A new study of the benefits of extending breast cancer treatment in post-menopausal women beyond the standard five-year period has found it can almost halve the risk of recurrence.
The findings of the study of 5,200 women across the US and Europe, including 10 patients at St Vincent's Hospital in Dublin, will be published next week in the New England Journal of Medicine.
The treatment of those women was extended using the drug Femara, and after two years and four months they were found to have a 43 per cent reduced risk of their cancer recurring compared to patients taking no further medication. The risk of them developing cancer in their other breast was also reduced by 46 per cent.
Women who have surgery for breast cancer traditionally receive a drug called Tamoxifen that reduces the risk of breast cancer recurring for five years. But because it has been shown to have no benefit after this time, doctors have not traditionally offered further medication.
However, this latest study, undertaken by the National Cancer Institute of Canada, shows that use of the drug Femara, following five years of treatment with Tamoxifen, may have a substantial impact on the overall treatment outcome for post-menopausal breast cancer patients.
There are an estimated 1,200 new cases of breast cancer among post-menopausal women in the Republic every year, and the number of post-menopausal women worldwide currently receiving Tamoxifen therapy is approximately one million.
Because of the significance of the results of the clinical trials, they have been called off so that women on placebo drugs can be offered the benefits of Femara.
The manufacturer Novartis now plans to approach health authorities around the world to obtain a licence for the use of the drug in post-menopausal patients who have received Tamoxifen for five years.
The drug works by reducing oestrogen levels in the body. Patients who have not entered the menopause cannot take it because younger women have a feedback mechanism that counters the drug's suppression of oestrogen.
Dr Arnold Hill, the consultant surgeon at St Vincent's Hospital who led the trial in the Republic, said the findings could have important implications for the management of breast cancer patients.
"However, it is only one prospective clinical trial, and further studies would be required before implementing significant changes in the current management of patients with breast cancer," he said.
Femara, a once-a-day drug, was generally well tolerated by the group which participated in the trial. However, some side-effects noted included hot flushes, sweating, headache, fatigue, constipation and dizziness. The authors also noted a trend to more newly diagnosed osteoporosis in women taking Femara.