Metastatic prostate cancer is prostate cancer that has spread beyond the prostate gland to other parts of the body, most commonly the bones. About 8% of prostate cancer cases are already metastatic at the time of diagnosis, and the five-year relative survival rate for this stage is roughly 38%, a significant drop from the near-100% survival rate for cancer that remains localized to the prostate.
How Prostate Cancer Spreads
For cancer to become metastatic, tumor cells must complete a series of steps. First, they invade through the tissue surrounding the original tumor. Then they break into either blood vessels or lymphatic channels by pushing through the walls of those vessels. Once in the bloodstream or lymphatic system, most cancer cells are destroyed by the immune system. The small fraction that survive latch onto blood vessel walls at a distant site, push through again, and establish a new tumor.
This process is not random. Prostate cancer cells have a strong preference for bone. In a large population-based study of nearly 75,000 men with metastatic prostate cancer, 84% had bone metastases. The next most common sites were distant lymph nodes (about 11%), liver (10%), and the chest/lungs (9%). Among men who already had bone metastases, secondary spread to the liver and lungs was also relatively common.
Symptoms to Recognize
Early prostate cancer often causes no symptoms at all, which is why the metastatic stage can feel like it came out of nowhere. Once cancer has spread, symptoms tend to reflect where it has landed. Bone metastases frequently cause pain in the back, hips, or pelvis that worsens over time. Some men experience fractures from bones weakened by tumor growth, or compression of the spinal cord, which is a medical emergency.
More general symptoms include persistent fatigue, unintentional weight loss, nausea, and needing to urinate more often or with discomfort. These can overlap with many other conditions, but in someone with a known prostate cancer history, they raise a flag for possible progression.
How Metastatic Disease Is Detected
Traditional imaging for prostate cancer staging has relied on bone scans and CT scans, but these tools miss a significant amount of disease. Bone scans detect about 70% to 80% of bone metastases and often produce false positives by flagging normal age-related bone changes. CT scans catch only about 38% of cancerous pelvic lymph nodes.
A newer imaging technique called PSMA PET/CT has dramatically improved detection. It works by targeting a protein found on the surface of most prostate cancer cells, lighting up even small deposits of cancer that conventional scans would miss. In head-to-head trials, PSMA PET/CT detected bone metastases with 97% to 99% sensitivity and identified pelvic lymph node metastases with 85% sensitivity, more than double the rate of standard CT. For distant metastases overall, it reached 95% sensitivity compared to 74% for conventional imaging. This technology is now widely used in staging and treatment planning, and it changed the risk classification for nearly 13% of patients in one major study, directly altering their treatment.
Two Stages of Metastatic Disease
Not all metastatic prostate cancer behaves the same way, and the distinction between two subtypes shapes every treatment decision. When metastatic disease is first diagnosed or still responds to hormone-lowering therapy, it is classified as metastatic hormone-sensitive prostate cancer (mHSPC). This is the earlier, more treatable phase.
Over time, the cancer typically adapts and begins growing again despite very low testosterone levels. At that point it becomes metastatic castration-resistant prostate cancer (mCRPC). The transition is defined by rising PSA levels during hormone therapy or the appearance of new metastases on imaging, all while testosterone remains suppressed. mCRPC is harder to control but still has several treatment options available.
Hormone Therapy as the Foundation
Prostate cancer cells rely on testosterone and other androgens to grow, so the cornerstone of treatment is cutting off that fuel supply. This approach, called androgen deprivation therapy (ADT), reduces testosterone levels by 90% to 95%. It can be done surgically by removing both testicles, but most men receive injections instead.
These injections come in two forms. One type initially causes a brief surge in testosterone before the body’s hormonal signaling system shuts down from overstimulation, eventually stopping testosterone production. The other type blocks the signal immediately, avoiding that initial surge. Both achieve the same end result: testosterone levels low enough to slow or stop cancer growth, at least temporarily.
For men with metastatic disease, ADT alone is no longer considered sufficient. Current treatment typically combines ADT with additional therapies from the start, which has been shown to extend survival compared to ADT on its own. These combinations may include drugs that block androgen receptors more completely or chemotherapy given early alongside hormone treatment.
When the Cancer Becomes Resistant
Once prostate cancer progresses to the castration-resistant stage, additional treatment lines become available. About 20% of men with prostate cancer carry mutations in DNA repair genes, including BRCA1 and BRCA2, the same genes associated with breast and ovarian cancer risk. For men whose tumors have these mutations, a class of targeted drugs called PARP inhibitors can be effective. These drugs exploit the cancer cell’s inability to repair its own DNA, causing the cells to die. Testing for these mutations is now a standard part of managing advanced prostate cancer, though access to testing still varies.
For men with mCRPC whose cancer has progressed through both hormone-blocking drugs and chemotherapy, a radioactive treatment option exists. This therapy uses a small radioactive molecule that seeks out the same protein targeted by PSMA PET scans, delivering radiation directly to cancer cells wherever they are in the body. In its pivotal clinical trial, men who received this treatment lived a median of 15.3 months compared to 11.3 months with standard care alone, and 30% of men with measurable tumors saw them shrink, compared to just 2% in the standard care group. Eligibility requires a PSMA PET scan confirming that the cancer cells express the target protein.
Protecting Bones During Treatment
Since bone is the dominant site of spread, protecting skeletal health is a major part of managing metastatic prostate cancer. Bone metastases can cause fractures, spinal cord compression, and severe pain. On top of that, hormone therapy itself weakens bones by stripping away the testosterone that helps maintain bone density.
Two types of bone-protecting medications are used. One is a class of drugs that bind directly to bone surfaces and slow the breakdown process. These are given intravenously every four weeks. The other is an injection given under the skin every four weeks that works by blocking a specific protein involved in bone destruction. Both are started once bone metastases are confirmed on imaging, with the goal of delaying or preventing fractures and other skeletal complications. At lower doses and less frequent intervals, the same medications can also be used earlier to counteract bone loss caused by hormone therapy itself.
The Role of Genetic Testing
Genetic testing has become increasingly important in metastatic prostate cancer, not just for treatment selection but for family planning. If a man carries a germline BRCA mutation (one he was born with, rather than one the tumor acquired), his close relatives may also carry it, putting them at higher risk for prostate, breast, and ovarian cancers. Roughly one in five men with metastatic prostate cancer will have a mutation in a DNA repair gene, making testing relevant for a substantial portion of patients. Results can open the door to targeted therapies and inform screening recommendations for siblings and children.
What Survival Looks Like Today
The 38% five-year survival rate for metastatic prostate cancer reflects cases diagnosed between 2015 and 2021. Treatment has evolved considerably even since then, with newer drug combinations for hormone-sensitive disease, expanded use of PSMA-targeted imaging and therapy, and broader genetic testing all entering routine practice. Many men live years with metastatic prostate cancer, particularly those diagnosed in the hormone-sensitive phase who respond well to combination therapy. The trajectory varies widely depending on how many sites are involved, whether the cancer is hormone-sensitive or castration-resistant, and how it responds to initial treatment.