Re: abnormal chromosomes and cancer

[Kai Kaletsch <info@eic.nu>]

What does this say: "Radon causes chromatid breaks which cause cancer" OR

"Radon causes both chromatid breaks and also causes cancer"?



The statement: "We obtained similar results when we

analyzed the incidence of lung cancer and the incidence other than lung

cancer separately." is interesting.



I thought that the other radon studies did not show an increase in cancers

other than lung. If we interpret the statement as evidence that some cancers

were caused by radon, would that mean that radon exposure also prevented an

equal (or greater) number of cancers form occurring?



Did this cohort also have gamma exposure?



Kai



----- Original Message -----

From: "Field, R. William" <bill-field@UIOWA.EDU>

To: <radsafe@list.vanderbilt.edu>

Sent: Friday, February 01, 2002 10:20 PM

Subject: abnormal chromosomes and cancer





> It is pretty rare to see a study actually relates the degree of abnormal

> chromosomes with cancer.  I would like to hear others thoughts on this

paper.

>

> Regards, Bill Field

>

>

> Increased risk of cancer in radon-exposed miners with elevated frequency

of

> chromosomal aberrations.

>

> Mutat Res 2002 Feb 15;514(1-2):165-176 I

>

>

> Smerhovsky Z, Landa K, Ro"ssner P, Juzova D, Brabec M, Zudova Z, Hola N,

> Zarska H, Nevsimalova E.

>

> National Institute of Public Health, Srobarova Str. 48, 10042 10, Prague,

> Czech Republic In spite of the extensive use of cytogenetic analysis of

> human peripheral blood lymphocytes in the biomonitoring of exposure to

> various mutagens and carcinogens, the long-term effects of an increased

> frequency of chromosomal aberrations in individuals are still uncertain.

> Few epidemiologic studies have addressed this issue, and a moderate risk

of

> cancer in individuals with an elevated frequency of chromosomal

aberrations

> has been observed.In the present study, we analyzed data on 1323

> cytogenetic assays and 225 subjects examined because of occupational

> exposures to radon (range of exposure from 1.7 to 662.3 working level

month

> (WLM)). Seventy-five subjects were non-smokers. We found 36 cases of

cancer

> in this cohort.Chromatid breaks were the most frequently observed type of

> aberrations (mean frequency 1.2 per 100 cells), which statistically

> significantly correlated with radon exposure (Spearman's correlation

> coefficient R=0.22, P<0.001). Also, the frequency of aberrant cells

(median

> of 2.5%) correlated with radon exposure (Spearman's correlation

coefficient

> R=0.16, P<0.02). Smoking and silicosis were not associated with results of

> cytogenetic analyses.The Cox regression models, which accounted for the

age

> at time of first cytogenetic assay, radon exposure, and smoking showed

> strong and statistically significant associations between cancer incidence

> and frequency of chromatid breaks and frequency of aberrant cells,

> respectively. A 1% increase in the frequency of aberrant cells was

> paralleled by a 62% increase in risk of cancer (P<0.000). An increase in

> frequency of chromatid breaks by 1 per 100 cells was followed by a 99%

> increase in risk of cancer (P<0.000). We obtained similar results when we

> analyzed the incidence of lung cancer and the incidence other than lung

> cancer separately.Contrary to frequency of chromatid breaks and frequency

> of aberrant cells, the frequency of chromatid exchanges, and

> chromosome-type aberrations were not predictive of cancer.

>

> Regards, Bill Field

>

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