Why do cancers come back?

Sometimes, cancer can come back. If you are diagnosed with cancer, your doctor will talk to you about your treatment options. Treatment for cancer aims to remove or destroy all the cancer cells. It also tries to reduce the risk of it coming back.

But sometimes after treatment, tiny cancer cells can stay in the body. Over time, they may start to divide and grow again to form a cancer. This means cancer can come back (recur). Sometimes, this happens many years later.

Most people have follow-up appointments with their cancer doctor for months, or years, after treatment. These appointments may include tests and scans. If the cancer comes back, tests and scans can help find it early. Some cancer types have a higher risk of coming back. Your doctor will talk to you about the risk of the cancer coming back.

A cancer that comes back is called a recurrent cancer. Sometimes, cancer can come back in the same area of the body. This is called a local recurrence. Or the cancer can come back in a different area of the body. This is called secondary cancer or metastasis. Recurrent and secondary cancers are sometimes called advanced cancer.

If cancer comes back, it is often possible to treat it again. Treatment can control the cancer (palliative treatment), sometimes for many months or years. For some people, treatment may aim to get rid of the cancer again.

Finding out that cancer has come back can be a shock. Everyone has their own way of dealing with this. But support is available if you need it. You can call our cancer support specialists.

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The lungs

When we breathe in, the lungs take oxygen into the bloodstream and circulate it all around the body.

About lung cancer

Lung cancer is a common cancer that is usually caused by smoking.

Types of lung cancer

The main types of primary lung cancer are small cell lung cancer and non-small cell lung cancer. They are treated differently.