Study Finds No Association Between Autoimmune Disease and Lung Cancer Survival

Patients with both lung cancer and autoimmune disease have no significant difference in survival than patients with lung cancer and no autoimmune conditions, according to recent research from Northwestern University.

Lung cancer is responsible for an estimated 1.76 million cancer deaths worldwide, making it the deadliest form of cancer. It has numerous well-known risk factors such as tobacco or environmental exposure, and a history of autoimmune disease is yet another factor that has been associated with lung cancer development. The recent study, published in JAMA Network Open, aimed to determine whether autoimmune disease is associated with a worse prognosis for lung cancer patients.

The retrospective, single-center study included patients with lung cancer and several autoimmune diseases between 2003 and 2019. Patients were identified via a query of the Northwestern Medicine Enterprise Data Warehouse, and the analysis was conducted from March 2020 to July 2020.

Initially, 349 patients with both lung cancer and autoimmune diseases previously associated with lung cancer (rheumatoid arthritis, systemic lupus erythematosus, systemic sclerosis, myositis, Sjögren syndrome, and mixed connective tissue disease) were identified. Patients with biopsy-proven lung cancer, autoimmune disease diagnosed by a board-certified rheumatologist, and death or follow-up within 2 years of the study end were included in the analysis. Of the originally identified patients, 177 met the inclusion criteria.

The main outcomes and measures in the study were overall survival (OS) and progression-free survival (PFS) in lung cancer patients with autoimmune disease compared with a control group of patients with biopsy-proven lung cancer and no autoimmune disease. Researchers estimated OS and PFS rates with the Kaplan-Meier method, and the log-rank test was used to assess differences between autoimmune disease groups or stages. Multivariate Cox regression was used to adjust for multiple factors in survival.

The mean age at lung cancer diagnosis in the autoimmune cohort was 67 years, and 76.8% of the patients were women. Of the 177 patients, 140 (79.1%) had a history of smoking. Rheumatoid arthritis (54.8%), systemic sclerosis (24.3%), and systemic lupus erythematosus (8.5%) were the most common autoimmune diseases in the study.

The control cohort included 219 patients with lung cancer and without autoimmune disease. The mean age of diagnosis was 65.9 years, 78.5% had a smoking history, and 79% of the cohort were women.

In both the autoimmune and control groups, the most commonly identified lung cancers were adenocarcinoma (55.9% and 72.1%, respectively), squamous cell carcinoma (16.4%, 13.7%), small cell lung cancer (9.6%, 5.9%), and non-small cell lung cancer not otherwise specified (7.3%, 4.6%).

The analysis found that none of the autoimmune diseases were associated with worse OS or PFS compared with the control population, regardless of stage at diagnosis. The only independent risk factor for worse PFS (hazard ratio [HR], 1.017; 95% CI, 1.003-1.03; P = .02) and OS (HR, 1.013; 95% CI, 1.00-1.027; P = .049) was age when the data were analyzed using multivariate Cox regression.

The authors noted that the study had limitations in cohort size and that the findings need further validation. “Future multicenter, prospective studies are needed to further validate our findings within both lung cancer and other tumor types,” they wrote. “Larger studies are needed to further evaluate the association of autoimmune disease and lung cancer survival.”

Even so, the findings are interesting given the fact that fewer patients with both lung cancer and autoimmune disease received standard-of-care lung cancer treatment, study authors wrote. Across 6 autoimmune subtypes and even in patients with evidence of interstitial lung disease, there was no significant association with lung cancer prognosis.

“The lack of difference in overall survival despite significant differences in treatment patterns between groups is intriguing and raises the possibility of a protective role of autoimmune disease. However, such a conclusion is beyond the scope of the current study,” the authors concluded. “Further research is needed to fully characterize the association of autoimmune disease with lung cancer survival, particularly studies that can control for differences in treatment practices between groups. Overall, our study highlights the need for a better understanding of underlying autoimmune physiology, particularly as it may relate to survival.”

Reference

Jacob S, Rahbari K, Tegtmeyer K, et al. Lung cancer survival in patients with autoimmune disease. JAMA Netw Open. 2020;3(12):e2029917. doi:10.1001/jamanetworkopen.2020.29917