Impact of a scientific presentation on community treatment patterns for primary breast cancer

Mar 15 2006

The oral presentation of data from a single study at a national scientific conference can have an important impact on patient treatment, even before study publication or Food and Drug Administration (FDA) approval, according to a study in the March 15 issue of the Journal of the National Cancer Institute.

Specifically, the authors found that use of the chemotherapy drugs called taxanes increased after the May 1998 annual meeting of the American Society of Clinical Oncology (ASCO) where preliminary data were presented suggesting that use of taxanes as adjuvant therapy could improve survival in women with lymph node-positive breast cancer.

Results from the Cancer and Leukemia Group B (CALGB) Study 9344 suggested that adjuvant treatment with the taxane drug paclitaxel is associated with improved survival in women with lymph node-positive breast cancer. The results were first presented at the 1998 ASCO meeting. Although paclitaxel had been approved by the FDA in 1994 for the treatment of women with metastatic breast cancer, FDA approval for this new use of paclitaxel for women with node-positive breast cancer did not come until October 1999. A final report of CALGB Study 9344 was published in 2003. However, the preliminary results of the study presented in May 1998 were highlighted in news stories published in numerous major media outlets, including the New York Times, Wall Street Journal, and U.S. News and World Report.

To investigate the impact of the meeting presentation on practice patterns, Sharon H. Giordano, M.D., at the University of Texas M.D. Anderson Cancer Center, and colleagues studied chemotherapy use in 3341 women older than age 65, identified in the Surveillance, Epidemiology, and End Results-Medicare database, who were diagnosed with stage I-III breast cancer between 1994 and 1999 and received adjuvant chemotherapy within 1 year of diagnosis. The authors examined the use of taxanes among these women.

The percentage of women receiving adjuvant chemotherapy who received taxanes such as paclitaxel remained at around 10% from 1994 to early 1998, and after early 1998 the rate of increase over time increased more than sevenfold. Rates of taxane use increased primarily in women with node-positive breast cancer in early 1998, and it also increased in women with node-negative breast cancer by the end of 1999, even though such women were not included in the CALGB study. The authors suggest the increased use resulted from publicity at ASCO and consequent media coverage. They caution medical decisions based on premature data from a meeting presentation may pose a risk for patients who could be exposed to drugs that may have toxic effects before the drugs' benefits have been definitively established.

The authors write, "Although in many ways this example represents a best-case scenario, in which the meeting report of a multicenter randomized trial turns out to have stimulated the adoption of a treatment that has eventually become part of evidence-based practice, it also illustrates the enormous power of highly publicized meeting presentations. Investigators should be aware of the potential impact of their presentations and exercise appropriate caution and judgment in their interpretation of research findings."

In an accompanying editorial, Lisa M. Schwartz, M.D., and Steven Woloshin, M.D., of the VA Outcomes Group in White River Junction, Vt., discuss the problems and benefits of adopting a new therapy or research finding based on preliminary evidence presented at a national meeting. They present the story of Iressa (gefitinib), a drug used for treating lung cancer, prescribed based on early studies that didn't have control groups and that used surrogate endpoints, such as decrease in tumor size, rather than clinical endpoints, such as improved survival. In addition to having the occasional toxic side effect of fatal pneumonia, Iressa later did not improve survival in a randomized trial of 1700 participants.

Schwartz and Woloshin write, "Physicians are confronted with preliminary research findings all the time. To decide whether the findings are good enough to change practice, they must be able to answer some fundamental questions. The most basic question, of course, is what is the rush?"