Trends in mastectomy rates at the Mayo Clinic Rochester: Effect of surgical year and preoperative MRI


R. Katipamula
18 may 2008--Background: Surgical treatment for early stage breast cancer (ca) includes mastectomy (mast) or lumpectomy. The influence of preoperative breast magnetic resonance imaging (pMRI) on mast rates is unknown. We sought to analyze trends in mast rates and their relationship to breast MRI and surgical year (yr) at the Mayo Clinic Rochester. Methods: A cohort of 5,596 stage 0-2 breast cas in 5,463 pts who had surgery between 1997-2006 were identified retrospectively. Surgery type was defined using institutional surgical index and tumor registry. All pts in the cohort with pMRI were identified from a prospective breast MRI database initiated in 2003. Trends over time in mast rate and the association of pMRI with surgery type were assessed. Multiple logistic regression was used to assess the effect of surgery yr and pMRI on surgery type, while adjusting for potential confounding variables. Results: TNM stage of the 5,596 breast cas was: 0- 18%, I- 48%, and II- 34%; mean age was 61 (23 to 95) yrs. Mast rates differed significantly across time (p<0.0001), and decreased from 45% in 1997 to 30% in 2003, followed by increasing rates for 2004-2006 (Table 1). Pts with pMRI were more likely to undergo mast than those without pMRI (52% vs 38%, p<0.0001); however a similar increase in mast rates was seen among pts without pMRI (28% in 2003 to 41% in 2006; p<0.0001). In a multivariate model adjusted for age, stage, contralateral breast ca, and density, both MRI (Odds Ratio (OR): 1.7, p<0.0001) and surgical yr (compared to 2003; OR: 1.4 for 2004, 1.9 for 2005, and 1.7 for 2006; p<0.0001) were independent predictors of mast. Conclusions: Following a steady decline over 7 years, mast rates have increased in recent years and are similar to 1997, with both surgery yr and pMRI as significant predictors of type of surgery. Because type of local therapy may not influence survival, further studies are needed to evaluate the role of pMRI and other factors influencing preoperative surgical planning.