title: Tumor histology helps to identify Lynch syndrome among colorectal cancer patients.
abstract: OBJECTIVE
  To determine the value of histology in identifying Lynch syndrome among those patients with early onset of colorectal cancer (CRC).
  
  
  METHODS
  Demographic, clinical and cancer history data from patients diagnosed with CRC before 60 years of age, and treated at our institution between 1997 and 2005, were collected from medical records and direct interview. Their tumors were assessed to identify histological features suggestive of high frequency microsatellite instability (MSI-H): tumor infiltrating lymphocytes, Crohn's like inflammatory reaction, mucinous, signet ring cells, medullary growth pattern and then, tested for microsatellite instability (MSI) and MLH1/ MSH2 protein expression.
  
  
  RESULTS
  Sixty-five patients were included in the study. The mean age at diagnosis was 48 +/- 9.9 years. Overall, 28 (43%) patients, including 13 of 35 diagnosed between ages 50 and 60, had tumor demonstrating one or more histological features suggestive of MSI-H. These patients were younger (45 vs. 50 years, P = 0.02) and more commonly had family history of Lynch syndrome-related cancers (36 vs. 19%), though the latter feature did not reach statistical significance (P = 0.07). Eleven of 25 tumors with MSI-H histology, but only 1 of 29 tumors without special histological features were found to be MSI-H (P < 0.0001). Histology had a positive predictive value of 44% and a negative predictive value of 97% for identifying MSI-H tumors.
  
  
  CONCLUSIONS
  Limiting MSI analysis only to those tumors with suggestive histology would have reduced the need for testing by nearly 60% of all tumors from patients that met the revised Bethesda guidelines.
authors.affiliation: Department of Medicine, Gastroenterology Division, University California San Francisco, 2330 Post St., suite#610, San Francisco, CA 94115, USA.
authors.forename: Brindusa
authors.initials: B
authors.lastname: Truta
authors.forename: Yunn-Yi
authors.initials: YY
authors.lastname: Chen
authors.forename: Amie M
authors.initials: AM
authors.lastname: Blanco
authors.forename: Guoren
authors.initials: G
authors.lastname: Deng
authors.forename: Peggy G
authors.initials: PG
authors.lastname: Conrad
authors.forename: Yong Ho
authors.initials: YH
authors.lastname: Kim
authors.forename: Eun Taek
authors.initials: ET
authors.lastname: Park
authors.forename: Sanjay
authors.initials: S
authors.lastname: Kakar
authors.forename: Young S
authors.initials: YS
authors.lastname: Kim
authors.forename: Fernando
authors.initials: F
authors.lastname: Velayos
authors.forename: Marvin H
authors.initials: MH
authors.lastname: Sleisenger
authors.forename: Jonathan P
authors.initials: JP
authors.lastname: Terdiman
mesh_terms: D000367:Age Factors; D015179:Colorectal Neoplasms / Q000235:genetics / Q000473:pathology; D003123:Colorectal Neoplasms, Hereditary Nonpolyposis / Q000235:genetics* / Q000473:pathology*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D012307:Risk Factors