By doing this study, doctors hope to learn more about factors that contribute to frailty (a condition where older adults feel weak, get tired easily, and struggle more with everyday activities) and serious side effects among men over the age of 65 who will receive androgen deprivation therapy (also called "hormone therapy") for prostate cancer that has spread to other parts of their body. Participation in this research will last about 5 years. For the first year, participants will have 5 study visits where they have give blood samples, answer survey questions, and use a wearable device. After study visits are complete, there is a 4-year follow-up period. Research team will check regular doctor visits and look at participants' medical records.

By doing this study, doctors hope to learn more about factors that contribute to frailty (a condition where older adults feel weak, get tired easily, and struggle more with everyday activities) and serious side effects among men over the age of 65 who will receive androgen deprivation therapy (also called "hormone therapy") for prostate cancer that has spread to other parts of their body. Participation in this research will last about 5 years. For the first year, participants will have 5 study visits where they have give blood samples, answer survey questions, and use a wearable device. After study visits are complete, there is a 4-year follow-up period. Research team will check regular doctor visits and look at participants' medical records.

The purpose of this research is to gather information about the physical, mental, and social health of study participants to help the research team identify factors that put older men with prostate cancer at greater risk for developing serious side effects during hormone therapy. This study is for individuals who are over the age of 65 and plan to receive hormone therapy as part of standard treatment for their prostate cancer. Participants will receive androgen deprivation therapy as part of their standard care with their doctor outside of this study. No drugs or treatments will be given in this study. Participants will instead fill out questionnaires, provide blood samples, and wear a smartwatch paired to a mobile application downloaded to the their personal smartphone or a phone/tablet provided by the research team. This application will help the research team collect information about each study participants' levels of function, general health, physical activity, body composition, memory, mood and side effects during hormone therapy. By collecting this information, doctors leading the study ultimately hope to learn new ways to potentially improve treatment options for older men with prostate cancer while lowering their risks for serious side effects.

Inclusion Criteria:

• Patients must have histologically or cytologically confirmed adenocarcinoma of prostatic origin without neuroendocrine differentiation or signet ring or small-cell histologic features.
• Patients must be metastatic by having at least one metastatic lesion seen at the time of diagnosis or upon initiation of treatment on bone scan or computed tomography (CT) or magnetic resonance imaging (MRI), or by next-generation molecular imaging (FDG, F-18 sodium fluoride (NaF), C-11 choline, F-18 Fluciclovine, Ga-68 Prostate-specific membrane antigen (PSMA-11) positron emission tomography/computed tomography or magnetic resonance imaging.
• Age ≥ 65years. positron emission tomography the aforementioned GA tools are only validated in those aged 65 and older.
• Planned initiation of intensified hormone deprivation (ADT and ARSI)
• Ability to understand and the willingness to sign a written informed consent document.

Exclusion Criteria:

• Participants with previous exposure to ADT/ARSI within 12 months of diagnosis, except those who initiated ADT/ARSI within 12 weeks of enrollment.
• Participants who had surgical orchiectomy outside of 12 weeks before their metastatic diagnosis.
• Participants who have had previous chemotherapy for metastatic prostate cancer.
• Uncontrolled intercurrent illness. "Uncontrolled intercurrent illness" refers to a concurrent medical condition that is not adequately managed or stable at the time of enrollment. This could be any illness, disorder, or medical issue occurring alongside the primary disease being treated or studied, and its lack of control poses additional risk to the patient or complicates the management of the primary condition. For example, in the context of enrolling patients in a clinical trial for a cancer treatment, a patient with uncontrolled diabetes mellitus or hypertension would be considered to have an uncontrolled intercurrent illness as diabetes and hypertension - if poorly managed - can lead complications that could interfere with the patient's ability to safely participate in the trial, potentially confounding the study results or posing additional health risks to the patient.
• Participants with small-cell carcinoma of the prostate or brain metastasis.
• Participants who are not fluent in reading/writing English or Spanish.
• Biologic and Pregnant women are excluded from this study because prostate cancer is a disease of biological males.
• Participants with implantable cardiac devices.
• Participants with limb defects precluding smart-watch wear.

participants with metastatic prostate cancer over the age of 65