Scientists at Oxford University and other institutions meta-analyzed data from 75 trials of breast cancer radiotherapy and found radiotherapy for breast cancer can significantly increase risk for secondary cancers and fatal heart diseases.

Radiotherapy is commonly used to treat breast cancer.  X-ray used in radiotherapy is known to cause cancer and cardiovascular disease because high doses are used for radiotherapy intended for breast cancer treatment.

In 75 trials, women treated with or without radiotherapy for breast cancer were followed up on average for nearly 10 years during which about 15 % of patients did not experience recurrence and 50% died from breast cancer or another disease.

Scientists found that radiotherapy for breast cancer increased risk of death from non-breast cancer causes by 15%.  Women treated with radiotherapy were 30% more likely to die from heart disease than those who did not receive the treatment.   High doses of radiation were linked to high risk of mortality due to heart disease.

The overall secondary cancer risk was increased by 23% among breast cancer survivors who received radiotherapy, compared to those who did not receive the treatment. Specifically, radiotherapy increased the risk of contralateral breast cancer by 20%.

The late side effects of radiotherapy seemed greater.    After the first decade, the risk of lung cancer, esophageal cancer and leukemia was increased by 110%, 142% and 71% respectively, among breast cancer survivors who received radiotherapy. (David Liu)

Taylor C, Correa C, Anderson S, Duane F, Ewertz M, Jagsi R, Pierce L, Swain S, Whelan T, Wang Z, Wang Y, Peto R, McGale P. Late side-effects of breast cancer radiotherapy: Second cancer incidence and non-breast-cancer mortality among 40,000 women in 75 trials. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr S5-08.