But the percentage of women who choose to have their other, cancer-free breast removed at the same time for preventive reasons is increasing, Dr. Elizabeth B. Habermann of the University of Minnesota in Minneapolis and her colleagues found.
In 1990, the National Institutes of Health recommended breast-conserving surgery-"lumpectomy," in which only the tumor and surrounding tissue are removed-along with radiation as the preferred treatment for breast cancer in one breast. Numerous studies done in the previous decade had found that women fared just as well with lumpectomy and radiation as they did with mastectomy, a more radical operation that carries greater risk of complications.
Habermann and her team decided to conduct their study after investigations by researchers at the Moffitt Cancer Center in Tampa, the Magee-Women's Hospital in Pittsburgh, and the Mayo Clinic in Rochester, Minnesota, found rates of mastectomy at their institutions had risen substantially in recent years.
Using the Surveillance, Epidemiology and End Results database, Habermann and her colleagues identified more than 230,000 women who had been diagnosed with breast cancer between 2000 and 2006.
While nearly 41 percent of the women diagnosed in 2000 had mastectomies, 37 percent of those diagnosed in 2006 did, the researchers found.
But the percentage of women who had their other, non-cancerous breast removed as well increased to around 6 percent by 2006, from around 2 percent in 2000.
The reason why mastectomy rates were increasing at the three centers while continuing to decline overall isn't clear, Habermann said. Patients who are referred to these centers might be seeking more aggressive treatment than women treated elsewhere in the US, she added.
On the other hand, according to the researcher, "it's possible that these cancer centers are seeing trends ahead of what's going to happen nationwide."
There was a small increase in mastectomy rates between 2005 and 2006, Habermann noted. While this increase wasn't statistically significant, meaning it could have been due to chance, it could also signal a future rise in mastectomy rates.
She and her colleagues will continue to follow the trend in mastectomy rates, and are particularly interested in monitoring outcomes for the women who opt for having both breasts removed.
"There are some good things about it," Habermann noted. "It's very uncommon to have breast cancer after having both breasts removed." However, she added, "there are issues...because it's a larger operation and there may be more complications."