Canadian Task Force Recommends Caution in Use of Tamoxifen

There is "fair evidence" to recommend against the use of tamoxifen to reduce the risk of breast cancer in women at low or normal risk of developing the disease, according to the Canadian Task Force on Preventive Health Care and the Steering Committee on Clinical Practice Guidelines for the Care and Treatment of Breast Cancer.

The recommendation is from the latest in the Canadian Medical Association Journal's series of clinical practice guidelines for the diagnosis and management of breast cancer.

"Although tamoxifen will reduce the likelihood of breast cancer for certain women at high risk, its use is associated with adverse events, some of which are severe," the Task Force said. It cited an increased risk of thrombotic events -- strokes -- as a reason "not to consider tamoxifen therapy in women with prior thromboembolism, documented thrombophilia or a strong family history of thromboembolism."

The Task Force said its overall recommendation against use of tamoxifen in women of low or normal risk was based on three factors: "The data from the randomized controlled trials are conflicting, a reduction in breast cancer mortality has not been demonstrated, and the harms from tamoxifen reported in other similar trials outweigh any benefits in this low-risk group."

The committee also suggested that counseling should be given to women at high risk of developing breast cancer on the potential benefits and risks of using tamoxifen.

Other sources: Canadian Medical Association Journal