From: Steve Harris <firstname.lastname@example.org>
Subject: Re: Drugmakers not following up speedy approval-US study
Date: 3 Jun 2005 10:36:16 -0700
Without knowing the mechanism for all cancers, obviously I can't give
you a complete answer.
At least SOME cancers are due to a gene mutation in a cell. It's NOT
present in all cells in that individual, or even all cells in that
tissue. It happens during replication in ONE cell, and it's somehow
conserved in the lineage of that cell. Often it takes MORE than one of
these events to trigger off a cancer (two or more somatic mutations),
but the concept is still the same--- not all cells in the parent tissue
have the cancer genetics. Therefore, once you kill all the cells which
do, you go back to the original state of risk. Which may not be that
high. Indeed may be low enough to allow a reasonable probability that
the organism will make it to old age and die of something else before
cancer strikes in that tissue again.
Now, what constitutes the baseline risk? Some of it is genetics of the
host, but not a lot. You have to work hard to find the increased
correlation in cancer risk between identical twins vs fraternal twins.
So don't imagine that what you're going to die of is written in your
DNA like some program. It isn't.
Some of the excess risk is environment. We all know about carcinogens
like cigarette smoke and chimney soot, and people often asssume that
all cancer risk which isn't genetic, some from mutagens and carcinogens
in the environment. Certainly if you've had lung cancer once and cure
it, you have an increase risk in the other lung if you continue to
smoke, and for many years, even if you quit. Colon cancer suffers
presumably also if they keep eating hot dogs (or whatever). That's why
people blame polution or food or something whenever their kids get
cancer. But population studies suggest that the environment is
responsible for no more than half the variation in cancer risk.
So what IS the rest due to? Probably to some kind of roll of the dice
in cell division. For years I used to do aging studies in rodents,
where the animals were all genetically essentially genetically
identical, identically housed side by side, and fed the same diet. We
had no other variables left to control. And yet they all died of
different things. Some got lymphomas, some hepatomas, some lived to old
age with arthritis and died of pneumonia. Every time we repeated the
experiment with the same strain we got the same percentages of the same
kinds of cancers, but we could never tell which animal was going to get
what. That says something.
There ARE events in cell division which are random. Indeed some are due
to straight quantum mechanical events like enol-keto form tautomersm in
cytidine. And these DO cause mutations. So perhaps we're seeing the
basic quantum dice roll at the most fundamental level of the laws of
nature operate here.
Or not. Random processes in science are where we sweep up all the
things for which we can't identify causal markers. Not all my mice had
the same mothers, nor the same place in the uterous during gestation,
etc, etc. The diets weren't PERFECTLY identical, and the radiation
environment from cosmic rays wasn't EACTLY the same for each animal,
and could never be, even for animal in the same cage. And so on.
Hope that helps. Bottom line is it's a risky world, and some of the
risk is in the deal of the cards where you can't get at it. Complain to
the Great Dealer about that. But not necessarily to your doctor or to
From: "Steve Harris" <sbharris@ix.RETICULATEDOBJECTcom.com>
Subject: Re: A Vaccine for Cervical Cancer...?
Date: Fri, 22 Nov 2002 04:39:00 GMT
Wyle E. Coyote, M.D. wrote in message
>"Steve Harris" <sbharris@ix.RETICULATEDOBJECTcom.com> wrote in message
>> Carey Gregory wrote in message ...
>> >Coyotedave <Coyotedave_member@newsguy.com> wrote:
>> >>Well , I not a doctor, but I find it hard to believe that a Virus
>> >>alone can cause Cancer in Humans,
>> >Well, so much for your opinions.
>> No kidding. If viruses cause cancers in animals (RSV, hepadnaviruses,
>> FeLV and so on) then why should it not be also the case with humans?
>> There's nothing special about our cells, or the way viruses attack
>You mean like HIV (lymphoma) and hepatitis B (liver cancer)?
>All the best,
Yep. There are even family resemblances in viruses, so that a cancer causing
virus in animals causes the same kinds of cancers in people. The hepadna
viruses cause liver cancer in woodchucks, and hep B is a hepadnavirus of
humans. FeLV causes leukemia in house cats, and HTLVs, the human analogues,
cause leukemia in humans (though most human leukemias are not caused by this
virus). FIV predisposes to lymphoma in house cats, SIV to lymphoma in Asian
monkeys, and HIV to lymphoma in humans-- all are lentiviruses, a type of
retrovirus. Kaposi's sarcoma isn't a typical cancer, but it's certainly
caused by a virus: HHV-8, also known as KSV. This virus causes KS in people
immunosuppressed, as for transplant, or from infection by HIV.
And by the way, viruses aren't the only cancer causing infectious agents.
Cancer is a consequence of too rapid cell turnover, and this can be caused
by an irritative factor, including irritative infections. There's a very
clear association, which is no doubt causal, between gastric lymphoma and H.
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