you did not mention the clinical history of your father. why the CEA estimation has been done is not clear. is there any history of altered bowel habit or stool mixed with blood? coumadin
can also be the cause. anyway CEA 7.5 ( you have not mention the unit
) dose not signify malignancy.slightly higher than normal (normal 2.5-5 microgram/L). increased in smokers also. anyway consult your doctor regarding this issue.