Having interstitial lung disease (ILD) is associated with a greater risk of lung cancer in scleroderma patients, according to Canadian researchers. Their findings also demonstrate that male sex and smoking are predictors for increased risk.
Their study, “Interstitial lung disease is associated with an increased risk of lung cancer in systemic sclerosis: Longitudinal data from the Canadian Scleroderma Research Group,” was published in the Journal of Scleroderma and Related Disorders.
Lung cancer in the most frequent malignancy associated with scleroderma. Previous research consistently showed a greater risk of lung cancer in scleroderma patients than in healthy people (controls). But studies evaluating predictive factors of lung cancer in these patients led to contradictory results.
To address this gap in literature, the research team assessed 1,560 adult patients with scleroderma from the Canadian Scleroderma Research Group to characterize the demographic, clinical, and blood-related risk factors for lung cancer in scleroderma.
Analyzed variables included exposure to smoking, disease duration, diffuse or limited disease, the use of immunosuppressant therapies (cyclophosphamide, methotrexate, mycophenolate, and azathioprine), and the presence of ILD for the risk of lung cancer.
Enrollment started in 2004 and follow-up was conducted for a maximum of 11 years. Scientists compared the results of patients with lung cancer with those of people without the disease.
The analysis revealed that 18 scleroderma patients in the study were diagnosed with lung cancer, mainly adenocarcinoma.
The incidence of lung cancer in these scleroderma patients (3.2 per 1,000 patient/years) was approximately five times higher than in the Canadian general population, researchers found, thereby supporting a greater risk of lung cancer in patients with the disease.
Among the scleroderma patients analyzed, the ones with cancer were more likely to be men, which also matches previous studies.
Also, cancer cases were more likely to have a past or current smoking history, to have diffuse cutaneous scleroderma, and to have interstitial lung disease compared to patients without cancer.
Interstitial lung disease was also found to be a factor independently associated with the risk of lung cancer.
Investigators did not find a link between taking immunosuppressive therapies and the risk of lung cancer. They hypothesized that this may be due to the limited number of patients treated with these medications.
“Male sex and smoking history were important predictors of lung cancer in [scleroderma]. Most interestingly, ILD was also associated with a threefold increase in lung cancer risk, independent of male sex and smoking history,” researchers wrote.
“These clinical risk factors may facilitate the identification of high-risk [scleroderma] subjects who require screening for lung cancer,” they added.