Unisersity of Notre Dame
College of Srience
Notre Dame, Indiana 46556

Department of Microhialagy May 21, 1971 Lobund Laboratory

Dr. Joshua Lederberg
Department of Genetics
Stanford University
Stanford, California

Dear Dr. Lederberg:

I read with great interest your thought-provoking column in
Current Topics of May 5, 1971 on the subject of Cancer Cure."

We have been much impressed with results of aging studies
in our germfree and conventionalized rats. We have arbitrarily
killed germfree rats at ages beyond two years and they show neither
lesions of aging nor of malignant neoplasms. The conventionalized
control rats usually die by age 18 months and they show the above
lesions. We have interpreted the data as evidence of pathogenic
factors in the environment which have been excluded by the germfree
system. This is further supported by the induction of malignant neo-
plasms in germfree rats by sterile carcinogenic agents (x-rays,
methylcholanthrene, DMBA), and the development of degenerative
lesions by dietary deficiencies and by x-rays. Actually, we do not
know how long germfree rats will live, nor what they will eventually
die of, In general, this supports your view that preventive measures
will provide more immediate benefits to man than are now evident in
the area of therapy.

With cordial regards,
Sincerely,
a}

Mey LIC CCC? Leree. one -p fin ban, /

eon Morris Pollard
CL ae Director