Pfizer Gets FDA Ok for Breast Cancer Drug Aromasin

LOS ANGELES (Reuters) - Pfizer Inc., the world's biggest drugmaker, on Wednesday said U.S. regulators have approved its breast cancer drug Aromasin for treating certain post-menopausal women who have already been treated with the drug tamoxifen.

The U.S. Food and Drug Administration approved the drug as a post-surgery treatment for women with early-stage cancer that depends on estrogen to grow.

Aromasin was approved for use following two to three years of treatment with tamoxifen, which has been the drug of choice in treating breast cancer for decades.

Aromasin is the latest in a new class of drugs, called aromatase inhibitors, that fight breast cancer by cutting the body's production of estrogen.

Earlier this month, the FDA approved AstraZeneca Plc's Arimidex for use after surgery in post-menopausal women whose disease has not spread.

An estimated two-thirds of breast cancer cases are estrogen-dependent.