Hormonal factors in association with lung cancer among Asian women: A pooled analysis from the International Lung Cancer Consortium.

Two thousand sixty-four lung cancer cases and 5342 controls were evaluated in this International Lung Cancer Consortium (ILCCO) pooled analysis on estrogen-related hormonal factors and lung cancer in Asian women. Random effect of study site and fixed effect of age, smoking status, comprehensive smoking index and family history of lung cancer were adjusted for in the multivariable logistic regression models. We found that late onset of menarche conferred elevated odds of lung cancer with adjusted odds ratio (OR) of 1.24 (95% confidence interval [CI] = 1.05, 1.45) for 17 years or older, compared to 14 years or younger. Late onset of menopause at 55 years old or older was associated with lung cancer with OR = 1.24 (95% CI = 1.02, 1.51). Nonnatural menopause was associated with an OR of 1.39 (95% CI = 1.13, 1.71). More live births showed reversed association with lung cancer (ORs of 5 or more live births: 0.71 (95% CI = 0.60, 0.84), compared to 0-2 live births (Ptrend < 0.001). A later first child delivery seemed associated with an increased susceptibility: OR of 21 to 25 years old: 1.23 (95% CI = 1.06, 1.40), 26 or older: 1.27 (95% CI = 1.06, 1.52), Ptrend = .010). The use of oral contraceptives appeared to be protective with an OR of 0.69 (95% CI = 0.57, 0.83). Stronger for adenocarcinoma than squamous cell carcinoma, these relationships were not clearly modified by smoking status, probably because of lower prevalence of smoking. This is a first and largest pooling study of lung cancer among Asian women and the results suggested potential roles of hormone-related pathways in the etiology of this disease.