Planning a full-body CT scan? Think twice!
You may be increasing your cancer risk
The American Cancer Society says don’t do it. The U.S. Food and Drug Administration concurs. Both are referring specifically to the full-body computed tomography (CT) scans some imaging centers offer as a way for healthy people without symptoms to pinpoint disease in its early stages. Without proper medical supervision, these scans may not only be ineffective (either failing to detect disease or erroneously identifying normal areas as suspicious), they may also be harmful to your health because of their high radiation doses. What about regular, diagnostic CT scans? Follow your doctor’s advice: If you have symptoms of an illness or high risk factors, getting a diagnostic CT scan helps detect disease—in which case, the tiny risks are worth the benefits.
Cancer-causing substances are all around us, from the water you drink (if it comes through lead-soldered pipes) to the tasty charbroiled burgers on your dinner plate. However, in most cases, you would have to have prolonged contact with high levels of these substances, called carcinogens, for them to cause cancer.
Every two years or so, the U.S. government updates its list of known or likely cancer-causing agents. In 2005, 17 new items were added to the list, some of which you can avoid and others that you can’t. Here are some common carcinogens you should be aware of.
- Hepatitis B and C viruses, which can cause liver cancer, are generally spread by blood transfusions, contaminated needles of illegal drugs and unprotected intercourse.
- Human papilloma virus (HPV) usually spread through unprotected sexual contact, can cause cervical cancer.
- Medical X-rays in sufficient doses can harm an unborn child or raise his or her risk of leukemia later in life. For everyone else, normal doses of X-ray radiation are generally safe, since the radiation amount emitted is usually small and any risk is greatly outweighed by its benefit. Risk of cancer is slight from diagnostic computed tomography (CT) scans, which emit more radiation than standard X-rays. Your doctor will consider any previous exposure you’ve had to radiation before prescribing a CT scan. Full-body screening CT exams, however, pose a higher cancer risk. (See “Planning a full-body scan?”)
- Gamma radiation found in radon, a gas that filters up through the ground, and neutron radiation, which penetrates the earth’s atmosphere from space, can cause leukemia and thyroid, breast and lung cancers.
- Heterocyclic amines, compounds found in foods cooked at high temperatures, may increase breast and colon cancer risk.
- Lead, which can cause kidney, brain and lung cancer in animals, is found in some batteries, ammunition and cable coverings, paints, glass, ceramics, fuels and cosmetics as well as in tap water that runs through lead pipes and pipes soldered with lead.
- Industrial chemicals, such as cobalt sulfate and naphthalene, found in moth repellants, and 4,4-thiodianiline, found in dye, make up the remainder of the newly added likely carcinogens.
The bottom line
If you’ve had more than a few charcoal-grilled steaks in your day, should you worry? Not necessarily. According to the American Cancer Society, carcinogens don’t cause cancer in every case and on every exposure. The length of time you’ve been exposed to the carcinogen, your genetic makeup and your lifestyle choices work together to determine your cancer risk. But you can help beat the odds by eating healthfully, exercising, not smoking, using sunscreen, getting regular screenings and talking to your doctor about other preventive measures, such as getting vaccinated for hepatitis B and HPV.