[Clinical phenotypes of hereditary nonpolyposis colorectal cancer in Chinese population]

To investigate the clinical phenotypes of hereditary nonpolyposis colorectal cancer (HNPCC) in Chinese population.

Data of 34 HNPCC families diagnosed according to Armsterdam II Criteria and Japan Criteria, including age of diagnosis, site of cancer inclusive of abenteric cancer, history of synchronous and/or metachronous colorectal cancer, histopathology of tumor, clinical manifestations, and genealogy were collected and analyzed.

Out of the 612 members aged over 18 of these 34 families 140 persons were diagnosed as HNPCC patients with 154 cancer foci, 93 males and 47 females. The median age of confirmed diagnosis of HNPCC was 45.3 years. 62.1% of them developed the cancer before the age of 50 and 87.1% of them developed the cancer before the age of 60. Out of the 154 primary cancer foci, 31 were extracolonic (20.1%), including synchronous and/or metachronous cancers, with gastric cancer accounting for 41.9% (13/31), and 123 were colonic cancers (79.9%). Out of the 116 cases of colorectal cancer, there were 77 cases of proximal colon cancer (66.4%) and 39 cases of distal colon cancer (33.7%). There were 11 cases of synchronous and/or metachronous cancer (7.86%). The main clinical manifestations included hematochezia, anemia, abdominal mass, and abdominal pain.

In comparison with the facts among Westerners, HNPCC occurred earlier; the proportions of proximal colon cancer, extracolonic cancer, and synchronous and/or metachronous cancers are larger; and gastric cancer accounts for a greater percentage among Chinese.