Concordance between vacuum assisted biopsy and postoperative histology: Implications for the proposed Low Risk DCIS Trial (LORIS)

AimThe recent Breast Cancer Screening Review has estimated that for one life saved three patients are overtreated. The dramatic increase in the diagnosis of Ductal carcinoma in-situ (DCIS) has not lead to the expected decrease in the incidence of invasive cancer. It is not clear if all DCIS progress to invasive cancer if untreated. The Low Risk DCIS Trial (LORIS) intends to compare the current treatment of low risk DCIS i.e. surgery, with active monitoring. For effective implementation, concordance between diagnostic biopsy using large volume vacuum assisted biopsy (VAB) and excision histology is vital. A two-centre UK audit was done to assess concordance in patients diagnosed with low grade DCIS diagnosed using VAB.MethodsData of DCIS diagnosed with VAB from year 2001–2010 in University Hospital Birmingham and Leeds Teaching Hospitals was retrospectively collected and concordance between diagnostic and excision histology was assessed. Low Grade DCIS diagnoses were further evaluated retrospectively with regard to their eligibility for LORIS.ResultsOf 225 DCIS diagnoses 128 (57%) were high grade, 66 (29%) intermediate grade and 31 (14%) low grade. Overall 18% were upgraded to invasive cancer. The upgrade rate to invasive cancer for high grade was 23% and for low grade DCIS was 10%. In the low grade group eligible for LORIS, there were no upgrades to invasive cancer.ConclusionThe upgrade rates to invasive cancer are comparable to series published in literature. The concordance for the low risk DCIS with zero upgrade to invasive cancer supports the stringent LORIS eligibility criteria for trial selection.