Objectives: There is no recommended observation time for patients who have undergone radical prostatectomy for prostate cancer. This study was undertaken to determine the postoperative observation time by investigating the hazard rate for prostate-specific antigen failure and other-cause death using Weibull analysis.
Methods: We included 612 patients who underwent laparoscopic radical prostatectomy for localized prostate cancer between June 2002 and December 2017. Risk classification was categorized by the D'Amico risk classification, and the patients were divided into three age groups: <60, 60-69 and ≥70 years. The hazard rates at each point were derived using Weibull analysis. The optimal observation time after laparoscopic radical prostatectomy was determined as the intersection point at which the hazard rate of other-cause death overtakes the hazard rate of prostate-specific antigen failure.
Results: In all groups classified by age, the hazard rate of other-cause deaths increased over time. In contrast, the hazard rate of prostate-specific antigen failure decreased gradually. The ≥70 years age group showed the highest hazard rate. The hazard rate of prostate-specific antigen failure was highest in the high-risk group. The patients aged ≥70 and 60-69 years in the low-risk group were recommended 6 years 6 months and 14 years 8 months, respectively, for observation. The remaining patients were recommended >25 years of postsurgical observation.
Conclusions: The observation time after laparoscopic radical prostatectomy could be estimated by comparing the estimated hazard rates of prostate-specific antigen failure and other-cause death based on Weibull analysis. Urologists should pay attention to age and risk classifications for optimal postoperative observation.
Keywords: Weibull analysis; hazard rate; laparoscopic radical prostatectomy; observation time; prostate cancer.
© 2022 The Japanese Urological Association.