Distribution trends of colorectal adenoma and cancer: a colonoscopy database analysis of 11,025 Chinese patients

A left-to-right shift of colorectal cancer (CRC) has been reported in Western studies. However, few Asian studies have investigated the anatomic distribution of colorectal adenoma and CRC. We aimed to describe the time trends in the distribution of colorectal adenoma and CRC in a Chinese population.A colonoscopy database was reviewed, and all consecutive patients with lower gastrointestinal symptoms who underwent colonoscopy from 1998 to 2009 were identified. Data, including patients' sex, age, symptoms, and the number and anatomic locations of colorectal adenoma and CRC, were documented.A total of 11,025 patients were included in the final analysis; 1012 and 363 patients were diagnosed with colorectal adenoma and CRC, respectively. Overall, there were more distal than proximal adenomas (54.4% vs 37.9%), and the proportion of proximal adenomas remained stable from 1998-2006 to 2007-2009 (38.2% vs 37.6%). Similarly, there were more distal than proximal CRC (56.5% vs 42.4%), and the proportion of proximal CRC declined from 45.8% in 1998-2006 to 38.4% in 2007-2009. Colorectal adenoma and CRC were equally distributed among both sexes. For elderly patients (50 years), there was a non-significant trend towards more proximal adenoma and CRC.The present study suggests no distal-to-proximal shift of colorectal adenoma and CRC among the Chinese population in Shanghai over the past 12 years. The distribution pattern of colorectal adenoma and CRC of Chinese patients is different from that of Western patients, who had more colorectal lesions located in the distal part.