Clinical Management Factors Contribute to the Decision for Contralateral Prophylactic Mastectomy (CPM).

Abstract

Abstract INTRODUCTION:Rates of CPM are reported to be increasing, yet factors driving this trend are unclear. We performed this analysis to determine if increasing rates of CPM are being driven by increased recognition of risk factors for contralateral breast cancer (CBC) or by treatment factors related to the index lesion.METHODS:From 1997-2005, 2967 patients with Stage 0-III primary unilateral breast cancer underwent mastectomy at MSKCC and were entered into a prospectively maintained database. Demographic, tumor and treatment factors were abstracted and comparisons made between patients who did and did not undergo CPM within one year of treatment for their index cancer. Generalized estimating equations were used to fit logistic regression models to identify independent predictors of CPM.RESULTS:The overall rate of CPM was 13.8%(n=408), increasing from 6.7% in 1997 to 24.4% in 2005 (p<0.0001). The median age of CPM pts was 44.9 vs 53.2 in the non-CPM group (p<.001) and only 7% of CPM pts were non-white compared to 25% of non-CPM pts (p<.001). Although 69% of CPM pts had a family history (FH) of breast cancer (vs 40% non-CPM; p<.001) only 8% had 2 or more first degree relatives affected. Genetic testing was performed in 29% of CPM pts; of those 37 (31%) were positive. The use of MRI increased from 1.3% to 36.3%of cases over the study period. MRI at diagnosis (43% vs 16%) and MRI generated biopsy in the contralateral or bilateral breasts (29% vs 4%) were strongly associated with CPM (p<.0001). Prior attempts at breast conservation (BCT) (28% vs 16%; p<.001) were more common in the CPM group, but number of attempts did not differ between groups. Patients undergoing CPM were more likely to have DCIS versus an invasive histology (p<0.0001), and of those with invasive disease, CPM patients had smaller tumors (1.2cm vs. 1.8cm, p<0.0001) and were more likely to be node negative (53% vs 43%, p<0.0001). ER, PR, and HER2 status were not associated with CPM. CPM rates among surgeons ranged from 9.8% to 26%. Multivariate analysis of predictors of CPM for 2387 patients with complete data is shown in the Table.VariableORp95%CIWhite race3.6<0.00012.4-5.4Age<502.3<0.00011.8-3.1FH breast cancer2.9<0.00012.3-3.7MRI at Dx2.2<0.00011.7-2.8BCT attempted1.60.000081.2-2.1Reconstruction3.2<0.00012.3-4.5DCIS histology1.40.021.1-1.9*adjusted for surgeonCONCLUSIONS: Factors associated with clinical management of the index cancer such as preoperative MRI with the potential for additional biopsy, failed attempt at BCT, and breast reconstruction were strongly associated with CPM. Age and FH were also independent predictors; however the FH profiles of CPM pts in this series do not support increased recognition of mutation carriers and truly high risk FH as a major cause of increasing rates of CPM. The lack of association with ER status, which results in treatment that decreases the risk of CBC, provides additional support that patients may be choosing CPM for reasons other than future risk. These data suggest that the need for additional procedures during management of the index cancer may be contributing to the increasing use of CPM among a relatively moderate risk patient population. Efforts to optimize BCT and minimize unnecessary tests may help to curb this trend. Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 38.