medwireNews: Going through menopause before the age of 45 years increases the risk for lung morbidities and mortality in women, regardless of their smoking status, and whether menopause occurred naturally or was surgically induced, report US researchers.
The team used data for 69,706 women from the Prostate, Lung, Colorectal, Ovarian (PLCO) trial with known smoking history, to investigate the links between early menopause and lung conditions, including emphysema, chronic bronchitis (CB), and lung cancer, as well as death from lung disease and other causes.
“Cigarette smoking is an established risk factor for early [menopause],” remark Shuguang Leng, from the University of New Mexico School of Medicine in Albuquerque, and colleagues, who add that “[m]ounting evidence supports early [menopause] as a detrimental factor for lung diseases.”
However, the team also suggests in Thorax that it is “largely unknown” whether early menopause induced by surgery has the same effect.
A total of 20,163 (29%) women from the cohort reported early menopause, including 4699 (10.2%) who went through early menopause naturally, 3922 (47.2%) who underwent early menopause after bilateral oophorectomy (BO), and 11,542 (75.1%) who underwent early menopause after a hysterectomy.
Women with early menopause who had ever smoked (n=9555) had a significantly increased risk for most lung diseases and mortality compared with women who went through the menopause at 45 years of age or older. The exceptions were CB in women who went through natural menopause and emphysema in those who had a hysterectomy.
For mortality outcomes in ever smokers, the team reports significant hazard ratios of 1.98, 1.35, and 1.27 for respiratory, non-cancer, and all-cause mortality among those who underwent BO, 1.28 for all-cause mortality and 1.35 for non-cancer mortality in those who underwent hysterectomy, and 1.36 and 1.32 for respiratory and non-cancer mortality in those who experienced natural menopause.
These associations remained significant after adjustment for potential confounding factors including age, race, education status, and BMI.
The researchers add that among never-smokers (n=38,883), early, natural menopause increased the risk for poor outcomes, including a significant 1.31-fold increased risk for CB and a 1.51-increased risk for respiratory mortality, versus later menopause. These risks were significantly increased almost twofold for never smokers who had BO-induced early menopause, at 1.86 and 1.91, respectively.
“These findings all support the importance of maintaining lung health in women with early [menopause],” suggest Leng et al, who also evaluated the impact of menopausal hormone therapy (MHT) use on outcomes.
For women who had ever smoked, those who used MHT (n=20,703) had a significantly reduced risk for almost all outcomes compared with their peers who had never used MHT. The exceptions were a nonsignificant reduction in emphysema risk, a nonsignificant increased risk for CB in those who experienced natural early menopause, and a significantly increased risk for CB for those who underwent BO.
All mortality outcomes were significantly reduced for ever smokers with natural menopause who had used MHT, including a 22% reduced risk for lung cancer and respiratory mortality, and for those who underwent BO, the only exception was non-ovarian cancer, which did not reach statistical significance.
In light of this consistent reduction in all-cause and cause-specific mortality with MHT, Leng and colleagues analyzed the impact of MHT duration and found that in the main every category studied (≤1 year, 2–3 years, 4–5 years, 6–9 years, and ≥10 years of use) “was associated with reduced all-cause, non-cancer and cardiovascular mortality regardless of smoking status,” compared with never use.
Notably, respiratory mortality was reduced by 29% in ever smokers who used MHT for over 10 years.
“We also identified evidence that oestrogen/progestin pills provided more protection compared with oestrogen pills alone in women with natural menopause,” write the researchers.
“We speculate that there may be shared mechanisms underlying lung and ovary maturation in early life that may subsequently lead to suboptimal development of both organs and functions,” they conclude.
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