A prospective study on lung cancer called the Women’s Health Initiative Study found no strong association between the risk for the disease and a wide range of variables concerning women’s reproductive history, revealing poor support for the role of hormone usage in lung cancer’s incidence. The results were published in the Journal of Thoracic Oncology.
About 40 percent of the total 160,000 deaths that lung cancer causes in the United States occur in women and women who are never-smokers are more likely to develop lung cancer than never-smoking men. Women also have a better prognosis, with 5-year survival rates of 20 percent in comparison to 15.4 percent in men.
Based on these gender differences, researchers believe it is necessary to understand if reproductive factors and hormones might play a role in lung cancer risk in women.
The Women’s Health Initiative Observational Study was an ethnically diverse clinical study including 161,808 postmenopausal women aged between 50 and 79 years old. Reproductive history, hormone therapy replacement and oral contraceptive usage were assessed in 160,855 women eligible in the study, with a total of 2,467 lung cancer cases observed and a patient follow-up of an average 14 years.
The results suggested that women who used estrogen plus progestin (< 5 years) had slightly lower risks of developing lung cancer. Also, while increased age at menopause implied a lower risk, increased number of children seemed to augment it. The study revealed that women who had their first child at 20 to 29 had a lower risk for non-small cell lung cancer (NSCLC), but not for other types of lung cancer. Risk estimates for previous surgery to remove both ovaries and hormone therapy use depended on tobacco exposure history.
The authors noted in a press release, “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. 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.”
Ann G. Schwartz from the Karmanos Cancer Institute, Wayne State University and member of IASLC, concluded that, “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.”