Misconceptions about cancer causes can lead to unnecessary worry about your health. Find out whether there's any truth to these common myths about the causes of cancer. By Mayo Clinic Staff

Scary claims circulate on the Internet that everyday objects and products, such as plastic and deodorant, are secret cancer causes. Beyond being wrong, many of these myths may cause you to worry unnecessarily about your own health and the health of your family.

Before you panic, take a look at the facts. Here, Timothy Moynihan, M.D., a cancer specialist at Mayo Clinic, Rochester, Minn., takes a closer look at some popular myths about cancer causes and explains why they just aren't true.

Fact: There's no conclusive evidence linking the use of underarm antiperspirants or deodorants with breast cancer, according to the National Cancer Institute.

Some reports have suggested that these products contain harmful substances such as aluminum compounds and parabens that can be absorbed through the skin or enter the body through nicks caused by shaving. No clinical studies have yet given a definitive answer to the question of whether these products cause breast cancer. But the evidence to date suggests these products don't cause cancer.

If you're still concerned that your underarm antiperspirant or deodorant could increase your risk of cancer, choose products that don't contain chemicals that worry you.

Fact: Microwave-safe plastic containers and wraps are safe to use in the microwave.

But plastic containers not intended for use in the microwave could melt and potentially leak chemicals into your food. So avoid microwaving containers that were never intended for the microwave, such as margarine tubs, take-out containers or whipped topping bowls. Check to see that any container you use in the microwave is labeled as microwave-safe.

Fact: Sugar doesn't make cancer grow faster. All cells, including cancer cells, depend on blood sugar (glucose) for energy. But giving more sugar to cancer cells doesn't speed their growth. Likewise, depriving cancer cells of sugar doesn't slow their growth.

This misconception may be based in part on a misunderstanding of positron emission tomography (PET) scans, which use a small amount of radioactive tracer — typically a form of glucose. All tissues in your body absorb some of this tracer, but tissues that are using more energy — including cancer cells — absorb greater amounts. For this reason, some people have concluded that cancer cells grow faster on sugar. But this isn't true.

Fact: In ancient times illness was often viewed as punishment for bad actions or thoughts. In some cultures that view is still held. If this were true, though, how would you explain the 6-month-old or the newborn who gets cancer? These little ones haven't been bad. There's absolutely no evidence that you get cancer because you deserve it.

Fact: There's no need to avoid someone who has cancer. You can't catch it. It's OK to touch and spend time with someone who has cancer. In fact, your support may never be more valuable.

Though cancer itself isn't contagious, sometimes viruses, which are contagious, can lead to the development of cancer. Examples of viruses that can cause cancer include:

  • Human papillomavirus (HPV) — a sexually transmitted disease — that can cause cervical cancer and other forms of cancer
  • Hepatitis C — a virus transmitted through sexual intercourse or use of infected intravenous (IV) needles — that can cause liver cancer

Talk to your doctor about ways to protect yourself from these viruses.

May 14, 2011