High-carb diet tied to breast cancer risk for some

July 27 |
Fri Jul 27, 2012 7:05am IST

July 27 (Reuters) – Older women who eat a lot of starchy and
sweet carbohydrates may be at increased risk of a less common
but deadlier form of breast cancer, according to a European
study.

The findings from a study of nearly 335,000 European women,
published in the American Journal of Clinical Nutrition, do not
prove that sweets, French fries and white bread contribute to
breast cancer – but they do hint at a potential factor in a
little understood form of breast cancer.

Specifically, the study found a link between high “glycemic
load” and breast cancers that lack receptors for the female sex
hormone estrogen, so-called “ER-negative” breast cancers.

A high glycemic load essentially means a diet heavy in foods
that cause a rapid spike in blood sugar, such as processed foods
made from white flour, potatoes and sweets.

The study, conducted by Isabelle Romieu of the International
Agency for Research on Cancer in Lyon, France, looked at nearly
335,000 women who took part in a long-running European study on
nutrition factors and cancer risk.

Of these, 11,576 developed breast cancer over a dozen years.
Overall, there was no link between breast cancer risk and
glycemic load, as estimated from diet questionnaires the women
completed at the study’s start.

But the picture changed when the researchers focused on
postmenopausal women with ER-negative cancer. Among women in the
top 20 percent for glycemic load, there were 158 cases of breast
cancer, versus 11 cases in the bottom 20 percent – a 36 percent
higher risk.

ER-negative tumors account for about one-quarter of breast
cancers. They typically have a poorer prognosis than ER-positive
cancers because they tend to grow faster and are not sensitive
to hormone-based therapies.

Christina Clarke, a research scientist at the Cancer
Prevention Institute of California in Fremont, and a consulting
assistant professor at Stanford University, said the results are
interesting because so little is known about what cases
ER-negative breast cancers. Most breast tumors have their growth
fueled by estrogen.

“This study gives us a really important clue for future
research,” said Clarke, who was not involved in the study.

Diets with a high glycemic load are associated with a bigger
secretion of insulin, a hormone that regulates blood sugar. High
insulin levels, in turn, have been linked to certain cancers,
possibly because insulin helps tumors grow.

The current findings hint at a role for “insulin pathways”
in ER-negative breast cancer, Clarke said, adding that more
research definitely needs to be done.

She noted that while there is no single factor in any
woman’s risk of breast cancer, the findings offer more incentive
to eat a balanced diet that limits refined carbohydrates in
favor of healthier fare – like lean protein, vegetables, “good”
fats and high-fiber grains.

“Really, you want to avoid these (high glycemic load) diets
anyway,” she added.
SOURCE: bit.ly/MZY2qw

(Reporting by Amy Norton; Editing by Elaine Lies and Bob
Tourtellotte)