Squamous cell carcinoma of the lung (LSCC) is the second most common histological subtype of non-small cell lung cancer (NSCLC) having smoking habit as the major risk factor. LSCC in non-smokers is an exceptional finding possibly related to professional exposure and subsequent carcinogenesis even though clinical and biological landscape is largely unexplored.
This is a retrospective multicenter study investigating clinical features of never-smoker LSCC patients (pts) referred to three Italian Centers between 2010 and 2016. Relapse (RFS) or progression free (PFS) and overall (OS) survival curves were calculated by Kaplan-Meier method. Cox regression proportional hazards model was used to estimate the impact of covariates on OS.
Among 791 LSCC pts, 37(4,6%) occurred in never-smokers; our case series included 19 males and 18 females with a median age of 63 years. ECOG PS was 0-1 in 30(81%) pts. Median Charlson Comorbidity Index (CCI) was 6. Two (5%) pts referred second-hand smoking history and 13(35%) occupational exposure. Additional tumor history was reported by 15(41%) patients: head and neck (N=4), basocellular skin (N=5), breast (N=2), lung (N=2), prostate (N=1) cancer and leukemia (N=1). Molecular characterization was performed in 12(32%)pts: EGFR and KRAS mutations were found in 2 and 1 pts respectively. Median time from symptoms appearance and diagnosis was 7 weeks. Twelve (32%) pts showed a limited stage, while the other 25(68%) showed advanced/metastatic disease at the diagnosis. Nineteen (52%) pts received a first-line palliative chemotherapy (pct), mostly platinum-based doublets plus gemcitabine (N=11) or taxane (N=3), achieving a response rate and disease control rate of 37% and 58% respectively. Median RFS in resected patients (N=9) was 21 months. Median PFS and OS after first-line pct were 5 months and 8.5 months respectively. No covariate significantly impacted on OS.
Never-smoker LSCC pts represent a rare subgroup characterized by more females, younger age and a not negligible CCI and second-tumor history compared with the known features of smoker LSCC. Treatment outcome of advanced disease is still dismal as for most LSCC pts.
Clinical trial identification
Legal entity responsible for the study
Istituto Oncologico Veneto IRCCS
All authors have declared no conflicts of interest.