Serum Procalcitonin in Patients With Combined Lung Cancer and Idiopathic Pulmonary Fibrosis (LC-IPF)

Background Procalcitonin (PCT) is a potential biomarker for sepsis and acts as a guide to antibiotic administration. Previous studies showed that lung cancer (LC) may increase serum PCT levels. However, no studies addressed serum PCT in patients with combined LC and idiopathic pulmonary fibrosis (IPF): LC-IPF. We aimed to evaluate the significance of serum PCT in patients with LC-IPF. Methods A total of 137 patients with IPF who had complete follow-up data were reviewed. They were categorized into two groups: 30 patients with LC and IPF (LC-IPF) and 82 patients with IPF only (IPF). PCT assays in the two groups were done using the enzyme-linked immunosorbent assay (ELISA) technique. Results Median serum PCT (IQR) was significantly higher in patients with LC-IPF in comparison to those with IPF only (0.655± 3.60 vs 0.07 ± 0.11 ng/ml, p=0.016), respectively. LC-IPF patients with neuroendocrine (NE) component, stage IV disease, and with >2 metastatic sites had a significantly higher PCT in comparison to those with non-NE, stages I-III, and <2 metastatic sites, respectively. The presence of the NE component was the only independent risk factor predictive for PCT positivity in patients with LC-IPF; OR1.8 (95% confidence interval (CI) 0.042-2.145; p = 0.042). Conclusion Patients with LC-IPF have higher serum PCT levels than those with IPF alone. These levels are related to the presence of NE component, advanced cancer stage, and the presence of multiple metastases. The presence of the NE component is the only independent risk factor predictive for PCT positivity in patients with LC-IPF. Further studies are warranted.