Two Breast Cancer Treatments Work Better Together

Studies show inexpensive, generic drugs can help reduce breast cancer mortality in postmenopausal women.

Two breast cancer studies recently explored a pair of potential treatment options that, when taken simultaneously, increase treatment benefits.

About 80% of breast cancers are hormone sensitive (ER-positive), allowing the body's natural hormones to stimulate cancer cells. The first study looked at aromatase inhibitors (AIs), a form of endocrine therapy that suppresses hormones and can stop cancer recurrence.

Bisphosphonates, typically used to treat osteoporosis, were tested in the second study for the potential to stop cancer metastasis. The bone is the most common site for breast cancers to spread. By making the bone an inhabitable zone for cancer, it could help decrease the spread of the disease.

The first study, led by Professor Mitch Dowsett of The Royal Marsden and The Institute of Cancer Research, studied 30,000 postmenopausal women over 5 years of newer endocrine therapy treatment (AI) versus a standard endocrine therapy (tamoxifen). AIs reduced cancer recurrence by 30% and lowered the risk of dying by 15%.

The second study, led by Professor Robert Coleman from the University of Sheffield, took 20,000 postmenopausal women, and studied them for 2-5 years of bisphosphonates treatment. Researchers found a 28% reduced recurrence of cancer spread in the bones for postmenopausal women, while the risk of breast cancer-related death dropped by 18%.

Although both studies produced positive results, there were drawbacks for each. AIs led to increased bone loss and fractures, and although bisphosphonates were beneficial in postmenopausal women, it was not enough of a treatment on its own.

"These studies provide really good evidence that both of these inexpensive, generic drugs can help to reduce breast cancer mortality in postmenopausal women,” said Professor Richard Gray, who was the lead statistician for both studies. “About two-thirds of all women with breast cancer are postmenopausal with hormone-sensitive tumors, so could potentially benefit from both drugs. 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."

These studies were published in The Lancet.