Contralateral Prophylactic Mastectomy for Unilateral Cancer Increasing

Laurie Barclay, MD

November 05, 2010

November 5, 2010 — Women with cancer in 1 breast increasingly opt to have both breasts removed, despite little evidence of survival benefit, according to a report from the National Cancer Data Base (NCDB), 1998 to 2007, published in the October issue of the Annals of Surgical Oncology.

"We have described a dramatic increase in the use of contralateral prophylactic mastectomy [CPM] over the last 10 years," senior author David P. Winchester, MD, FACS, medical director of cancer programs at the American College of Surgeons and faculty member at the University of Chicago, in Illinois, said in a news release. "Younger women, in particular, who have a very long life expectancy with a very long risk period — particularly those with a family history and knowing that they already have breast cancer — are making these decisions."

Using the NCDB, the investigators collected data concerning women who were diagnosed with unilateral breast cancer between 1998 and 2007 and who had CPM. The investigators analyzed temporal trends for different patient demographic, tumor, and provider characteristics and used logistic regression models to determine characteristics independently associated with CPM.

Of 1,166,456 patients, 23,218 patients underwent CPM. Rate of CPM in surgically treated patients increased from 0.4% in 1998 to 4.7% in 2007. Independent factors associated with use of CPM included patient-related factors (demographic and socioeconomic factors), tumor-related factors (stage and histopathology), and provider-related factors. The greatest comparative increases occurred in white women younger than 40 years from areas of high socioeconomic status, with private or managed care insurance plans, who received treatment at high-volume medical centers in the Midwest United States.

"In general, the trend showed the more early stage a cancer, the higher the rate for [CPM] as compared with a later stage cancer," said lead author Katharine Yao, MD, FACS, director of the breast program at NorthShore University HealthSystem, in Evanston, Illinois, and faculty member at the University of Chicago. "Patients seen at a teaching or academic medical center were 2.5 times more likely to have a [CPM] when compared with a small community hospital.... Treatment with [CPM] was also more frequent in high-volume centers — almost 3 times as likely as opposed to low-volume centers."

Compared with women who had invasive disease, a greater proportion of women with in situ disease underwent CPM (2.4% for T4 vs 6% for in situ tumors). Cancer of the breast and lobular carcinomas had a CPM rate of 5.6% compared with 3.9% for ductal cancers.

"It's usually necessary to operate on the companion breast to make a match when the cancer side undergoes reconstruction," Dr. Winchester said. "Very often this approach makes cosmetic sense."

However, Dr. Winchester noted that “if a woman with locally advanced breast cancer wants the opposite breast removed, the surgeon needs to carefully counsel that patient that her major risk is the breast cancer,” not the contralateral breast, and that taking the time for CPM could delay postoperative chemotherapy or other treatment.

Limitations of this study include the failure of US surveillance systems to capture many of the patient factors that may contribute to decisions favoring use of CPM, lack of data on family history or genetic testing, and possible selection bias resulting from review only of breast cancers reported from Commission on Cancer–accredited cancer programs. In addition, the NCDB does not collect direct patient identifiers, so studies using the NCDB must rely on area-based measures of socioeconomic status estimated at the Zip code level.

"Nonetheless, this report — the largest and most current to date — adds to a growing body of literature demonstrating that an increase in CPM is strongly associated with age and other patient-related factors," the study authors conclude. "Further studies are needed to explain rising CPM rates and how patients make surgical treatment decisions. Currently, National Comprehensive Cancer Network guidelines discourage CPM in women other than those at high risk because of its small benefit-to-risk ratio.... Finally, outcomes studies involving CPM are needed to demonstrate to patients and clinicians alike whether CPM influences disease-free and overall survival after diagnosis of noninvasive and invasive breast cancers."

Ann Surgical Oncol. 2010;17:2554-2562.

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