New drug combination prevents breast cancer growth pre-surgery

May 17 2005

A new type of drug originally developed for lung cancer can reduce the size of breast cancer tumours when taken in combination with other drugs.

A London-based group of scientists, reporting today (Tuesday 17 May) in The Lancet Oncology, say that taking the new drug combination prior to surgery could make breast cancer surgery less invasive and more effective, and reduce the risk of cancer spreading to other parts of the body.

Around 80% of breast cancers depend on the hormone oestrogen to survive, and removing oestrogen from the body is standard treatment for the disease. However, only half of primary breast cancers respond well to this therapy, leading doctors to use more toxic chemotherapy, which causes many side effects. The researchers have found that by combining existing oestrogen-blocking drugs with a new drug called gefitinib that blocks another receptor on the cancer cell surface, tumour growths shrink more rapidly and to a smaller size.

The study followed 56 post-menopausal women who had cancer cells with oestrogen receptors (ER) and epidermal growth factor receptors (EGFR). Half received the oestrogen-blocker anastrozole and the EGFR-blocker gefitinib, the other half received gefitinib and a placebo. Treatment was for 4-6 weeks, prior to surgery to remove the cancer.

Levels of a molecule that indicates cell proliferation, Ki67, were reduced in both groups. Tumour size was reduced substantially in 14 of the 28 patients assigned both anastrozole and gefitinib, and in 12 of 22 assigned gefitinib alone.

"The presence or EGFR seems to be one of the reasons that standard oestrogen-blockers do not always work in ER-positive breast cancers," comments Professor Charles Coombes, head of cancer medicine at Hammersmith Hospitals NHS Trust and Imperial College London. "In women that are resistant to anti-oestrogen therapy, it may provide a 'back door' mechanism for cancer cell proliferation. Targeting both these receptors seems to increase the effectiveness of treatment."

"The significant reduction in tumour size, combined with minimal side-effects, makes this an exciting prospect for pre-surgery cancer treatment. We are currently designing larger studies to verify this approach."