The rates of increase were steepest among women with lymph node-negative and in situ (contained) disease.
This is a reversal of trends seen since the 1990s when breast conservation surgery (BCS) was found to produce equivalent cancer outcomes and was endorsed as a standard of excellence by a National Institutes of Health Consensus Conference.
The Vanderbilt University study, led by Kristy Kummerow, M.D., and Mary Hooks, M.D., MBA, was published online in the Nov. 19 edition of JAMA Surgery.
Using the National Cancer Data Base, the investigators studied records of more than 1.2 million adult women treated at centers accredited by the American Cancer Society and the American College of Surgeons Commission on Cancer from Jan. 1, 1998, to Dec. 31, 2011.
During that time, a total of 35.5 percent of those women underwent mastectomy. The adjusted odds of mastectomy in BCS-eligible women increased 34 percent during the most recent eight years of the study period. Rates of bilateral mastectomy (removal of both breasts) for cancer in one breast increased from 1.9 to 11.2 percent from 1998 to 2011.
In women undergoing mastectomy, rates of breast reconstruction increased from 11.6 to 36.4 percent in the same time period.
The rise in mastectomy rates in the U.S. was most pronounced among younger women with noninvasive disease, those with smaller tumors, and those with node-negative disease, indicating the cancer was less likely to spread beyond the initial tumor. This suggests that factors unrelated to disease burden or cancer control are influencing women, especially younger patients.
“Our findings of still-increasing rates of mastectomy, breast reconstruction and bilateral mastectomy in women with early-stage breast cancer has implications for physician and patient decision making, as well as quality measurement,” said Kummerow.
The authors note that the trend toward breast reconstruction may be explained by multiple factors. The National Accreditation Program for Breast Centers expects that all women undergoing mastectomy be offered reconstruction. And the Women’s Health and Cancer Rights Act, passed in 1998, mandated insurance coverage of postmastectomy reconstruction. Prior research found that this law significantly increased the proportion of women insured by Medicare and Medicaid who underwent reconstructive procedures.
The study could not determine the number of patients who have tested positive for mutations in the BRCA gene which greatly increases the risk of developing breast cancer, and may influence women to remove both breasts. The research also could not determine the number of patients whose tumors have been identified as triple-negative. These hormone receptor negative tumors are more aggressive and difficult to treat.
The authors note that further research is needed to understand patient, provider, policy and social factors associated with these trends.
Other investigators for the study include Liping Du, Ph.D., David Penson, M.D., MPH, and Yu Shyr, Ph.D.
The research was supported by the U.S. Department of Veterans Affairs, the Veterans Affairs Office of Academic Affiliations, the Veterans Affairs National Quality Scholars Program, and with use of facilities at Veterans Affairs Tennessee Valley Healthcare System in Nashville.