Reuters: HRT, Drinking Milk Tied to Cancer Hormone in Women (Michelle Holmes, Harvard Medical School)

[Guest guest]

Reuters - Health - Tuesday, September 10, 2002

HRT, Drinking Milk Tied to Cancer Hormone in Women

By Suzanne Rostler

 

NEW YORK, NY, USA (Reuters Health) - Drinking milk may raise blood levels of a

cancer-promoting hormone in women, according to two recent studies. What's more,

taking hormone replacement therapy (HRT) or having multiple children appears to

reduce levels of the hormone.

 

But it is too soon to recommend that women avoid milk products, since it is not

clear whether milk, or a particular component of milk, is the culprit, the study

authors point out. Similarly, more research is needed into the effects of HRT on

cancer risk, since a large study recently found that taking HRT increased the

risk of breast cancer ( news - web sites), they note.

 

" We cannot yet make the leap to say that higher levels of milk intake will

increase the risk of cancer, " Dr. Michelle D. Holmes, the primary investigator

of both reports, told Reuters Health. " Foods are complicated, with many

components, and they may have many different actions on the body. "

 

The data on more than 1,000 women analyzed in both reports was drawn from the

Nurses' Health Study, the longest national health study conducted in women. The

findings are published in the September issue of Cancer Epidemiology Biomarkers

and Prevention.

 

One report found that levels of insulin-like growth factor-1 (IGF-1), a hormone

that can raise cancer risk when levels are too high, fell as the number of

pregnancies increased. Women who had been through at least four pregnancies had

IGF-1 levels that were 14% lower on average than their peers who had fewer

children.

 

Pregnancy is known to decrease a woman's risk of breast and colon cancer, and

the study--the first to report an association between parity (the number of

times a woman has given birth) and IGF-1 levels--suggests a possible mechanism

behind this effect.

 

However, more research is needed, cautioned Holmes, from Brigham and Women's

Hospital in Boston, Massachusetts.

 

" If this connection between parity and IGF levels should turn out to be

consistent in other similar studies, it would be interesting to know something

about how parity affects IGF levels over time, " she said in an interview.

 

Her study also reported a link between HRT, especially oral estrogen, and lower

IGF-1 levels among postmenopausal women, a finding that supports the results of

other studies. Women using oral estrogen had lower levels than those using the

estrogen skin patch and women who did not use any hormones.

 

A second study found that IGF-1 levels rose in tandem with women's intake of

protein, especially from milk. There was no association between IGF-1 levels

and vegetable protein intake. Yogurt, cheese, and ice cream also had no

association with the hormone.

 

Taken together, the study findings suggest a link between lifestyle factors and

levels of a hormone associated with cancer risk.

 

" For something like milk intake, it means we have a potential mechanism, but we

do not yet know whether there is a connection between milk intake and cancer

risk, " Holmes explained.

 

" For something like parity...this may represent a mechanism by which parity

helps prevent cancer. As scientists, it is always more reassuring if we know how

something works rather than just knowing that it works, " she added.

SOURCE: Cancer Epidemiology Biomarkers and Prevention 2002.

 

 

 

 

 

 

 

News - Today's headlines