RESUMO
INTRODUCTION: This study investigates the rate of histological underestimation of invasive breast carcinoma following diagnosis of ductal carcinoma in situ (DCIS) on a radiologically guided core needle biopsy, and factors that may influence this upgrade rate. METHODS: A retrospective review of the results of breast core biopsies performed between 1st January, 2005 and 2nd July, 2014 was conducted, and those with a diagnosis of DCIS were identified. Data including final excision pathology, lesion size, performing radiologist, core biopsy system and guidance method used were collected and included in the analysis. RESULTS: We report an overall upgrade rate to invasive cancer of 20.5% (95% CI = 16.1-24.9%). No statistically significant relationship was identified between biopsy systems used or clinicians performing the biopsies and the rate of upgrade to invasive cancer. Initially a statistically significant relationship was demonstrated between upgrade rates and lesion size, DCIS grade, as well as guidance method. Subsequent multivariable analysis showed no statistically significant relationship between guidance method and upgrade rates but a trend towards statistical significance (P < 0.1). CONCLUSION: Our recommendation is to inform women diagnosed with DCIS preoperatively in our programme, that there is a one in five chance the diagnosis will prove to be invasive cancer on definitive surgery. This is particularly important for women contemplating whether or not to undergo surgery for DCIS. Additionally, as the most significant predictor of upgrade rate demonstrated in this study is increasing lesion size, consideration should be given to increasing the number of core samples taken of larger lesions.