A new drug regimen can markedly reduce the chance that breast cancer will recur in postmenopausal women, a large international study has found. The results were so strongly, and surprisingly, positive that the investigators ended the study early and offered the drug to women taking a placebo.
The study involved 5,187 women at hundreds of medical centers in the United States, Canada and Europe. It asked what to do after they finish the recommended five-year course of tamoxifen, the standard treatment to prevent breast cancer recurrences.
Tamoxifen, which blocks the hormone estrogen, is remarkably effective in postmenopausal women whose cancers are fueled by the hormone, about 100,000 women each year. But women gain no additional benefits after they take tamoxifen for five years, and so doctors have told them to simply stop taking it then and hope for the best. They are better off for having taken it: the drug's effects last for years after it is stopped. But they are left vulnerable to a return of their cancer.
... The new study found that if women take a different drug, letrozole, sold by Novartis under the brand name Femara, after their five years of tamoxifen, they can cut that yearly risk nearly in half.
The NYT article deemphasizes the big problem with stopping the study. Recently we found that Tamoxifen doesn't increase lifespans. It reduces the risk of breast cancer recurrence, but the benefits are offset by increases in other diseases. We expect that Femara does reduce cancer recurrence, but we won't now know if it really increases life expectancy or just shifts mortality.
The lessons of post-menopausal hormone replacement may have been missed. You need to look at all cause mortality.
The same problem, by the way, lurks over the statins -- a bazillion dollar industry. They reduce death due to heart disease, but other causes of death increase. For asymptomatic people without active heart disease they don't increase life expectancy.