London, July 24: Two different classes of inexpensive generic drugs can each improve survival prospects for post-menopausal women with early breast cancer, researchers have reported in two studies.
About two-thirds of all women with breast cancer are post-menopausal.
The two types of drugs - aromatase inhibitors (AIs) and bisphosphonates - can be used together, increasing the benefits while also decreasing some side-effects, the findings published in the journal The Lancet showed.
"These studies provide really good evidence that both of these inexpensive, generic drugs can help to reduce breast cancer mortality in postmenopausal women," said lead statistician for both studies Richard Gray, professor at University of Oxford.
"The drugs are complementary, because the main side effect of aromatase inhibitors is an increase in bone loss and fractures, while bisphosphonates reduce bone loss and fractures as well as improving survival," Gray pointed out.
The first study analysed data from 30,000 post-menopausal women who participated nine randomised trials.
The researchers found that compared to standard therapy, taking AIs for five years further reduced the likelihood of the cancer recurring by about a third, and the risk of dying from breast cancer by around 15 percent throughout the decade after beginning treatment.
The researchers estimated that, compared to no endocrine treatment, the risk of dying from breast cancer for women who took AIs would be reduced by around 40 percent in the decade after beginning treatment.
The second study found that two-five years of treatment with a class of drugs called bisphosphonates, which are usually used to treat osteoporosis, reduces the risk of breast cancer recurring in post-menopausal women, and also significantly extends survival. However, bisphosphonate treatment appears to have little effect in premenopausal women.
The most common site for breast cancers to spread to is bone and the researchers found that bisphosphonates treatment resulted in 17 percent reduction in recurrence of cancer in the bone.
However, among post-menopausal women, bisphosphonate treatment produced larger reduction in bone recurrence of 28 percent and also reduced the risk of dying from breast cancer by 18 percent during the first decade after diagnosis.