From: sbharris@ix.netcom.com(Steven B. Harris)
Newsgroups: sci.bio.immunocytochem,sci.med,sci.med.diseases.cancer,
	sci.med.immunology,sci.med.pathology
Subject: Re: Could cancer be contagious between identical twins ?
Date: 6 Sep 1998 21:23:51 GMT

In <1dexr31.1s2hefb10qrvpqN@p45-nothura-gui.tch.virgin.net>
swilnews@stones.com (Simon) writes:

>Everyone knows cancer is not contagious as someone's cancer cells are
>recognised as foreign if they infect someone else, but are 'self' to the
>sufferer.
>
>Would the identical twin of a cancer sufferer be able to catch cancer if
>they recieved cancerous cells from their identical sibling (Leukimia
>blood cells or skin cancer cells for example) as these cells would be
>seen as self ?


   Yes, in theory, leukemia would indeed be transmissable between
identical twins, though you'd probably have to have a pretty good blood
contact to do it.  Not just using the same toothbrush, but rather a
needle stick, or blood on an open cut, etc.

    There are cases in the literature of cancers being transmitted even
from one NON-RELATED person, to another.  In one fairly famous case, a
surgeon stuck himself with a needle from a biopsy of a man with a
malignant sarcoma, and ended up with a sarcoma at the stick site, in
his hand.  Genetic analysis proved it to be the other man's tumor,
growing along nicely (if locally).  It was resected, apparently
sucessfully.  Thus, if you do happen to get somebody else's tumor from
something like this, if they aren't related to you, your body probably
has an additional weapon against the cancer, and it's probably less
dangerous (less likely to metastasize and kill you).  But the number of
cases is so low that nobody really knows.

                                        Steve Harris, M.D.

From: sbharris@ix.netcom.com(Steven B. Harris)
Newsgroups: sci.bio.immunocytochem,sci.med,sci.med.diseases.cancer,
	sci.med.immunology,sci.med.pathology
Subject: Re: Could cancer be contagious between identical twins ?
Date: 7 Sep 1998 02:28:18 GMT

In <6sv443$ivt@bgtnsc02.worldnet.att.net> "Robert Reck"
<bcreck@worldnet.att.net> writes:

>I have a similar question.  Is it possible to contract cancer from a blood
>transfusion?

   Maybe.  Just maybe.  Certainly you can get several viruses that
cause cancer (hep B and C, HTLV's, HIV), but the ones we know about, we
screen for.  The problem is the ones we don't know about.

   And as for direct engraftement of cancer cells, we know that some
engraftment of stem cells happens in transfusions.  If it never ever
happens with cancer cells, and can't, it will surprise me.  But proof
is lacking either way. They don't let people with known cancer donate
blood, which means that somebody is worried about it.  I don't think
this policy is only to protect donors, either.

> Many people are walking around unaware of cancers growing
>within them.  Would the testing that blood products go through show evidence
>of any type of tumor in blood donors??

    Nope.

>If not, isn't it possible then that
>the tumor cells could be passed, particularly to an immunosuppressed cancer
>patient needing a blood transfusion?


   My guess, and it is no more than a guess, is yes.  Very rarely, but
yes.


                                       Steve Harris, M.D.

From: jrfox@no.spam.fastlane.net.no.spam (Jonathan R. Fox)
Newsgroups: sci.bio.immunocytochem,sci.med,sci.med.diseases.cancer,
	sci.med.immunology,sci.med.pathology
Subject: Re: Could cancer be contagious between identical twins ?
Date: Mon, 07 Sep 1998 07:44:00 GMT

On 6 Sep 1998 21:23:51 GMT, sbharris@ix.netcom.com(Steven B. Harris)
wrote:
>    There are cases in the literature of cancers being transmitted even
>from one NON-RELATED person, to another.  In one fairly famous case, a
>surgeon stuck himself with a needle from a biopsy of a man with a
>malignant sarcoma, and ended up with a sarcoma at the stick site, in
>his hand.  Genetic analysis proved it to be the other man's tumor,
>growing along nicely (if locally).  It was resected, apparently
>sucessfully.  Thus, if you do happen to get somebody else's tumor from
>something like this, if they aren't related to you, your body probably
>has an additional weapon against the cancer, and it's probably less
>dangerous (less likely to metastasize and kill you).  But the number of
>cases is so low that nobody really knows.

I read about this case as well.  There is also a case of an organ
donor whose liver and two kidneys apparently carried tumor cells, and
the three recipients were affected.

--
Jonathan R. Fox, M.D.

From: jrfox@no.spam.fastlane.net.no.spam (Jonathan R. Fox)
Newsgroups: sci.med
Subject: Re: Is Cancer Contagious?
Date: Wed, 25 Aug 1999 03:26:28 GMT

On Tue, 24 Aug 1999 17:00:19 GMT, "Jeffrey Peter, M.D."
<kidsdoc2000@hotmail.com> wrote:

>From a practical standpoint, it works well too. You cannot catch AIDS by
>being in the same room as another person with AIDS, unless there is transfer
>of bodily fluids. Same with cancer. And as Dr. Fox so kindly (and timely,
>for I have not heard this before) pointed out, we need to avoid the body
>fluid of all people, for you do not know what cells are lurking there.
>(Thanks Dr. Fox)

You're quite welcome.  I do want to stress that the two cases I
reported of transmission of cancer cells from one human to another are
examples of incredibly rare incidences, and in my opinion were freak
accidents.  Cancer is generally not to be considered a contagious
condition.

--
Jonathan R. Fox, M.D.