To determine the prevalence of colorectal neoplasms in first degree relatives of those affected with sporadic colorectal cancer using colonoscopy as a screening tool. The prevalence will be compared to that of a defined matched cohort.

Colorectal cancer is a second commonest tumor in Hong Kong and the second commonest cause of cancer related death. About 1 in 23 males will develop colorectal cancer in his life time. The disease tends to cluster in families. This may be a combination of factors including shared genes, shared environment or chance. Known familial syndromes occur in only about 5% of cases. The majority is not well understood and labelled sporadic colorectal cancer. The screening strategy in families of subjects with colorectal cancer has not been defined. Colonoscopy is among the most sensitive and specific screening tool for colorectal neoplasm. The current study determines the prevalence of adenomas among first degree relatives of patients diagnosed with colorectal cancer. To quantify risk in this cohort, a case control analysis is used. The prevalence of the cohort is compared to that of a control population. The control group consists of relatives of patients with normal colonoscopic findings during the same study period.

Inclusion Criteria:

• First degree relatives (age >40 and <70) of individuals affected with sporadic colorectal cancer (those not associated with inflammatory bowel disease, familial adenomatous polyposis or HNPCC syndrome).

Exclusion Criteria:

• A family history compatible with that of Hereditary Non-polyposis Colon Cancer (HNPCC) based on the Amsterdam criteria [Table 5].
• Known Familial Adenomatous Polyposis (FAP) syndrome
• Patients and relatives with known inflammatory bowel disease
• Relatives that have received colonoscopy examinations in the past 5 years [details of colonoscopic examinations will be sought and information on colonic neoplasms recorded]. Those who have had barium enema examinations are eligible for trial inclusion as barium examinations often have low sensitivity and specificity for adenomas (around 70% respectively)
• Severe cardio-pulmonary or other medical co-morbidities that preclude safe colonoscopic examination

First degree relatives of patients having CRC or patient having normal colonoscopy