Cancer of the caecum. Endoscopic view of a cancerous growth in the caecum, the pouch that connects the ileum (small intestine) to the colon (large intestine). This tumour is an adenocarcinoma, a type of colorectal cancer arising from glandular epithelial tissue. Adenocarcinoma accounts for 90-95 per cent of all colorectal cancers. Certain dietary habits, such as a diet high in fat, appear to be significant risk factors.