Lung cancer in women who have never smoked is more frequently associated with EGFR mutations and estrogen receptor overexpression, according to a new study.

The incidence of lung cancer in women affects an estimated 516,000 women worldwide, of which 100,000 are in the United States and 70,000 in Europe. Until now, lung cancers occurring in women have been treated similarly to lung cancers in men. However, numerous studies have highlighted different characteristics of lung cancer in women.

Researchers at the UniversitéToulouse III Paul Sabtier in France aimed to compare clinical, pathological, and biological characteristics of lung cancer in cohorts of women smokers and women never-smokers. They hypothesized that genetic events or hormonal factors may be partly involved in the high rate of tobacco-independent lung cancer in women. They looked at a total of 140 women who had adenocarcinoma, with 63 being never-smokers and 77 being former or current smokers.

They observed differential genetic alteration repartition in women according to their tobacco status: 50.8% of never-smokers displayed an EGFR mutation versus 10.4% of smokers. In contrast, K-Ras was more frequently mutated in smokers (33.8%) than in never-smokers (9.5%). The researchers also observed a higher percentage of estrogen receptor alpha expression in patients who never smoked compared with smokers. The expression of estrogen receptor alpha was correlated with the presence of a mutation in EGFR.

The never-smokers had a higher age (67 years versus 58.7 years) and greater frequency of lepidic features (60.3% versus 37.7%) compared with the smokers. The groups did not significantly differ in estrogen receptor beta and progesterone receptors.

“These findings underline the possibility of treatment for women who have never smoked with drugs to target hormonal factors, genetic abnormalities, or both,” the authors said. This study was published in the Journal of Thoracic Oncology (2013; doi:10.1097/JTO.0b013e3182904dfb).