People who receive CT scans have a higher rate of cancer. This seems like a logical fallacy. People who receive CT scans are more likely to get cancer. So CT s

People who receive CT scans have a higher rate of cancer. This seems like a logical fallacy. People who receive CT scans are more likely to get cancer. So CT scans must cause cancer. The alternate hypothesis are that people who are more likely to develop cancer are more likely to have a CT scan. Given the tiny number involved here (in absolute number of people who develop cancer after having a CT scan), is it not possible that these people had a CT scan because of early symptoms of cancer?