Significant increases in the mastectomy rate among women with early breast cancer who were candidates for breast conservation surgery during a recent 14-year period in the United States were accompanied by increases in breast reconstruction and bilateral mastectomies, in a retrospective cohort study that tracked national trends in this group of women.

The results, based on outcomes of about 1.2 million women with early breast cancer in a national oncology outcomes database, “are generally consistent with trends noted in other state, regional, and national studies,” reported Dr. Kristy Kummerow of the division of surgical oncology and endocrine surgery, Vanderbilt University, Nashville, Tenn., and her associates. While they speculated on some of the reasons behind these findings, “further research is needed to understand patient, provider, policy, and social factors associated with these trends,” they concluded in the study, which was published online Nov. 19 in JAMA Surgery (doi:10.1001/jamasurg.2014.2895).

While the use of breast conservation surgery (BCS) as an alternative to mastectomy for early-stage breast cancer increased steadily after studies showed the two approaches had equal outcomes, and after endorsement by a National Institutes of Health Consensus Conference in 1990, the authors noted that there has been evidence that the trend is reversing.

Using data from the National Cancer Data Base, which collects outcomes data on about 70% of the patients diagnosed with cancer in the United States, they evaluated trends in mastectomies among adult women newly diagnosed with early (unilateral) breast cancer from January 1998 through December 2011. Women were included if TNM stage information was available, tumors were 5 cm or less with nine or fewer involved axillary lymph nodes based on clinical staging, and they underwent BCS (lumpectomy, segmental mastectomy, or re-excision of the biopsy site) or mastectomy (subcutaneous, total, modified radical or radical).

Over the 14-year period, among the approximately 1.2 million women who met the criteria, 64.5% had BCS and 35.5% had a mastectomy. The women who had a mastectomy were slightly younger (mean age 59.6 years vs. 61.6 years), and the proportion of racial and ethnic minorities was lower in this group.

The proportion of women eligible for BCS who underwent a mastectomy increased from 34.3% in 1998 to 37.8% in 2011, a statistically significant increase, “with steeper increases” seen in women who had node-negative and noninvasive disease, the authors reported. For the most recent 8-year period – 2003 to 2011 – the rate increased by 34%, “with the most notable rise in mastectomy rates occurring after 2006,” and the highest increases seen among women with clinically node-negative disease. Age and tumor size were “the most influential covariates,” with younger women “more likely to undergo mastectomy irrespective of tumor size, while in older women mastectomy was strongly associated with tumor size greater than 2 cm.”

During the period studied, there were significant increases in breast reconstruction and bilateral mastectomies among women who had mastectomies, which were secondary outcome measures. The proportion of women who underwent breast reconstruction increased from 11.6% in 1998 to 36.4% in 2011, and the proportion of women who had a bilateral mastectomy for unilateral disease increased from 1.9% to 11.2% during this period. The trend toward more reconstruction surgery could be due to 1998 legislation mandating insurance coverage of reconstructive surgery after mastectomy, the authors wrote.

Study limitations included missing clinical staging information for a large proportion of the women, no information on BRCA status or triple-negative tumors, and an inability to determine why the mastectomy was performed in individual cases, they noted.

None of the authors had disclosures to report. The study is based on work supported by the Office of Academic Affiliations, Department of Veterans Affairs, the VA National Quality Scholars Program, and with the use of facilities at the VA Tennessee Valley Healthcare System, Nashville.