Proteomics Shows Promise in Colon Polyp Chemoprevention Study

Using proteomics technology, NCI researchers have made a step toward predicting which people with familial adenomatous polyposis (FAP), an inherited condition that often leads to colon cancer, will respond to the COX-2 inhibitor celecoxib. In a study published in the April 15 Cancer Research, Dr. Iqbal U. Ali and colleagues examined protein patterns from serum samples of participants in a chemoprevention clinical trial in which celecoxib reduced the number of colon polyps characteristic of those seen in patients with FAP. The results of the chemoprevention trial, reported in the June 2000 New England Journal of Medicine, led to approval by the Food and Drug Administration of celecoxib as an adjunctive chemopreventive agent for people with FAP.

Not all participants in the 2000 study who took celecoxib, however, experienced polyp reduction. Dr. Ali's laboratory took serum samples from the blood of 55 people who had participated in the celecoxib prevention trial and, using mass spectroscopy, identified specific proteomic markers that differentiated trial participants who did and did not respond to the drug. Although the technique has not been sufficiently tested for use in a clinical setting to identify those with FAP who will respond to celecoxib, Dr. Ali explained, the scientists are refining the technique and plan to evaluate it again in future trials.

Aspirin Use Is Not Associated with Pancreatic Cancer Mortality, Study Reports

Results from a large U.S. cohort of nearly 1 million adults found that aspirin use was not associated with mortality from pancreatic cancer. Dr. Eric Jacobs and colleagues from the American Cancer Society concluded that aspirin use did not have an important effect on pancreatic cancer mortality, even when measured by frequency of use that ranged from no use to more than 30 times a month.

The study, published in the April 7 issue of the Journal of the National Cancer Institute, was based on questionnaires completed by 987,590 U.S. adults from the Cancer Prevention Study II. The participants filled out a baseline report in 1982 that included questions about aspirin use. Participants were followed for mortality through 2000.

The research team also looked at the associated risk factors of cigarette smoking, body mass index, and diabetes. They found no apparent differences from those risks in the cohort of mainly white and middle-aged or elderly participants.

"An important strength of this analysis is its unusually large size, resulting in risk estimates with narrow confidence intervals that excluded a strong association between aspirin use and pancreatic cancer mortality," the study authors wrote. "Our results therefore provide evidence against an important effect of aspirin use on risk of pancreatic cancer."

Five previous studies of aspirin use and pancreatic cancer, including the Nurses' Health Study and the Iowa Women's Health Study, gave conflicting results showing reduced and increased risks.

Study Demonstrates Limitations of Virtual Colonoscopy

Virtual colonoscopy "is not yet ready for widespread clinical application," concludes a study published in the April 14 issue of the Journal of the American Medical Association. The study, by Dr. Peter Cotton and colleagues, was conducted at nine major hospital centers across the United States. Virtual colonoscopy's "techniques and training need to be improved," caution the study's authors. Moreover, "multidisciplinary collaboration will be needed to ensure its efficient application."

Virtual colonoscopy detected only 55 percent of polyps at least 10 millimeters (mm) in diameter and 39 percent of polyps at least 6 mm in diameter. In contrast, using standard colonoscopy, 100 percent and 99 percent of all polyps at least 10 mm and 6 mm in diameter, respectively, were detected.

These results are in stark contrast to the findings of a study published in the New England Journal of Medicine last December, which reported that virtual colonoscopy could be as effective as or more effective than standard colonoscopy - at least in the hands of experts using the latest technology. In that study, Dr. Perry Pickhardt and colleagues reported that virtual colonoscopy detected 92 percent of polyps 10 mm in diameter or greater and 86 percent of polyps 6 mm in diameter or greater.

Dr. Cotton and colleagues state, "Even if the results of [virtual colonoscopy] continue to be good in the hands of experts, it has yet to be proven that this expertise can be taught and disseminated reliably into daily practice."

Trends Indicate Lung Cancer Disparities Between Women and Men

Lung cancer remains the leading cause of cancer death in American women, surpassing breast cancer and all gynecological cancers combined, according to a report published in the April 15 Journal of the American Medical Association. New cases of diagnosed lung cancer in men have been on the decline since the early 1980s, authors Drs. Jyoti D. Patel, Peter B. Bach, and Mark G. Kris reported. For women, however, a 60 percent increase in the number of diagnosed cases occurred between 1990 and 2003. Overall, lung cancer was expected to account for an estimated 25 percent of cancer deaths among women in the United States in 2003.

Although it is still debatable whether women are more susceptible to the carcinogenic effects of tobacco smoke than are men, the authors noted, it is clear "that important differences exist among men and women with lung cancer. Women smokers are more likely than men to develop adenocarcinoma of the lung." Many studies have demonstrated genetic differences between women smokers who develop lung cancer and their male counterparts; such differences include higher mutation rates of p53 and greater numbers of smoking-related DNA adducts in women as compared with men. The researchers also observed that "women who have never smoked are more likely to develop lung cancer than men who have never smoked. Mounting evidence suggests that this could be due, in part, to estrogen signaling."

The authors recommend that the trends highlighted in their report be factored into the design of new and emerging lung cancer studies. And they stressed that "effective tobacco control measures" must be implemented in developing countries where smoking rates among women continue to rise.