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 scientific considerations:
  • BST administration induces a sustained increase in levels of an uncharacterized insulin growth factor (IGF-1) in milk.
  • 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 IGF-1.
  • 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.