Can breast tissue density change at mammography predict survival in patients with breast cancer treated with tamoxifen?

This article evaluated whether a reduction in tissue density at mammography after tamoxifen treatment can predict survival in breast cancer patients.

Mammography uses x-rays to look at the breasts for signs of cancer. This diagnostic method is generally used for women over the age of 50. Younger patients usually have a dense breast tissue, which limits the use of mammography in this population. Postmenopausal women who have increased breast density are thought to have an increased risk of developing breast cancer. Many breast cancers grow as a response to estrogen, the main female sex hormone. Tamoxifen (Nolvadex) is a hormone therapy drug which prevents estrogen from getting to the cancer, thus stopping its growth or shrinking it. Previous studies have shown that tamoxifen treatment in healthy women has reduced breast density at mammography, with a reduced risk of developing breast cancer. This study tested whether change in mammographic density in breast cancer patients treated with tamoxifen had any effects on survival.

This study included 974 postmenopausal women with breast cancer. 474 patients received tamoxifen treatment and 500 patients did not receive tamoxifen. Each patient underwent at least two mammograms, one taken before starting tamoxifen and another follow up mammogram, after starting treatment. Results show that 15 years after the first mammograms, patients treated with tamoxifen who experienced a reduction in breast density of at least 20%, had a 50% higher survival rate compared to women who did not experience a change in mammographic density. In patients who did not receive tamoxifen there was no association between breast density at mammography and survival. 

These results show that a reduction in breast tissue density at mammography improved survival in patients with breast cancer treated with tamoxifen.