(Reuters Health) - One of the first symptoms of pancreatic cancer --
often noticed even years before diagnosis -- is indigestion. A new study
suggests that these timely tummy troubles may be enough to explain away
previous links made between a high carbohydrate diet and an increased risk
of the disease.
"We started out just aiming to replicate other studies that looked at the
association between carbohydrates and pancreatic cancer," Rachael
Stolzenberg-Solomon, from the National Cancer Institute, Bethesda, Maryland
and an investigator on the new study, told Reuters Health. "But it turned
out to be something more interesting."
It also turned out to be more complicated.
Like many of the prior studies, Stolzenberg-Solomon and her colleagues did
initially find evidence of a link between a high carbohydrate diet and
pancreatic cancer among more than 100,000 older men and women. The top 10
percent of the participants in rankings of carbohydrate consumption had an
almost 50 percent greater risk of the cancer than the bottom 10 percent, the
investigators report in the American Journal of Epidemiology.
It's important to note, however, that even with this increase in pancreatic
cancer risk, the risk remained extremely low. Pancreatic cancer is rare:
less than one-quarter of 1 percent of all participants were diagnosed over
about a 7-year study period.
But what got the researchers' attention was how this apparent increase in
risk was limited to carbohydrate consumers followed fewer than 4 years.
The researchers only collected information on food intake at the start of
the study. And follow-up ended when a cancer diagnosis was made. So those
participants diagnosed early on, explained Stolzenberg-Solomon, may have
already been suffering cancer-related indigestion when they filled out the
dietary questionnaire.
Further, since fatty foods can exacerbate indigestion, they may have
replaced some of the fat in their diet with more easily digestible
carbohydrates. Stolzenberg-Solomon recalled that a fat-carbohydrate swap was
common among the pancreatic cancer patients she saw during her previous work
as a dietitian.
In other words, carbohydrate intake may be a consequence rather than a cause
of pancreatic cancer.
"It's all very complex," noted Stolzenberg-Solomon. "But it's one possible
explanation for this change in risk between 3 and 4 years."
The finding could shed light on inconsistent results from previous studies
that may not have been as careful or detailed in their data collection,
Kristin Anderson, of the University of Minnesota and a co-author on other
recent pancreatic cancer studies, told Reuters Health in an email: "You
can't try to understand a puzzle by looking at one piece."
