How much does the risk for cancer increase after having 3 abdominal and pelvic ct scans and 1 ct coronary angiogram?

Medical use of X--rays has some radiation exposure which is mostly considered insignificant unless you exceed 10 CT scan procedures over a period of 5 years. In your case, I do not think you have had excessive radiation exposure...not enough to worry about Cancer development as a result of these radiological procedures.

These imaging studies are unlikely to measurably increase your risk of cancer, over your background risk. You can reduce your risk of cancer by adopting healthy habits: Eat a mostly vegetarian diet, avoid alcohol, tobacco and street drugs, avoid excessive to sun, get HPV vaccine, exercise 30 minutes each day, drink enough water so your urine is mostly colorless. Wish you good health!