The aetiology and risk factors for both Ca colon and CA rectum are same
D- dietary factors (red meat is bad, fibre is good)
Familial polyposis coli
IBD – ulcerative colitis
Old age ,obese and lack of physical activity predispose to cancer colon and rectum
Apart from these general aetiology for cancer such as genetics , family history etc
For both of these answers imagine an american old obese man who is smoking and drinking and eating beef burger (red meat) on a couch.