A single gene variant predicts breast cancer survival after tamoxifen treatment, a new study finds.

In the 46% of women with the "good" gene, tamoxifen works as well as newer drugs. For women with the gene variant linked to poor response to tamoxifen treatment, other treatment strategies would be a better choice.

In the past 25 years, tamoxifen has prevented more than half a million deaths from breast cancer. The drug helps prevent breast cancer recurrence after surgery. Tamoxifen is still a useful drug, although newer drugs called aromatase inhibitors seem to work better in clinical trials.

Now it appears that some women will do at least as well if they're treated with tamoxifen. Such women carry a version of a gene called CYP2D6 that makes tamoxifen work better.

The gene encodes an enzyme crucial to tamoxifen activity. About 46% of women have a version of the gene that contributes to high enzyme activity. Others have genes that contribute to low or intermediate activity of the enzyme.

Werner Schroth, PhD, of Germany's Fischer-Bosch Institute of Clinical Pharmacology, and colleagues analyzed CYP2D6 genes in 1,325 postmenopausal women treated with tamoxifen for early-stage breast cancer in Germany and in the U.S.

They found that women with the highly active version of the gene were significantly less likely to have their breast cancer come back after five years of tamoxifen treatment. These women had outcomes similar to those seen in women treated with aromatase inhibitors.

"[This] should provide new impetus to the medical and scientific community to revisit the issue of the relative efficacy of these two approaches in women with early breast cancer," Schroth and colleagues conclude.

The researchers suggest that genetic testing could identify women who should not be treated with tamoxifen.

最新发现表明，单个基因变异体可以预测经过它莫西芬治疗后乳腺癌患者的存活情况。

在46%携带该"好"基因的妇女中，它莫西芬与新药的治疗效果相同。携带该基因变异体的妇女，对它莫西芬治疗耐受，因此其他的治疗方案会更好。

在过去的25年中，它莫西芬使超过50万的患者免于死于乳腺癌。该药物还阻止术后乳腺癌的复发。因此它莫西芬仍然是一个非常有效的药物，虽然新的芳香酶抑制剂药物在临床试验上效果似乎更好。

现在看起来一些妇女用它莫西芬治疗的效果会很好。这些妇女携带有CYP2D6基因的一个变异体，该变异体使它莫西芬的作用效果更好。

该基因编码一个酶，这个酶在它莫西芬活性发挥过程中非常关键。大约46%的妇女携带该基因的一种变异体，这种变异使该酶的活性大大增强。而其他妇女携带的变异体的酶活性较低或中等。

Werner Schroth是德国Fischer-Bosch临床药理研究所的博士。他和同事研究了1325例德国以及美国使用它莫西芬治疗早期乳腺癌的绝经后的妇女的CYP2D6基因。

他们发现携带该基因高活性变异体的妇女在经过5年它莫西芬治疗后，乳腺癌复发率很低。其治疗效果与使用芳香酶抑制剂治疗的妇女的治疗效果相似。

Schroth及同事断定说："这将给医学以及科学协会新的动力去评价这两种方法在治疗妇女早期乳腺癌的作用。

研究人员认为遗传检测可以确定哪些妇女应该用它莫西芬治疗。