Sarcopenia is a poor prognostic factor of castration-resistant prostate cancer treated with docetaxel therapy

BACKGROUND: Sarcopenia is a geriatric syndrome that is characterized by the gradual muscle loss and frailty in the elderly. Meanwhile, the prevalence of prostate cancer is on the rise worldwide. Mainstay treatments for metastatic prostate cancer are androgen-deprivation therapy and taxane-based chemotherapy. Owing to the indolent nature of prostate cancer, these treatments tend to be long-lasting, giving rise to the problem of tolerance to the treatments. Especially given the fact that long-term chemotherapy is closely associated with muscle loss, we aimed to elucidate the correlation between chemotherapy and sarcopenia in the clinical setting. MATERIALS AND METHODS: This study was a retrospective study. Participants with castration-resistant prostate cancer were recruited from November 2009 to September 2015. Participants were recruited at two hospitals, Juntendo and Teikyo University Hospital, Tokyo, Japan. Participants were 77 Japanese males with castration-resistant prostate cancer who underwent docetaxel chemotherapy. Sarcopenia was defined as L3-psoas muscle index < 5.7 cm(2)/m(2). We statistically investigated whether the existence of sarcopenia has an impact on the survival time, and identified potential covariates that affect it. RESULTS: Out of 77 patients, 26 patients (34%) were diagnosed as sarcopenia. Analysis showed that sarcopenia is independently associated with mortality risk (hazards ratio = 2.74, P = 0.0055). Sarcopenic patients showed significant decrease in body mass index, pretreatment hemoglobin, C-related protein, and L3-psoas muscle index as compared with nonsarcopenic patients. The median observation period was 499 days (330–790). Thirty-five patients (45%) died of prostate cancer during that period. Sarcopenic patients showed significantly shorter survival time after the initiation of docetaxel treatments (P = 0.0055). CONCLUSION: Sarcopenia is an independent predictive factor for a poor tolerance to docetaxel treatment. Given that cessation of the treatment leads to death from the disease, our study identified sarcopenia as an independent factor that raises mortality risk.