Risk of primary lung cancer after adjuvant radiotherapy in breast cancer\u2014a large population-based study

Anna-Karin Wennstig,Mikael Johansson,Charlotta Wadsten,Greger Nilsson,Carl Blomqvist,Lars Holmberg,Malin Sund,Irma Fredriksson,Hans Garmo

doi:10.1038/s41523-021-00280-2

Abstract

Adjuvant radiotherapy (RT) for breast cancer (BC) has been associated with an increased risk of later radiation-induced lung cancer (LC). We examined the risk of primary LC in a population-based cohort of 52300 women treated for BC during 1992 to 2012, and 253796 age-matched women without BC. Cumulative incidence of LC was calculated by the Kaplan–Meier method, and the risk of LC after BC treatment was estimated by Cox proportional hazards regression analyses. Women with BC receiving RT had a higher cumulative incidence of LC compared to women with BC not receiving RT and women without BC. This became apparent 5 years after RT and increased with longer follow-up. Women with BC receiving RT had a Hazard ratio of 1.59 (95% confidence interval 1.37–1.84) for LC compared to women without BC. RT techniques that lower the incidental lung doses, e.g breathing adaption techniques, may lower this risk.

Highlights

Long-term side effects of breast cancer (BC) treatment and quality of life for BC survivors have become an issue of great importance with improved prognosis and increasing BC incidence rates leading to a high prevalence of BC survivors[1].In adjuvant postoperative BC radiotherapy (RT), the main longterm hazards are ischemic heart disease and lung cancer (LC)[2,3].Several studies show an increased risk of LC after adjuvant BC RT4–12
Most published studies include women treated with older radiation regimens with techniques and dosages no longer in clinical use, and it is uncertain whether these results may be applied on more contemporary RT regimens, a few studies report an increased risk of primary LC after BC
Characteristics of women diagnosed with LC within the first year from BC diagnosis are shown in Supplementary Table 3

Summary

Introduction

Several studies show an increased risk of LC after adjuvant BC RT4–12. Most published studies include women treated with older radiation regimens with techniques and dosages no longer in clinical use, and it is uncertain whether these results may be applied on more contemporary RT regimens, a few studies report an increased risk of primary LC after BC diagnosis in women receiving RT in the 1990s and 2000s13–15. In addition to RT, many women receive adjuvant endocrine therapy and chemotherapy, and some of these agents are related to a higher risk of second malignancies[16,17,18]. On the other hand, has been suggested to reduce the risk of LC after BC diagnosis[19]. Another study has reported opposite results[20]

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Conclusion