The Dec. 4th online edition of the journal Breast Cancer Research featured a study whose findings indicated that anti-estrogen therapy, specifically the drug Tamoxifen, may actually have an adverse effect (PDF) in a large number of estrogen-receptor breast cancer patients, even though they initially respond well to treatment with the drug.
The researchers from Cardiff University noted that the first part of the problem is that after prolonged use, some patients eventually develop a resistance to Tamoxifen. This resistance factor was first uncovered last month by another British team of researchers when they found that Tamoxifen uses a protein called PAX2 to turn off the breast cancer gene. Women with low levels of this protein are very likely to become resistant to the effects of treatment with Tamoxifen.
However, the new study discovered a more serious problem with Tamoxifen therapy than developing a resistance. The findings concluded that using drugs like Tamoxifen in patients who had low levels of another protein, E-cadherin, could make the cancer spread more aggressively.
We're talking more about this and have more news on the way this week at TotallyHer: Should You Be Concerned about Taking Tamoxifen for the Treatment of Estrogen-Receptor Breast Cancer?