Common cancer myths and misconceptions


There's so much misinformation out there about cancer and cancer prevention that it's easy to feel overwhelmed when it comes to making healthy lifestyle choices. We've separated the facts from fiction here to assist with your risk-reducing decisions.

Myths and misconceptions about cancer can result in unnecessary anxiety and can prevent you from making healthy lifestyle decisions. Instead of drowning in confusion, let our latest science-based information be your guide.

Not necessarily. Cancer is caused by harmful changes (mutations) in genes. Only about 5 to 10% of cancers are caused by harmful mutations that are inherited from your family, according to the US National Cancer Institute. In families with an inherited cancer-causing genetic pattern, multiple family members often develop the same type of cancer. These cancers are called familial or hereditary cancers. The other 90 to 95% of cancers are caused by mutations that occur during your lifetime as a natural result of multiple factors such as aging and exposure to environmental factors including tobacco smoke and radiation.

How can I lower my cancer risk?

At least 30 to 50% of cancers are preventable, says World Health Organisation (WHO). Potential cancer risks can be significantly reduced by avoiding exposure to cancer-causing agents and by making healthy lifestyle choices:

Read the World Health Organisation's Cancer Prevention Fact Sheet here.

Does sugar 'feed' cancer?

Although research has shown that cancer cells consume more sugar (glucose) than normal cells, no studies have shown that sugar consumption will cause cancer or make it worse. However, a high-sugar diet may contribute to excess weight gain, and obesity is associated with an increased risk of developing several types of cancer.

Do artificial sweeteners cause cancer?

Researchers have conducted studies on the safety of artificial sweeteners, such as saccharin, cyclamates, aspartame, acesulfame potassium, sucralose and neotame and have found no evidence that they cause cancer. Except for cyclamates, all of these artificial sweeteners have been approved by the US Food and Drug Administration.

Is cancer contagious?

Cancer is definitely not contagious. The only situation in which cancer can spread from one person to another is in organ or tissue transplantation. If you receive an organ or tissue from a donor who had cancer in the past, you have a very low risk of developing a transplant-related cancer in the future.

In some people, cancers may be caused by certain viruses (the Human Papillomavirus, linked to head and neck and cervical cancer, for example) and bacteria (such as Helicobacter pylori) and although viruses do spread from person to person, cancers do not.

Can cancer surgery or a tumour biopsy cause cancer to spread in your body?

The chances of this happening are extremely low as surgeons take many steps to prevent cancer cells from spreading during biopsies or surgery.

Do cell phones cause cancer?

Until more studies are completed, the Cancer Association of South Africa suggests exercising caution when using mobile phones adding, ‘The jury is out at this stage – research is ongoing and must be closely monitored.’ CANSA notes that as cell phones are used and held near the head, there is great  the main concern has been whether they might cause or contribute to tumours in this area, including Malignant (cancerous) brain tumours such as gliomas

  • Non-cancerous tumours of the brain such as meningiomas
  • Non-cancerous tumours of the nerve connecting the brain to the ear (acoustic neuromas)
  • Non-cancerous tumours of the salivary glands

CANSA adds: “In order to prove that the use of cell phones can cause cancer, many thousands of cell phone users would need to be studied over many years. Such studies are now in progress in many countries and it is expected that definitive results will be forthcoming in the near future. However, just because there is no definite evidence at this stage, does not mean that there is no potential danger.

CANSA’s advice on using mobile phones with caution:

  • Limit the number and duration of calls
  • Use text messages when possible
  • Switch sides of the head when the call is long
  • Use hands-free kits or speaker phone mode to keep the phone at a distance from the head
  • Instruct children and teenagers to limit calls to emergencies only as they are more vulnerable to electro-magnetic radiation

Do power lines cause cancer?

There’s no evidence that power lines cause cancer. Power lines emit both electric and magnetic energy and while the electric energy is easily shielded or weakened by walls and other objects, the magnetic energy is a low-frequency form of radiation that does not damage genes.

Can herbal remedies cure cancer?

Although some studies suggest that alternative or complementary therapies, including some herbs, may help you to cope with the side effects of cancer treatment, no herbal products have been shown to be effective for treating cancer. In fact, some herbal products may be harmful when taken during chemotherapy or radiation therapy because they may interfere with how these treatments work. Speak to your doctor about any complementary and alternative medicine products (including vitamins and herbal supplements) that you use.

Are there cancer risks associated with haemorrhoids?

While there’s no evidence to support the idea that haemorrhoids will become cancerous, they sometimes do co-exist with cancer. Never assume that all bleeding is caused by haemorrhoids so always mention any rectal bleeding to your doctor as bright red blood in the stools is one of the symptoms of colon or rectal cancer, as are noticeable changes to one’s bowel habits.  Find out more here.

Are stomach ulcers indicative of cancer?

Stomach ulcers are not necessarily a sign of cancer, although for a long time it was believed that stomach ulcers could result in stomach cancer. The danger of stomach ulcers is not so much the possibility that they may result in cancer, but rather that stomach cancer may be incorrectly diagnosed and treated as an ulcer.

Do deodorants cause breast cancer?

The best studies to date have found no evidence linking the chemicals typically found in antiperspirants and deodorants with changes in breast tissue.

Does colouring my hair increase the risk of cancer?

There is no convincing scientific evidence that personal hair dye use increases the risk of cancer.

Remember that your best sources when it comes to cancer information are a trusted doctor - and evidence-based science. With the correct information you’ll be well-equipped to ask questions and to make informed choices about cancer prevention and, in the case of a diagnosis, your treatment and care.

Learn more about cancer

  • Read more about the cancer journey in the Discovery Health Oncology Programme booklet here.  

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