BOVINE SOMATOTROPHIN (BST) AND BREAST CANCER
by Samuel S. Epstein, MD, Professor of Occupational and Environmental
Medicine, The University of Chicago School of Public Health, and Chairman,
Cancer Prevention Coalition, Inc.
As of February 3, 1994, the Food and Drug Administration (FDA) has authorized
the nationwide sale of unlabeled milk from cows receiving shots of synthetic
bovine somatotrophin (BST), and they have restricted the labeling of milk
from untreated cows. The following article is excerpted from a letter,
dated February 14, 1994, from Dr. Epstein to Dr. David Kessler, Commissioner
of the FDA.
I am writing to express grave concerns about the risks of breast cancer
from consumption of BST milk. These concerns are based on the following
- BST administration induces a sustained
increase in levels of an uncharacterized insulin growth factor (IGF-1)
- IGF-1 is not destroyed by pasteurization.
- IGF-1 is not inactivated by digestion
in the human gut.
- Intact protein molecules, such as IGF-1,
are absorbed across the gut wall, particularly in infants. . . .
- There are close biological similarities,
including an identical amino acid sequence, between bovine and human
- BST administration induces prominent
uptake of IGF-1 by specific receptors in breast epithelium.
- IGF-1 induces rapid division and multiplication
of cultured human breast epithelial cells.
- IGF-1 induces malignant transformation
of normal human breast epithelial cells.
- IGF-1 is a growth factor for human breast
cancer cells, maintaining their malignancy, progression, and invasiveness.
IGF-1 has been similarly associated with colon cancer.
- Apart from increasing IGF-1 levels in
milk, BST directly stimulates further IGF-1 production at the local
cellular level. Thus, undigested BST or partially digested active fragments
absorbed across the permeable infant gut may still further IGF-1 production
by breast epithelium. . . .
- The undifferentiated prenatal and infant
breast is particularly susceptible to hormonal influences. Such imprinting
by IGF-1 may not only constitute a direct breast cancer risk factor,
but may also increase the sensitivity of the breast to subsequent unrelated
risk factors, such as carcinogenic and estrogenic pesticide contaminants
in food, and mammography.
On the basis of these data and women’s right to know, I urge that minimally
you revoke recent FDA restrictions on labeling of BST-free milk. More
prudently, I further urge that you revoke approval of BST registration.
Article from NOHA NEWS, Vol. XIX, No. 2, Spring
1994, page 6.