Reproductive and Hormonal Factors in Relation to Lung Cancer Among Nepali Women

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.

Menstrual factors, reproductive history, and risk of lung cancer: a multi-center population-based cohort study in Chinese females

“…Since the HRs below 45 also revealed increased lung cancer risk despite of the insignificant intervals, we considered that there may be a normal range (in a medical sense) for menopause age concerning the health status and lower lung cancer risk. Notably, some studies reported inverse associations between age at menopause and lung cancer risk (15,23,30,32,38), which are opposite to our findings. These opposite results were mainly attributed to different ethnicity.…”

Reproductive factors and lung cancer risk: a comprehensive systematic review and meta-analysis

“…A total of 133 duplicates, 1791 irrelevant publications, and 63 studies with full-text screening were excluded. Finally, 66 studies were eligible for inclusion into this meta-analysis [ 22 – 28 , 31 , 36 – 93 ] (Fig. 1 ).…”

Age at first birth and lung cancer: a two-sample Mendelian randomization study

“…Likewise, Kabat et al published a prospective cohort study (89,835 women and 750 incident LC cases) which found that women's AFB older than age 30 were at a 38% lower risk of LC compared with women's AFB below age 23 (15). Nevertheless, subsequent studies concerning the relationship of AFB and LC risk have primarily been negative (16)(17)(18)(19). In general, previous conventional observational studies provided evidence that late AFB can lower or have no significant effect on LC risk.…”