[Hereditary predisposition of colorectal cancer and prevalence of hereditary nonpolyposis colorectal cancer in general population of colorectal cancer patients in China].

Objective: To analyze hereditary predisposition of CRC and the prevalence of HNPCC in general population of CRC patients in China.

Methods: CRC patients were from two sources. One is that we consecutively investigated 594 patients by ourselves. They were proved to be colorectal cancer by histology. The following data of all patients should be registered: sex, age diagnosed colorectal cancer, site, number and histological type of primary cancer. The other was the published Chinese and foreign literatures related to Chinese HNPCC prevalence, and there were cumulatively 3596 patients in all. Hereditary predisposition of CRC (or malignant tumors) is that CRC patients have two or more first- or second-degree relatives (or both) with CRC (or malignant tumors). HNPCC was diagnosed by Amsterdam Criteria I (AC I) or Amsterdam Criteria II (AC II), Japanese Criteria of HNPCC (JC).

Results: Hereditary predisposition of both malignant tumors and CRC were 17.2% and 5.2% in 594 patients with CRC, respectively. Multiple primary cancers and multiple CRC were 13.1% and 10.1% , respectively. Among them, multiple primary cancers and multiple CRCs without familial history were 9.1% and 6.7%, respectively. There was a correlation between familial history of malignant tumors and multiple primary cancers and multiple CRCs (both P < 0.01). Patients with familial history of malignant tumors had more frequently multiple primary cancers and multiple CRCs than patients without history of malignant tumors. Younger patients (< or = 50) were 21.4% in all CRC patients. there was a correlation between younger patients (< or =50) and familial history of malignant tumors and familial history of CRC (both P < 0.05). When CRC was diagnosed, patients with familial history of malignant tumors and familial history were younger than patients without them. In the population of CRC patients in China, prevalence of HNPCC diagnosed AC I, AC II and JC were 1.24%, 2.15% and 2.93%, respectively.

Conclusions: Hereditary predispositions of malignant tumors and CRC were 17.2% and 5.2% in CRC patients, respectively. Familial history of malignant tumors, multiple primary cancers and younger patients with CRC (< or =50) were the clinical markers of hereditary predisposition of malignant tumors including CRC. Multiple primary cancers and younger patients with CRC (< or =50) were all correlated with familial history of malignant tumors. The prevalence of HNPCC in China was similar to that in Western countries.