What is it like for siblings if their brother or sister has cancer?

Many siblings say that it can be difficult for them if their brother or sister has cancer. Their brother or sister may have to spend a lot of time in hospital, which means that they miss them, which can make them feel sad. This can also mean that siblings spend more time being looked after by other family members or friends. They can also worry about them a lot, especially whilst they are in hospital. This can make it hard to concentrate at school or might behave differently at home. The sibling may also struggle to understand what is happening to their brother or sister and why. Sometimes siblings say they can feel a bit left out, whilst everyone focuses on helping their brother or sister. They might also find that they have to stop going to clubs or certain places, to help try to keep their brother or sister well. The way that their brother or sister with cancer looks, acts or plays may change too. They might not have the energy to join in with games or may look or seem different for a while. Although being a sibling to a brother or sister with cancer can be hard at times, one positive can be that the sibling relationship can change, making their bond much stronger and more special than before.  Whatever you are feeling, it is OK and normal. It helps to tell a grown up you trust how you are feeling.

What causes cancer?

There is still a lot for doctors and scientists to learn about cancer, but we know that it is caused by a mistake in our own bodies that happens when cells are growing and dividing. If you cut your finger, your body makes some new skin cells to heal the cut. If you are growing taller your body is making new bone cells to help your bones grow. Bodies are making and replacing new and different cells all the time, and most of the time everything is just fine. Our bodies are also very good at spotting if a mistake happens, and will destroy a new cell that has gone wonky and looks like a cancer cell. But in a very small number of people a wonky broken cell is missed and turns into cancer cell, which makes more cancer cells and forms a lump (tumour) or thick blood. This does not happen very often in children, and there is nothing you or they did to cause it. You cannot catch cancer from someone else. We don’t know why this happens in children, because the scientists don’t yet know what causes the mistakes or causes our body not to spot the mistake and kills the wonky broken cell.

What does it mean?

People who have cancer have lots of tests to work out where the cancer is. These may be blood tests, X-rays, scans or a biopsy and they will see a doctor who is trained to look after people with cancer tumours called an oncologist, or one trained to look after people with blood cancer (leukaemia) called a haematologist. Doctors who look after people with brain tumours are called a neuro-oncologist.

What treatment is there?

Cancer can be treated in a number of ways:

• Surgery – doctors might carry out an operation to remove as many cancer cells as possible.
• Chemotherapy – this is the use of a particular type of medicine to treat the cancer. This is usually given through an intravenous line (IV) – a bag of medicine is attached to a tube, and a needle on the end is put into one of the person’s blood vessels, or connected to a tube they have inserted called a central line or wiggly. The medicine can then flow in to kill the cancer cells. Sometimes the chemotherapy might be a tablet or a liquid to drink, or an injection.
• Immunotherapy – this helps a person’s immune system in their body to get better at spotting and killing cancer cells using the immune system. It is given like chemotherapy, via an intravenous infusion (IV), tablet, medicine or injection.
• Radiotherapy – this uses radio waves (like X-rays) to pass through the body to damage and destroy cancer cells. It can make tumours shrink or even go away completely.

This information has been approved by Young Lives vs Cancer and Children’s Cancer and Leukaemia Group, March 2025