The finding that women should be taking the drug for twice as long as is now customary came out of a study of nearly 7,000 women from 36 countries.

The New York Times: Bigger Role Seen For Breast Cancer Drug
The widely prescribed drug tamoxifen already plays a major role in reducing the risk of death from breast cancer. But a new study suggests that women should be taking the drug for twice as long as is now customary, a finding that could upend the standard that has been in place for about 15 years (Pollack, 12/5).

USA Today: Long-Term Treatment Cuts Breast Cancer Deaths
Tamoxifen, which has been used for decades, is far cheaper than most new chemotherapies and biological drugs, which cost thousands of dollars a month. A generic version costs about $100 a month in the USA, according to Susan G. Komen for the Cure (Szabo, 12/5).