Dairy Products Linked to Ovarian Cancer Risk.
She and her associates at Beth Israel Deaconess Medical Center in Boston prospectively investigated the link between lactose and ovarian cancer risk among 80,326 women enrolled in the Nurses' Health Study.
During 16 years of follow-up, 301 cases of invasive epithelial ovarian cancer were diagnosed; 174 were the serous subtype.
Women who consumed the highest amount of lactose (one or more servings of dairy per day) had a 44% greater risk for all types of invasive ovarian cancer compared with those who ate the lowest amount (three or fewer servings monthly).
There was a twofold increase in the risk of serous ovarian cancer with the highest compared with the lowest lactose consumption.
Skim and low-fat milk were the largest contributors to dietary lactose among the women in the study.
"For each 11-g per day increase in lactose consumption--about one glass of milk--there was a 19% increase in the risk of serous cancers," she said, adding that the excess risk was most apparent for this type of ovarian cancer "and was observed at consumption levels often recommended...to reduce fracture risk."
Based on the results "it's probably reasonable to think about having less dairy," commented Dr. Larry Kushi, professor of human nutrition at Columbia University in New York and author of the only other prospective study linking lactose and ovarian cancer (Am. J. Epidemiol. 149:21-31, 1999).
"I certainly think of dairy as a lot less healthy than has been advertised," said Dr. Dan Cramer, professor of ob.gyn. and reproductive biology at Harvard Medical School in Boston.
Several osteoporosis experts dispute the study's conclusions.
"This is an observational study" which means that it's "not able to establish cause and effect," commented Dr. Robert Heaney, professor of medicine at Creighton University in Omaha, Neb.
And even if a causal link is proven between dairy and ovarian cancer, the absolute risk is very low.
"It's almost a nonissue because in the real world there are few people whose dairy consumption warrants concern.
"The average intake in our patients is less than one serving a day and many people have none," said Dr. Michael McClung of the department of medicine at Oregon Health Sciences University and director of the Oregon Osteoporosis Center in Portland.
"In this study there were less than two cases of ovarian cancer per 10,000, which is a very low risk. You need to weigh that against the frequency of osteoporosis," added Dr. Heaney.
Dr. Kushi concedes that ovarian cancer is a rare disease and "in the context of fracture risk, a much smaller portion of the population will get ovarian cancer than will get osteoporosis."
Dr. Heaney said that the study "is not grounds for changing dairy consumption. Aside from calcium, dairy contains magnesium, phosphorous, and protein. And there is evidence that dietary calcium, not supplements, is protective against colon cancer and hypertension."
For now when advising women at his familial ovarian cancer clinic, rather than asking them to cut down on their dairy consumption, Dr. Cramer simply tells them to emulate the Asian diet, which is low in dairy low in fats, and high in soy and vegetables.
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|Comment:||Dairy Products Linked to Ovarian Cancer Risk.|
|Publication:||Family Practice News|
|Article Type:||Brief Article|
|Date:||Jun 15, 2000|
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