Clinical and molecular analysis of lung cancers associated with fibrosing interstitial lung disease

Background: Interstitial lung disease is a heterogeneous group of diseases, some of which are known to present an independent risk factor for lung cancer. Its pathophysiological mechanism has not been fully elucidated and therapeutic management is also complex. We aim to both describe a cohort of patients with lung cancer associated with pre-existing fibrosing interstitial lung disease and to characterize their molecular profile.

Methods: We conducted a retrospective, single centre cohort study, at Toulouse University Hospital. Immuno-histochemical (PD-L1, CD8) and molecular analysis was performed on archived tumour sample. Molecular signalling pathways involved were analysed with the Reactome Pathway Database.

Results: Forty-nine patients were analysed. Most common histology was adenocarcinoma (65,3%), followed by squamous cell carcinoma (30.6%). Idiopathic pulmonary fibrosis (30,6%) and interstitial lung disease associated with connective tissue disease (22,4%) were mostly diagnosed. Usual interstitial pneumonia dominated the scans patterns. A high proportion of early tumour stages was observed and overall survival was 34,5 months. In metastatic stages response rate to first line chemotherapy was 38% and overall survival was 11,2 months. Main cause of death was complex cancer progression. PD-L1 expression (n=23) was low (0%) to intermediate (1-49%). Tumour mutational burden was low in 69,2% of analysed cases (n=12) and microsatellite status was stable in all cases (n=13). Sample genotyping (n=14) showed frequent involvement of the TP53 gene and the implication of signalling pathways common to fibrotic processes such as TGFβ and PI3K/AKT.

Conclusions: We suggest a particular phenotype of lung cancer associated with fibrosing interstitial lung disease that could provide the basis for specific therapeutic strategies.