 24 patients in the upstaging group, 20 (83.3%) were upstaged to pT3a, and 4 (16.7%) were up-staged to pT3b. Among the 36 patients who were upgraded, 30 (83.3%) were upgraded to Gleason grade group 3, and 6 (16.7%) were upgraded to Gleason grade group 4 (Fig. 1).

Table 2 shows patients’ characteristics according to up-staging and upgrading status. Mean prostate size was small-er and PSA density was higher among patients who were upstaged compared with those who were not (25.5±5.5 vs. 34.5±10.8, p<0.001 and 0.28±0.13 vs. 0.20±0.09, p=0.012, respectively). Mean preoperative serum testosterone was significantly lower in the upstaged patients compared with those who were not upstaged (284.6±108.8 vs. 367.6±156.8, p=0.017). The proportion of patients with a positive core number ≥3 at biopsy was higher in the upstaged group compared with the nonupstaged group (75.0% vs. 35.7%, p=0.001). There were no significant differences in age, body mass index, PSA, biopsy Gleason grade group, or op-erative method (robot-assisted RP vs. open RP) according upstaging status after RP.

In terms of upgrading status, mean preoperative serum testosterone level was significantly lower among upgraded patients compared with those who were not upgraded (308.4±106.9 vs. 369.5±165.7, p=0.047). In addition, biopsy Gleason grade group and clinical/radiologic stage were sig-nificantly different between patients who were upgraded and those who were not (p=0.034 and p=0.006, respectively). Other variables did not show any significance.

The multivariate logistic regression model revealed that preoperative serum testosterone level (odds ratio [OR], 0.993; 95% confidence interval [CI], 0.987-0.999; p= 0.034), prostate size (OR, 0.765; 95% CI, 0.669-0.875; p<0.001), and a positive core number ≥3 at biopsy (OR, 9.856; 95% CI, 2.230-43.557; p=0.003) were associated with upstaging after RP (Table 3). The cutoff value for pre-operative serum testosterone level for upstaging was 273.7 ng/dL (sensitivity, 71.3%; specificity, 66.7%, as determined by receiver operating curve analysis) (Fig. 2). In addition, clinical/radiologic stage (T2 vs. T1c) and Gleason grade group at biopsy (2 vs. 1) were significantly associated with upgrading in the multivariate analysis (OR, 11.260; 95% CI, 1.410-89.914; p=0.022 and OR, 2.526; 95% CI, 1.063-5.998; p=0.036, respectively).

Currently, NSRP is a widely accepted surgical method for select patients with clinically localized PCa, to minimize postoperative complications, including erectile dysfunction and postprostatectomy incontinence. However, postoperative upstaging and upgrading— which might have altered the op-erative technique selection if they had been predicted— are not uncommon after NSRP. Recently, several studies re-vealed that preoperative serum testosterone reflects tumor aggressiveness among PCa patients.^12-16 Therefore, we as-sessed the incidence and predictive factors for upstaging and upgrading among PCa patients after NSRP at our institution. We observed significant incidences of upstaging (22.2%) and upgrading (33.3%). Furthermore, preoperative serum testosterone was negatively associated with upstaging and upgrading after RP. Multivariate analysis revealed pre-operative serum testosterone as a significant predictor up-staging, despite its lack of a significant association with postoperative upgrading.

The key objectives of RP for PCa include ensuring good postoperative erectile function and urinary continence with-out compromising oncological outcomes. Techniques that emphasize the preservation of neurovascular bundles during RP have been developed to minimize postoperative compli-cations for appropriately selected patients.³ Several studies have confirmed the benefits of NSRP for the recovery of erectile function and urinary continence.^20-23 While nerve- sparing techniques have several advantages in terms of quality of life, dissection closer to the prostate capsule during NSRP may increase the risk of incising the tumor or incomplete tumor excision, resulting in a positive surgical margin, and may increase risk of biochemical progression and cancer recurrence.⁵

When choosing the treatment method, particularly when considering NSRP, the surgeon most strongly considered the index PSA, clinical stage, and the biopsy Gleason grade group. However, recent research has shown that patho-logical stage and grade after surgery are often inconsistent with clinical stage and biopsy grade, and this is usually ex-pressed as upgrading or upstaging.^6-11 For patients whose re-al pathological stage and grade exceed the clinical stage and biopsy grade, the selected surgical method— nerve-sparing surgery, for example— could underestimate the aggressive-ness of the PCa and compromise cancer control. Therefore, it is necessary to identify predictive factors for upstaging and upgrading for selecting a proper treatment strategy or surgical method for PCa patients for whom there are several options.

Several recent studies have focused on determining predictors of upstaging and upgrading among PCa patients.^6-11 In a large cohort study including 7,643 patients who under-went RP, 36.3% of patients had their needle biopsy Gleason score upgraded from 5 or 6 to a higher grade after RP.⁶ Sooriakumaran et al.¹⁰ reported that 40.4% patients were ei-ther upstaged (3.9%) or upgraded (39.6%) after RP among 750 patients with low-risk PCa, clinically eligible for AS. In a Korean multicenter study with 324 RP specimens from low-risk PCa patients, upstaging and upgrading were ob-served in 9.6% and 43.8% samples, respectively.⁹ In another study of Korean PCa patients who were eligible for AS (clinical stage T1c/T2a, PSA level 10 ng/mL or less, and Gleason score 6 or less), upstaging and upgrading were ob-served in 11.0% and 57.8% of 593 patients, respectively.¹¹ A recent study with similar inclusion criteria (biopsy Gleason score≤6, clinical stage≤ T2c, and PSA<10 ng/mL) to our study revealed that upstaging occurred in 43.7%, and upgrading occurred in 37.1% of 167 patients.⁸ Unlike pre-vious studies, however, our study showed relatively high upstaging (33.3%) and low upgrading (22.2%). We assumed that this discrepancy from previous research was caused by differences in the participant characteristics and radiologic staging using multiparametric magnetic resonance imaging in the present study. This study was conducted on patients eligible for NSRP (biopsy Gleason grade group 1 or 2, PSA<10, and clinical/radiologic stage≤ T2) at our in-stitution, while previous studies investigated patients who were eligible for AS.

In the present study, preoperative serum testosterone was negatively correlated with upstaging and upgrading after RP, and it was identified as a predictive factor for upstaging in multivariate analysis. Although it is still controversial, testosterone has been widely evaluated as a predictive factor for worse pathological outcomes, such as upstaging and up-grading, and oncologic outcomes.^13-17,24,25 Previous studies have suggested that serum testosterone level is inversely correlated with tumor aggressiveness, which is a descriptor that encompasses both high stage^13,14 and high grade.^15,16 Teloken et al.¹⁷ reported that low serum testosterone levels were associated with positive surgical margins after RP, while not with PSA levels, Gleason score (biopsy or speci-men), pathological stage, or capsular perforation. Moreover, Asian studies have identified preoperative serum testoster-one level as an independent predictor of biochemical recurrence after RP among patients with clinically localized PCa.^24,25

Recently, several reports have highlighted the association of low serum testosterone levels with upstaging and upgrading after RP among patients with localized PCa.^8,12 Gao et al.⁸ investigated the association between serum testosterone and upgrading or upstaging among PCa patients with biopsy Gleason scores≤6, clinical stage≤ T2c, and PSA<10 ng/mL. They confirmed preoperative serum testosterone level as a unique independent predictor of pathological upstaging and upgrading after RP. Moreover, Ferro et al.¹² assessed the impact of serum testosterone for predicting unfavorable out-comes among PCa patients eligible for AS, which is cur-rently considered acceptable for clinically localized PCa. They suggested that patients with hypogonadism were not eligible for AS because low serum testosterone is associated with unfavorable pathological outcomes, including upstaging, upgrading, and positive surgical margins. Our findings also supported the clinical impact of low serum testosterone as a predictive factor of upstaging and upgrading among patients with localized PCa eligible for NSRP on preoperative evaluation. Therefore, surgeons should be cautious when se-lection of a treatment course and proceeding with NSRP for eligible patients with low serum testosterone.

Recent studies, including the present study, have demon-strated that serum testosterone level is predictive of tumor aggressiveness, including the potential for upstaging and upgrading. Although the exact mechanism is not yet fully understood, it may be assumed that involves the inhibition of testosterone by highly aggressive prostate tumors and negative feedback control of pituitary gonadotropin secretion.⁸ Moreover, metabolic disorders that are associated with hypogonadism might contribute to unfavorable PCa outcomes.^12,26,27

In this study, small prostate size and positive core number ≥3 on biopsy were also identified as predictive factors for upstaging in multivariate analysis. Previous studies have shown small prostate size and high positive core number on prostate biopsy to be associated with aggressive features of PCa.^9,11,28-30. Similar with our results, 2 Korean studies found that prostate volume and positive core number were significantly associated with upstaging¹¹ or worsening prog-nosis⁹ in multivariate analyses. Additionally, a Japanese study²⁹ and a Swedish study³⁰ also reported that smaller prostate volume was associated with adverse pathology. Regarding the mechanism by which prostate volume and positive core number are predictors of PCa aggressiveness, they might reflect a relatively larger tumor burden with a high probability of disease that has progressed beyond the prostate capsule.

Several limitations of our study should be considered. First, this was a retrospective analysis of the records of a relatively small sample of patients treated at a single insti-tution. Although the criteria for NSRP eligibility were fol-lowed in this study, selection bias regarding the surgical in-dication was unavoidable. Additionally, we did not access to data reflecting long-term oncologic outcomes, such as bi-ochemical recurrence and metastasis-free survival. These limitations highlight the need for more standardized study designs and outcome reporting methods in the future. Furthermore, additional studies are necessary to elucidate the underlying mechanisms involving serum testosterone in relation to PCa. Although this retrospective study had sev-eral limitations, it demonstrated that low preoperative serum testosterone level, small prostate size, and positive core number≥3 on biopsy should be considered valuable pre-dictors of upstaging after RP in clinically localized PCa amenable to NSRP. We hope that the results of this study can help clinicians develop appropriate management strat-egies and choose appropriate surgical methods to treat clin-ically localized PCa.

Low preoperative serum testosterone level, small prostate size, and positive biopsy core number≥3 were identified as predictive factors for upstaging after RP in clinically lo-calized PCa eligible for nerve-sparing surgery. Therefore, preoperative serum testosterone should be measured and considered as a predictor of non-organ confined disease in patients with clinically localized PCa eligible for nerve-sparing surgery.