Cancer-specific and net overall survival in older patients with de novo metastatic prostate cancer initially treated with androgen deprivation therapy

Objective: This study aimed to assess survival outcomes in older patients with de novo metastatic prostate cancer who initially received androgen deprivation therapy. Methods: The retrospective multicenter study included 2784 men with metastatic prostate cancer who were treated with androgen deprivation therapy between 2008 and 2017. Patients were classified into <75, 75–79, and ≥80 age groups. Propensity score matching was conducted to assess the cancer-specific survival of the groups. The 5-year net overall survival of each group was derived to evaluate relative survival compared with the general population using the Pohar–Perme estimator and the 2019 Japan Life Table. Results: During the follow-up (median, 34 months), 1014 patients died, of which 807 died from metastatic prostate cancer progression. Compared with the <75 group, the cancer-specific survival of the 75–79 group was similar (hazard ratio 1.07; 95% confidence interval 0.84–1.37; P = 0.580), whereas that of the ≥80 group was significantly worse (hazard ratio 1.41; 95% confidence interval 1.10–1.80; P = 0.006). The 5-year net overall survival of the <75, 75–79, and ≥80 age groups were 0.678, 0761, and 0.718, respectively. The 5-year net overall survival of patients aged ≥80 years with low- and high-volume disease were 0.893 and 0.586, respectively, which was comparable with those in patients aged <75 years (0.872 and 0.586, respectively). Conclusions: Older metastatic prostate cancer patients aged ≥80 years had poorer cancer-specific survival compared with younger patients. Conversely, 5-year net overall survival in older patients aged ≥80 years was comparable with that in younger patients aged <75 years.