Cancer Biomarker Detection Method is Found Reliable
Investigators have created a reliable method to calibrate instruments across several different laboratories to detect potential cancer biomarker proteins with uniform accuracy, according to a study in the January 1 Clinical Chemistry. The method uses surface-enhanced laser desorption (SELDI) mass spectrometry (MS) to help clinicians detect protein biomarkers for prostate and other cancers.
The study was led by Dr. John Semmes of Eastern Virginia Medical School, and is part of a multi-institutional collaboration spearheaded by NCI's Early Detection Research Network (EDRN). Standard calibration algorithms for SELDI MS were established in six cancer research laboratories, including Dr. Semmes' lab at the Virginia Prostate Center, Fred Hutchinson Cancer Research Center, Johns Hopkins Medical Institutions, University of Alabama at Birmingham, University of Pittsburgh Cancer Institute, and University of Texas Health Science Center at San Antonio. Each lab then analyzed the same human serum samples - both cancerous and control - and obtained virtually identical protein expression profiles.
Dr. Sudhir Srivastava, NCI program officer and EDRN coordinator, noted that, "We established, for the first time, that mass spectrometry can yield reproducible output among different laboratories analyzing the same set of clinical samples." However, this is only the first phase of the study. In a follow-up study, NCI is testing the robustness of the developed algorithm in correctly classifying prostate cancers and controls obtained from multiple institutes in a blinded fashion.
If successful, the SELDI MS profiling of prostate cancer study may improve early detection of prostate cancer beyond the current utility of the widely used prostate-specific antigen test. However, Dr. Srivastava cautioned that any MS instrument must be carefully cross-validated for analytical sensitivity and precision before using it in the clinical setting.
Many clinicians do not administer colorectal cancer screening with the fecal occult blood test (FOBT) as recommended in the U.S. Preventive Services Task Force's 2002 guidelines, according to a study in the January 24 Annals of Internal Medicine. The Task Force had concluded that only in-home, three-sequence FOBT sampling has been proven to reduce colorectal cancer mortality. In-office FOBT conducted by the physician obtaining a single stool specimen during a digital rectal exam was not recommended.
In the study, researchers from the Centers for Disease Control and Prevention, the American Cancer Society, and NCI retrospectively analyzed responses from physicians participating in the national Survey of Colorectal Cancer Screening Practices (SCCSP) and from adults over age 49 who responded to the 2000 National Health Interview Survey (NHIS).
They found that only 26.3 percent of physicians used the FOBT home test exclusively, as recommended by the guidelines. Among the 1,120 surveyed physicians who used FOBT, 32.5 percent used the in-office test, and 41.2 percent used both home and in-office testing. In the NHIS, of 2,652 adults who reported having FOBT in the past year, 29.1 percent reported an in-office test only, 61.5 percent a home test only, and 9.4 percent reported both tests. Although guidelines further advise against repeating FOBT by way of following up a positive test, analysis of the SCCSP data showed that nearly 30 percent of physicians did repeat the tests. The adults surveyed in the NHIS also reported follow-on FOBTs, as well as many failures to have their positive test followed by a total colon exam
Research published in the February 2005 Medical Care Research and Review illuminates a quality of care problem in colorectal cancer screening. The study found that 37 percent of primary care physicians and 24 percent of gastroenterologists and general surgeons surveyed did not recommend a complete diagnostic evaluation (CDE) for average-risk patients with a positive FOBT. Lead author Dr. Robin Yabroff of NCI's Division of Cancer Control and Population Sciences explained, "Physician recommendation for CDE is a critical component in the process of identifying and treating colorectal cancer. Lack of this recommendation may limit the effectiveness of colorectal cancer screening programs." Primary physicians play an important role in improving the quality of care and outcomes for colorectal cancer patients. This study was conducted by NCI and other federal agencies to support provider surveys related to cancer control.
Factors associated with primary care physicians' recommendations of CDE included aspects of physician background, experience, and practice patterns; practice environment; and perceptions of colorectal cancer screening test effectiveness. Patient characteristics were associated with gastroenterologists' and general surgeons' recommendations of CDE.
A team of European scientists has found that there is no link between the amount of fruits and vegetables that a woman eats and her risk for breast cancer. These results are featured in the January 12 Journal of the American Medical Association (JAMA). The 285,526 women in this prospective study, who came from Denmark, France, Germany, Italy, the Netherlands, Spain, Sweden, and the United Kingdom, were followed over a median course of 5 years, during which 3,659 of them developed invasive breast cancer. In addition to providing information about lifestyle, the women completed country-specific questionnaires on their dietary habits, detailing the types of vegetables that they ate: leafy vegetables, fruiting vegetables, root vegetables, cabbages, mushrooms, grain and pod vegetables, onions and garlic, stalk vegetables and sprouts, and mixed salads and vegetables.
The difference in fruit and vegetable intake varied by as much as 300 percent among the women, but after controlling for many factors, the researchers found no evidence of a protective effect, even according to vegetable type. The size of the cohort and the range of fruits and vegetables the women ate bolster these results, but the authors cite a relatively short follow-up and a lack of information on the history of breast cancer in participants' families as caveats. An accompanying JAMA editorial suggests that when it comes to cancer prevention, the critical period for fruit and vegetable consumption may be in childhood, and adds that "reductions in blood pressure and epidemiological evidence for lower risks of cardiovascular disease provide sufficient reason to consume these foods in abundance."
The American Cancer Society has released Cancer Facts & Figures 2005, based on data from NCI's Surveillance, Epidemiology, and End Results (SEER) Program and the CDC's National Center for Health Statistics. In addition, an article published in the January/February issue of CA: A Cancer Journal for Clinicians provides the scientific underpinnings for the user-friendly Facts & Figures.
Both publications report that the death rate from all cancers combined has decreased annually by 1.5 percent since 1993 among men and by 0.8 percent since 1992 among women. The mortality rate from the three most common cancer sites (lung, colon, and prostate) has also continued to decline.
More than 1.3 million new cancer cases are expected in the United States in 2005, with more than 570,000 deaths expected this year. The 5-year relative survival rate for all cancers diagnosed between 1995 and 2000 is 64 percent, compared with 50 percent for cancers diagnosed between 1974 and 1976.
The report estimates that 17 percent of new cancers diagnosed worldwide can be linked to infectious diseases, such as the hepatitis B and C viruses, human papillomavirus, Helicobacter pylori, HIV, and Epstein-Barr Virus.
Also included in the report is a section on tobacco use and its relationship to cancer; the report estimates that smoking is responsible for at least 30 percent of all cancer deaths and 87 percent of all lung cancer deaths.
Cancer Facts & Figures 2005 is available from the American Cancer Society at http://www.cancer.org.