[ RadSafe ] Cancer
Mohan.Doss at fccc.edu
Mon Aug 18 13:50:30 CDT 2014
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 Doss, Ph.D., MCCPM
Associate Professor, Diagnostic Imaging,
Fox Chase Cancer Center,
333 Cottman Avenue,
Philadelphia, PA 19111-2497.
Phone: 215 214-1707
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
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
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
You are currently subscribed to the RadSafe mailing list
Before posting a message to RadSafe be sure to have read and understood the RadSafe rules. These can be found at: http://health.phys.iit.edu/radsaferules.html
For information on how to subscribe or unsubscribe and other settings visit: http://health.phys.iit.edu
CONFIDENTIALITY NOTICE: This email communication may contain private, confidential, or legally privileged information intended for the sole use of the designated and/or duly authorized recipient(s). If you are not the intended recipient or have received this email in error, please notify the sender immediately by email and permanently delete all copies of this email including all attachments without reading them. If you are the intended recipient, secure the contents in a manner that conforms to all applicable state and/or federal requirements related to privacy and confidentiality of such information.
More information about the RadSafe