[ RadSafe ] FW: RE: So called bystander effect for brain tumors in irradiated mice

[HOWARD.LONG at comcast.net]

-------------- Forwarded Message: -------------- 
From: "Scott, Bobby" <BScott at lrri.org> 
To: <HOWARD.LONG at comcast.net> 
Subject: RE: So called bystander effect for brain tumors in irradiated mice 
Date: Thu, 21 Aug 2008 19:11:36 +0000 

Howard,
 
You may forward it if you like. Rainer has again commented in Radsafe on bystander vs. abscopal effects.
 
Bobby
 



From: HOWARD.LONG at comcast.net [mailto:HOWARD.LONG at comcast.net] 
Sent: Thursday, August 21, 2008 1:05 PM
To: Scott, Bobby
Subject: Re: So called bystander effect for brain tumors in irradiated mice
 
Bobby,
Because of current discussions, I believe this would be interesting to radsafe at radlab.nl  
 
May I forward it?
 
Howard Long
 
-------------- Original message -------------- 
From: "Scott, Bobby" <BScott at lrri.org> 
To: Clayton Bradt, Glenn Marshall, Howard Long, and Rainer Facius
 
Dear Colleagues:
 
In light of your interest in the so-called bystander effect that was discussed in Radsafe Digest (Volume 160, Issue 3, August 20, 2008) that relates to brain tumors in radiosensitive mice, I thought you may find the attached paper by Camphausen et al. (2003) to be of interest.  The paper is entitled “Radiation abscopal antitumor effect is mediated through p53.” Please note the terminology “abscopal effect” as mentioned by Rainer Facius is used as has been done historically. The terminology bystander effect is more recent and has usually referred to un-hit cells in the vicinity of hit cells that are also affected. With the study design indicated for the mouse study of brain tumors, one has to consider the dose scattering.  One cannot have a bystander effect if there is a small scattered dose irradiating the brain as apparently was the case for the PNAS paper by Mancuso et al. (2008).  An abscopal effect can occur in un-irradiated tissue and can be either detrimental or beneficial (s
ee the attached paper for an example of a benefit).  A 3 Gy dose to a large portion of the body can suppress the immune system possibly allowing for a small scattered dose (e.g., few mGy) to induce cancers at other sites in radiosensitive mice that would otherwise not occur after a small dose alone. 
 
Best wishes,
Bobby R. Scott
Senior Scientist
Lovelace Respiratory Research Institute
2425 Ridgecrest Drive SE
Albuquerque, NM 87108 USA