Lung cancer mortality risk among breast cancer patients treated with anti‐estrogens

Abstract

The Women's Health Initiative randomized clinical trial reported that menopausal hormone therapy increases lung cancer mortality risk. If this is true, use of anti-estrogens should be associated with decreased lung cancer mortality risk. The authors compared lung cancer incidence and mortality among breast cancer patients with and without anti-estrogen therapy. Our study included all 6655 women diagnosed with breast cancer between 1980 and 2003 and registered at the Geneva Cancer Registry. Among these women, 46% (3066) received anti-estrogens. All women were followed for occurrence and death from lung cancer until December 2007. The authors compared incidence and mortality rates among patients with and without anti-estrogens with those expected in the general population by Standardized Incidence Ratios (SIRs) and Standardized Mortality Ratios (SMRs). After a total of 57,257 person-years, 40 women developed lung cancer. SIRs for lung cancer were not significantly decreased among breast cancer patients with and without anti-estrogens (0.63, 95% confidence intervals [CI], 0.33-1.10; and 1.12, 95% CI, 0.74-1.62, respectively) while SMR was decreased among women with anti-estrogens (0.13, 95% CI, 0.02-0.47, P<.001) but not for women without anti-estrogens (0.76, 95% CI, 0.43-1.23). Compared with expected outcomes in the general population, breast cancer patients receiving anti-estrogen treatment for breast cancer had lower lung cancer mortality. This study further supports the hypothesis that estrogen therapy modifies lung cancer prognosis.