15 July 2014
A study published today in Clinical Cancer Research demonstrates that tamoxifen applied to the skin in a gel form was as effective as oral tamoxifen in decreasing breast cancer cell growth and was associated with fewer side effects in patients with ductal carcinoma in-situ (DCIS).
Dr. Seema Kahn and colleagues randomized 27 women diagnosed with DCIS to receive either tamoxifen gel or oral tamoxifen for 6-10 weeks prior to surgery. They measured blood and breast tissue concentration of tamoxifen as well as the proliferative activity (growth rate – also known as Ki67) of breast cancer cells before and after treatment. They found that both forms of tamoxifen resulted in a decrease in the growth rate of cancer cells. Both groups showed similar concentrations of tamoxifen in the breast tissue, but the women who used the gel had lower tamoxifen concentrations in the blood.
Tamoxifen is used to treat breast cancer and is also used to reduce the risk of developing breast cancer in those at high risk. In women who have been diagnosed with breast cancer, tamoxifen can reduce the risk of cancer returning and can improve overall survival rates. However, many studies have shown that women often stop tamoxifen due to side effects. Those side effects can include vaginal discharge and exacerbation of menopausal symptoms such as hot flashes, sleep and mood disturbance, depression, and weight gain. The two most significant potential complications related to tamoxifen use are uterine cancer and blood clots. The study was too small to note any difference in side effects, but as the concentrations of tamoxifen in the blood are lower in patients using the gel, it is thought that this might result in fewer side effects.
This was a small study and many questions remain, but it is promising that an effective form of tamoxifen associated with fewer side effects may be eventually be available for widespread use.