Risk of primary lung cancer after breast cancer radiotherapy: a systematic review and meta-analysis

Bushra Zareie,Jalal Poorolajal,Mohammad Aziz Rasouli

doi:10.1007/s12282-021-01318-w

Abstract

BackgroundEpidemiological studies have shown that the risk of secondary malignancies may increase by radiotherapy. Lung cancer is the most important long-term complication of breast cancer radiotherapy.MethodsMajor electronic databases including Scopus, Web of Science, and MEDLINE were searched. All cohort studies that investigated the association between radiotherapy for breast cancer and risk of primary lung, bronchus, and trachea cancers conducted until March 2021 were included. The study participants were evaluated regardless of their age and ethnicity. The Newcastle–Ottawa Scale was used to assess the quality of the studies. The designated effects were risk ratio (RR). The random-effects model was used to estimate the average effects.ResultsFifteen studies including 1,640,247 women with primary breast cancer were identified of which 937,151 had not received radiotherapy and 703,096 subjects had received radiotherapy. In general, there was no significant association between breast cancer radiotherapy and lung cancer based on 10 studies (RR = 0.95, 95% CI 0.87–1.02, P = 0.15), There was no association between breast cancer radiotherapy and lung, bronchus, and trachea cancers either based on 5 studies (RR = 0.98, 95% CI 0.93–1.02, P = 0.32).ConclusionRadiotherapy for breast cancer is not associated with an excess risk of lung cancer. Due to the limited number of studies, lack of data regarding smoking status, and substantial variation in exposure of the lungs in breast cancer radiotherapy worldwide, further investigations based on randomized controlled trials are suggested to address the potential risk of lung cancer after breast cancer radiotherapy.

Highlights

Randomized clinical trial studies have shown that radiotherapy significantly reduces breast cancer recurrence
Radiotherapy for breast cancer is not associated with an excess risk of lung cancer
1,640,247 women with primary breast cancer were enrolled in the studies, of which 937,151 had not received radiotherapy and the remaining 703,096 had received radiotherapy (Table 1)

Summary

Introduction

Randomized clinical trial studies have shown that radiotherapy significantly reduces breast cancer recurrence. During radiotherapy for the breast and chest wall, the lungs are exposed to radiation, which is unavoidable. This accidental exposure may increase the risk of primary lung cancer, pneumonitis, and pulmonary fibrosis[5]. Epidemiological studies have shown that the risks of secondary malignancies may be increased by radiotherapy or systemic therapy[6, 7]. Primary lung cancer and heart disease are the most important long-term complications of breast cancer radiotherapy[8, 9]. Epidemiological studies have shown that the risk of secondary malignancies may increase by radiotherapy. Lung cancer is the most important long-term complication of breast cancer radiotherapy

Methods

Results

Conclusion