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.

    最新發現表明，單個基因變異體可以預測經過它莫西芬治療后乳腺癌患者的存活情況。

    在46%攜帶該"好"基因的婦女中，它莫西芬與新藥的治療效果相同。攜帶該基因變異體的婦女，對它莫西芬治療耐受，因此其他的治療方案會更好。

    在過去的25年中，它莫西芬使超過50萬的患者免于死于乳腺癌。該藥物還阻止術后乳腺癌的復發。因此它莫西芬仍然是一個非常有效的藥物，雖然新的芳香酶抑制劑藥物在臨床試驗上效果似乎更好。

    現在看起來一些婦女用它莫西芬治療的效果會很好。這些婦女攜帶有CYP2D6基因的一個變異體，該變異體使它莫西芬的作用效果更好。

    該基因編碼一個酶，這個酶在它莫西芬活性發揮過程中非常關鍵。大約46%的婦女攜帶該基因的一種變異體，這種變異使該酶的活性大大增強。而其他婦女攜帶的變異體的酶活性較低或中等。

    Werner Schroth是德國Fischer-Bosch臨床藥理研究所的博士。他和同事研究了1325例德國以及美國使用它莫西芬治療早期乳腺癌的絕經后的婦女的CYP2D6基因。

    他們發現攜帶該基因高活性變異體的婦女在經過5年它莫西芬治療后，乳腺癌復發率很低。其治療效果與使用芳香酶抑制劑治療的婦女的治療效果相似。

    Schroth及同事斷定說："這將給醫學以及科學協會新的動力去評價這兩種方法在治療婦女早期乳腺癌的作用。

    研究人員認為遺傳檢測可以確定哪些婦女應該用它莫西芬治療。