Drop in Breast Cancer Deaths Tied to Treatment

Over the last decade, better treatment has slashed breast cancer death rates by about one-fourth in the United States and Britain and will save the lives of 14,000 women this year in the two countries, according to a survey of data from both nations.

Most of the credit goes to the drug tamoxifen, taken by about 1 million women worldwide, said Sir Richard Peto, a professor of epidemiology at Oxford University who headed the study, published this week in the Lancet, a British medical journal.

“This is the first time that improvements in the treatment of any type of cancer have ever produced such a rapid fall in national death rates,” Peto said. “They really are remarkable trends.”

Death rates from lung cancer have plummeted, but mostly because many people have quit smoking. Cervical cancer rates have also fallen, primarily because of early detection.

Britain and the United States were studied mainly because they had the most current, detailed statistical information and because they were among the first to use tamoxifen, Peto said.

Dr. Kent Osborne, director of the breast center at Baylor University in Waco, Texas, and Peto said breast cancer screening, which started to become widespread only in the 1980s, has not been around long enough to have caused the death rates to drop.

Peto said death rates will continue to decline, once the benefits of screening emerge.

About 40,000 women will die of breast cancer in the United States this year, Peto said. If treatment methods were still at their pre-1989 stage, 50,000 would die.

Breast cancer is particularly problematic because remnants may remain after a tumor has been cut out and can cause a recurrence of cancer years later.

There are three main treatments after surgery. Radiation targets the remnants of cancer lurking in or near the breast. Chemotherapy is a cocktail of cell-killing drugs, and tamoxifen and other hormonal drugs block hormones from nurturing the cancer.

Tamoxifen alone has been found to head off one in six recurrences and cut the risk of relapse by more than one-third. It also halves the risk of a new cancer in the other breast, according to Peto’s analysis, which examined the largest-ever collection of existing evidence on cancer therapy.

Although tamoxifen fights cancer, it can also cause uterine cancer and blood clots in the lungs. But using the drug for five years does 30 times more good than harm, the study found.

Chemotherapy seems to work as well as tamoxifen in young women, but only about a third as well as tamoxifen in middle age.

When the two are used together, the chances of survival are even better.

Radiation, the oldest treatment, prevents about two-thirds of recurrences but has yielded only a 1% decrease in the overall death rates. Although it works well in clearing up rogue bits of cancer in the breast, it also increases the risk of heart attacks and strokes.