Hormone therapy for prostate cancer can lower the levels of sex hormones (testosterone) in the blood. This can lead to thinning and weakness of your bones.
Bone loss (osteoporosis) and ageing
Getting older can also cause your bones to get thinner and weaker. Thinner bones are more at risk of breaking (fracturing). This bone thinning is called osteoporosis.
Bone loss and cancer treatment
Low testosterone levels in the blood can cause bone loss. The hormone treatments for prostate cancer aim to lower the amount of testosterone or block its action.
Hormone treatments include:
- drug treatments including goserelin (Zoladex), leuprorelin (Prostap), decapeptyl (Triptorelin)
- surgery to remove your testicles (orchidectomy)
Bone loss is a common side effect. But how much bone loss you might have varies from person to person. The spine is most likely to be affected.
Not all hormone treatments cause bone loss, for example the drug bicalutamide (Casodex) doesn't.
Your nurse or doctor will tell you if they think you might be at risk of bone loss and in particular problems with your spine.
Contact them urgently if you have:
- any changes in sensation such as numbness, tingling
- have pain that doesn’t go away or gets worse
- have any changes to opening your bowels or passing urine.
Tests for bone loss
Your doctor will assess if you are at high risk of bone loss. Getting older and having cancer treatment can increase the risk of bone loss. You'll have a bone density scan (also called a DEXA or DXA scan) if you are at high risk.
Reducing the risk of bone loss
Calcium and vitamin D
Adults should generally have 700mg of calcium a day. People with osteoporosis should aim for 1000mg a day.
Dairy products (milk, cheese and yogurt) contain calcium. Some foods have added calcium. Check food labels to see how much calcium they contain. Milk substitutes such as soya or rice milk do not contain as much calcium as dairy products.
You can also get calcium from:
- green vegetables (cabbage, broccoli and okra)
- soya products including tofu
- tinned fish with bones (sardines, salmon and pilchards)
- nuts and dried fruit
- fortified breakfast cereals
- bread and foods made from flour
- tap water
Calcium supplements are available. Dietitians recommend that you do not have more than a total of 1500mg of calcium. This total calcium could come from your diet or a combination of diet and supplements. Too much calcium can cause tummy (abdominal) pain and diarrhoea.
Your body needs vitamin D to absorb calcium. Sunlight helps the body to make vitamin D. A daily short walk in natural sunlight makes enough vitamin D for most people. It is also found in margarine, oily fish and egg yolks. You should eat most foods in moderation.
Your GP can refer to a dietitian to check that your diet has enough calcium and vitamin D to keep your bones healthy.
Alcohol and caffeine
Drinking alcohol increases the risk of bone loss (osteoporosis). National guidelines recommend that you don't drink more than a total of 14 units of alcohol per week. Caffeine can cause calcium to be lost in urine.
Exercise is important for bone health but it needs to be weight bearing exercise. This means that you are supporting your own weight with your legs and arms. This can strengthen muscle, improve posture, and could help with pain.
Many of us don’t take enough regular exercise. Bringing exercise into your daily life is the best way to make sure you get enough. Walking is good. Household activities are helpful, such as cleaning, gardening, shopping or even going up and down stairs. Or you could join an exercise group or class. It doesn’t have to be very energetic.
Gentle controlled exercise such as Tai Chi can be good. Although swimming doesn’t help, exercise classes in the swimming pool (aqua-aerobics) can. Walking and exercising in the pool is quite hard work because of the resistance of the water.
Don’t jog or take exercise that involves jumping if you already have osteoporosis. It puts too much strain on your bones. Take advice from your doctor or specialist nurse before starting any new type of exercise.
Medicines to help bone loss
Bones naturally break down and repair themselves. Hormone treatment can make bones break down faster than they are repairing themselves. This makes them weaker.
You might have bisphosphonates if you have cancer that has spread to other parts of your body (advanced prostate cancer) to help with:
- bone pain
- to help prevent bone thinning
You might also have bisphosphonates if you have osteoporosis and are having hormone therapy to help.
Bisphosphonates move calcium cells from your blood stream into your bone. This helps to keep the bone strong. As you need to keep some calcium in your blood stream, your doctor may give you calcium tablets.
- alendronate tablets
- risedronate tablets
- zoledronic Acid (Zometa) - this is a drip that you have into your bloodstream
Denosumab is a different type of drug. It works by stopping the activity of bone cells called osteoclasts. Denosumab can increase bone density to help strengthen the bone. It can be used instead of bisphosphonates to help to reduce fractures in people whose cancer has spread.