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The proportion of women with early breast cancer opting for contralateral prophylactic mastectomy (CPM) almost tripled from 2004 to 2012, despite no changes in the indications for the procedure, data from cancer registries showed.

Overall, the rate of CPM increased from less than 5% of women with early breast cancer in 2004 to 13% to 14% in 2012. Similar increases emerged from analyses of women ≥45 (3.6% to 10.4%) and those who were 20 to 44 at diagnosis (10.5% to 33.3%).

Encompassing 45 states and the District of Columbia, the analysis showed increases in CPM in all states, but the magnitude of increases varied substantially across the states, including one contiguous five-state region that had a combined CPM rate exceeding 42% in younger women during 2010 to 2012, as reported online in .

"This regional variation was partly explained by state variations in the reconstructive surgical procedures among all women with a mastectomy but not among women who underwent a CPM," Ahmedin Jemal, DVM, PhD, of the American Society Society in Atlanta, and co-authors said in conclusion. "Future studies should examine patient-level, clinician-level, and health system-level factors to provide additional insight into the reasons for temporal changes and regional variation in the receipt of CPM.

"In the meantime, however, surgeons and other healthcare professionals should educate their patients about the benefit, harm, and cost of a CPM to help patients make informed decisions about their treatments."

The study essentially confirms previous reports of increased rates of CPM but is the first to document increases in virtually every state, said Todd Tuttle, MD, of the University of Minnesota in Minneapolis. The study did not address the potential factors driving in increase in CPM and the geographic variation.

"We know that a number of factors are associated with a higher CPM rate, including the use of breast MRI, genetic testing, and the availability of breast reconstructive services," Tuttle told 名媛直播. "These may be playing a role in the state variation. There might be differences in resources and use of the resources, such as breast MRI, and there are certainly differences in genetic testing by state."

The findings followed those from previous studies documenting marked increases in CPM rates, particularly among younger women. The increases occurred despite lack of evidence that CPM improves survival in patients with early breast cancer, Jemal and co-authors noted.

Additionally, studies based on data from the NCI (SEER) program and the showed regional variations in CPM rates. However, both studies had limitations related to the databases' geographic coverage.

Jemal and colleagues analyzed trends in CPM, using data from , which includes data from SEER and the CDC's .

The analysis included 1,224,947 women with early-stage breast cancer treated with surgery (breast conserving surgery, N=715,914; unilateral mastectomy, N=402,434; bilateral mastectomy, N=106,599) from 2004 through 2012. Investigators examined trends in CPM rates by age group (20 to 44 and ≥45) and by state.

The data showed that CPM, as a proportion of surgically treated early breast cancers, increased from 3.6% to 10.4% among women ≥45 and from 10.5% to 33.3% of younger women. CPM rates increased in all states but varied substantially from one state to another. For example, the rate among younger women in New Jersey increased from 14.9% during 2004 to 2006 to 24.8% during 2010 to 2012. In Virginia CPM rates in the same age group increased from 9.8% to 32.2%.

Some previous studies suggested that the rate of CPM reflected access to surgical reconstruction services. The current study showed no such association. Jemal and co-authors found the highest rates of CPM with surgical reconstruction clustered in six Northeastern states (Massachusetts, Maine, New Jersey, Connecticut, New York, and Delaware), whereas the highest rates of CPM in that age group during 2010 to 2012 clustered in the five contiguous states of Nebraska, Missouri, Colorado, Iowa, and South Dakota.

A thorough discussion of the risks and benefits with a surgeon or other physician affords the best assurance that CPM is appropriate for a given patient.

"The most important thing physicians can do is talk patients through the issues," said Tuttle. "A number of survey studies have shown that women markedly overestimate their risk of getting cancer in the normal breast and other studies indicate that women markedly overestimate the survival benefit they get from removing the normal breast. There is also quite a bit of information to indicate that women underestimate the side effects and recovery from the double mastectomy, especially when it's associated with reconstruction."

Noting that the study by Jemal and colleagues covered CPM rates through 2012, Tuttle pointed out that American Society of Breast Surgeons published a consensus statement last year, discouraging use of CPM for most women. The impact of that clinical guidance on CPM awaits future studies.

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