Potential overtreatment among men aged 80 years and older with localized prostate cancer in Japan

Despite treatment guidelines recommending observation for men with low‐risk prostate cancer with life expectancy <10 years, a majority of elderly patients choose active treatment, which may result in overtreatment. Given the growing burden of prostate cancer among men aged ≥80 years (super‐elderly men), accumulation of survival data for evaluation of overtreatment among super‐elderly patients is imperative. Here, we report results of a population‐based cohort study to clarify potential overtreatment of super‐elderly men with localized prostate cancer. We used cancer registry data from the Monitoring of Cancer Incidence in Japan project, which covers 47% of the Japanese population. The subjects were men diagnosed with prostate cancer between 2006 and 2008. Follow‐up period was 5 years. We calculated 5‐year relative survival rates among the active treatment and observation groups after imputation for missing values. Of the 48 782 patients with prostate cancer included in the analysis, 15.1% were super‐elderly men. The 5‐year relative survival rates of super‐elderly men with localized cancer were 105.9% and 104.1% among the active treatment and observation groups, respectively. This excellent relative survival rate in the observation group remained consistent even after stratification by tumor grade. Of the 2963 super‐elderly men with localized cancer, 252 (8.5%) with curative treatment and 1476 (49.8%) with hormone therapy were assumed to have been overtreated. The proportion of overtreatment was estimated to reach 80% after imputation. These specific survival data in super‐elderly men in the observation group can be useful in shared decision‐making for these patients and may lead to a reduction in overtreatment.