Currently the guidelines of the American Urological Association, the European Association of Urology and the NCCN endorse RP, LDR and EBRT therapy as appropriate treatment options for IRPC. No differences have been observed in OS or CSS among the three approaches in the recent studies (14, 15). However, treatment options for Pca are diverse, and therapeutic decisions are largely based on the condition of each medical institution, the preference of doctors and the cognition of patients (14). The comparison of the oncological outcomes of RP and LDR treatments remains a challenge, due to differential definitions for recurrence and methodological biases arising from the differences in baseline characteristics, including age, comorbidity and cancer risk features (14, 16-18). A randomized controlled trial is the ideal approach for comparing competing treatment modalities (19). However, most of the previously reported literatures comparing the efficacy of LDR and RP are retrospective studies (14, 20). Compared with candidates for RP, patients who are offered LDR generally tend to be older and have higher comorbidity scores, therefore, a random trial is impractical (17, 18).
We retrospectively analyzed data from 361 IRPC patients treated in our hospital. Our results showed there were no statistically significant differences in the cRFS, CSS and OS between the two therapeutic groups. This result was consistent with recent publications in the literature, though they were not supported by randomized prospective studies (21-23). Hamdy et al reported 10-year outcomes after monitoring, surgery, or radiotherapy for localized prostate cancer, and there were no significant difference in cRFS, CSS and OS between treatments of surgery and radiotherapy (15). However, his study included patients of all risk categories, and thus we cannot make any conclusions regarding IRPC. Goy et al statistically analyzed 1503 IRPC patients who underwent treatment from 2004 to 2007. There were no significant differences in cRFS or CSS. The 10-year bRFS was 80.2% for LDR vs 57.1% for RP vs 57.0% for EBRT, which showed improved bRFS with LDR, P = 0.0003(24). But LDR patients had a significantly smaller proportion number compared with RP (7.3% Vs 54.5%) in his study, which might cause some bias in the results. In our study, the proportion of patients in both groups was more balanced than that in Goy’s study. Consistent with Goy's results, in the present study, the 5- and 8-year bRFS rates were 70.2% and 63.1% in the RP group, and 83.2% and 68.9% in the LDR group, respectively. The log-rank test showed the bRFS for RP was significantly lower than LDR. However, in terms of the pretreatment characteristics, patients treated with LDR were older, experienced longer follow-up time, and had a higher preponderance of combined ADT treatment. In previous studies using models adjusted for risk, ADT was not shown to be an independent predictor (18, 25). Our study supports the use of LDR as a reasonable treatment option for IRPC.
Neither treatment modality has proven superior to the other with respect to RP and LDR; therefore, the optimal treatment for different risk categories in Pca remains a matter of debate. Although our median follow-up time of 54 months was sufficient to capture a considerable number of systemic failure events, it may still be too short to achieve mortality results. Therefore, we chose bRFS as the main evaluation criterion of curative effect. We observed that bRFS was significantly higher with LDR than RP in patients with GS 7, prostate volume >30ml, iPSA ≤ 10 ng/ml, clinical T stage with T1c-T2a, any PPBC or unfavorable IRPC. Supported by the results of our study, LDR may be a better option than RP in patients with the above conditions. In our experience, a subgroup analysis of unfavorable IRPC had improved bRFS with LDR compared to RP. These results showed that LDR was also a good option for those with unfavorable IRPC. Taussky et al reported RP and LDR treatment did not result in significantly different outcomes at four years post-treatment in patients with low- and low-intermediate- risk Pca (26). However, Ferreira et al found the 5-year bRFS of patients with early Pca who had undergone LDR was significantly higher than those who had undergone surgery (27). Furthermore, Ciezki et al reported high-risk Pca treated with EBRT, LDR, or RP yields efficacy with better bRFS for LDR and EBRT compared with RP (21). It should be noted that these studies were obviously heterogeneous, because different centers adopted different LDR technologies, and different methods were used to compare the results between RP and LDR (28).
As the previously studies reported, there were many factors affecting the prognosis of Pca, including general situation, tumor stage, tumor grade, iPSA, age and bone scintigraphy (29-31). Ciezki et al found clinical stage T3, GS 8 to 10, higher iPSA and more frequent PSA testing after therapy were all associated with a significantly worse bRFS (21). Taussky et al reported younger age, higher percentage of positive biopsies, and PSA at diagnosis were predictive of BF (26). On univariate analysis of the entire cohort in the present study, treatment with RP, age <70 years old，clinical T stage with T2b-T2c, prostate volume ≤30ml and PPBC>50% were associated with significantly worse bRFS. Previous studies had reported that clinical stage was the most dangerous factor influencing Pca prognosis (32, 33). On multivariate analysis of the entire cohort, treatment with RP, prostate volume ≤30ml and PPBC>50% were associated with significantly worse bRFS. Therefore, they were important independent prognostic factors.
The limitations of this study include the following: (1) The baseline characteristics of the two groups did not completely match, which was inevitable due to random grouping in a retrospective study. Therefore, a prospective study comparing eligible patients is needed to make a more accurate conclusion. (2) The aim of our study was to provide a guide to aid clinical decision making at diagnosis. Thus, duration of ADT following initial treatment, which may contribute to survival, was not adjusted. However, in previous studies using models adjusted for risk, ADT was not shown to be an independent predictor (18, 25). (3) The definition of BF is different for the RP versus LDR groups. Although this definition is commonly used in the world(15, 23, 24), it could cause some bias in interpretation of the results. (4) There were fewer deaths in this study; therefore, whether higher bRFS rates observed in patients could translate into superior oncological endpoints is still undetermined. A longer observational period is needed for a meaningful comparison of overall survival.