What are bone metastases in prostate cancer?
Metastasis is the term for cancer spreading to other parts of the body. Although prostate cancer can spread to any part of the body, it most commonly goes to the bones.
Even when cancer has spread from the prostate to the bones, doctors still refer to it as prostate cancer rather than bone cancer.
When treating bone metastases, doctors aim to minimize any further spreading of cancer and relieve pain and other symptoms.
In this article, we discuss the symptoms of advanced prostate cancer and bone metastases. We also cover treatment options for bone metastases, side effects of treatment, and survival rates.
Frequent urination can be a symptom of advanced prostate cancer.
Early prostate cancer often has no symptoms. Once cancer has spread beyond the prostate, doctors refer to it as advanced prostate cancer.
Symptoms of advanced prostate cancer can include:
- difficulty urinating or a weak or slow urine stream
- the need to urinate more frequently, usually at night
- blood in the urine or semen
- erectile dysfunction
- weakness or a numb feeling in the legs or feet
- loss of control of bladder or bowel
Although many of these symptoms can occur due to conditions other than prostate cancer, anyone who experiences them should see a doctor for an evaluation.
Once prostate cancer has spread to the bones, symptoms can include:
- bone pain
- weak bones that are more likely to fracture
- pain or stiffness in the neck or back
- trouble urinating
- numbness and weakness from spinal cord compression
Bone metastasis can cause bones to release their calcium into the bloodstream, resulting in high levels of calcium building up in the blood. This condition is known as hypercalcemia. Untreated hypercalcemia can be very dangerous, and symptoms may include:
- appetite loss
- feeling very thirsty
- urinating more frequently
- fatigue and weakness
- bone pain
- depression, memory loss, and irritability
People who experience any of these symptoms should see a doctor immediately. Treating bone metastases early on can help prevent further complications.
Treatment for bone metastasis can help relieve pain and prevent complications. A doctor will work with the individual to develop a suitable treatment plan.
Treatments options include:
Bisphosphonates are drugs that work by reducing bone loss, and they can help:
- strengthen bones
- relieve bone pain
- reduce high calcium levels in the blood
- lower the risk of fractures
- slow cancer growth in the bones
Bisphosphonates can also reduce the side effects of hormone therapy, which some people may receive to treat their prostate cancer.
Zoledronic acid (Zometa) is the bisphosphonate that doctors most commonly prescribe for people with prostate cancer. They usually administer this drug by intravenous injection every 3 to 4 weeks.
Denosumab, which has the brand names Xgeva and Prolia, is another drug that reduces bone loss. It can help:
- lower the risk of fractures, especially if zoledronic acid is not working
- slow down the spread of cancer that has not yet reached the bones
Doctors inject the denosumab under the person’s skin every 4 weeks.
Radiation therapy uses a machine to aim an external radiation beam at the cancer cells in a person’s body. This treatment can:
- reduce bone pain
- shrink tumors on the spine to relieve pressure
- shrink tumors in other areas of the body to alleviate symptoms
Doctors can also inject medications called radiopharmaceuticals to treat people with bone metastases. Once inside the body, these drugs move to the bones and release radiation that can kill cancer cells.
Radiopharmaceuticals treat all the affected bones at the same time rather than just targeting one area.
Radiopharmaceuticals that doctors use for prostate cancer that has spread to bones include:
- strontium-89 chloride (Metastron)
- samarium-153 lexidronam (Quadramet)
- radium-223 (Xofigo)
All of these drugs can help relieve bone pain. According to the American Cancer Society (ACS), if prostate cancer has only spread to the bones and not to other organs, radium-223 can also help people live longer.
Side effects of treatment
Treatment for bone metastasis can cause side effects in some people:
Bisphosphonates and denosumab
Some treatments for bone metastasis can cause fatigue.
Bisphosphonates and denosumab can cause similar side effects, including:
- flu-like symptoms
- bone or joint pain
People taking bisphosphonates or denosumab may need to take calcium and vitamin D supplements to prevent their calcium levels from becoming too low.
Bisphosphonates can also cause kidney problems, so doctors may not recommend these drugs for people with reduced kidney function.
Rarely, taking bisphosphonates or denosumab can cause osteonecrosis of the jaw (ONJ). ONJ is a serious condition in which the bone tissue in the jaw dies due to the blood supply being cut off. It can lead to:
- pain and swelling in the mouth
- tooth loss
- gum infections
Before taking bisphosphonates or denosumab, it is essential to make the doctor aware of any dental problems. Doctors often advise people to see a dentist to address any dental issues before starting these medications. Practicing good oral hygiene, such as brushing correctly and flossing daily, may help prevent ONJ.
External radiation therapy can cause some side effects, including:
- Bowel problems, such as diarrhea, bloody stools, and rectal leakage. Some people may need to follow a special diet to help reduce these side effects.
- Fatigue, which may continue for a time after treatment stops.
- Lymphedema, which can cause fluid to build up in certain parts of the body, such as the legs and groin. Physical therapy can help reduce pain and swelling.
- Erectile dysfunction. Doctors can prescribe medications to help with erection problems.
- Urination difficulties, such as pain while urinating, accidental leakage, and loss of control. Many treatments are available for urination problems, including catheters, medications, exercises, and surgery.
Radiopharmaceutical treatment can lead to a decrease in blood cells. A low blood cell count can increase a person’s risk of infection and bleeding.
People who are taking radiopharmaceuticals should speak to their doctor about the symptoms that may indicate a low blood cell count and the precautions they can take to prevent this.
Pain medication can be very effective in relieving the pain of prostate cancer and bone metastases.
A person should talk to a doctor about any pain that they are experiencing. The doctor can prescribe appropriate pain relief and work with the individual to develop a pain control plan.
Pain relievers are most effective when people take them at regular intervals and not just when pain is severe.
Doctors can also offer advice and treatment for any other symptoms or side effects that a person may have.
Survival rates and outlook
A person’s doctor can prescribe pain relief and help them establish a pain control plan.
There is currently no cure for advanced prostate cancer, but advances in treatments are extending life expectancy and improving quality of life.
The ACS state that the 5-year relative survival rate for individuals with prostate cancer that has spread to distant lymph nodes, organs, or the bones is 29 percent. Accordingly, people with this stage of prostate cancer are about 29 percent as likely as people without the condition to live for at least 5 years after diagnosis.
However, survival rates are only estimates, and everyone is different. The following factors are among those that can affect a person’s outlook:
- general health
- how the cancer responds to treatment
- how far the cancer has spread
Ongoing research on cancer is also facilitating the development of more effective treatments and leading to improvements in survival rates.
Prostate cancer can spread to other organs in the body. When cancer spreads to the bones, this is known as bone metastasis.
Although there is currently no cure for prostate cancer that has spread to the bones, treatment can help relieve pain, improve quality of life, and extend life expectancy.
A doctor will work closely with a person to develop a treatment plan. Many people also find it beneficial to join a support group and connect with others who understand how they may be feeling. The Prostate Cancer Foundation provide information to help people find a local support group.