BOUSOULEGAS SPEAKING

August 1, 2009 — After a steady decline, women have increasingly been opting to undergo mastectomy to treat early-stage breast cancer at the Mayo Clinic in Rochester, Minnesota, according to an analysis of surgeries conducted there.

Although the reasons for this increase remain unclear, researchers speculate that it might be related to the use of magnetic resonance imaging (MRI) prior to surgery. Women who had a breast MRI were more likely to have a mastectomy than those who did not (54% vs 36%).

The findings, published online July 27 in the Journal of Clinical Oncology, were presented at the American Society of Clinical Oncology 2008 Annual Meeting, and were reported by Medscape Oncology at that time.

Mastectomy rates at the Mayo Clinic declined from 1997 to 2003, but in 2004, there was a reversal of this trend. The rate of mastectomies rose from 31% to 43% between 2003 and 2006, which was equivalent to rates seen in 1997.

In a 1990 consensus statement, the National Institutes of Health Consensus Development Panel supported breast-conservation surgery as the preferred method of primary surgical therapy for women with early-stage breast cancer. The percentage of those opting to undergo breast-conservation therapy (lumpectomy followed by radiation) increased after the release of this statement, from 35% in 1989 to 60% in 1995 for stage I disease and from 19% in 1989 to 29% in 1995 for stage II disease. But data regarding the rates of mastectomy during the past 10 years are limited, the authors note.

What Has Changed?

"The obvious question is: What has changed?" according to an accompanying editorial. In addition to the current study, other studies have shown rising rates of mastectomy during the same period.

In their commentary, Monica Morrow, MD, from Memorial Sloan-Kettering Cancer Center in New York City, and Jay R. Harris, MD, from the Dana-Farber Cancer Institute in Boston, Massachusetts, point out that an increased awareness of and testing for BRCA1 and BRCA2 mutations are frequently cited as factors that have increased the use of mastectomy.

However, these mutations occur in only 5% to 10% of all breast cancer patients, they write. Although the proportion of women with a first-degree relative with breast cancer did not increase over time, the rate of mastectomy did. Therefore, it is an unlikely explanation for a large part of the effect seen in this series and in other studies.

Breast MRI is being increasingly used at the time of diagnosis to exclude the presence of multifocal or multicentric breast cancer in the ipsilateral breast, explain the editorialists, who point to a recent meta-analysis in which MRI identified additional tumor foci in 16% of newly diagnosed breast cancer patients. This led to a change in treatment for 8% to 33% of patients, and most commonly resulted in mastectomy that would otherwise not have been performed (J Clin Oncol. 2008;26:3248-3258).

In the current study, lead author Matthew P. Goetz, MD, medical oncologist at the Mayo Clinic, and colleagues attempted to evaluate the role of MRI in the increased rate of mastectomy. In their retrospective analysis, they identified 5405 patients who underwent breast surgery at the Mayo Clinic between 1997 and 2006.

The results showed that mastectomy rates varied significantly according to year of surgery. Mastectomy rates gradually, decreased from 45% in 1997 to 31% in 2003 (P < .0001), but then rose from 37% in 2004 to 43% in 2006. Concurrently, the use of MRI increased, from 10% in 2003 to 23% in 2006 (P < .0001).

"The key finding of this study is that patients who underwent MRI were more likely to undergo mastectomy than those who did not undergo MRI," the editorialists note. "In a multivariable model, both MRI and year of surgery were independent predictors of mastectomy."

Even though women who underwent MRI were more likely to have a mastectomy, the largest increase in the mastectomy rate occurred in women who did not have a breast MRI. Although mastectomy rates increased from 2003 to 2006 in patients who had and had not undergone an MRI, the study authors write, this increase was not statistically significant in women who had undergone an MRI. But the increase was significant among those who had not undergone an MRI (29% in 2003 vs 41% in 2006).

Better Communication Needed

The editorialists note that although these findings about the use of MRI and increased mastectomy rates are "troubling," they represent only 1 piece of the puzzle, since increasing rates of mastectomy were also observed in patients who did not undergo MRI. "In many parts of the United States, patients are pushing their surgeons for mastectomy, even bilateral mastectomy, despite being told that such treatment will not improve prognosis," they write. They also point out that this trend toward mastectomy does not seem to be occurring in Europe.

An increasing body of evidence suggests that the biology of the cancer rather than a specific type of local therapy largely determines the risk for local recurrence. "Clearly, we are not communicating this to our patients if they continue to choose mastectomy in the belief that it is a reasonable choice for decreasing risk of cancer recurrence," write the editorialists. "More work is also clearly needed on how to effectively communicate complex treatment choices to women facing the stress of a new cancer diagnosis."

The study authors and editorialists agree that new studies are needed to evaluate whether these changes in surgical management lead to improvements in quality of life and/or patient satisfaction.

The authors and editorialists have disclosed no relevant financial relationships.

J Clin Oncol. Published online before print July 27, 2009. Abstract