A hormone therapy for breast cancer can reduce the chances of the disease spreading by a fifth, according to a new study presented at the San Antonio Breast Cancer Symposium in Texas. Experts say the spread of the disease may be directly related to estrogen, progesterone, or testosterone levels.

A new drug that works by stopping production of estrogen, the hormone which fuels most breast tumours, could give hope to breast cancer sufferers, though the treatment is not yet licensed in the U.S.

Patients given the aromatase inhibitor exemestane after surgery were 19% less likely to suffer metastatic, or spreading cancer than those receiving standard treatment. The reduction in risk was significantly greater for the types of breast cancer that are driven by hormones, such as estrogen-receptor positive breast cancer and progesterone-receptor positive breast cancer.

Estrogen-receptor (ER)-positive breast cancer accounts for the majority of breast cancers diagnosed each year. About 75% of breast cancers are estrogen-receptor positive. Cells with estrogen receptors grow and multiply when estrogen attaches to their receptors. These types of cancer respond well to hormonal therapy.

The clinical trial compared initial treatment with Tamoxifen or Exemestane Adjuvant Multicentre in a group of almost 10,000 women with breast cancer. The study’s authors have found that hormonal therapy with exemestane lowers the risk of death by nearly a fifth compared with patients given Tamoxifen.

The findings of the study were presented at the San Antonio Breast Cancer Symposium in Texas.

Another study presented at the symposium in Texas has shown that women with small breast tumors that seem cured after surgery have a substantially increased risk for relapse. The researchers said women who have breast cancer tumors known as HER2-positive, even those a centimeter or less in diameter, might need extra treatment with drugs such as Herceptin in order to avoid the risk for relapse.

A study released by the Women’s Health Initiative, which tested estrogen and progesterone pills that were prescribed to prevent heart disease, bone loss and other problems after menopause, has found that taking hormones for five years doubles the risk of breast cancer. “These findings also indicate that women who take estrogen plus progestin continue to be at increased risk of breast cancer, even years after stopping therapy,” said National Heart, Lung, and Blood Institute director Dr. Elizabeth G. Nabel, in a press release. The report confirms the study’s primary conclusion that hormone treatment should not be used to prevent disease in healthy, postmenopausal women, she added.

Researchers present at the San Antonio Breast Cancer Symposium in Texas have presented a new genetic test that could predict a woman’s breast cancer risk better than other tests. The new test, called OncoVue, looks at variations in 19 genes associated with breast cancer risk and associates them with information evaluated by the Gail model for a better accuracy of the diagnostic. Trials have shown that the test was 2.4 times more accurate than the Gail model in identifying which women had breast cancer. It identified 56 cases of breast cancer compared with 37 for the Gail model.