Table 1.

Main epidemiological features of molecular alterations in main candidate genes in non-small cell lung cancer.

Gene	Most Common Variants	Prevalence	Age	Gender	Smoking	Histology	Prognostic Significance
EGFR	Mutations in exons 19 and 21	10–16% in Western populations, 40–50% in Asians.	Younger patients	Females	Never smokers	Adenocarcinoma	Response to specific TKIs, T790M predictor of resistance
ALK	EML4-ALK variants	1–10% of NSCLC	Younger patients	Females? Not clear	Never smokers	Adenocarcinoma	Aggressive tumors, response to specific TKIs
ROS1	CD74-ROS1 variants	0.9–2.6% of NSCLC	Younger patients	Females	Never smokers	Adenocarcinoma	Less aggressive tumors, response to specific TKIs
KRAS	Mutations in codons 12 and 13	30–40% of NSCLC, more common in Caucasians	Older ages	Males? Not clear	Smokers	Adenocarcinoma	Poor prognosis or response to TKIs? Not clear
BRAF	Mutations in exon 15	2–4% of NSCLC	No predilection	V600E in females and others in males	Smokers	Adenocarcinoma	Aggressive tumors and poor prognosis? Not clear. Response to BRAF inhibitors.
MET	Mutations in exon 14, amplification	Mutations in 1–10% of NSCLC, amplification in 5–22%	Older ages	Not clear	Smokers	Adenocarcinoma and SCC	Resistance to EGFR-TKIs. Response to MET inhibitors.
HER2	Mutations in exons 18–21, amplification	Mutations in 2–3% and amplifications in 2–5% of adenocarcinomas	Not clear	Mutations in females and amplifications in males	Mutations in never smokers and amplifications in ex-smokers	Adenocarcinoma Rare in SCC	Resistance to EGFR-TKIs? Not clear

NSCLC: non-small cell lung cancer; SCC: squamous cell carcinoma; TKIs: tyrosine kinase inhibitors; EML4: echinoderm microtubule-associated protein like 4.