Some IBD Drugs May Raise Skin Cancer Risk
Study Shows Increased Risk for Patients Taking Immune-Suppressing Medications
By
Kathleen Doheny
WebMD Health News
Reviewed By
Louise Chang, MD
Oct. 26, 2009 -- Patients with inflammatory bowel disease or IBD may be at
an increased risk for getting skin cancer, according to a study presented at
the American College of Gastroenterology's annual meeting in San Diego.
The risk appears to be linked to medications to control IBD, says researcher
Millie Long, MD, MPH, at the University of North Carolina, Chapel Hill.
And some medications boost risk more than others, she found.
"Patients on immunosuppressant medications, particularly of the thiopurine
class, have an increased risk of skin cancer, greater than three times,
compared to patients with IBD who do not use these medications," Long tells
WebMD. Purinethol and Imuran are examples of thiopurines.
While previous research by others has also found an increased risk of skin
cancer in IBD patients, Long says her study is thought to be one of the first
to zero in on specific medications.
For the study, Long and her colleagues first looked at the records of 26,403
IBD patients with Crohn's disease and 26,974 with ulcerative colitis,
evaluating their records from 1996 through 2005. Each of the patients was
matched according to age, sex, and region of the country with records from
three patients who did not have IBD.
IBD is used to refer to both ulcerative colitis and Crohn's disease. While
different parts of the gastrointestinal tract are usually affected, both
diseases involve chronic inflammation, resulting in symptoms such as diarrhea,
rectal bleeding, and abdominal cramps. (IBD is different than IBS or irritable
bowel syndrome, which does not involve intestinal inflammation or damage.)
The cause of IBD isn't known, but experts say it is related to the immune
system responding to the body inappropriately.
Overall, Long found that the risk of getting a nonmelanoma skin cancer was
1.6 times higher for the IBD patients than patients in the comparison
group.
Nonmelanoma skin cancers include squamous cell and basal cell skin cancers.
About 1 million people in the U.S. are diagnosed annually with these cancers,
which are extremely curable if detected early.
IBD Patients Only
Long's team took a closer look at just the IBD patients in the study and the
specific medicines they took. Several types of medications are used to treat
IBD, with a goal of decreasing excess activity of the immune system. Long
compared 742 IBD patients with skin cancer to 2,968 IBD patients without skin
cancer.
Among the findings:
- Use of any immunosuppressant medicines in the past 90 days increased risk
of skin cancer by 3.2, she found.
- Thiopurine medicine boosted the risk the most, followed by biologics.
Among thiopurines are mercaptopurine (Purinethol) and azathioprine (Imuran).
Biologics include infliximab (Remicade) and others.
- Long-term use, defined as a year or more, was more strongly associated with
risk of skin cancer. Those who had taken the thiopurine medicines for more than
a year, for instance, had a fourfold increased risk of skin cancer; Crohn's
patients on long-term biologics had a twofold increased risk.
Exactly why the medications seem to boost the risk of nonmelanoma skin
cancers, Long says, isn't certain.
Other research has suggested that the medications may increase the
sensitivity of skin to sunlight, she says.
Changes to the immune system itself as a result of the IBD can't be ruled
out, however, as a factor increasing skin cancer risk, she says.
Second Opinion
The new study results are no surprise, says Sunanda Kane, MD, MSPH,
associate professor of medicine at the Mayo Clinic in Rochester, Minn., a
gastroenterologist who focuses her research and clinical work on IBD.
"We have always sort of suspected that perhaps the common cancers are even
more common in patients who are chronically immunosupressed."
The findings should get patients and doctors thinking differently, she says,
about who is at risk for skin cancers. "Historically we think of skin cancer
patients as Caucasians from the Northern Hemisphere," she says. But many others
are also at risk, she says.
"People should not change their medications whatsoever because of these
findings," Long says. The take-home message for patients, she says, is to be
aware of the risk and keep a closer eye on their skin as well as adhere to safe
sunning practices such as wearing a broad-spectrum sunscreen.
Deborah S. Sarnoff, MD, vice president of the Skin Cancer Foundation,
agrees: "Patients taking immunosuppressive medication for prolonged periods
need to be extra vigilant about checking their skin and practicing sun safety
every day."
Considering both benefits and risks of drugs is important, says Brian
Kenney, a spokesman for Centocor, which makes the biologic Remicade.
"It is important for people living with Crohn's disease or ulcerative
colitis, and physicians treating these diseases, to remain vigilant throughout
the course of treatment, regardless of the type of immunosuppressive therapy,"
Kenney says.
SOURCES: Millie Long, MD, MPH, fellow in gastroenterology and preventive medicine,
University of North Carolina, Chapel Hill.
American College of Gastroenterology annual meeting, San Diego, Oct.
23-27, 2009.
Sunanda Kane, MD, MSPH, associate professor of medicine and
gastroenterologist, Mayo Clinic, Rochester, Minn.
Brian Kenney, spokesman, Centocor.
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