Hi thanks for your question. There is no doubt that cigarette smoking causes cancer, besides many more problems, But ordering for repeat CT scan doesn t means cancer. There could be many more reasons for which your physician wants to repeat the scan. May be he/ She wants more description of the findings for which CT was ordered or he wants some missing details to be looked into and finally he wants contrast study of the disease, in which scan is done after injecting a dye to confirm or rule out cancer Hope this answers your question