In a new study published in the Journal of Clinical Oncology, researchers found that smokers treated for breast cancer have a higher risk than non-smokers when it comes to developing lung cancer or heart attack as a result of radiotherapy.

Researchers used data from a worldwide study by the Early Breast Cancer Trialists’ Collaborative Group of the lung and heart radiation doses and risks among women with breast cancer.

Data suggests that for non-smokers, the long-term risk of death from lung cancer or heart attack caused by radiation is only 0.5 percent. However for smokers, the risk is about 5 percent.

The team of researchers also took into account that modern breast care radiotherapy techniques have improved over the years, so they used recent literature when looking at how radiotherapy is being targeted today.

"This research highlights that breast cancer patients who smoke need to be offered help and support in order to try and quit to minimise any risks from their treatment,” said Julie Sharp, head of health information at London's Cancer Research UK, in a statement. “It's important to remember that modern day radiotherapy techniques have been refined and improved to make sure it is targeted and effective while reducing the risk of side effects."