Gus M's medical history is nearly as tangled and convoluted
as the plotlines of his favourite soap operas. The 67-year-old
retired police officer not only has diabetes but has recently
been diagnosed with hepatocellular carcinoma (HCC) as
well. It may be that Gus's diabetes contributed to the
onset of HCC. But whether diabetes is a risk factor itself
or is simply linked with another malady that instigates
HCC has remained obscure. A study published in the April
issue of Gut settles the debate and makes a strong
case that diabetes is in fact a major independent risk
factor for HCC.
ONE-OF-A-KIND
STUDY
Researchers from the Houston, Texas, Veterans Affairs
Medical Center, headed by Dr Hashem El-Serag, undertook
this population based control study to investigate the
link. This US study is the first of its kind that adjusts
for the other known major risk factors for HCC.
The Surveillance Epidemiology and
End-results Program (SEER) Medicare database —
the repository of information about Medicare claims
data — was scoured for HCC patients who were aged
65 and older, as well as randomly selected non-cancer
patients. All subjects chosen were entered into the
database between 1994 and 1999. The patients, who were
scattered all over the US, had been enrolled in the
Medicare system for at least three years.
The patients' records were checked
for diagnostic codes that indicated the presence of
diabetes, hepatitis B or C viruses, alcoholic liver
disease, and the poor absorption and storage of iron
— all of which have been linked with HCC. The database
trawl unearthed 2,061 HCC patients and a whopping 6,183
non-cancer controls.
Compared to their non-cancerous
counterparts, those with HCC tended to be male (66%
vs 36%) and non-Caucasian (34% vs 18%). Furthermore,
43% of the HCC patients also had diabetes, compared
with only 19% of the non-cancer control population.
When the aforementioned risk factors
were all adjusted for, having diabetes almost tripled
the risk of HCC.
HEP
C DRIVES UP RISK
Having diabetes and an infection with hepatitis C virus
was really bad news. These folks displayed a 37-fold
increase in HCC, relative to the others. This may reflect
a direct interaction between the virus and diabetic
physiology that manifests as HCC, according to Dr El-Serag
and his colleagues.
Even without this possible association,
diabetes appears to stand out as a risk factor for liver
cancer. "We found diabetes to be an independent risk
factor for HCC, regardless of the presence of [hepatitis
C virus], [hepatitis B virus], alcoholic liver disease,
or non-specific cirrhosis," say the researchers in their
Gut article. They suggest "that diabetes may
account for a significant proportion of patients with
idiopathic HCC."
"Further studies are needed to
clarify the role of diabetes on the progression of pre-existing
major risk factors, and how the presence of multiple
risk factors with diabetes affect the development of
HCC," conclude the researchers in their paper.
Gut April, 2005;54:533-9
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