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Outcomes of Treatment for Localized Prostate Cancer in a Single Institution: Comparison of Radical Prostatectomy and Radiation Therapy Using Inverse Probability of Treatment Weighting (IPTW) Analysis

C. Chu¹, H. Luo¹

¹Kaohsiung Chang Gung Memorial Hospital, Department of Urology, Kaohsiung, Taiwan

Introduction:

Numerous studies have examined the oncological outcomes of stage II and III prostate cancer, comparing radical prostatectomy and radiation therapy, with results often favoring radical prostatectomy. However, there is limited research focusing on Asian patients. This study aims to analyze the oncological outcomes of Asian patients with localized prostate cancer receiving different treatment modalities.

Material and methods:

This study collected data from a total of 2,717 patients with localized prostate cancer treated between January 2005 and June 2022, utilizing the Chang Gung Research Database (CGRD). We analyzed the oncological outcomes of radical prostatectomy versus radiotherapy separately for stage II and III groups. To account for patient variability in treatment selection, we employed inverse probability of treatment weighting (IPTW). During IPTW adjustment, we considered age, PSA level, Gleason score, stage, Charlson Comorbidity Index (CCI), and comorbidities (hypertension, diabetes, coronary artery disease), with age being the most adjusted variable, initially exhibiting a standardized difference greater than 1. Additionally, we examined subgroups of patients who underwent initial radiotherapy versus those who received adjuvant radiotherapy post-surgery.

Results:

In stage II patients, overall survival (OS) exhibited a significant difference favoring radical prostatectomy before IPTW adjustment (unweighted log-rank test: p < 0.001). However, after IPTW adjustment, no significant difference was observed (weighted log-rank test: p = 0.103). For stage III patients, OS showed no significant differences either before or after IPTW adjustment (unweighted log-rank test: p = 0.953; weighted log-rank test: p = 0.103). Subgroup analysis of patients who received initial or adjuvant radiotherapy revealed a significant difference in stage II OS (favoring adjuvant radiotherapy post-surgery) before IPTW adjustment (unweighted log-rank test: p = 0.017), but no significant difference afterward (weighted log-rank test: p = 0.652). Cancer-specific survival (CSS) showed no significant difference regardless of IPTW adjustment (unweighted log-rank test: p = 0.092; weighted log-rank test: p = 0.906). For stage III patients, both OS and CSS exhibited no significant differences whether IPTW adjustment was applied (OS: unweighted log-rank test: p = 0.108, weighted log-rank test: p = 0.494; CSS: unweighted log-rank test: p = 0.719, weighted log-rank test: p = 0.921).