Tamoxifen and asthma

I have been on Tamoxifen for the last 16 months.  I recently had 6 chest infections since March and I have just been diagnosed with asthma.  My dr mention there was a study recently in US looking at Tamoxifen and asthma.  I was wondering if anybody else with breast cancer and on Tamoxifen have developed asthma and is there a connection?

[Fernando Roque, MD]

Hi.  There have been reported cases of asthma attacks induced by Tamoxifen intake (see Smith RP, et al. Tamoxifen Induced Asthma. Lancet. 1993 Mar 20;341(8847):772).  However, the exact percentage of women who take Tamoxifen and who develop asthma has not been reported in the scientific literature.  What has been mentioned is dyspnea (difficulty in breathing), which 8% of those taking Tamoxifen have experienced during the course of treatment.  My guess is that some of those cases reported as "dyspnea" are actually asthma attacks.

Your recent diagnosis of asthma may or may not be related to Tamoxifen intake.  Repeated chest infections can also stimulate your airways to become "hyper-reactive".  If your asthma attacks are mild, infrequent and are easily controlled by medication, it may still be advantageous for you to continue taking Tamoxifen for its benefits in reducing breast cancer recurrence.  If the attacks are increasing in frequency and severity, you may wish to discuss the option of stopping Tamoxifen with your oncologist.