Abstract
Background: Of the 1.8 million global incident lung cancer cases estimated in 2012, approximately 60% occurred in less developed regions. Prior studies suggest sex differences in lung cancer risk and a potential role for reproductive and hormonal factors in lung cancer among women. However, the majority of these studies were conducted in developed regions. No prior study has assessed these relationships among Nepali women.Methods: Using data from a hospital-based case-control study conducted in B. P. Koirala Memorial Cancer Hospital (Nepal, 2009–2012), relationships between reproductive and hormonal factors and lung cancer were examined among women aged 23–85 years. Lung cancer cases (n = 268) were frequency-matched to controls (n = 226) based on age (±5 years), ethnicity and residential area. The main exposures in this analysis included menopausal status, age at menarche, age at menopause, menstrual duration, gravidity, and age at first live-birth. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using multivariable logistic regression.Results: Among postmenopausal women, those with a younger age at menopause (<45 years; 45–49 years) had an increased odds of lung cancer compared to those with an older (≥50 years) age at menopause [OR (95%CI): 2.14 (1.09, 4.17); OR (95% CI): 1.93 (1.07, 3.51)], after adjusting for age and cumulative active smoking years. No statistically significant associations were observed with the other reproductive and hormonal factors examined.Conclusion: These results suggest that Nepali women with prolonged exposure to endogenous ovarian hormones, via later age at menopause, may have a lower odds of lung cancer.
Highlights
Lung cancer is the most commonly diagnosed cancer and the primary cause of cancer mortality worldwide [1,2,3,4]
No statistically significant associations were observed with the other reproductive and hormonal factors examined. These results suggest that Nepali women with prolonged exposure to endogenous ovarian hormones, via later age at menopause, may have a lower odds of lung cancer
Cases and controls varied in their ethnic background (p < 0.0001); controls had a higher proportion of Brahmins (29.2%) compared to cases (11.6%), and more than fifty percent of cases were included in the “other” ethnic groups
Summary
Lung cancer is the most commonly diagnosed cancer and the primary cause of cancer mortality worldwide [1,2,3,4]. While smoking is a well-established risk factor for lung cancer, several studies have suggested that reproductive and hormonal factors may play a role in lung cancer development due to observed sex differences [8,9,10,11,12]. These sex differences include increased susceptibility to the carcinogenic effects of tobacco [8,9,10] and a higher proportion of non-smoking lung cancer diagnosed [11] among women, as compared to men. No prior study has assessed these relationships among Nepali women
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