NCI Cancer Bulletin: A Trusted Source for Cancer Research NewsNCI Cancer Bulletin: A Trusted Source for Cancer Research News
October 18, 2005 • Volume 2 / Number 40 E-Mail This Document  |  Download PDF  |  Bulletin Archive/Search  |  Subscribe

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Cancer Research HighlightsCancer Research Highlights

FDA Approves Expanded Indications for Exemestane
The Food and Drug Administration has approved expanded indications for the breast cancer drug Aromasin (exemestane), allowing its adjuvant use in postmenopausal women with estrogen-receptor positive tumors.

According to a randomized trial published last December in the New England Journal of Medicine (NEJM), switching from tamoxifen to exemestane for the last 2 to 3 years of the normal 5 years of adjuvant hormonal treatment decreased risk of recurrence by 32 percent. However, overall survival rates between the group switching to exemestane and the group staying on tamoxifen were not significantly different.

Of the 4,742 patients enrolled in the NEJM study, 2,362 were randomly assigned to switch to exemestane, and 2,380 continued to receive tamoxifen. After a median follow-up of 31 months, researchers reported 183 recurrences, deaths, or new primary tumors in the opposite breast for the exemestane group and 266 such events in the tamoxifen group.

After the study, the American Society of Clinical Oncologists and the National Comprehensive Cancer Network updated their guidelines to support adjuvant regimens that include exemestane.

Drug maker Pfizer also received similar expanded approval in the European Union. Exemestane was originally approved in the United States for primary treatment of advanced breast cancer in postmenopausal women whose tumors stopped responding to tamoxifen.

Lower Screening Mammography Rates Found Among Women with Diabetes

A large Canadian study found that women with type 2 diabetes were less likely to receive screening mammograms for breast cancer than women without diabetes, according to a report in the October 10 Archives of Internal Medicine.

The study, led by Dr. Lorraine L. Lipscombe of the Institute for Clinical Evaluative Sciences at the University of Toronto, examined the utilization of mammography in a population of women in Ontario Province to determine whether the presence of diabetes affects mammogram rates. The retrospective cohort study compared 69,168 women who had diabetes and 663,519 women without diabetes for a minimum of 2 years.

Evidence from previous studies suggested that screening mammography may be especially important among women with type 2 diabetes mellitus due to their increased risk of breast cancer. However, study results showed that only 38.1 percent of the diabetic women received a mammogram during the study period, compared with 47.3 percent of the women without diabetes.

According to the researchers, the study results "did not change after adjustment for age, income, region of residence, comorbidity, frequency of primary care physician visits, specialist care, and having a regular provider of care." The findings support earlier studies that found that various kinds of preventive care, such as mammography, lipid-lowering therapy, arthritis treatment, colon cancer screening, and Pap smears, may be relatively neglected in patients with chronic diseases such as diabetes.

Colorectal Cancer Screening Rates Prove Difficult to Increase

The difficulty of improving the rates of colorectal cancer (CRC) screening was underscored in a study that sought to help health care providers increase the screening effort at a large managed care institution, as reported in the October 10 online edition of Cancer.

CRC is the third-leading cause of cancer mortality in adults in the United States. However, the rate of CRC screening is extremely low and has only modestly improved in the past decade.

A randomized controlled trial conducted by researchers at UCLA's Jonsson Comprehensive Cancer Center tried to increase the rate of CRC screening within a managed care organization by working directly with the group's associated provider organizations (POs). Nineteen POs received a quality-improvement (QI) intervention that included start-up materials and support to encourage CRC screening among patients. Another 17 POs served as controls. After supplying the initial materials to the QI group, the research team did not provide any substantial onsite assistance, since the goal of the study was to test an intervention that could be maintained without external support.

During the 2.2 years of the study, only 29 percent of eligible patients within the QI group were up to date according to existing CRC screening guidelines. This screening rate did not differ significantly between the intervention and control PO groups. The authors concluded that, "Although well intentioned, the medical directors, facilitators, and providers with whom we worked were unable to galvanize their organizations to make the changes necessary to have an impact on CRC screening rates."

Study Analyzes Errors in Cancer Diagnosis

A study appearing in the October 10 online edition of Cancer examined the causes and effects of errors that occur when testing for cancer. The analysis, funded by the Agency for Healthcare Research and Quality, looked at errors according to six parameters: health care facility, type of cancer (gynecologic or other), cause of error (sampling or interpretation), effect of diagnosis on patients' clinical management and outcome, and severity of any resulting patient harm.

Dr. Stephen Raab of the University of Pittsburgh School of Medicine and colleagues analyzed 17,003 samples from 4 medical institutions in mid-Atlantic and Midwest states. Each sample included discordant, paired results - that is, results where one test was positive and the other negative - from patients who received both histologic and cytologic tests for cancer or precancerous lesions at the same tissue site.

The study showed that error frequencies were correlated with the institution where the sample was collected. Among all four institutions, most of the errors were attributed to cytology, rather than surgical sampling or interpretation. Non-gynecologic errors were more common than gynecologic ones.

The researchers found that pathologists disagreed on the severity of patient harm resulting from errors. They calculated, however, that harm could befall a minimum of 127,950 patients per year in the United States because of diagnostic mistakes. "The pathology culture is one of individual diagnostic responsibility and errors are not attributed to poorly designed systems that may be fixed," they wrote. "The standardization and uniform reporting of errors…is a first step in improving safety."

Variation in COX-2 Gene Assessed in Colorectal Adenoma Patients

The overall structure of the gene cyclooxygenase 2, or COX-2, may be an important determinant of the risk of colorectal cancer and may influence a patient's response to drugs that inhibit the COX-2 enzyme, according to researchers who conducted a pilot study of variations in the gene. Levels of the COX-2 enzyme often are elevated in colorectal and other cancers.

A large number of variants, or polymorphisms, in the COX-2 gene have been reported. Using four polymorphisms in the COX-2 gene, researchers in NCI's Division of Cancer Prevention (DCP) tested associations between the variants and the susceptibility to colorectal cancer and the responsiveness to aspirin and ibuprofen, two of the nonsteroidal anti-inflammatory (NSAIDs) drugs that nonselectively inhibit COX-2.

An interesting finding of the study is that some colorectal adenoma patients carrying certain COX-2 polymorphisms benefited more from the use of COX-2 inhibitors than did other patients without the polymorphisms. The study, published in the October 17 British Journal of Cancer, included more than 700 patients with advanced colorectal adenoma and a matched group of controls. Future studies involving more patients and testing of additional polymorphisms are being planned.

"The results in this pilot study, especially the association with the widely used class of COX-2 inhibitors, are encouraging and if confirmed in future studies, would have significant implications in maximizing response and minimizing toxicity," says Dr. Iqbal Ali, the first author of the study.