Re: X-ray Acne Treatment

[isurveyor@vianet.net.au (Ivor Suveyor)]

>>Joel:
>     There was an extensive use of x-ray for treatmeent of ringworm of the
>scalp in Israel between 1948 nd 1960.  Of approximately 20,000 children so
>treated, 10,834 were studied in a follow up. Treatment was with 75 - 100
>kVp. EAch of five scalp fields was treated with 350-400 roentgens on
>sucessive days.  10% of subjects had more than one treatment.
>     Ron et al report on mortality of the follow-up group in Am.
>J.Epidemiol. vol 127, 13-25, 1988.  Modan in the 1993 G. William Morgan
>lecture, (Health Physics vol. 65 475-480, 1993) on "Low Dose Radiation
>Carcinogenesis" reports a two fold increase in the risk of breast cancer
>and a fourfold increase of thyroid cancer, following a minimal exposure of
>16 mGy and 90mGy respectively.." (These I believe are tissue dose
>estimates ) Carcinogenesis rates were higher in the
>children treated at younger ages.  Ron et al. report a relative risk of 3
>for tumors of the head and neck, of 2.3 for leukemia, and bone and soft
>tissue sarcoma of 9, all of which were significant.  The last follow-up
>observations were in 1987.  The expectation is that radiation induced
>solid cancers would continue to be observed. 
>    O.K. its not acne.        John Goldsmith gjohn@BGUMAIL.bgu.ac.il

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PERTH WA
19-September-1997

Dear Radsafers,

The question raised by the thread on possible cancers induced by childhood
irradiation  are relevant to discussions on the acceptance or rejection of
the no threshold linear hypothesis.  It is likely that supporters of the
hypothesis would argue that the evidence from childhood irradiation  shows
that in some instances there is NO EVIDENCE OF A THESHOLD.    I would be
very interested to learn from expert opinion how this literature evidence
fits with the recent HPS position paper. 

There have been a  number of reports of an association between childhood
radiation and thyroid and cancers since Duffy  and Fitzgerald published in 1950.

Radiation was administered to treat a large variety of diseases in the upper
chest, head and neck since the 1920's and  earlier.   Including  So called
thymic enlargement, hypertrophy of tonsils and adenoids, deafness due to
lymphoid hypertrophy around the Eustachin tube.    Cervical adenitis,
mastoiditis, sinusitis, hemangioma, keloid scars, tinea capitus, and acne  (
editorial. Walfsh PG et al JAMA 1978; 88: 261-262).         

According to Webber BN ( Ann of Int Med 1977; 86: 449-450) there are 17
English language papers between 1920 and 1935 relating to the radiation
treatment of whopping cough.

Thus there seemed to have been a plethora of cases for epidemiological
study.    Some of which have been considered in an email from  Dr John
Goldsmith. 

Modan B, Ron E, and Werner A  Radiology  1977,123: 741-744.   Gives some
details of technique used in skull radiation.  The mean  dose to thyroid was
less then 9 rad (90 mGy )and the risk of cancer is given as 6.3/10e6/y.
If tissue weighting factors are applied the whole body or effective dose
would be very small indeed.
 
The questions that I am putting are these.   Do experts agree that following
a latent period of 10-15 years the association of thyroid and other cancers
with childhood radiation is causal?.   The actual exposure to thyroid from
scattered radiation was small. 
Does the evidence from these studies argue against the HPS position paper?
Is there No threshold in case of children? 
It is unlikely that the dose estimates to thyroid are wrong by a large
factor.  So a further question is why is the thyroid and breast tissue of
young female children so sensitive to radiation?   If there is to be a
relaxation in regulations, ( so as to allow for no threshold ),  will a
special and more stringent provision have to be made for youngsters? 
 I would be interested, if anybody can put these studies into a  modern
perspective.  
Ivor Surveyor

Ivor Surveyor
Emeritus Consultant Physician, Nuclear Medicine. 
E-mail:    isurveyor@vianet.net.au