Breast Cancer Drug Found Effective Nearly Six Years After Treatment
According to new research, nearly six years after discontinuing a five-year regimen of the breast cancer drug anastrozole, women at high risk for breast cancer were 50% less likely to develop the disease.
More than 3,800 postmenopausal women with a high risk of breast cancer participated in the trial. High-risk factors included having two or more blood relatives with breast cancer, having a mother or sister who developed breast cancer before age 50, and having breast cancer in both breasts.
Approximately half of the participants were randomly assigned to take the aromatase inhibitor anastrozole...Arimidex... for five years, while the other half received a placebo.
One breast cancer expert who was not involved in the study explained that drugs such as anastrozole are used to prevent breast cancer from recurring.
"One of the most important parts of my job as a breast programme director is running our' high risk clinic, and the most common question that I get from our patients is 'What else can I do to prevent breast cancer?'" said Dr. Alice Police, who directs breast surgery at the Northwell Health Cancer Institute in Sleepy Hollow, New York.
"Aside from lifestyle interventions, such as diet and exercise, and prophylactic surgery, there are medications that we know can reduce the future risk of breast cancer in this group by 50 percent or more," according to her."Tamoxifen is the drug that has historically been used for this purpose and this study looks at the drug anastrozole as an alternative."
The new findings were scheduled to be presented Thursday at the annual San Antonio Breast Cancer Symposium and published simultaneously in The Lancet.
According to study author Jack Cuzick, the study "was designed to investigate whether five years of anastrozole can safely and effectively prevent breast cancer in postmenopausal women who are at high risk for the disease."
In 2013, the research team "reported that in the first seven years of follow-up, anastrozole significantly reduced breast cancer incidence compared to placebo, and that it did so with very few side effects," Cuzick stated in a symposium news release.
"Our new data show that after a median of 10.9 years of follow-up, there continues to be a significant reduction in breast cancer incidence," Cuzick said in a statement. He directs the Wolfson Institute of Preventive Medicine, leads the Centre for Cancer Prevention, and is the John Snow Professor of Epidemiology at Queen Mary University of London.
Hair straighteners and dyes are linked to an increased risk of breast cancer.
"It is exciting to see that anastrozole has a continued impact on breast cancer incidence even after stopping treatment, as this strengthens the case for its use as a breast cancer prevention therapy," she said.
"Another way to consider the data is that it translates into anestimated 29 women needing to be treated with anastrozole for five years to prevent one breast cancer during treatment and in the next five years," he said.
"This is far fewer women than the estimated 49 women that need to be treated with tamoxifen for five years to prevent one breast cancer in the same time period," he went on to say.
Cuzick observed that anastrozole has preventive benefits for oestrogen receptor-positive breast cancer and ductal carcinoma in situ, but not for oestrogen receptor-negative breast cancer.
Anastrozole targets the oestrogen pathway.
Astrazeneca funded the study, and Cuzick, the study's co-chair, consults for Myriad Genetics.Police described the new findings as "exciting and important."
"Even after stopping the drug, the protection continued for atleast five more years for most types of breast cancer," she said. "I now have an even better answer for the question 'What else can I do?'"
Dr. Lauren Cassell is the chief of breast surgery at Lenox Hill Hospital in New York City. After reviewing the findings, she agreed that the data was "extremely exciting news" for patients.
"We have known that tamoxifen can decrease a woman's risk of developing breast cancer, which actually persists longer than the five years that it was taken," Cassell said. However, "we did not have the same data for anastrozole."According to Cassell, both tamoxifen and anastrozole have advantages and disadvantages.
"Anastrozole does not carry an increased risk for uterine cancer or blood clots, which we find with tamoxifen," she went on to explain, "but many patients complain of significant joint pains [with anastrozole], which causes them to discontinue the medication."
So far, it is unclear whether anastrozole reduces the risk of breast cancer death, so the researchers intend to continue following the study participants to answer that question.
