1. Abstract: Previously, docetaxel-based chemotherapy regimens have been recommended only when prostate cancer has progressed to the CRPC stage. This study evaluated the therapeutic effect of simultaneous ADT combined with chemotherapy in metastatic hormone-sensitive prostate cancer. The results found that six cycles of docetaxel chemotherapy applied concurrently with ADT treatment significantly prolonged the overall survival of patients with metastatic hormone-sensitive prostate cancer. 2. Background As early as the 1840s, androgen-deprivation therapy (ADT) was first used in the treatment of metastatic prostate cancer. For more than half the world, ADT has been the first-line treatment option for metastatic prostate cancer. However, after androgen deprivation therapy, prostate cancer can progress from androgen-sensitive to the stage of depression-resistant prostate cancer (CRPC). For patients with CRPC, docetaxel chemotherapy is now mostly used as the primary treatment option. Previously, chemotherapy has been administered only after prostate cancer has progressed to the CRPC stage. This study evaluates the therapeutic effect of simultaneous ADT combined with chemotherapy in metastatic hormone-sensitive prostate cancer. The findings of this study will further clarify the value of chemotherapy for prostate cancer. 3. Results <1> A total of 790 cases of metastatic hormone-sensitive prostate cancer with a median age of 63 years and a median follow-up time of 28, 9 months were included in this study. Patients were divided into two groups: one group of 397 patients received 6 cycles of docetaxel-based chemotherapy concurrently with ADT treatment; the other group of 393 patients received ADT treatment only. <2>, Simultaneous ADT combined with chemotherapy prolonged metastatic hormone-sensitive prostate cancer by 13, 6 months, with a median OS of 44, 0 months in patients treated with ADT only and 57, 6 months in patients treated with simultaneous ADT combined with chemotherapy. <3>, The median time to PSA progression, symptom progression or imaging progression in patients in the synchronous ADT combined with chemotherapy group was 20, 2 months, while the median time to the above progression was 11, 7 months in patients treated with ADT only. <4>, In the synchronous ADT combined with chemotherapy group, PSA decreased to less than 0.2 ng/ml in 27.7% of patients after 12 months of treatment, while in patients treated with ADT, PSA decreased to less than 0.2 ng/ml in only 16.8% of patients. <5>, Further analysis revealed that the benefit of simultaneous ADT combined with chemotherapy was more pronounced in patients with high-load metastatic prostate cancer, which prolonged the median OS by 17,0 months, with a median OS of 32,2 months in patients with high-load metastases treated with ADT only, compared with 49,2 months in patients treated with simultaneous ADT combined with chemotherapy. 5. Review of clinical significance This study found that simultaneous application of 6 cycles of docetaxel chemotherapy with ADT treatment significantly prolonged the overall survival of patients with metastatic hormone-sensitive prostate cancer. The results of this study will revolutionize the current guidelines for the treatment of metastatic hormone-sensitive prostate cancer. 2015 NCCN prostate cancer guidelines already recommend docetaxel-based chemotherapy for high-load metastatic androgen-sensitive prostate cancer. Previously, chemotherapy was administered only when the prostate cancer progressed to the CRPC stage. The findings of this study support the advancement of chemotherapy to the first diagnosis of metastatic prostate cancer patients.