Does CT lung cancer screening LOWER lung cancer risk?

["Howard Long" <hflong@pacbell.net>]

"4,687 non-leukemic cancer deaths occurred in 50,115 [exposed] survivors

where we estimated 4,306 would have occurred, had they not been exposed [to

1 to 10 cSv or rads]." (ref below). Indeed, that would suggest a slight

INCREASE in cancer deaths from CT, (c 1 rad).



However, the small difference (8%) might be explained by many variables.



Mostly I doubt the conclusion because it is inconsistent with other data:

The Breast Cancer Incidence Among Atomic Bomb Survivors (Land CE, McGrgor

DH, JNatl Cancer Inst 1979 Jan;62(1):17-21 table 2 shows "average tissue

dose, rads Observed 109 vs Expected 127.8 p,0.0001", but broken down,

rads 1-9, Observed 34 breast cancers, Expected 42.3 breast cancers!



Thus for that dosage, there is evidence that 1-9 rad acute exposure may

LOWER breast cancer risk. I abandoned design for a study using mammography

and CT

because the 1 rad acute from the CT would lower the power to detect

significant differences, since it would have much the same benefit as the

exposure (no good placebo). This is much the same problem as drug companies

are having with placebo in anti depressants (Wall St Journal, 6/18/04).



I think CT may LOWER lung cancer risk.



Howard Long



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

From: "John Jacobus" <crispy_bird@YAHOO.COM>

To: "Keith Welch" <welch@jlab.org>; <radsafe@list.vanderbilt.edu>

Sent: Friday, June 18, 2004 1:43 PM

Subject: Re: Article: Lung cancer screening raises lung cancer risk





> The Radiation Effects Research Foundation show 63

> deaths (2% of 3391 cancer deaths) between 5 mSv and

> 200 mSv

> http://www.rerf.or.jp/eigo/radefx/late/cancrisk.htm

>

> Of course I have not read any of the reports which

> might have more current information.  However, it

> appears to be a bit of data mining (word-smithing?) to

> enhance the risk value.

>

> Keith, the HPS position paper I think you are

> referring to is at

> http://hps.org/documents/radiationrisk.pdf

>

> --- Keith Welch <welch@jlab.org> wrote:

> > Is this really right?  Are the bomb survivor

> > statistics correct?  How does the cancer risk in the

> > atomic bomb cohort reconcile with the HPS position

> > paper on "radiation risk in perspective" which

> > states that quantitative risk estimates should not

> > be used below 10 rem?  (coincidentally, it seems

> > that position paper is no longer on the HPS website.

> >  Is it under revision?)

> >

> > "For example, 10 low-dose CT lung screening

> > examinations would produce lung doses in the range

> > of

> > 25 to 90 mGy," he wrote. "Among approximately 30,000

> > individuals in the cancer incidence cohort of atomic

> > bomb survivors who received doses between 5 and 100

> > mSv (mean dose, 29 mSv), there was a statistically

> > significant increase in cancer risk (77 excess

> > cancers, p = 0.05) compared to that in the control

> > population."

> >

> >

> > Keith Welch

> >

> >

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> =====

> +++++++++++++++++++

> "To be persuasive, we must be believable,

> To be believable, we must be credible,

> To be credible, we must be truthful."

> Edward R. Murrow

>

> -- John

> John Jacobus, MS

> Certified Health Physicist

> e-mail:  crispy_bird@yahoo.com

>

>

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