Pulse
Briefs
New Screening Tests Approved
The American Cancer Society, the American College of Radiology, and the U.S. Multi-Society Task Force on Colorectal Cancer have developed new guidelines for colorectal cancer screening. The new guidelines essentially endorse older invasive tests, indicate that newer occult blood tests are better than old ones, and introduce a new stool DNA test and CT colonography as screening tools, according to University of Minnesota surgery professor David Rothenberger, M.D., who was part of a team that developed screening guidelines in the 1990s.
Current Recommendations
Tests that find polyps and cancer
- flexible sigmoidoscopy (every five years)
- colonoscopy (every 10 years)
- double-contrast barium enema (every five years)
- CT colonography (every five years)
Tests that find cancer
- fecal occult blood test (every year)
- fecal immunochemical test (every year)
- stool DNA test (interval uncertain)
Source: American Cancer Society
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CT colonography (also known as virtual colonoscopy) uses CT to image the colon and rectum and computer software to display the images. The DNA test assesses stool for abnormal DNA shed by adenoma and carcinoma cells.
The authors of a review of the guidelines published in the May-June 2008 issue of Cancer wrote that it was their “strong opinion” that colonoscopy, sigmoidoscopy, barium enema, and CT colonography were preferred over the fecal tests because they can prevent cancer rather than just detect it. But they pointed out that referring physicians need to know about all of the tests.
Rothenberger notes there are unanswered questions about the new screening tests. It is not clear, for instance, how often someone should undergo DNA testing, and the accuracy of CT colonography depends on the skill of the practitioners doing the exam and interpreting the results. “It takes a lot of attention to detail and a commitment of time to learn how to do this and interpret the test accurately,” he says. And CT colonography may not identify flat lesions on the lining of the colon, which recently were found to be more likely than polyps to turn cancerous.
Rothenberger insists that having any of the tests, despite their limitations, is better than not being screened.—Carmen Peota
A Strong Link for Some Tumors
For decades, researchers have tried to establish a link between smoking and colorectal cancer, producing evidence that has been either inconclusive or only shown a weak association. Some now suggest that’s because most studies haven’t taken subtypes of cancers into consideration.
A recent study led by Mayo Clinic gastroenterologist Paul Limburg, M.D., M.P.H., not only supports the notion that tobacco may increase the likelihood of certain types of cancer, it also suggests an underlying mechanism.
Using data from the Iowa Women’s Health project, an ongoing multicenter study on risk factors for multiple cancer types, Limburg, with investigators from the University of Minnesota and the University of Iowa, identified a population of 1,421 women older than 50 who had developed colorectal cancer. They collected tumor specimens from them (thus far, they’ve retrieved specimens from half) and then analyzed the samples for the presence of four MMR proteins, correlating that data with information about whether the women had smoked.
The team found that smokers were two to three times more likely to develop a type of tumor that lacks DNA “mismatch repair” (MMR) proteins, which are thought to fix genetic damage and mistakes that occur during cell division. Conversely, they found that smoking did not appear to be a risk factor for colorectal cancers that had the ability to produce these proteins.
Limburg says the findings suggest that smoking might prevent the MMR proteins from being expressed by masking the genetic code through a process called DNA hypermethylation. Mayo Clinic researchers are currently pursuing that hypothesis. Limburg speculates the mechanism may be relevant to tumors in other parts of the body. He says the next step is to identify additional molecular features of colon cancers to further identify associations between subtypes of cancer and risk factors.—Carmen Peota
First Woman of GI
Seeing the consequences of malnutrition set Amy Foxx-Orenstein, D.O., on the road to a career in gastroenterology—a field that traditionally hasn’t attracted many women. Foxx-Orenstein was doing an internal medicine residency and became fascinated with nutrition after hospitalizing a patient who had gone into heart failure as a result of alcohol-related malnutrition.
When she started looking into fellowships, she discovered that nutrition aligned either with endocrinology or gastroenterology. In 1991, she was accepted into a two-year program at Virginia Commonwealth University’s Medical College of Virginia (MCV). She spent the first year focused on nutrition and the second on general gastroenterology. “It turned out I cared more for the GI piece than the nutrition piece,” she says.
Foxx-Orenstein credits Alvin Zfass, M.D., a professor of gastroenterology at MCV, with turning her on to the specialty. “He’s a doctor’s doctor,” she says. “I found joy in medicine through my interaction with him.”
As an associate professor at Mayo Clinic College of Medicine and as the 2007-2008 president of the American College of Gastroenterology (ACG), Foxx-Orenstein hopes to have a similar influence on other young physicians—particularly, women.
“For the longest time, the percentage of women in GI hovered between 12 and 16 percent,” she says. “Within the last five years, we’ve seen those numbers inch up.” Today, she says, the percentage of women in the field stands at about 18 percent.
Foxx-Orenstein attributes the low numbers in part to the lack of female mentors. She says Christina Surawicz, M.D., the ACG’s first woman president, was a mentor who encouraged her to become involved in the organization. The two physicians met when Surawicz was chairing the ACG’s committee on women in gastroenterology—a position she later passed along to Foxx-Orenstein.
As president of the ACG, Foxx-Orenstein hopes to help physicians become the kind of leaders and mentors who can influence the career choices of medical students and residents. “It isn’t something people are born with,” she says. “It takes education.” She has been working with the ACG to develop leadership training opportunities for members. The initiative will initially target women physicians.
Foxx-Orenstein is also working to increase the number of women in gastroenterology at Mayo Clinic and currently chairs Mayo’s clinical practice subcommittee on diversity.—Kim Kiser
More Trickle than Trend?
Before the mid-1980s, few women opted for fellowships in gastroenterology. But slowly that’s been changing, according to Roger L. Gebhard, M.D., gastroenterology training program director at the University of Minnesota. Between 1985 and 2000, nine out of 31 graduates of the university’s program were female. Since then, seven of 24 trainees have been women.
At the Mayo School of Graduate Medical Education, which offers both general gastroenterology fellowships as well as specialized training in diseases and procedures, about a third of the 35 or so trainees have been women over the last five years.
Gebhard says hospitals and GI groups are actively recruiting women gastroenterologists. He notes that the biggest hurdle for women now may be the competition for fellowship slots. “There was a time between 1995 and 2000, when nobody wanted to go into GI. The conventional wisdom was that the world didn’t need more GIs,” he says. This year, there were 327 applicants for the university’s four positions.—Carmen Peota