Women who have had early stage breast cancer surgically removed, and whose tumor cells are stimulated by the hormone estrogen, can benefit from taking Luteinizing hormone releasing hormone (LHRH) antagonists, a Cochrane Systematic Review has concluded. This medication may be taken alone or alongside the use of tamoxifen.

In over half of the premenopausal women who develop breast cancer, the cells in the tumors grow faster in the presence of estrogen. Their tumors are said to be ER+. Treatment often starts with the surgical removal of the tumor, but some cancer cells may be left behind. The challenge then is to slow down their rate of growth.

A well recognized chain of events leads to estrogen-stimulated tumor cell growth. First LHRH causes the pituitary gland to release luteinizing hormone (LH). This LH travels to the ovaries and triggers the release of estrogen. The estrogen moves to the region of the tumour where it locks on to receptors on the cells and stimulates tumor growth.

There are two possible ways of preventing estrogen from stimulating growth. One is to block the estrogen receptors that are present on the cells so that they can't respond to the hormone. Tamoxifen works this way. The second is to reduce the amount of estrogen that is present in the bloodstream. This can be done by blocking LHRH's ability to cause a release of LH.

A team of Cochrane Researchers searched for evidence on the value of using LHRH antagonists. They identified 14 randomized trials that involved nearly 12,000 premenopausal women with operable breast cancer, most of whom were ER+. The LHRH agonist in most trials was goserelin.

"While we cannot yet recommend using ovarian suppression as the standard therapy for these women, it is possible that LHRH antagonists may reduce the risk of cancer recurring and extend survival times in premenopausal women who have early breast cancer that is not known to be ER negative. Given this potential, we eagerly await the results of current clinical trials that could answer this important issue," says lead researcher Rohini Sharma, who works in the Department of Medical Oncology, Hammersmith Hospital, London, UK.

SOURCE:
Cochrane Library (http://www.wiley.com/wiley-blackwell)