Study objectives: To determine whether there is an
association between cigarette smoking and the development of pulmonary
metastatic disease among women with breast cancer.
Design: A case-control study.
University of California, Davis Medical Center.
Participants: Eighty-seven women patients with unilateral,
invasive breast cancer and pulmonary metastatic disease were identified
as cases, and each patient was matched with two control patients
who did not have pulmonary metastatic disease. Case patients and
control patients were matched for year of diagnosis, age at diagnosis,
size of primary tumor, and nodal status.
analysis: Multivariate analysis using conditional logistic
regression was used to determine the odds of smoking among women with
pulmonary metastatic disease compared to matched control patients
without pulmonary metastatic disease, after correction for potential
Results: Thirty-eight percent of
the case patients vs 29% of the control patients were classified as
ever-smokers; 24.1% of case patients were actively smoking at the time
of breast cancer diagnosis vs 15.3% of the control patients. The
unadjusted odds ratio for active smoking was 1.76 for women with
pulmonary metastatic disease compared to women without pulmonary
metastatic disease (p = 0.06). In the final multivariate model, the
odds ratio for active smoking among women with pulmonary metastatic
disease was 1.96 (p = 0.06).
appears to be an association between cigarette smoking and the
development of pulmonary metastatic disease among women with breast
cancer. This may explain the previously noted higher breast cancer
fatality rate among smokers. The relationship between smoking behavior
and pulmonary metastasis from breast and other cancers warrants further