Re: Cohen's Observation

[epirad@mchsi.com]

Dr. Cohen, 



I wrote: You stated in a previous paper that 27% of bedrooms in your 

         data set were located in the basements.

 

Cohen wrote: I am quite sure this is not correct. If you insist, I will try

             to find my papers on this.



If we can not agree on what you write in your own papers, we surely can not 

agree on more scientific issues.  I previously accepted your offer to allow a 

mutually agreed upon scientists to review my stated reason why you are finding 

an inverse association, but you did not agree to any of the highly regarded 

scientists I suggested so lets agree to let this is in the hands of the NCRP 

at this time. 



The reason I enter this debate is not about ego, but rather because so many 

people including knowledgeable HPs and Physicists misinterpret your findings 

to indicate prolonged residential radon exposure does not cause lung cancer 

(eventhough the vast majority of case-control studies indicate it does). You 

have stated yourself ecologic studies can not assess risk.  This needs to be 

stated by you more often. While ecologic studies can not assess causality, 

analytic epidemiology studies (such as case-control studies) do have the 

ability to establish causality.



If you would have found a positive ecologic association between radon and lung 

cancer and used that to state this proves the LNT is valid, I would be just a 

fervent in my opposition in you using it to test the LNT because of the 

limitations of the ecologic design.  This debate has not been about the 

validity of the LNT, this debate has been about the limitations of ecologic 

studies. You state the limitations inherent in ecologic studies do not exist 

if you use an ecologic design to test the LNT, no knowledgeable epidemiologist 

would agree with such a contention.  



The validity of the LNT should be tested, but not by such a weak tool as an 

ecologic study. 



I am sure there are many other areas we do agree on, but the proper use of an 

ecologic study is not one of them. 



Regards, Bill Field































> 

> On Sun, 15 Jun 2003 epirad@mchsi.com wrote:

> > Dr. Cohen stated, he did not use the SEER data because it is not available for

> > most counties, because I don't understand why it is better than mortality 

> data.

> >

> > Response -

> >

> > The SEER Program is the only comprehensive source of population-based

> > information in the United States that includes stage of cancer at the time of

> > diagnosis and survival rates within each stage. SEE:

> > http://www.seer.cancer.gov/about/

> > Data is easily available using SEER stat which I previously sent Dr. Cohen

> > information about.   http://www.seer.cancer.gov/seerstat/

> 

> 	--It would take a lot of time and trouble for me to get the SEER

> data into my data bases, and I don't think the results of that effort

> would be publishable. If I can be assured that the results will be

> publishable, I will undertake that effort. I still don't understand why

> the SEER data are better for my purposes, and I don't see how I would use

> info on stage of cancer at time of diagnosis and survival rates at each

> stage. It is my understanding that lung cancer is nearly always fatal.

> 

> > Quantity of data should not be as important as quality of data.

> 

> 	--It is important to have counties from all over the U.S. as that

> reduces the potential for confounding. For example, in a single state, it

> is easily possible that an ethnic group that is less susceptible to lung

> cancer lives in a region with high radon levels. When all states are

> included, with numerous areas of high and low radon and numerous

> ethnic groups in populations, this would be extremely improbable.

> 

>  In many

> > state cancer registries, lung cancer is reported even if it is a secondary

> > cancer.

> 

> 	--I did not know this. I sent an inquiry to CDC asking what

> fraction of reported lung cancers are primary.

> 

> > Within your references, you also state that within your data –

> >

> > Low-income families are grossly underrepresented.

> > High rise apartments are not represented.



> > People concerned with environmental issues are overrepresented

> > Urban areas are greatly underrepresented

> > Cigarette smokers (and those socioeconomic factors associated with smoking)

> > are

> >           underrepresented

> > Rented homes are grossly under represented

> 

> 	--These problems are considered in several of our papers. The

> principal reason for my confidence in our radon levels is the agreement

> with EPA studies and with studies sponsored by various states

> 

> > You also indicated that 27% of bedrooms in your data set were located in the

> > basements.

> 

> 	--I am quite sure this is not correct. If you insist, I will try

> to find my papers on this.

> 

> > When we replicate Cohen’s regression of Riggan’s lung cancer mortality data on

> > Cohen’s radon measurements, we get the same large negative associations as

> > reported by Cohen.  However, when we use the more temporally correct Iowa SEER

> > lung cancer incidence rates and regress them on Cohen’s radon measurements and



> > smoking percentages the large negative correlations go away.

> 

> 	--See my above example of how info on an individual state can be

> affected by confounding factors

> 

> >  when Cohen's adjusted smoking percentages for males and females were

> > regressed on radon levels, significant (p < 0.00001) negative associations

> > between smoking and radon were noted for both males and females.

> 

> 	--Why is this a problem? I reduces the discrepancy with LNT. If it

> were not so, the discrepancy would be greater.

> 

> > when we (Smith et al. 1998) repeated the regression of lung cancer mortality

> > rates on Cohen's adjusted smoking percentages, the resulting R2 values

> > indicated that Cohen's smoking summary data explained very little (23.7% for

> > females; 34.5% for males) of the variation in lung cancer mortality rates.

> 

> 	--R-squared reflects statistical fluctuations; see my paper in

> Health Physics 72:622-627;1997. This subject is treated in more detail in

> Item #15 on my web site -- see discussion around Eqn.(5)

> 



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