Hormone use and lung cancer incidence: the Rancho Bernardo cohort study.

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.