Breast cancer patients who continue to smoke after having radiotherapy are at much higher risk of their treatment causing them lung cancer in the future, research has found.

Two in three of those diagnosed with early breast cancer in the UK are given radiotherapy. It is a long-established and highly effective treatment but does also have potential side-effects.

Radiotherapy cuts the risk of someone’s breast cancer recurring after treatment and also of them dying from the disease, but its dangers include a higher risk of dying from heart disease, lung cancer or oesophageal cancer.