Re: LNT Remarks

[Scott Crail <crail@ENGR.ORST.EDU>]

According to the latest theory, as I understand it,cancer is caused by a 
series of mishaps that are presuamably the same no matter the 
carcinigen.  It is a thought that at least three different "hits" on the 
DNA strand are required to cause a cell to become cancerous(benign) and a 
couple more for it to start to metastisize(ie spread through out the 
body).  The the minimum nuber of hits required ranged from 3-7.  All of 
this adds up to why it is so hard to "prove" what caused a specific 
cancer.  Hope this helped at least a little.  If you want more, contact 
me and Ill look up the title of a good cell bio book.


Scott Crail
Grad Student, OSU
crail@engr.orst.edu

On Thu, 28 Mar 1996, Cummings, Frederick wrote:

> 
>      Hi, all,
> 
>      What an interesting thread this Lin-No-Thresh has been.  I couldn't
>      help asking what I think is an associated question to further stir the
>      waters (and show my ignorance of the basic question.)
> 
>      Is cancer a one-step process caused by a single 'carcinogen'?  What
>      basis should be used to determine causality, even for cancers which
>      are considered 'radiogenic' in origin (from high dose studies?)
> 
>      I seems to me that the reason that carcinogenicity is observed at high
>      doses lies in the fact that radiation can interact with tissue as an
>      initiator and as an immunosuppressant.  At lower doses, the spatial
>      and temporal distribution of dose may not coincide to the extent that
>      cancer can be produced by the radiation alone.  I think that this
>      probably holds for many of the chemical compounds that are currently
>      labelled carcinogenic.
> 
>      Another confounding factor which comes to mind is the temporal
>      distribuion of dose itself.  If sufficient radiation is present to
>      disrupt the proteins used to regulate the frequency of cell division
>      during the time that the affected cells are in recovery from the
>      division process, then perhaps the cell division rate may be affected
>      in an adverse way causing decreasing functionality and differentiation
>      in future generations of daughter (or son) cells.
> 
>      These are just a few thoughts.  Please help me out.  Are these random
>      wanderings of a mad man, or just plain half-truths?
> 
>      Rick Cummings
>      cumminfm@inel.gov
> 
>      *** The remarks above are too ridiculous to be considered damaging to
>      anyone but the author himself.  In no way do they reflect the opinions
>      of any responsible agency in the public arena.  ***
> 
>