Bone thinning and osteoporosis

Age and some cancer treatments can reduce bone density. This is called bone thinning. It can lead to a condition called osteoporosis.

What causes bone thinning?

Bones are living tissue. They have a blood and nerve supply to keep them healthy. Bones are constantly being renewed. This helps maintain their strength and shape.

Our bones stop growing longer by the time we are about 18 years old. But bones continue to increase in thickness (density) until our late-20s.

As we get older, our bone density slowly decreases. This is called bone loss or bone thinning.

The hard, outer shell of the bones (compact bone) gets thinner and the holes in cancellous (spongy) bone get larger. In time, bones become more fragile. This is why bone fractures are more common after the age of 65.

Some cancer treatments can affect your bone health, and cause more bone loss than usually happens with age. For example, radiotherapy can cause changes to the bone. Some drugs such as hormonal therapy or targeted therapy drugs can cause bone loss.

Bone mass chart
Image: Bone mass chart

What is osteoporosis?

Osteoporosis means bone density is much lower than normal. This means the bones are weaker and more likely to break (fracture). The most common places to have fractures are the wrists, hips and spine.

Who gets osteoporosis?

Some people develop osteoporosis as they get older. Some cancer treatments can also increase your risk of osteoporosis.

Anyone can develop osteoporosis, but it is more common in women. This is because after the menopause, women lose bone density more quickly as their oestrogen levels fall.

Osteoporosis does not cause symptoms until a weakened bone breaks (fractures). But your doctor can do tests to assess your risk of osteoporosis and to check the strength of your bones. The results of these tests help doctors decide if you need treatment to lower your risk of osteoporosis and risk of fractures.

Your doctor can give you advice on things that you can do to help lower your risk. They may prescribe vitamin D and calcium supplements for you. Bisphosphonates may be used to treat bone loss and osteoporosis.

We have information about bone health and looking after your bones.


A healthy bone and a bone with osteoporosis
Image: A healthy bone and a bone with osteoporosis

About our information

  • Reviewers

    This information has been written, revised and edited by Macmillan Cancer Support’s Cancer Information Development team. It has been reviewed by expert medical and health professionals and people living with cancer. It has been approved by Chief Medical Editor, Professor Tim Iveson, Consultant Medical Oncologist.

    Our cancer information has been awarded the PIF TICK. Created by the Patient Information Forum, this quality mark shows we meet PIF’s 10 criteria for trustworthy health information.

Date reviewed

Reviewed: 01 September 2020
Next review: 01 September 2023

This content is currently being reviewed. New information will be coming soon.

Trusted Information Creator - Patient Information Forum
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