884 
GENETIC AND BIOLOGICAL EFFECTS OF RADIATION 
100 
- 80 
60 
- 40 
r ^ Uterine Tumors \ Controls 
o o Hepatic Tumors (mole 8 female) J 
A A uterine Tumors 
• • Hepatic Tumors(male B female) I 
■ ■Intestinal Tumors (male & female) L 
20 
Virradiated 
5 6 7 8 9 
Time Postirradiation (Years) 
Figure 7.— The cumulative incidence of uterine, hepatic, and intestinal tumors in swine exposed to mixed gamma- 
neutron (bomb) and X-radiation and controls. Dose range: 15 to 850 rads. 
to 100 R fractional whole-body gamma ray irra- 
diation. Amer. J. Physiol. 180:403-407, 1955. 
28. Rust, J. H., Trum, B. F., Lane, J. J., Kuhn, 
U. S. G. Ill, Paysinger, J. R., and Haley, T. J. 
Effects of 50 roentgens and 25 roentgens fractional 
daily total-body y-irradiation in burros. Radiat. 
Res. 2:475-482, 1955. 
DISCUSSION 
John Sesmenic, University of Michigan: 
Did you or the pathologist speculate on a reason 
for the high incidence of uterine tumors and 
those of the broad ligaments? Is it just that 
that happened to be the tissue in line with where 
the radiation was coming into or through the 
animal or is there a more involved explanation? 
Dr. Brown: Uniformity of dose is an im- 
portant factor to consider. In this case the swine 
were positicned for unilateral exposure so that 
the dose-in-£ ir would be equal from the anterior 
to posterior of the animals. We do not believe 
that the uterus and broad ligaments received 
doses larger than any other organs or tissues 
of equal depth in the swine. The data indicate 
that these tumors occurred earlier in the swine 
because of irradiation. Although the highest 
doses may have been sufficient to cause induc- 
tion of tumors, we have doubts about this be- 
cause of the incidence of tumors in the aged 
control swine. 
H. A. Ragan, Battelle Pacific Northwest 
Labs : Also in reference to these uterine tumors, 
I'd like to preface my question with a remark. 
We see near a 50 per cent incidence of uterine 
tumors in our miniature swine and this is not 
dose related. These tumors occur between six 
and eleven years of age. I'm wondering whether 
you know of any surveys of the incidence of 
uterine tumors in the swine population in gen- 
