52 Breast Diseases: A Year Book®

Quarterly52 Vol 19 No 1 2008

cytotoxic chemotherapy. The main objec-tions to reporting Ki-67 expression forall invasion breast cancers are that themethods for assessing Ki-67 have notbeen standardized and that it has notbeen shown clearly to have independentprognostic significance. The authors ofthis study acknowledge both of thesepoints. Some studies included in thismeta-analysis used arbitrary cut-off val-ues to define positivity, whereas othersused a mean or median value.Consequently, the cut-off values used todefine positivity ranged from 3.5% to34%. Moreover, the authors acknowl-edge that the study assessed only the uni-variate prognostic value of Ki-67, so itcannot be inferred that Ki-67 is an inde-pendent prognostic factor.

Because mitotic activity is also amarker of tumor proliferation and is acomponent of the Nottingham histologic

grading system, it is not clear that Ki-67positivity provides prognostic informa-tion independent of tumor grade. That isone reason why the College of AmericanPathologists recommends reporting themitotic figure count for every invasivebreast cancer with MIB-1 immunohisto-chemistry being optional.1 Nevertheless,Ki-67 is a more sensitive marker thanmitotic figure count. Given that tumorproliferation appears to be one of themost important factors for predicting tu-mor response to cytotoxic chemotherapy,standardization of Ki-67 assays for rou-tine clinical use could lead to improvedselection of patients for chemotherapy.Ki-67 is one of the most important com-ponents of the 21-gene Oncotype Dx™assay.2 The principal advantages of thelatter appear to be the improved quanti-tation of estrogen receptor and Ki-67levels provided by quantitative poly-

merase chain reaction, but the impor-tance of quantitating 21 genes (and thejustification for the expense) is debat-able. Improvements in quantitating es-trogen receptor and Ki-67 by immuno-histochemistry have the potential ofproviding similar predictive informationat a more reasonable cost.

M. Z. Gilcrease, MD, PhD

References1. Fitzgibbons PL, Page DL, Weaver D,

et al. Prognostic factors in breast can-cer. College of American PathologistsConsensus Statement 1999. ArchPathol Lab Med. 2000;124:966-978.

2. Paik S, Tang G, Shak S, et al. Geneexpression and benefit of chemothera-py in women with node-negative, es-trogen receptor-positive breast cancer.J Clin Oncol. 2006;24:3726-3734.

SURGICAL TREATMENT

Results database to review the treatmentof patients with unilateral breast cancerdiagnosed from 1998 through 2003. Wedetermined the rate of contralateral pro-phylactic mastectomy as a proportion ofall surgically treated patients and as a pro-portion of all mastectomies.

Results.—We identified 152,755 pa-tients with stage I, II, or III breast cancer;4,969 patients chose contralateral pro-phylactic mastectomy. The rate was 3.3%for all surgically treated patients; 7.7%,for patients undergoing mastectomy. Theoverall rate significantly increased from1.8% in 1998 to 4.5% in 2003. Likewise,the contralateral prophylactic mastecto-my rate for patients undergoing mastecto-my significantly increased from 4.2% in1998 to 11.0% in 2003. These increased

rates applied to all cancer stages and con-tinued to the end of our study period.Young patient age, non-Hispanic whiterace, lobular histology, and previous can-cer diagnosis were associated with signif-icantly higher rates. Large tumor size wasassociated with a higher overall rate, butwith a lower rate for patients undergoingmastectomy.

Conclusion.—The use of contralater-al prophylactic mastectomy in the UnitedStates more than doubled within the re-cent 6-year period of our study. Prospec-tive studies are needed to understand thedecision-making processes that have ledto more aggressive breast cancer surgery.

Please see the expert perspectiveby Tuttle, Habermann, and Virnig.

Increasing Use of ContralateralProphylactic Mastectomy forBreast Cancer Patients: A TrendToward More AggressiveSurgical Treatment Tuttle TM, Habermann EB, Grund EH, et al(Univ of Minnesota, Minneapolis)

J Clin Oncol 25:5203-5209, 2007

Purpose.—Many patients with uni-lateral breast cancer choose contralateralprophylactic mastectomy to prevent can-cer in the opposite breast. The purpose ofour study was to determine the use andtrends of contralateral prophylactic mas-tectomy in the United States.

Patients and Methods.—We usedthe Surveillance, Epidemiology and End