Higher Cancer Risk Found in People With Asthma

Cancer Medicine published a study on 31 March 2023 finding that people with asthma, particularly those not using inhaled steroids, were more likely to develop cancer.

Asthma is a chronic respiratory disease affecting the airways. Narrowing and inflammation of the airways can make breathing difficult, causing cough, breathlessness, chest tightness and wheezing. During an asthma attack, these symptoms may suddenly worsen and cause severe breathing difficulties.

• What Is Asthma? Symptoms, Causes and Treatment

The Relationship Between Chronic Inflammation and Cancer

Cancer is the second leading cause of death worldwide after cardiovascular disease, accounting for one in every four to six deaths in developed countries. One major area of research into cancer causes is the relationship between chronic inflammation and cancer. Previous studies suggest that around 25% of all cancer cases may arise from chronic infection and inflammation. Inflammation usually follows infection or tissue injury, and the innate and adaptive immune systems provide coordinated responses. Failure to control acute inflammatory responses precisely can lead to chronic inflammation, creating a pathological tumour microenvironment that favours cancer initiation and progression. This probably explains why people with chronic inflammatory diseases have an increased risk of cancer.

Asthma is common and involves complex, chronic inflammation. One of the most frequently diagnosed respiratory diseases, it affects more than 20 million adults (8%) and 5 million children (7%) in the United States. A 2019 Turkish Thoracic Society study reported an adult asthma prevalence of 7.8% in Türkiye.

Because asthmatic inflammation may have carcinogenic effects, studies have examined asthma and cancer risk in different populations. A 2017 meta-analysis, for example, found that people with asthma were 44% more likely to develop lung cancer than those without asthma. However, earlier studies of asthma and cancers other than lung cancer reported positive associations, negative associations or none.

The Current Study

Using electronic health records and claims data from the OneFlorida+ clinical research network between 2012 and 2020, researchers identified a matched cohort of 90 thousand adults with asthma and 270 thousand without asthma.

The researchers found that people with asthma were 1.36 times as likely to develop cancer as those without asthma (hazard ratio [HR], 1.36; 99% CI, 1.29-1.44).

Higher risk was found for 5 of the 13 cancer types studied: lung cancer (HR, 1.56; 99% CI, 1.33-1.83), blood cancer (HR, 1.26; 99% CI, 1.08-1.47), melanoma (HR, 1.98; 99% CI, 1.67-2.36), kidney cancer (HR, 1.48; 99% CI, 1.11-1.99), and ovarian cancer (HR, 1.88; 99% CI, 1.40-2.51).

Among people diagnosed with asthma, those not using inhaled steroids had greater cancer risk (HR, 1.60; 99% CI, 1.50-1.71) than users (HR, 1.11; 99% CI, 1.03-1.21). Risk was elevated for 9 of 13 cancer types in non-users and 2 of 13 in users, suggesting a protective effect of inhaled steroids.

Inhaled steroids are commonly used to treat asthma. They reduce airway inflammation and help control symptoms, potentially reducing the frequency and severity of attacks and improving respiratory function. Regular use can reduce symptoms and long-term airway damage.

People with asthma reading this should not be alarmed, but should remain attentive and attend regular check-ups. Although the findings suggest greater cancer risk in people with asthma, this is a single study. More research is needed before firm conclusions can be drawn.

People with asthma already take precautions against its effects and can also take steps to address cancer risk. These include avoiding tobacco, maintaining a healthy lifestyle, exercising regularly and keeping up with check-ups.

People with asthma should maintain regular contact with their doctors and continue treatment to control symptoms. Treatments such as inhaled steroids can reduce airway inflammation and may therefore also reduce cancer risk. However, long-term steroid use can have adverse effects, so it is important to consult a doctor before changing treatment.

In conclusion, this study provides important information as the first to identify an association between asthma and overall cancer risk. More detailed, comprehensive studies are needed to understand the mechanisms involved. Using real-world data can help improve understanding of cancer risk in people with asthma.