"The group that benefited the most -- who had the biggest difference in breast cancer survival -- were those women over 50 with estrogen-receptor positive disease," Hwang said. This means their cancer depends on estrogen to grow.
Among those women, the lumpectomy group had a 13 percent lower risk of death from breast cancer and a 19 percent lower risk of death from any cause than those who had a mastectomy.
Not all women with early stage breast cancers can have a lumpectomy, Hwang said. In this procedure, just the tumor and some healthy tissue are removed, sparing the rest of the breast. Among the exceptions are those whose cancers are too large, or those who have different cancers in the same breast.
The percent of women with early breast cancers choosing a mastectomy has risen recently, after a dip in previous years. Hwang and others suspect that women told they could safely opt for lumpectomy were still afraid to try it.
The new research, which was funded by the U.S. National Cancer Institute, suggests that if a lumpectomy is possible, it may actually increase survival, Hwang said.
The findings may reverse the mastectomy trend, said Dr. Laura Kruper, co-director of the breast oncology program at the City of Hope Comprehensive Cancer Center in Duarte, Calif., who was not involved in the study.
The study is scientifically sound in many ways, Kruper said. "They broke it down by year of diagnosis and by age category," she said. "They looked at socioeconomic status, and they kept it early stage."
Dr. Wendy Woodward, section chief for breast radiation oncology at the University of Texas MD Anderson Cancer Center in Houston, said that for women with early cancers, the study "clearly reiterates there is no detriment to cancer control in having a lumpectomy and radiation for breast-conserving surgery candidates."
But, Woodward added,
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