Vomiting can be caused by a number of normal occurrences: motion sickness, a virus, or unpleasant sights or smells. If nausea and vomiting are accompanied by other symptoms, however, such as constipation or pain, colon cancer could be the cause. When vomiting is a symptom of colon cancer, it is usually because a tumor is causing a bowel obstruction. Depending on the severity of the blockage, solids, liquids and even gases may be prevented from passing through the colon. This can lead to painful stomach cramps and constipation. Either of these symptoms can result in nausea and vomiting.