Medically reviewed by Jimena Vicencio, MD, on September 16, 2026.
Prostate cancer and multiple myeloma can occur in the same person. But research has not proven that one cancer causes the other. Here is what researchers know about a possible link and why both cancers can affect bones.
Looking at cases of both cancers
Researchers have reported cases of people with both cancers. Some people had prostate cancer first. Others had myeloma first. A few were diagnosed with both at about the same time.
One review found 18 published cases involving both cancers. Eight people developed myeloma after prostate cancer. Five were diagnosed with both cancers at the same time. Five developed prostate cancer after myeloma.
These cases show that the two cancers can occur together. However, the number of reported cases is small. The findings do not prove that having one cancer causes the other.
Why researchers are studying a possible connection
In the review, some theories about why the cancers may occur together were presented. One involved the bone marrow microenvironment. This is the area around cells inside the bone marrow. It can affect how cells grow and work.
Myeloma and prostate cancer may use some of the same cell signals. Researchers have studied proteins called interleukin-6 (IL-6) and insulin-like growth factor 1 (IGF-1). These proteins can affect cell growth.
Family history may also play a role in the link between myeloma and prostate cancer. One study found a higher risk of myeloma in families with several cases of prostate cancer. The link appeared stronger when prostate cancer occurred at a younger age.
Shared genes or cell signals could help explain a link. But more research is needed to know for sure.
Does prostate cancer treatment affect myeloma risk?
Researchers have questioned whether treatments that lower male hormones could affect myeloma risk.
One review looked at seven people who developed myeloma after prostate cancer. All seven had received treatment that lowered male hormones. However, this was a very small number of people.
The study did not show that prostate cancer treatment causes myeloma. Larger studies are needed to see if there is a connection.
Both cancers can cause bone changes
Prostate cancer and myeloma can both affect bones. This can make it harder to tell which cancer is causing a bone problem.
Myeloma often causes lytic lesions. These are weak areas where bone has broken down. Prostate cancer that spreads to the bone more often causes sclerotic lesions. These are areas where bone becomes unusually hard or thick.
These patterns are not always clear. Prostate cancer can sometimes cause lytic lesions too. Rare reports have even found both cancers within the same bone lesion.
Doctors may need several tests to find the cause of a bone change. These can include blood tests and imaging scans. Doctors may also check prostate-specific antigen (PSA). PSA is a protein made by prostate cells, and it can be found in a blood test. A bone marrow test or biopsy may be needed in some cases.
For people with myeloma, new bone changes may need more testing. Your healthcare team can determine which tests are right for you.
A possible connection, but no proven cause
Research has not proven that prostate cancer causes myeloma. It also has not been shown that myeloma causes prostate cancer. Researchers have found possible shared factors, but the evidence is limited.
Having myeloma does not mean you will develop prostate cancer. If you notice new symptoms, tell your healthcare team. Testing can help find the cause and guide your care.
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