A new study in the Journal of the American Medical Association says that for many of the 70 percent of women whose breast cancers are fed by estrogen--those with estrogen-receptor positive tumors-- the benefits of estrogen-blocking hormonal therapy, such as tamoxifen, are so strong that chemotherapy doesn’t add much to the chances for long-term survival.
The study poses a challenge to traditional breast cancer therapy, where guidelines call for chemotherapy if tumors are larger than a centimeter. Women whose cancer is estrogen-receptor negative would still benefit from chemotherapy.
Now, as someone whose breast cancer was “highly” estrogen–receptor positive, I find this study fascinating. It suggests that my five-year regimen of tamoxifen, followed by my current regimen of four years plus counting of an aromatase inhibitor, which also blocks estrogen, is what most likely has kept me cancer free (knock wood), not the chemotherapy I endured. I wonder, though, if I had been told about this new study at the time of my diagnosis whether I would have chosen to have the chemotherapy anyway, just in case, as an added protection. That is the choice many women will be facing now. Another complicating factor is that the tests that tell how sensitive a tumor is to estrogen are not as fail-proof as doctors would like them to be.
However, a new genetic test that costs $3,500, and is not always covered by insurance, can predict more accurately than past diagnostic tests how likely a breast cancer patient’s disease will recur. The Oncotype DX test was developed by Genomic Health. It is unclear whether this test will lead to less use of chemotherapy over time.
Another study of post-menopausal women taking estrogen to ease hot flashes and other symptoms found that taking the hormone alone doesn’t boost the risk of developing breast cancer. The seven-year federal study of 10,700 women whose uteruses had been removed showed some evidence that estrogen may protect some women against tumors, contrary to earlier research that showed taking estrogen increased the risk. However, the study’s findings apply only to menopausal women who have had hysterectomies.