According to The International Association for the Study of Lung Cancer (IASLC), female hormones may be a factor in why lung cancer survival rates have been better for women than men.

Results from a study published in the Journal of Thoracic Oncology showed the most significant improvements in survival came from a combination of estrogen plus progesterone and the use of long-term hormone therapy.

Investigators noted that the study was designed to explore the influence of several reproductive and hormonal factors on overall survival of women with non-small cell lung cancer (NSCLC). After adjusting for stage of disease at diagnosis, treatment type (surgery or radiation), smoking status, age, race, and education level, the only factor studied that predicted survival after a diagnosis of NSCLC was use of hormone therapy.

Researchers evaluated 485 women for the study; the median survival time was 80 months for women receiving hormone therapy and 37.5 months for women not receiving hormone therapy. Combined estrogen and progesterone was associated with a slightly higher median survival time (87.0 months) than estrogen alone (83.0 months).

According to the study results, the use of hormone therapy for 11 years or more was associated with significantly improved survival, and this finding remained significant among women who took either estrogen alone or estrogen plus progesterone and among women who had never smoked or were smokers.

“What has emerged from this study and other published findings is a complex relationship between hormone use and lung cancer outcomes, with variation in results based on years of use,” said lead author Ann G. Schwartz, PhD, MPH, of the Karmanos Cancer Institute in Detroit.

The IASLC noted that studies on the effect of hormone use on lung cancer survival have been limited, and the results have been inconsistent. Because of this, additional research is needed to evaluate the significance of long-term use of hormone therapy on outcomes in lung cancer, with better characterization of tumors in terms of expression of estrogen and progesterone receptors.

Schwartz added, “There is more to learn about survival differences between men and women; hormone use may contribute to those differences. The largest impact on lung cancer outcomes will come from successful early detection and treatment.”