Is cancer contagious?

A subtle difference between that question and the one we asked yesterday, but one that perhaps accounts for the difference in opinion between angry doc critics of Andy Ho's article, a few of whom wrote a letter jointly to the ST Forum:


Cancer is not a contagious disease

WE REFER to the article by Andy Ho last Saturday, "'Catch' cancer? Yes, you can". It highlights the role of infectious agents, particularly viruses in causing cancer, and suggests that since viruses are infectious, one might "catch" cancer from a cancer patient.

Viruses have been known to play a role in cancer causation since the Nobel Prize-winning discovery of the transforming activity of the rous sarcoma virus in chickens by Dr Peyton Rous nearly 100 years ago.

However, an infectious virus causing cancer is different from cancer being a contagious disease. In other words, healthy patients do not acquire cancer from another patient.

One of our patients mentioned this as a concern recently, and we feel it is important to point this out as cancer patients require the full support and care of their loved ones. It would be sad to see our patients with advanced cancer dying alone and or with relatives fearing to hold their hands or touch them. Some may even use such excuses to neglect or isolate their relatives with cancer.

Viruses are widespread and many people may have been exposed without symptoms. Hepatitis B carriers, for example, have an increased risk of liver cancer. Carriers could pass on hepatitis B as an infection, and all necessary precautions should be taken to minimise this.

However, only a minority of hepatitis B carriers develop liver cancer. These patients frequently acquired their infection many years ago at birth or during childhood. The liver cancer itself is not contagious.

It is estimated that 80 per cent to 90 per cent of the adult American population has been exposed to the virus mentioned in the article, Epstein-Barr virus (EBV), which is related to nasopharyngeal cancer (NPC) and lymphoma.

About 50 per cent of the world population has been exposed to the bacterium, helicobactor pylori, related to stomach cancer.

Overall, very few people who are exposed eventually develop these cancers.

Certainly, hand washing and other general hygiene measures are needed when we care for our loved ones with cancer, mainly to protect them from germs. However, we should not let that prevent us from touching and loving them.

Dr Peter Ang Cher Siang
Dr Tay Miah Hiang
Dr Leong Swan Swan
Oncocare Cancer Centre


Can cancer spread directly from one person to another? Not as far as we know.

But it is an undeniable fact that one can 'catch' an infection that increases one's chances of having certain types of cancer.

So is Andy Ho (and angry doc) justified in saying that you can 'catch' cancer? Well, that's a matter of opinion and semantics - angry doc thinks it's correct to say that one can catch cancer, but not so to say that cancer is contagious. Semantics.

But from a public health point of view angry doc thinks there is value in looking at certain types of cancers as 'infectious diseases'.

Recognition of the role of Human Papillomavirus in the pathogenesis of cervical cancer has allowed us to develop methods to screen for the cancer, and to develop a vaccine against the virus (and indirectly the cancer itself). No doubt recognition of the role H. pylori plays in the pathogenesis of gastric cancer will allow us to develop strategies to reduce its transmission, to screen for and treat asymptomatic 'carriers', and perhaps one day to develop an effective vaccine against the bacterium, all of which will indirectly reduce gastric cancer incidence.

If a man is diagnosed with liver cancer today, we screen the family for Hepatitis B. We do not yet (as far angry doc knows - do correct him if you know he is wrong) screen family members of patients with gastric cancer for H. pylori, although we know that theoretically if they are found positive and treated, their risk of developing gastric cancer will be reduced. Although angry doc is not directly involved in the field of research on H. pylori, a look at the amount of new research and information generated on the subject tells him that it must be an exciting time for those who are.

So yes, angry doc thinks that thinking of some forms of cancers as infections you can catch is useful.

But does that mean that we should be "careful with food or eating utensils of a loved one with cancer - to prevent transmission, if any, of his or her disease" as Andy Ho suggested?

Well, no.

Not yet anyway.