A study of U.S. women published May 9 in the LANCET links insulin-like
growth factor-1 (IGF-1) with breast cancer.[1,2] Earlier this year a
study linked IGF-1 to prostate cancer. (See REHW #593.) Prostate and
breast cancers are major killers of men and women in the U.S. and in
other industrialized countries. IGF-1 levels are now being artificially
increased in much of the cows' milk being sold throughout the U.S.
These new cancer studies raise serious questions about the wisdom of
allowing IGF-1 levels to be raised in milk.
The latest study found a 7-fold increased risk of breast cancer
among pre-menopausal women younger than age 51 with the highest levels
of IGF-1 in their blood. The prostate cancer study published in SCIENCE
in January, 1998, found a 4-fold increase in risk of prostate cancer
among men with the highest levels of IGF-1 in their blood. Thus IGF-
1 in blood is associated with larger relative risks for common cancers
than any other factor yet discovered.
It is not clear from these studies whether IGF-1 causes these cancers,
or whether elevated IGF-1 accompanies some other factor that causes
these cancers. At the very least, researchers are hoping that
measurements of IGF-1 will identify individuals at high risk of getting
these cancers, so that surveillance might be increased. (However, it
would be common practice in the U.S. for people under such surveillance
to find their health insurance canceled, which tends to discourage
participation in surveillance programs.)
IGF-1 is a powerful naturally-occurring growth hormone found in the
blood of humans. Dairy cows injected with genetically-engineered bovine
growth hormone (rBGH) give milk containing elevated levels of IGF-1,
and the IGF-1 in milk can pass into the blood stream of milk consumers.
Cows' IGF-1 is chemically identical to that in humans. Ingested IGF-1
would ordinarily be broken down in the stomach, but the presence of
casein in milk prevents such breakdown.[4,5,6,7,8] (See REHW #454.)
Thus these latest cancer findings raise important public health
questions about the safety of milk from cows treated with bovine growth
rBGH is injected into cows to extend by several weeks their period of
lactation, and thus to force them to produce more milk. rBGH is not
needed in any way because U.S. dairy cows already produce such an
excess of milk that the U.S. government spends more than $200 million
each year purchasing surplus milk, a subsidy to the milk industry. (See
REHW #381, #384.) Because rBGH injections can cause numerous ill
effects in cows, veterinarians in Germany have refused to administer
rBGH to cows on grounds that it violates their professional code of
ethics, which forbids intentional harm to animals. (See REHW #483.)
U.S. veterinarians have not taken a similar stand.
The latest study of IGF-1 and cancer, reported this week in the LANCET -
-approximately the British equivalent of the JOURNAL OF THE AMERICAN
MEDICAL ASSOCIATION --examined 397 women with breast cancer, and 620
carefully-matched controls. Their blood had been drawn before any of
the women were diagnosed with breast cancer, so this was a prospective
study --the most convincing kind there is. (The prostate cancer study
reported in January was also a prospective study.)
The study found no relationship between IGF-1 in blood and breast
cancers among the entire group, or among the post-menopausal group.
However among pre-menopausal women increasing levels of IGF-1 in blood
were strongly associated with increasing risk of breast cancer in a
consistent dose-response relationship. Adjusting for other known breast
cancer factors (age at which menstruation began; age at birth of first
child; number of children; family history of breast cancer; and weight
in relation to height) did not change the results.
Two previous studies had reported a relationship between IGF-1 levels
in blood and breast cancer.[9,10] However those were "retrospective"
studies in which the IGF-1 levels in blood were measured AFTER the
diagnosis of breast cancer, so it was possible that the cancers caused
the IGF-1 increases instead of the IGF-1 increases causing the cancers.
This latest study minimizes the likelihood that IGF-1 levels are raised
by breast cancers.
The authors of the latest study say there is "substantial indirect
evidence of a relation between IGF-1 and risk of breast cancer." They
point to experiments showing that IGF-1 enhances the growth of
cancerous breast cells in mice, and growth of healthy breast cells in
rhesus monkeys. In humans, very-low-calorie diets protect against
breast cancer and they also reduce blood levels of IGF-1. Low birth
weight is protective against breast cancer and low birth weight also
leads to low levels of IGF-1. Tall women tend to have an increased
likelihood of breast cancer and they also tend to have increased levels
of IGF-1. Tamoxifen, a chemical now being used to prevent breast
cancer, is known to reduce IGF-1 levels in the blood. Several other
chemicals thought to protect against breast cancer --such as vitamins A
and D --may also lower blood levels of IGF-1.
It will be difficult for the U.S. Food and Drug Administration (FDA) to
acknowledge that milk from rBGH-treated cows might be implicated in
common cancers. Historically, FDA has maintained a very close
relationship with Monsanto, the chemical company that spent a billion
dollars developing rBGH. FDA approved rBGH for cows in 1993 and issued
regulations that made it appear to be illegal to label milk rBGH-
produced or rBGH-free. Some of the FDA officials who approved rBGH and
who established the regulations discouraging labeling had previously
worked for Monsanto. (See REHW #381.) In 1994, Monsanto sued two
grocery stores that labeled milk rBGH-free, because the chemical giant
feared that, given a choice, consumers would reject rBGH-produced milk.
FDA's anti-labeling regulations --signed into law by a former Monsanto
official --were clearly intended to help Monsanto succeed in this
marketing ploy. Eleven separate surveys have shown that Americans
strongly prefer to have rBGH-treated milk labeled as such. (See REHW
Monsanto officials say their rBGH product has been so successful among
dairy farmers that they are building a new factory in Augusta, Georgia
to produce a lot more of it. They say they intend to market the product
world-wide. However in Canada and the European Union, rBGH has so
far not been approved for use, partly because of unanswered health
questions. The new studies linking IGF-1 to breast and prostate cancers
are unlikely to help rBGH gain approval in Canada or Europe.
Because of FDA's and Monsanto's aggressive steps to prevent labeling of
rBGH-produced milk, U.S. consumers of milk, chocolate milk, buttermilk,
cream, whipped cream, ice cream, iced milk, cheese, cottage cheese,
cream cheese, yogurt, frozen yogurt, custards --and perhaps many baked
goods as well --are very likely ingesting increased quantities of IGF-1
today. (See REHW #383, #454, #483.)
The milk industry --a powerful lobby in the U.S. --is currently
conducting a campaign to increase milk consumption and top U.S. health
officials are participating in the campaign. Recent advertisements show
Donna Shalala, the U.S. secretary of health and human services, with a
glass of milk in her hand and a "milk mustache" on her upper lip.
Ms. Shalala oversees the U.S. FDA, among other agencies.
A few bold companies --such as Ben and Jerry's, makers of gourmet ice
cream --now label their products as rBGH-free. However, other
companies, such as Whole Foods, Inc. --an "organic" grocery chain that
owns Fresh Fields stores --claim to sell no dairy products containing
rBGH. Yet the Annapolis, Maryland Whole Foods outlet sells cheeses from
Cabot Dairies in Vermont and Cabot readily acknowledges that it uses
some milk from rBGH-treated cows. Thus rBGH may be even more widespread
than advertisements and store policy statements would lead consumers to
believe. In the U.S., it is legal for merchants to mislead consumers in
Dr. Samuel S. Epstein at the University of Illinois in Chicago in 1996
published a paper arguing that IGF-1 from rBGH-treated cows may well
promote cancer of the breast and of the colon in humans who drink such
milk. Epstein pulled no punches: "In short," he wrote, "with the active
complicity of the FDA, the entire nation is currently being subjected
to an experiment involving large-scale adulteration of an age-old
dietary staple by a poorly characterized and unlabeled biotechnology
product [rBGH, which is genetically engineered by Monsanto].
Disturbingly, this experiment benefits only a very small segment of the
agrichemical industry while providing no matching benefits to
consumers. Even more disturbingly, it poses major potential public
health risks for the entire U.S. population," Dr. Epstein wrote.
Monsanto has bet the company's future on genetically-engineered
products, and rBGH is the first such product to be marketed. Therefore,
it seems unlikely that Monsanto will voluntarily terminate the
uncontrolled IGF-1 experiment being conducted now on the American
people. This is a company that plays hard ball. As we saw in REHW #593,
Monsanto lawyers frightened Fox TV executives into killing an
investigative series that raised questions about rBGH and cancer. Just
last month Monsanto wrote a threatening letter to Vital Health
Publishing in Bloomingdale, Illinois over the proposed publication of
AGAINST THE GRAIN, a book by Marc Lappe and Britt Bailey. Monsanto said
the new book would libel its best-selling product, the herbicide
Roundup (glyphosate). Lappe is an established medical writer and an
acknowledged health policy expert. His earlier books include TOXIC
DECEPTION (1991), BREAKOUT --THE EVOLUTION OF DRUG RESISTANT DISEASE
(1995), and THE TAO OF IMMUNOLOGY (1997). Lappe and Bailey run the
Center for Ethics and Toxics in Gualala, California (telephone 707-884-
1700). After receiving Monsanto's threats, Vital Health Publishing
abandoned its plans to publish AGAINST THE GRAIN --even though the book
had already been printed --for fear of a Monsanto lawsuit, which might
put them out of business even if Monsanto lost in court. Happily,
Common Courage Press (Monroe, Maine; telephone 800-497-3207) will
publish AGAINST THE GRAIN in September. AGAINST THE GRAIN is a detailed
account of the perils of the new genetic technologies in agriculture.
Monsanto's rBGH represents the tip of a very dangerous iceberg.
--Peter Montague (National Writers Union, UAW Local 1981/AFL-CIO)
 Susan E. Hankinson and others, "Circulating concentrations of
insulin-like growth factor I and risk of breast cancer," LANCET Vol.
351, No. 9113 (May 9, 1998), pgs. 1393-1396.
 Jeff Holly, "Insulin-like growth factor-I and new opportunities for
cancer prevention," LANCET Vol. 351, No. 9113 (May 9, 1998), pgs. 1373-
 June M. Chan and others, "Plasma Insulin-Like Growth Factor-I and
Prostate Cancer Risk: A Prospective Study," SCIENCE Vol. 279 (January
23, 1998), pgs. 563-566.
 C.J. Xian and others, "Degradation of IGF-I in the adult rat
gastrointestinal tract is limited by a specific antiserum or the
dietary protein casein," JOURNAL OF ENDOCRINOLOGY Vol. 146 (1995), pgs.
 R.K. Rao and others, "Luminal Stability of Insulin-Like Growth
Factors I and II in Developing Rat Gastrointestinal Tract," JOURNAL OF
PEDIATRIC GASTROENTEROLOGY AND NUTRITION Vol. 26, No. 2 (February
1998), pgs. 179-185.
 Toshikiro Kimura and others, "Gastrointestinal Absorption of
Recombinant Human Insulin-Like Growth Factor-I in Rats," THE JOURNAL OF
PHARMACOLOGY AND EXPERIMENTAL THERAPEUTICS Vol. 283, No. 2 (November
1997), pgs. 611-618.
 Douglas G.G. Burrin and others, "Orally administered IGF-I
increases intestinal mucosal growth in formula-fed neonatal pigs,"
AMERICAN JOURNAL OF PHYSIOLOGY Vol. 270, No. 5 Part 2 (May 1996), pgs.
 A.F. Philipps, "Growth of artificially fed infant rats: effect of
supplementation with insulin-like growth factor I," AMERICAN JOURNAL OF
PHYSIOLOGY Vol. 272, No. 5 Part 2 (May 1997), pgs. R1532-R1539.
 Peter F. Bruning and others, "Insulin-Like Growth-Factor-Binding
Protein 3 is Decreased in Early-Stage Operable Pe-Menopausal Breast
Cancer," INTERNATIONAL JOURNAL OF CANCER Vol. 62 (1995), pgs. 266-270.
 J. P. Peyrat and others, "Plasma Insulin-like Growth Factor-1 (IGF-
1) Concentrations in Human Breast Cancer," EUROPEAN JOURNAL OF CANCER
Vol. 29A, No. 4 (1993), pgs. 492-497.
 David J. Hunter and Walter C. Willett, "Diet and Body Build: Diet,
Body Size, and Breast Cancer," EPIDEMIOLOGIC REVIEWS Vol. 15, No. 1
(1993), pgs. 110-132.
 See Monsanto's rBGH information at
http://www.monsanto.com/protiva/ where rBGH is referred to by its trade
name, Posilac, or by another name Monsanto invented for the product,
bovine somatotropin or BST.
 One of Ms. Shalala's milk ads was reprinted in the BRITISH MEDICAL
JOURNAL Vol. 316 (February 14, 1998), pg. 498. The caption
reads, "Donna Shalala, the United States secretary of health and human
services, has been criticised for her promotion of milk. The milk
industry is a powerful lobby in the US and critics say the endorsement
could be the first step on a slippery slope."
 Samuel S. Epstein, "Unlabeled Milk from Cows Treated with
Biosynthetic Growth Hormones: A Case of Regulatory Abdication,"
INTERNATIONAL JOURNAL OF HEALTH SERVICES Vol. 26, No. 1 (1996), pgs.
Descriptor terms: milk; igf-1; rbgh; bovine growth hormone; monsanto;
carcinogens; breast cancer; prostate cancer; fda; donna shalala;
canada; europe; whole foods; fresh fields; ben and jerry's;