Breast cancer is one of the most common types of cancer, which affects women worldwide. To reduce the risk of reoccurrence, women look toward radiotherapy for treating the disease.

According to a new study, breast cancer patients — who smoke — are at a higher risk of complications because of radiation therapy.

The researchers revealed that long-term smokers, who continue smoking during the therapy, are at a greater risk of developing lung cancer and cardiac problems.

How Was The Study Conducted?

For the purpose of the study, the scientists gathered data from 75 radiation therapy trials, which took place before 2000.

This data focused on the cause of death for all women, and not specifically on women who were chain smokers. Thus, the excess rate ratio for the cause of death was assumed for all the subjects.

The researchers examined the excess rate ratio by analyzing the "per unit of radiation by the lungs and heart doses."

They used the rates to observe the number of deaths due to lung cancer, as well as ischemic heart disease among both the smokers and non-smokers. This allowed the team to calculate the death risk due to lung cancer and heart ailments for women who were below 80 years old.

Are Breast Cancer Patients Who Smoke During Radiation At Risk?

The research was conducted on women who smoked till their adolescence, who never smoked, and those who gave up smoking during radiotherapy.

"Assuming a 50-year-old nonsmoker received a radiotherapy dose that increased lung cancer rates by 55%, her risk of lung cancer mortality before age 80 would rise from 0.5% to 0.8%," note the researchers.

On the other hand, if a smoker received the same dose, the lung cancer mortality risk for the woman — before 80 years — would increase from 9.4 percent to 13.8 percent. In the event a woman stopped smoking prior to her radiotherapy, the risk of radiation-related lung cancer death would decrease to 1.3 percent from 4.4 percent.

In case of deaths due to heart ailments, a similar process was used. The study revealed that chances of death due to cardiac arrest increased by 0.3 percent and 1.2 percent for non-smokers and smokers, respectively, when they underwent radiotherapy. The risks altered depending on the dosage.

The researchers surmise that smoking during cancer treatments inhibits the proper functioning of radiotherapy. It also encourages the recurrence of the disease.

Therefore, it is better to completely cease smoking in such scenarios to avoid health issues in the future.

The study has been published in the Journal of Clinical Oncology.