Objective: To review the studies investigating the increased risk of lung cancer in patients with idiopathic pulmonary fibrosis (IPF).
Data sources: Data cited in this review were obtained mainly from PubMed and Medline from 1999 to 2013 and highly regarded older publications were also included.
Study selection: We identified, retrieved and reviewed the information on the frequency, risk factors, anatomical features, histological types, clinical manifestations, computed tomography findings and underlying mechanisms of lung cancer in IPF patients.
Results: The prevalence rates of lung cancer in patients with IPF (4.8% to 48%) are much higher than patients without IPF (2.0% to 6.4%). The risk factors for lung cancer in IPF include smoking, male gender, and age. Lung cancers often occur in the peripheral lung zones where fibrotic changes are predominant. Adenocarcinoma and squamous cell carcinoma are the most common types of lung cancer in patients with IPF. Radiologic features of these patients include peripherally located, ill-defined mass mimicking air-space disease. The underlying mechanisms of the development of lung cancer in patients with IPF have not been fully understood, but may include the inflammatory response, epithelial injury and/or abnormalities, aberrant fibroblast proliferation, epigenetic and genetic changes, reduced cell-to-cell communication, and activation of specific signaling pathways.
Conclusions: These findings suggest that IPF is associated with increased lung cancer risk. It is necessary to raise the awareness of lung cancer risk in IPF patients among physicians and patients.