When researchers followed more than 112,000 women in California with early stage breast cancer for 14 years, they found women were more likely to survive breast cancer after having breast conserving surgery plus radiation than mastectomy.
"The findings in this study should reassure women that among all age groups and tumor types, lumpectomy continues to be an excellent choice for women with small early breast cancers, " study author Dr. Shelley Hwang of Duke Cancer Institute in Durham, N.C., said in a release.
The effect was strongest for women over age 50 with hormone-sensitive cancers, the study's authors said in Monday's issue of the journal Cancer.
"These findings support the notion that breast-conserving therapy, when combined with radiation, confers at least equivalent and perhaps even superior survival to mastectomy as definitive breast cancer treatment," they concluded.
Differences in mastectomy rates
The findings come as some women in the U.S., particularly those who are younger, affluent and living in cities are increasingly opting for mastectomy for very small cancers, the researchers said. They speculated that improvements in reconstructive techniques, changing attitudes toward mastectomy or a desire to reduce anxiety associated with long-term surveillance could be contributing to the trend in the U.S.
In Canada, mastectomy rates vary widely between provinces, with the highest rates reported among those living in the least affluent areas, the opposite of the U.S. trend. In a report last year, researchers with the Canadian Institute for Health Information and the Canadian Partnership Against Cancer suggested the long courses of radiation often recommended after lumpectomies and travel time could be reducing use of the less-invasive surgery.
Earlier randomized clinical trials showed equivalent survival for breast conserving surgery with radiation and mastectomy for early-stage breast cancer but didn't look at women in the general population.
In the latest study, 55 per cent of the women received lumpectomy and radiation, while 45 per cent had mastectomy without radiation.
Among those over 50 years old with hormone-sensitive breast cancers, the risk of dying from breast cancer during the follow-up was 14 per cent lower in the breast conserving group than similar cancers treated with mastectomy.
In the first three years after surgery, women who underwent mastectomy had a higher risk of dying from heart disease and other diseases than women who had lumpectomy. It's possible that those in the lumpectomy group were generally healthier, Hwang said.
Since the study was observational in nature, the link between breast-conserving treatment and survival is only an association and no cause-and-effect relationship can be drawn.
Surgical patterns changed over the course of the study, the authors noted. Factors such as tumour grade, race, tumour size and age at diagnosis were considered in the analysis.
The study was funded by the U.S. National Cancer Institute.
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