Cancer causes: Popular myths about the causes of cancer

Scary claims circulate on the internet that everyday objects and products, such as plastic and deodorant, cause cancer. 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 reality behind these common myths.

Myth: Antiperspirants or deodorants can cause breast cancer.

Fact: There's no conclusive evidence linking the use of underarm antiperspirants or deodorants with breast cancer.

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.

Myth: Microwaving food in plastic containers and wraps releases harmful, cancer-causing substances.

Fact: Plastic containers and wraps labeled as safe for use in the microwave don't pose a threat.

There is some evidence that plastic containers that aren't intended for use in the microwave could melt and potentially leak chemicals into your food. Avoid microwaving plastic containers that were never intended for the microwave, such as margarine tubs, takeout containers or whipped topping bowls.

Check to see that any container you use in the microwave is labeled as microwave-safe.

Myth: People who have cancer shouldn't eat sugar, since it can cause cancer to grow faster.

Fact: More research is needed to understand the relationship between sugar in the diet and cancer. All kinds of cells, including cancer cells, depend on blood sugar (glucose) for energy. But giving more sugar to cancer cells doesn't make them grow faster. Likewise, depriving cancer cells of sugar doesn't make them grow more slowly.

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.

There is some evidence that consuming large amounts of sugar is associated with an increased risk of certain cancers, including esophageal cancer. Eating too much sugar can also lead to weight gain and increase the risk of obesity and diabetes, which may increase the risk of cancer.

Myth: Cancer is contagious.

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 infection — that can cause cervical cancer and other forms of cancer
• Hepatitis B or C — viruses transmitted through sexual intercourse or use of infected IV needles — that can cause liver cancer

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