Are mastectomy rates really increasing? Experiences from a single institution and a population-based database.

1028 Background: Recent studies have reported increased mastectomy rates for the treatment of early stage breast cancer during the last decade. The aims of this study were to examine trends in mastectomy rates at a single institution and in a population-based database and to compare differences between the two cohorts. Methods: Patients with stage 0-II breast cancer diagnosed from 2000 to 2008 were identified from our cancer center institutional database (CC cohort, n=8,915) and the Surveillance, Epidemiology and End Results database (SEER cohort, n=359,572). Patients without primary surgery or unknown surgery type were excluded. Mastectomy rates by the year of diagnosis were evaluated and multivariable logistic regression models were built to identify clinicopathologic factors that predicted mastectomy as the treatment choice. Results: The proportion of patients treated with mastectomy decreased from 44.5% to 37.8% between 2000 and 2005 in the CC cohort (P=0.003) and from 42.8% to 36.6% in the SEER cohort (P<0.0001). Subsequently, the mastectomy rate increased to 48.6% in the CC cohort (P<0.0001) and to 40.1% in the SEER cohort by 2008 (P<0.0001). Multivariable analysis found that patients with younger age (<50), stage 0 or II cancer vs. stage I, high grade tumor, low median household income, and lobular histology were more likely to choose mastectomy in both the SEER and CC cohorts. In the CC cohort, patients with preoperative breast MRI were also more likely to undergo mastectomy. The percentages of patients receiving preoperative MRI and choosing prophylactic contralateral mastectomy increased each year in the CC cohort. The rate of preoperative breast MRI increased from 4.7% in 2005 to 9.6% in 2008 (P<0.0001). Patients choosing prophylactic contralateral mastectomy increased from 8.4% in 2005 to 11.8% in 2008 (P=0.06). Conclusions: Our study shows that there was a decrease in mastectomy rates from 2000 to 2005 and a subsequent increase in mastectomy rates from 2005-2008 in both the CC and SEER cohorts. Increased use of preoperative breast MRI and the decision to undergo contralateral prophylactic mastectomy likely contributed to the increased mastectomy rates in the CC cohort.

Predictors of Contralateral Prophylactic Mastectomy in Women With a BRCA1 or BRCA2 Mutation: The Hereditary Breast Cancer Clinical Study Group

Purpose To evaluate the rate of prophylactic contralateral mastectomy in an international cohort of women with hereditary breast cancer and to evaluate the predictors of uptake of preventive surgery. Patients and Methods Women with a BRCA1 or BRCA2 mutation who had been diagnosed with unilateral breast cancer were followed prospectively for a minimum of 1.5 years. Information was collected on prophylactic surgery, tamoxifen use, and the occurrence of contralateral breast cancer. Results Nine hundred twenty-seven women were included in the study; of these, 253 women (27.3%) underwent a contralateral prophylactic mastectomy after the initial diagnosis of breast cancer. There were large differences in uptake of contralateral prophylactic mastectomy by country, ranging from 0% in Norway to 49.3% in the United States. Among women from North America, those who had a prophylactic contralateral mastectomy were significantly younger at breast cancer diagnosis (mean age, 39 years) than were those without preventive surgery (mean age, 43 years). Women who initially underwent breast-conserving surgery were less likely to undergo contralateral prophylactic mastectomy than were women who underwent a mastectomy (12% v 40%; P < 10−4). Women who had elected for a prophylactic bilateral oophorectomy were more likely to have had their contralateral breast removed than those with intact ovaries (33% v 18%; P < 10−4). Conclusion Age, type of initial breast cancer surgery, and prophylactic oophorectomy are all predictive of prophylactic contralateral mastectomy in women with breast cancer and a BRCA mutation. The acceptance of contralateral preventive mastectomy was much higher in North America than in Europe.