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.

About bone health and cancer

Some cancer treatments can affect your bone health and the strength of your bones. This may cause bone thinning and increase your risk of a condition called osteoporosis.

Bone is made from a protein called collagen, which is strengthened by calcium and other minerals. Bones have developed so that they are strong and rigid without being heavy.

There are two types of bone – compact bone and cancellous bone.

Compact bone is the hard, rigid shell on the outside of bones. Inside this shell is cancellous bone, which is arranged like a honeycomb or mesh with lots of spaces. It is sometimes called spongy bone, because the holes in it make it look a bit like a sponge.

The structure of a long bone

Bone tissue is alive. It has a blood and nerve supply to stay healthy. Bones are constantly renewing themselves. This helps maintain their strength and shape.

Inside the bones, there are two types of bone cell:

  • Osteoclasts, which break down and remove old bone.
  • Osteoblasts, which build new bone.

Bone thinning

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

Bone density then stays about the same into our mid-thirties. After this, osteoclasts remove more bone than osteoblasts make. This causes bone density to slowly decrease.

This means as we age, our bone density slowly decreases. This is called ‘bone loss’ or ‘bone thinning’. The hard, outer shell of the bones (compact bone) thins 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 increase this affect and cause more bone loss than usually happens with age. We have more information about bone health.

Bone mass chart


Some people develop a bone condition called osteoporosis as they get older. Osteoporosis means bone density is much lower than normal.

The bones are weaker and more likely to break (fracture). The most common places to have fractures are the wrists, hips and spine. Osteoporosis does not cause symptoms until a weakened bone fractures.

Some cancer treatments can increase your risk of osteoporosis. Your doctor can do tests to assess your risk and to check the health of your bones. The results of these tests help doctors decide if you need treatment to lower your risk of a fracture.

A healthy bone and a bone with osteoporosis