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 But the authors also found that other sex-specific cancers,
including prostate and breast, were significantly less common among
people with type 1 diabetes.
Diabetes has been tied generally to increased cancer risk in the
past, but studies have relied mostly on data from people with type 2
diabetes, which develops slowly, usually in adults who are
overweight or obese, and affects about 28 million Americans.
Type 1 diabetes, typically diagnosed in children and young adults,
affects about 1.25 million Americans, according to the American
Diabetes Association.
“People with diabetes and (those with) cancer have many common risk
factors, including obesity, poor diet, physical inactivity and
smoking,” said study coauthor Jessica H. Harding of the Baker IDI
Heart and Diabetes Institute in Melbourne, Australia.
However, “the overall excess cancer risk among type 1 diabetes is
moderate,” Harding told Reuters Health by email. “People with type 1
diabetes should not be alarmed about the results from this study but
follow current guidelines for cancer prevention and participate in
national screening programs as per the general population.”
The researchers analyzed data from national registries of people
with type 1 diabetes in Australia, Denmark, Finland, Scotland and
Sweden through 2008 or 2012, and linked these records to national
cancer registries.
There were 9,149 first incidences of cancer in the diabetic patients
they identified, half of which happened before age 51. Compared to
the general population for the same time period, men with type 1
diabetes had a similar rate of cancer diagnosis overall, and women
with type 1 diabetes were about seven percent more likely to be
diagnosed with cancer.
Cancers of the stomach, liver, pancreas, endometrium and kidney were
about 25 percent to 50 percent more common among people with type 1
diabetes, though breast cancers were 10 percent less common and
prostate cancers were 56 percent less common, as reported in
Diabetologia.
The researchers found the biggest risk increase for liver cancer in
men, which was twice as common in those with type 1 diabetes, and 78
percent more common in women with diabetes.
Liver cancer occurs at a rate of 7.5 cases per 100,000 people each
year in the U.S., according to the American Cancer Society. So, even
doubled, the overall risk remains low, the researchers note.
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“The risk of some cancers is altered slightly among people with type
1 diabetes but not enough to cause serious concern,” said Sarah
Wild, who researches diabetes and cardiovascular disease at The
University of Edinburgh in Scotland, and is also a coauthor of the
new study.
“One question that the work addresses is whether long-term insulin
treatment increases the risk of cancer and the good news is that
there does not appear to be a strong effect,” Wild said.
But the pattern of cancers is similar to that seen with people that
are overweight or have type 2 diabetes, although the changes in risk
are smaller, so weight may play a role, she told Reuters Health by
email.
“The apparent reduction in breast cancer among women with type 1
diabetes needs confirming but may be related to different patterns
of child-bearing,” she said.
Cancer risk was highest shortly after diabetes diagnosis.
“This could happen if the cancer caused symptoms that meant people
received a test for diabetes before the cancer was diagnosed,
because liver and pancreatic cancers can cause diabetes and also
because people with newly diagnosed diabetes will be seeing doctors
and nurses frequently and so may report symptoms and get cancers
picked up earlier than people without diabetes,” Wild said.
SOURCE: http://bit.ly/1WT5zfh Diabetologia, online February 29,
2016.
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