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Minimal link observed between hormone use in women, lung cancer

There is very little evidence suggesting a strong association between a woman’s reproductive history and use of hormones and the risk for lung cancer, according to study results.

“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,” Ann G. Schwartz, PhD, MPH, deputy center director of the Karmanos Cancer Institute at Wayne State University, said in a press release.

Schwartz and colleagues evaluated the role reproductive factors, oral contraceptives and hormone use had in determining the risk for lung cancer in 160,855 women from the Women’s Health Initiative Observational Study and clinical trials. Menopausal women aged 50 to 79 years were enrolled in the study between October 1993 and December 1998 at 40 medical centers nationwide.

The women were separated into four randomized control trials that tested the use of estrogen or estrogen plus progestin, calcium plus vitamin D, or a low fat diet. Participants were followed yearly during the observational study, biannually through 2005 and annually until 2012.

As of September 2012, 2,467 lung cancers have been reported to researchers. They include 2,220 cases classified as non–small cell lung cancer (NSCLC).

There was a slight reduction in risk associated with previous use of estrogen plus progestin for less than 5 years for all lung cancers (HR = 0.84; 95% CI, 0.72-0.98). Data also showed a decrease in NSCLC incidence, but not all lung cancers, among women who were aged 20 to 29 years at the birth of their first child (HR = 0.84; 95% CI, 0.73-0.98).

Schwartz said more research is required to determine factors behind the relationships between hormone therapy and the risk for lung cancer in women.

“Questions remain about estrogen and lung cancer risk that will not easily be answered by 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,” she said. –by Ryan McDonald

Disclosure: Schwartz reports no relevant financial disclosures. Please see the full study for a list of all other authors’ relevant financial disclosures.