Interstitial lung disease in metastatic breast cancer: a landscape review using SEER-Medicare

Interstitial lung disease (ILD) is a serious side effect of certain mBC treatments, but our understanding of its prevalence outside of clinical trials and treatment-specific studies is limited. We sought to characterize the incidence of ILD among a large, population-based cohort of adults with mBC in the United States.

We included females and males aged 66 + years who were diagnosed with Stage IV breast cancer (as their first cancer) between January 1, 2002-December 31, 2017, using the SEER-Medicare linked. Our primary outcome was an incident ILD diagnosis after their mBC diagnosis, which was operationalized as a binary outcome. We examined demographic and clinical factors associated with incident ILD using logistic regression models.

Among the 14,343 patients with mBC and no evidence of ILD at baseline, the median age at diagnosis was 76 (IQR 70, 82) years and 98% were female. Overall, 1,806 (12.6%) had an ILD diagnosis after mBC diagnosis. There was no significant difference in proportion of patients who received a pharmacologic treatment that carries the potential risk of ILD between patients who received an ILD diagnosis and those who did not (14% vs. 12%).

ILD is prevalent in 12.6% of adults with mBC, yet oncology guidelines for monitoring for this intrusive and potentially fatal complication are sparse and non-specific. Patient education raising awareness of ILD symptoms and engaging primary care and pulmonary medicine in may improve patient outcomes and quality of life.