[Genealogical research of hereditary nonpolyposis colorectal cancer]

OBJECTIVES To analyse the diagnosis and treatment of 24 hereditary nonpolyposis colorectal cancer (HNPCC) kindreds and report mismatch repair gene mutations. METHODS The diagnosis, treatment and follow-up of 24 HNPCC kindreds were reviewed retrospectively, cancer incidence and spectrum were recorded. Clinical characteristics and treatment were analyzed. Peripherial blood and genomic DNA were extracted from family members who had provided informed consent. PCR and SSCP were used to screen coding regions of the hMLH1 and hMSH2 genes. Variant bands were sequenced by 377 DNA sequencer after purification. RESULTS One hundred and 25 malignant neoplasms were diagnosed in 75 patients (multiple cancers in 24) with an average age of 51 years in 24 pedigrees. The onset of the disease occurred earlier than expected with the passing of each generation within large kindreds. The neoplasm mainly included colonic cancer (63 patients), rectal cancer(21), stomach cancer(13), endometric cancer(7), and esophageal cancers(6). 84% patients received radical operations. Of 64 patients with colorectal cancer 16 had metachronous colorectal cancer. 24% colorectal patients developed metachronous cancer within 10 years after initial operation and received re-operation. In 3 detected families with germline hMSH2 and hMLH1 mutations resulting in truncated protein, 12 carriers were found. CONCLUSIONS The main characteristics of hereditary nonpolyposis colorectal cancer include early onset and frequence of cancer; predominance of colorectal cancer, especially right-sided colonic cancer; frequency of multiple primary cancer, especially colorectal cancer; and age anticipation in large HNPCC pedigrees. Segmental resection of colorectal cancer is not suitable for colorectal cancer patient in HNPCC kindred. Intensive follow-up is important for all patients and possible gene carriers.