Abstract

BackgroundIn 1996, the National Cancer Institute hosted an international workshop to develop criteria to identify patients with colorectal cancer who should be offered microsatellite instability (MSI) testing due to an increased risk for Hereditary Nonpolyposis Colorectal Cancer (HNPCC). These criteria were further modified in 2004 and became known as the revised Bethesda Guidelines. Our study aimed to retrospectively evaluate the percentage of patients diagnosed with HNPCC tumors in 2004 who met revised Bethesda criteria for MSI testing, who were referred for genetic counseling within our institution.MethodsAll HNPCC tumors diagnosed in 2004 were identified by accessing CoPath, an internal database. Both the Tumor Registry and patients' electronic medical records were accessed to collect all relevant family history information. The list of patients who met at least one of the revised Bethesda criteria, who were candidates for MSI testing, was then cross-referenced with the database of patients referred for genetic counseling within our institution.ResultsA total of 380 HNPCC-associated tumors were diagnosed at our institution during 2004 of which 41 (10.7%) met at least one of the revised Bethesda criteria. Eight (19.5%) of these patients were referred for cancer genetic counseling of which 2 (25%) were seen by a genetics professional. Ultimately, only 4.9% of patients eligible for MSI testing in 2004 were seen for genetic counseling.ConclusionThis retrospective study identified a number of barriers, both internal and external, which hindered the identification of individuals with HNPCC, thus limiting the ability to appropriately manage these high risk families.

Highlights

  • In 1996, the National Cancer Institute hosted an international workshop to develop criteria to identify patients with colorectal cancer who should be offered microsatellite instability (MSI) testing due to an increased risk for Hereditary Nonpolyposis Colorectal Cancer (HNPCC)

  • Of hereditary colorectal cancers associated with MSH2 or MLH1 mutations and 10-15% of sporadic colorectal cancers demonstrate high microsatellite instability using a panel of 5 microsatellite markers (MSH-H) [1,4,10,11,12]

  • high microsatellite instability (MSI-H) histology refers to characteristic histologic features of colorectal cancer (CRC) associated with defective DNA mismatch repair (MMR) and includes a cribiform/solid architectural pattern, infiltrating lymphocytes intimately associated with tumor cells, a Crohn’s-like lymphocytic reaction, and mucinous/signet ring differentiation [13,14]

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Summary

Introduction

In 1996, the National Cancer Institute hosted an international workshop to develop criteria to identify patients with colorectal cancer who should be offered microsatellite instability (MSI) testing due to an increased risk for Hereditary Nonpolyposis Colorectal Cancer (HNPCC). These criteria were further modified in 2004 and became known as the revised Bethesda Guidelines. MSI-H histology refers to characteristic histologic features of CRC associated with defective DNA MMR and includes a cribiform/solid (medullary) architectural pattern, infiltrating lymphocytes intimately associated with tumor cells, a Crohn’s-like lymphocytic reaction, and mucinous/signet ring differentiation [13,14] These histologic features can further aid in the identification of patients with HNPCC-associated colorectal cancer

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