Does Asthma Affect the Risk of Developing Breast Cancer?

Sample size: 202055 publication 10 minutes Evidence: moderate

Author Information

Author(s): Karin B. Michels, Orianne Dumas, Raphaelle Varraso, Carlos A. Camargo Jr

Primary Institution: Institute for Prevention and Cancer Epidemiology, Faculty of Medicine and Medical Center University of Freiburg

Is asthma associated with breast cancer risk?

Women with asthma had a somewhat lower risk of breast cancer, especially among never smokers.

Women with asthma had a hazard ratio of 0.92 for developing breast cancer compared to those without asthma.
The association was most pronounced among never smokers with a hazard ratio of 0.86.
The study included over 4 million person-years of follow-up.

This study found that women with asthma might be less likely to get breast cancer, which could be because their immune systems are more active.

Data from two large cohorts, the Nurses' Health Study and Nurses' Health Study II, were analyzed using Cox proportional hazards models.

Self-reported diagnoses may not be as reliable as clinical assessments.

The study relied on self-reported data for asthma and breast cancer diagnoses, which may introduce bias.

The study included 202,055 women, primarily registered nurses, with a mean age of 65.6 years for NHS and 47.2 years for NHS II.

0.017

0.87–0.98

p<0.05

Access the complete publication on the publisher's website