Sex-based differences in CEACAM5 expression in lung cancer

Carcinoembryonic antigen-related cell adhesion molecule 5 (CEACAM5) is expressed in 20-25% of non-small cell lung cancer (NSCLC) and there is interest in CEACAM5 as a biomarker given its potential for blood-based detection and investigational study as a drug target. Increased expression of CEACAM5 has been observed in semi-solid lung adenocarcinoma lesions, which have an increased prevalence in women and never smokers. Given this association, sex-based differences in CEACAM5 were evaluated. The Cancer Genome Atlas (TCGA) data on CEACAM5 expression in NSCLC tumors (n=994) in women (n=398) and men (n=596) were analyzed for differences in expression of CEACAM5 based on sex and histologic subtypes of adenocarcinoma and for correlations with overall survival (OS). Among all stages of NSCLC, mean expression of CEACAM5 was 143.3 fragments per kilobase of transcript per million (FPKM) with differences observed between female and male patients (194.5 vs. 109.2 FPKM, P<0.0001) and between adenocarcinoma and squamous cell carcinoma (239.3 vs. 46.2 FPKM, P<0.0001). Differences persisted among combined sex and histology subgroups. High CEACAM5 was not predictive of survival in NSCLC or adenocarcinoma overall, but was associated with worse survival among stage I female patients with adenocarcinoma (5-year OS CEACAM5 high =33% vs. low =64%, log-rank P=0.008). Higher levels of CEACAM5 expression are observed in NSCLC tumors in female patients and adenocarcinoma histology. High CEACAM5 expression in lung adenocarcinoma is associated with worse survival among female patients. The biologic impact of sex on CEACAM5 as a biomarker warrants further study.