Angry Doctor

Wednesday, March 11, 2009

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.

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11 Comments:

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


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

    isn't it a little arrogant for us to bend the terminology for public health 'value'?

    terminology depends on facts, not on The Greater Good. we aren't living in orwellian times, or at least i hope we aren't

    fact: some cancers have an infective etiology

    but you can't consider cancer as a classical 'infectious disease'.

    the same way that a drug addict who gets killed by a gunshot wound while procuring his drugs, cannot be directly classified as a victim of a drug addiction

    he wouldn't have been shot if he had never taken drugs, but most drug addicts don't routinely suffer gunshots, the same way most EBV carriers don't go on to develop nasopharyngeal cancer

    in addition, you can infect someone with EBV, H pylori or HPV, but you can't infect someone with cancer.

    i personally think that none of the cancers we know so far are 'infectious diseases'

    By Blogger kc, At March 11, 2009 6:31 pm  

  • Semantics, kc, semantics.

    You can infect someone with HIV, but you can't infect someone with AIDS.

    The question here is not whether cancers are infectious diseases, but whether one can 'catch cancer'.

    We understand the role infective agents play in the pathogenesis of some cancers, and we vaccinate people against Hep B and HPV as an indirect form of immunisation against cancers (well, against cirrhosis and genital warts too).

    We know that people can catch infections that increase their risks of getting cancer.

    We immunise people partly so they won't get cancer.

    Yet we don't want to say that people can 'catch cancer'?

    Or are we worried that admitting that fact means admitting that people can 'spread' cancer?

    Well, ask yourself this: what does a large pool of carriers of Hep B and HPV in the population do to your cervical and liver cancer rates?

    All semantics, kc.

    Call it viral-related cancers if you want.

    Fact is that looking at some cancers as infectious diseases and implementing public health issues based on that understanding has contributed to reducing cervical cancer rates, and the same will probably happen for gastric cancer rates.

    By Blogger angry doc, At March 11, 2009 7:14 pm  

  • 6. Scanlon EF, Hawkins RA, Fox WW, Smith WS. Fatal homotransplanted melanoma: a case report. Cancer. 1965; 18:782-9.

    By Anonymous Anonymous, At April 09, 2010 2:34 am  

  • What about a carer who is also a spouse looking after aliver cancer patient. I'm dealing 24/7with someone who has low level sepsis /bloodinfections -not hep or hiv by the way-urine infections, faecal infections, suffers daily/night sweats. I'm cleaning up continually -are you Angry Doc saying that no virus from this frightful disease can be transmitted to me as his only carer from faecal contamination for example?

    By Anonymous Anonymous, At May 27, 2010 3:40 am  

  • hi, i hope you can help me. my mother in law has undergone chemotherapy for pancreatic cancer. she has the habit of sharing food and water with my 2 year old daughter. will this put my daughter at risk of 'catching' the disease esp when her immune system is low? thanks.

    By Anonymous Anonymous, At July 29, 2010 8:29 pm  

  • Anon,

    If you are concerned, you should see a doctor.

    By Blogger angry doc, At July 29, 2010 11:07 pm  

  • I had my fathers genome studied with decodeme et al a year ago so knew he had a very high risk of prostate cancer 42.7% vs the 16% avge,I also knew his father died of prostate cancer.

    6 mths ago my fathers closest friend developed Prostate cancer he spent a good deal of time at our house he is a widow,staying o/night using the same bthroom etc.

    On Monday my father was diagonosed with Prostate cancer.I can;t help but think that on a cell level something in my fathers genetic predispostion/code was activated.I study molecular genetics by myself occasionally so its something I'm going to look into.

    By Blogger Katie, At August 24, 2010 7:42 pm  

  • A simple yes or no could help me understand a lot more clearly then reading all and getting confused. A yes and explaining the reasons why or how etc., and or a no and the reasons of why or how etc.

    By Anonymous Anonymous, At September 15, 2010 5:45 am  

  • "A simple yes or no could help me understand a lot more clearly..."

    No, it wouldn't.

    By Blogger angry doc, At September 15, 2010 6:55 pm  

  • so how do one define what "catch"? infected, developed symptoms? transmitted? This is too vague for such a complicated question.

    you have to look at how cancer manifest in the body (mainly via genetic mutation). virus caused cancer isnt common, and is very different from other virus caused diseases such as flu, STDs, etc.

    Besides, I dont think there are enough scientific evidence to show that cancerous cells can manifest and survive in vitro to "infect" other organisms.

    By Anonymous Anonymous, At January 13, 2012 9:29 am  

  • Thankfully, most people do not think of "catching" cancer in this way. They understand that there are certain forms of cancer, such as cervical cancer, that have been linked to viruses but even then, I don't think most people think of the transmission of the virus from one person to another as "catching" the tumors, etc that may result.

    By Anonymous Communicable diseases, At September 09, 2013 4:53 am  

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