East Asian females treated with radiation therapy for invasive breast cancer are at a higher risk of developing second primary lung cancer (SPLC). Globally, lung cancer is the leading cause of deaths from cancer.1

Risk factors for developing lung cancer include medical or occupational radiation exposure, tobacco smoking, family history, age, and chronic inflammatory disease such as pulmonary fibrosis. A previous history of cancer is also a risk factor for developing SPLC.

In this study, the researchers used the Taiwan Longitudinal Health Insurance Database (LHID), which contains data randomly drawn from the National Health Insurance Research Database in Taiwan, to investigate whether patients who underwent radiation therapy for breast cancer were at greater risk for SPLC in the East Asian country.

The researchers assessed data from 986,713 patients with medical events between 2000 and 2010. All women were 18 years or older and had no previous history of any type of malignancy before 2000 or during the follow-up period.

From LHID, researchers identified 7408 female patients with a diagnosis of invasive breast cancer. In total, 5696 patients underwent radiation therapy, and 1713 patients did not.

By the end of follow-up, 128 patients in the radiation therapy cohort (2.25%) developed lung cancer. Only 4 patients (0.23%) in the non-radiation therapy group developed lung cancer.

Cox regression analysis indicated the adjusted hazard ratio was 10.08 times higher in the radiation therapy group. Age, comorbidities, urbanization level, location, insurance premium, date of event, and level of hospital care were analyzed. Age and disease stage both correlated with an even higher risk of developing SPLC in the radiation therapy cohort.

“The results of this study showed that radiation for breast cancer, which is an important treatment option, was correlated with a significant increase in the incidence of SPLC, particularly among older women or those with advanced-stage breast cancer,” concluded the researchers.

Based on their findings, the researchers suggest patients whose multidisciplinary treatment of breast cancer includes radiation therapy should be monitored for potential SPLC.

Reference

1. Huang YJ, Huang TW, Lin FH, Chung CH, Tsao CH, Chien WC. Radiation therapy for invasive breast cancer increases the risk of second primary lung cancer: a nationwide population-based cohort analysis. J Thorac Oncol. 2017 Jan 31. doi: 10.1016/j.jtho.2017.01.021. [Epub ahead of print]