Patients With Interstitial Lung Disease Face Elevated Lung Cancer Risk, Study Finds

A large prospective cohort study conducted by Ye and Kang et al and published in JAMA Network Open found that, after adjusting for familial and other cancer-related factors, interstitial lung disease (ILD) was associated with an increased risk of developing most histologic subtypes of lung cancer.

“[Prior to this analysis,] an association between [ILD] and lung cancer had been hypothesized but never established…, [and] whether this potential association persists after controlling for genetic factors had not been addressed,” the investigators commented. “[Our] findings suggest that the presence of [ILD] should be incorporated into lung cancer risk assessment models.”

Study Details

Using data from the Swedish Total Population Register and Swedish Multi-generation Register, the investigators identified 5,425,976 individuals (14,624 with ILD and 5,411,352 from the general population) who were born between 1932 and 1987; the follow-up period started on January 1, 1987, and continued until December 31, 2016.

Both population-based and sibling-controlled designs were used for the analyses. The investigators evaluated the association between ILD and lung cancer using multivariable hazard ratios (HRs) and 95% confidence intervals (CIs).

Key Findings

During the 30-month follow-up period, 227 (incidence rate = 355.4 per 100,000 person-years) and 40,592 (incidence rate = 26.2 per 100,000 person-years) cases of lung cancer were diagnosed in patients with and without ILD, respectively. After adjusting for sex, age, calendar period, educational attainment, and smoking-related diseases, those with ILD were found to have a higher risk of developing lung cancer (HR = 2.16, 95% CI = 1.89–2.46); this also appeared to hold true in sibling-controlled analyses (HR = 2.91; 95% CI = 1.98–4.27).

Elevated risks were shown for adenocarcinoma (HR = 1.60, 95% CI = 1.28–2.01), squamous cell carcinoma (HR = 2.56, 95% CI = 1.99–3.29), small cell carcinoma (HR = 3.29, 95% CI = 2.32–4.68), and other histologic types (HR = 2.32, 95% CI = 1.78–3.01). Results from sibling-controlled analyses generally mirrored these findings, according to the investigators.

The investigators concluded, “This study is the first, to our knowledge, to use a sibling-controlled design, thereby incorporating genetic considerations and minimizing potential familial confounding. Our findings indicate that [ILD] is associated with an elevated risk of lung cancer, even after adjusting for familial factors. Furthermore, additional analyses across different histological subtypes of lung cancer demonstrated that [ILD] increases the risk for all subtypes examined.”

Weimin Ye, MD, PhD, of Karolinska Institutet, Stockholm, Sweden, and Mingqiang Kang, MD, PhD, of Fujian Medical University Union Hospital, Fuzhou, China, are the corresponding authors of the JAMA Network Open article.

Disclosure: The study was funded by a grant from the Swedish Cancer Society. The study authors reported no conflicts of interest.