Individuals With Asthma More Likely to Develop Cancer, Study Finds

A study analyzing the possible association between asthma and cancer risk found individuals with asthma were more likely to develop cancer compared vs those without, and not just lung cancer.

“Using EHR [electronic health records] and claims data from the OneFlorida+ Clinical Research Network, we found that patients with asthma were 1.36 times as likely to develop cancer compared to patients without asthma in multivariable analysis,” wrote the researchers of the study. “Overall, elevated cancer risk was observed in asthma patients with or without inhaled steroid use.”

To the researchers’ knowledge, this retrospective cohort study, published in Cancer Medicine, is the first of its kind to find a positive association between asthma and cancer risk.

The study was conducted using health records and claims data from 2012 to 2020, and it included 90,021 US adults with asthma and 270,063 adults without asthma. An asthma diagnoses was identified using International Classification of Diseases (ICD) codes for asthma. Additionally, patients were given an asthma diagnosis if they had at least 1 inpatient visit or 2 outpatient hospital visits within 1 year.

Using Cox proportional hazards models, the researchers sought to examine an association between asthma and overall cancer risk, as well as asthma and cancer risk by cancer type.

Patients with asthma had a higher overall cancer risk (HR, 1.36; 99% CI, 1.29-1.44) compared with patients without asthma. Furthermore, higher cancer risk was observed in patients without (HR, 1.60; 99% CI, 1.50-1.71) or with (HR, 1.11; 99% CI, 1.03-1.21) inhaled steroid use.

Additionally, elevated cancer risk was observed among 9 of 13 cancer types without inhaled steroid use:

• Prostate (HR, 1.50; 99% CI, 1.13-1.99)
• Lung (HR, 1.74; 99% CI, 1.44-2.11)
• Colorectum (HR, 1.51; 99% CI, 1.21-1.88)
• Blood (HR, 1.44; 99% CI 1.21-1.72)
• Melanoma (HR, 2.05; 99% CI, 1.66-2.52)
• Corpus uteri (HR, 1.76; 99% CI, 1.26-2.46)
• Kidney (HR, 1.52; 99% CI, 1.06-2.17)
• Ovary (HR, 2.31; 99% CI, 1.66-3.21)
• Cervix (HR, 1.46; 99% CI, 1.08-1.98)

Lastly, elevated cancer risk was observed among 2 of 13 cancer types with inhaled steroid use:

• Lung (HR, 1.39; 99% CI, 1.14-1.70)
• Melanoma (HR, 1.92; 99% CI, 1.55-2.38)

The researchers suggest that these results show the use of inhaled steroids may act as a protective factor against cancer. However, the researchers acknowledge the study had limitations, including being retrospective, in which causal relationship cannot be established. Furthermore, patients with more than 1 type of cancer were grouped according to the type of cancer at first diagnosis.

Despite these limitations, the researchers believe this study provides a real-world representation of the association between asthma and cancer risk, in which further studies should be conducted.

“This is the first study to report a positive association between asthma and overall cancer risk in the US population,” wrote the researchers. “More in-depth studies using real-word data are needed to further explore the causal mechanisms of asthma on cancer risk.”

Reference

Guo Y, Bian J, Chen Z, et al. Cancer incidence after asthma diagnosis: Evidence from a large clinical research network in the United States. Cancer Med. Published online March 31, 2023. doi:10.1002/cam4.5875