(RxWiki News) More people die of lung cancer each year than any other kind of cancer. The survival rate among women, however, is better than men — and the reasons aren't exactly clear.
Women's naturally occuring hormones, and the hormones they take in birth control pills or as hormone therapy, may be the reason why women with lung cancer have better survival rates than men.
The effect of women’s reproductive history and hormone therapy on survival rates in non-small cell lung cancer was the topic of an investigation by a research group from Michigan.
This research team found that long-term hormone therapy helped to increase survival of women with non-small cell lung cancer. This effect was even greater in women who had never smoked.
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Ann G. Schwartz, PhD, MPH, from Karmanos Cancer Institute and the Department of Oncology at Wayne State University School of Medicine in Detroit, MI, was the lead author of this study.
The study enrolled 485 women aged 18 to 74 who had been diagnosed with non-small cell lung cancer (NSCLC). At the start of the study, only women with adenocarcinoma type NSCLC were enrolled, but the study later opened to women with other cell types of NSCLC.
Dr. Schwartz and team collected information on the women that included smoking history, medical history and reproductive history, such as age at first period, age at menopause, use of birth control pills and use of hormone therapy.
The researchers took note of the kind of hormone in the hormone therapy, whether it contained estrogen, progesterone or both.
A total of 92 percent of the women in the study were current or former smokers, 77 percent were white, 92 percent were post-menopausal, 72 percent had used birth control pills and 47 percent had used hormone therapy.
The type of hormone therapy used was known for only 187 women; 99 took estrogen, three took progesterone and 85 had taken a combination of both.
The researchers evaluated the link between reproductive and other factors and survival from NSCLC. They found that only hormone therapy changed the odds of survival.
Use of any hormone therapy before a diagnosis of NSCLC increased the odds of survival by 31 percent compared to not using hormone therapy.
The odds of survival increased by over 40 percent among women with at least 11 years of hormone therapy compared to those who did not take hormone therapy, with the greatest survival increase in the women who took hormone therapy containing both estrogen and progesterone. Those women had a 50 percent increase in survival odds compared to women who did not take hormone therapy.
Women who had never smoked had the greatest increased odds of survival. Compared to those who never took hormone therapy, non-smoking women who had used hormone therapy before diagnosis had 81 percent increased odds of survival.
Non-smoking women who took hormone therapy containing both estrogen and progesterone for over 11 years had 88 percent increased odds of survival after an NSCLC diagnosis.
“Increased duration of [hormone therapy] use was associated with a decreased risk of death after an NSCLC diagnosis,” Dr. Schwartz and colleagues concluded.
"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," says Dr. Schwartz.
This research was published in the March issue of the Journal of Thoracic Oncology.
Funding for the study was provided in part by grants for the National Institutes of Health.
The authors did not disclose any conflicts of interest.