Objective: This study examines the association of hormone use and lung cancer among women.
Methods: This is a prospective study of 2,861 women aged 31 to 79 years from the Rancho Bernardo cohort. After enrollment in 1972 to 1974, women were followed up for 31 years for morbidity and mortality. Incident lung cancer was based on self-report or death certificates. Diagnosis was validated from the California Cancer Registry for cases that occurred after 1988. Cox proportional hazard models were used to estimate the adjusted association of hormone use and lung cancer.
Results: During the 31-year follow-up, 87 women developed lung cancer. There was no association between hormone use and lung cancer (hazard ratio, 1.13; 95% CI, 0.73-1.73). Stratification by age 55 years (proxy for menopause status) showed divergent results. In women 55 years and older, lung cancer risk was 1.58 (95% CI, 0.95-2.53), whereas in women younger than 55 years, lung cancer risk was 0.44 (95% CI, 0.16-1.23). The confidence intervals for both groups contained the null value.
Conclusions: Although not statistically significant, our results from a long follow-up suggest that postmenopausal women on hormone therapy may have an increased risk of lung cancer, whereas younger women do not.
There was no overall association of hormone use and lung cancer incidence in a cohort of women residing in Rancho Bernardo, California. However, when stratified by age 55 years (as a proxy for menopause status), lung cancer risks diverged, and postmenopausal women on hormone therapy had an increased risk of lung cancer whereas premenopausal women did not, although both confidence intervals contained the null.
From the Department of Family and Preventive Medicine, School of Medicine, University of California San Diego, La Jolla, CA.
Received November 20, 2008; revised and accepted February 5, 2009.
Funding/support: This study was supported by grants AG007181 and AG028507 from the National Institutes of Health/National Institute on Aging and by grant DK31801 from the National Institute of Diabetes and Digestive and Kidney Diseases.
Financial disclosure/conflicts of interest: None reported.
Address correspondence to: Wael K. Al-Delaimy, MD, PhD, Moores Cancer Center, 3855 Health Sciences Drive #0901, La Jolla, CA 92093-0901. E-mail: email@example.com