Re: Cohen's Observation

[epirad@mchsi.com]

Just to clear up a few more statements you made- 



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/



Quantity of data should not be as important as quality of data.   In many 

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

cancer.  



For example, in Iowa, Cohen’s county female lung cancer mortality data had 

minimal power for predicting actual female county lung cancer incidence rates 

for the more temporally correct time period (R = 0.15).    



Cohen said, --I used the mortality data for 1970-1979 and for 1979-1994. These

are the only sets of data for which lung cancer mortality rates are  available 

for anywhere nearly all of the counties. I did not use the SEER data because 

it is not available for most counties, because it would take a lot of time to 

data enter.  



Response:



The ease of data entry should not be a pressing consideration for valid data



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

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

basements.



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.  

I stated, we already showed that Cohen's summary smoking information alone

does a poor job of explaining the lung cancers within the counties.

 

Cohen stated, On the contrary, it does an excellent job of inndicating that

 the great majority of lung cancers are caused by smoking.



Response: We previously showed (Smith et al. 1998 HPJ, Field et al. 1999 HPJ) 

that 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. In addition, 

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.



Surely these disagreements will not be resolved on Radsafe, only by a mutually 

agreed 3rd party.

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