Prevalence and characteristics of hereditary nonpolyposis colon cancer (HNPCC) syndrome in immigrant Chinese cancer patients.

Abstract

e12019 Background: Hereditary nonpolyposis colon cancer (HNPCC) syndrome is a hereditary disorder that predisposes to colon, endometrial, and gastric cancers before 50 years old. Molecular diagnoses, by testing microsatellite instability (MSI), or immunohistochemical staining (IHC) of the lack of the mismatch repair (MMR) protein expression and genomic sequencing of the MMR genes, is more sensitive and specific than the clinical diagnostic criteria, such as Amsterdam or Bethesda criteria. HNPCC affects 2-5% of Caucasian population. We aim in this study to evaluate the prevalence and clinical characteristics of HNPCC in Chinese patients (immigrants) newly diagnosed of colon, endometrial, and gastric cancer. Methods: Patients of Chinese ethnicity diagnosed of colorectal, endometrial, or gastric cancer in Maimonides Medical Center from 2000 to 2009 were eligible and 150 cases were identified. Medical records were reviewed and IHC staining of four MMR genes, namely MLH1, MSH2, MSH6, and PMS2 were performed on primary tumor specimens. Results: Forty-nine cases were studied so far, 33 of colon cancer, 3 of endometrial cancer and 13 of gastric cancer. There were 24 males and 25 females, age ranges from 32 to 93 years old. Nine patients (4 colon cancers and 5 gastric cancers) were diagnosed at age younger than 50 years old, and none had deficiency of MMR expression by IHC. Two abnormal cases were detected as described below and were confirmed in Ohio State University. Conclusions: Colon cancer with suspected HNPCC MSH6 mutation can have first presentation in patients greater than 50 years old in Chinese patients. The prevalence and characteristics of HNPCC in Chinese patients warrants further study, which is still ongoing. Case Age Gender Cancer site Tumor grade and differentiation Family history IHC staining result and interpretation 1 66 M Ascending colon T2N0M0 adeno ca, moderately differentiated None MSH6 negative, suggestive of HNPCC 2 86 F Ascending colon T1N0M0 adeno ca, poorly differentiated, mucin production None MLH1, PMS2 negative, consistent with MLH1 hypermethylation No significant financial relationships to disclose.