Concomitant abdominal aortic aneurysm and colorectal cancer: a decision analysis approach to a therapeutic dilemma.

The therapeutic approach to a patient with concomitant abdominal aortic aneurysm and colorectal carcinoma is not clear. Decision analysis helps clarify decision options and quantify therapeutic outcomes. Variables used in decision analysis include life expectancy after resection for colorectal cancer and abdominal aortic aneurysm, rupture rate of abdominal aortic aneurysm, complications of colorectal The results support the concept that the symptomatic lesion should be treated first. When both lesions are asymptomatic and the aneurysm is 4-5 cm in diameter, it should be resected first, if the colorectal cancer has a less than 5% chance of obstruction or perforation, as is found in noncircumferential lesions. When the aneurysm is greater than 5 cm, it should be resected first if the cancer has a less than 22% chance of obstructing or perforating, as with circumferential lesions. Simultaneous resection should be considered for patients with aneurysms greater than 5 cm and cancers with a greater than 75-80% chance of obstruction or perforation, provided the dual procedures can be performed with a less than 10% operative mortality and less than 50% complication rate.