Lung Cancer Risk in Women Not Dependent on Reproductive or Hormone Use History

Reproductive history or hormone use has no link to women’s lung cancer risk, according to findings published in the Journal of Thoracic Oncology.

Researchers from the International Association for the Study of Lung Cancer examined the reproductive history, oral contraceptive use, and postmenopausal hormone therapy in more than 150,000 women with known hormone therapy exposure in order to explore the association between estrogen and estrogen related reproductive factors in association with lung cancer risk. The researchers followed up with the patients for a median period of 14 years, lasting through September 2012. There were nearly 2,500 cases of lung cancer identified.

For all the cases of lung cancer, the researchers noted, women with previous use of estrogen plug progestin of less than 5 years were at a reduced risk. There also appeared to be a trend toward decreased risk with age at menopause as well as a trend toward increased risk with increasing number of live births. A reduced risk of non small cell lung cancer was linked to age between 20 and 29 years at first live birth.

“Indirect measures of estrogen exposure to lung tissue, as used in this study, provide only weak evidence for an association between reproductive history or hormone therapy use and risk of lung cancer,” the authors wrote. “More detailed mechanistic studies and evaluation of risk factors in conjunction with estrogen receptor expression in the lung should continue as a role for estrogen cannot be ruled out and may hold potential for prevention and treatment strategies.”

Additionally, the risk estimates varies with smoking history, the researchers added, as well as years of hormone therapy usage and previous bilateral oophorectomy.

“Our study does not support the idea that reproductive history independently contributes to lung cancer risk, and recapitulates the inconsistent findings within epidemiologic literature on lung cancer risk and reproductive history measures,” the authors continued. “Likewise, the epidemiologic literature is also inconsistent with regard to the role of hormone use in lung cancer risk and the overall results presented by our study suggest that oral contraceptives and hormone therapy use are not associated with risk of lung cancer.”

However, the investigators cautioned that there are still questions about estrogen and lung cancer risk. These questions may be examined through “studies focusing on hormone use and emphasizes that the interplay between cigarette smoking, estrogen, genetic susceptibility and lung cancer is complex and continued study is necessary to tease apart these relationships,” they concluded.