Objective: Sixteen percent of US population is Hispanic, mostly Mexican. Recently, two independent American reports demonstrated a higher overall survival (OS) in Hispanic populations compared with non-Hispanic-white populations (NHW) with non-small-cell lung cancer (NSCLC), even when most Hispanic patients are diagnosed at advanced disease stages and have lower income status. We analyzed the clinical, pathological, and molecular characteristics as well as outcomes in a cohort of NSCLC Hispanic patients from the National Cancer Institute of Mexico that could explain this "Hispanic Paradox".
Material and methods: A cohort of 1260 consecutive NSCLC patients treated at the National Cancer Institute of Mexico from 2007 to 2014 was analyzed. Their clinical-pathological characteristics, the presence of EGFR and KRAS mutations and the prognosis were evaluated.
Results: Patients presented with disease stages II, IIIa, IIIb and IV at rates of 0.6, 4.8, 18.4 and 76.3%, respectively. NSCLC was associated with smoking in only 56.5% of the patients (76.7% of male vs. 33.0% of female patients). Wood smoke exposure (WSE) was associated with 37.2% of the cases (27.3% in men vs. 48.8% in women). The frequency of EGFR mutations was 27.0% (18.5% in males vs. 36.9% in females, p<0.001) and the frequency for KRAS mutations was 10.5% (10.3% men vs. 10.1% in women p=0.939). The median OS for all patients was 23.0 [95% CI 19.4-26.2], whereas for patients at stage IV, it was 18.5 months [95% CI 15.2-21.8]. The independent factors associated with the OS were the ECOG, disease stage, EGFR and KRAS mutation status.
Conclusion: The high frequency of EGFR mutations and low frequency of KRAS mutations in Hispanic populations and different prevalence in lung cancer-related-developing risk factors compared with Caucasian populations, such as the lower frequency of smoking exposure and higher WSE, particularly in women, might explain the prognosis differences between foreign-born-Hispanics, US-born-Hispanics and NHWs.
Keywords: Carcinoma; Gene expression; Hispanic Americans; Human; KRAS Protein; Mutation; Non-Small-Cell Lung; erbB-1.
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