Universal Screening for Lynch Syndrome in Newly Diagnosed Colorectal Cancer Significantly Increases the Detection Rate .
Jane C Post, Mary P Bronner, Xiuli Liu. Cleveland Clinic Foundation, OH
Background: Lynch syndrome (LS) is the most common hereditary form of colorectal cancer (CRC). In our institute, prior to universal testing of all colorectal cancers, LS screening rates and MSI-H detection rates in newly diagnosed CRCs were 35.6% and 8.5% using the revised Bethesda guidelines and histomorphology in patients 60 years or older, indicating the inadequacy of these approaches for LS screening in newly diagnosed CRC. The degree to which universal screening has improved these results forms the subject of this report.
Design: All CRC cases surgically resected since the initiation of a universal testing paradigm (7/2009 to 7/2010) were retrieved from the pathology database and the MSI testing rates and results were determined. Exclusionary criteria included: recurrent or metastatic CRCs, idiopathic inflammatory bowel disease, familial adenomatous polyposis, and known LS patients.
Results: 267 newly diagnosed CRCs resected during the study period met our inclusion criteria. The cumulative reflex MSI testing rate was 69.3%, or 183 total CRCs, including 139 of 185 (75.1%) untreated CRCs, 43 of 75 (57.3%) CRC resections following neoadjuvant treatment, and 1 of 14 (14.3%) CRC re-excisions following polypectomy. The MSI-H detection rate among the screened cases was 16.9%. The LS screening rate in this cohort (69.3%) was far from universal, but was significantly higher than our previously reported rate prior to the institution of the universal paradigm of 35.6% (p<0.00001). Of the 185 CRCs without neoadjuvant therapy, polypectomy and transanal resection specimens accounted for 10 out of 40 (25%) untested, and 7 of 145 (4.8%) tested (p=0.0004). Universal LS screening in newly diagnosed CRCs significantly increased the detection rate of MSI-H CRCs (29 out of 185 newly diagnosed CRCs without neoadjuvant treatment, 15.6%) compared to our previously reported rate of 8.5% using only revised Bethesda guidelines and histomorphology in patients 60 years or older (p=0.01).
Conclusions: The institution of universal LS screening in newly diagnosed CRCs has significantly improved the LS screening rate at our institution and the detection of potential LS patients. CRCs diagnosed in polypectomy and transanal resection specimens were less likely to be screened for LS, as were those treated by neoadjuvant therapy, which are target areas for quality improvement.
Wednesday, March 2, 2011 9:30 AM
Poster Session V # 48, Wednesday Morning