An older study by Secco et al. [17], which used only CEA and ultrasound imaging as part of the follow-up regimen, defined high risk patients, as those who had a left sided Dukes B2 or higher colon, any low rectal cancer, a pretreatment CEA greater than 7.5 ng/mL, poorly differentiated grade and/or a mucinous or signet cell adenocarcinoma. The gene discussed is CEACAM5; the disease is rectal cancer.