[ RadSafe ] Cancer

Tue Aug 19 11:03:21 CDT 2014

Mohan/Radsafe:

      If one can model computationally radiation  scattering from DNA, 
cells etc., one could probably also model the adaptive  response you mention.  
Adaptive Estimation --- I seem to remember a book by  Widroe/Widrow???
Take Care.

     Regards,   Joe Preisig

In a message dated 8/18/2014 2:50:54 P.M. Eastern Daylight Time,  
Mohan.Doss at fccc.edu writes:

Dear  Joe,
The basic concept you are implying, that DNA damage  causes cancer, is not 
consistent with evidence.  Of course DNA damage is  needed to have cancer, 
but it is not sufficient.  In fact almost everyone  has covert cancer 
http://www.nature.com/nrc/journal/v14/n4/full/nrc3703.html ,  i.e. cells with 
carcinogenic mutations, but a majority of us are not diagnosed  with cancer even 
in all of our lifetime.  What gives rise to clinical  cancer is the 
depression of the immune system, which allows these covert  cancers to grow 
uncontrollably.  If the immune system is not depressed,  the slightly increased 
number of mutations from any cause, e.g. radiation,  would not affect cancer 
risk.    Low-dose radiation boosts the  immune system and so would reduce 
rather than increase cancers.  The  adaptive response due to low-dose radiation 
would boost defenses like DNA  repair enzymes and so would reduce the damage 
to DNA over the longer term,  since the increased protection would reduce 
the endogenous
DNA  damage that would have occurred otherwise. I have described this 
briefly in  the recent debate on health effects of low-dose radiation in Medical 
Physics  
http://scitation.aip.org/content/aapm/journal/medphys/41/7/10.1118/1.4881095.  
So, doing MCNP, etc. to calculate the DNA damage, without  including the 
adaptive response of the body, may not help with estimating  cancer risk from 
radiation.
There is evidence cancers have  resolved spontaneously, and this is 
probably because the immune system got rid  of the cancer cells.   
With best regards,
Mohan

Mohan Doss, Ph.D., MCCPM
Medical Physicist,
Associate  Professor, Diagnostic Imaging,
Fox Chase Cancer Center,
333 Cottman  Avenue,
Philadelphia, PA 19111-2497.
Phone: 215 214-1707
Website:  http://www.fccc.edu/research/pid/doss/
Blogs:  http://mohan-doss-home-page.blogspot.com/

-----Original  Message-----
From: radsafe-bounces at agni.phys.iit.edu  
[mailto:radsafe-bounces at agni.phys.iit.edu] On Behalf Of  JPreisig at aol.com
Sent: Sunday, August 17, 2014 11:20 PM
To:  radsafe at agni.phys.iit.edu
Subject: [ RadSafe ]  Cancer

Radsafe,

I guess in cancer  production, the carcinogen  is in some volume within the 
body, and this  volume can grow if the carcinogen  continues to be 
introduced into the  body.  The cancer is probably in the  vicinity of this 
carcinogen  volume.  One question I might ask is that once  the cancer grows  
outside of the carcinogen volume, will the cells (upon cellular   division) 
continue to be cancerous?  I expect bodily circulation and  other  processes could 
also cause the carcinogen volume to diminish  in size.   Quite a dynamic 
process....

I guess cancer production via radiation is a whole   different process, 
mostly a scattering process of the various forms of  radiation  by cells, DNA 
and so on.  Any new science on single  strand breaks, double  strand breaks 
etc. in the literature  lately???

Maybe someone (a young person) could start to  use MCNP,  MCNPX or some 
similar computer code, to model computationally  (on a  supercomputer these
days) the scattering of radiation from DNA  strands, whole  human cells, 
groups of cells, various human tissues  and so on.   Computationally 
setting up 
the first DNA strand or  human cell would be pretty  daunting.  The 
repeated 
structures  capability of MCNP might be  helpful.   Doing some studies  
computationally may allow us to avoid  doing all the studies via lab  
experiments on various animals.  I guess  animal studies would still  be required 
for important intellectual steps...

Has it  ever been observed that a cancerous human cell  has reverted to a  
non-cancerous state????

Have a good week.   Regards,    Joseph R.  Preisig

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