IGF1 and colorectal carcinoma: to elucidate genetic risk modifiers influencing age of onset of CRC in patients with LS using CART analysis (classification and regression tree) identified CDKN2A C580T and IGF1 CA-repeat as the initial splits, indicating that the polymorphisms in these genes are the most informative for separating patients into those LS patients who are more likely to develop CRC early versus those who are more likely to develop CRC at a later age.