January 6, 2011

Surgeon may Determine Breast Cancer Surgery Success

(Ivanhoe Newswire) -- Non-invasive breast cancer, or ductal carcinoma in situ (DCIS), is commonly treated with either breast-conserving surgery (with or without follow-up radiation) or mastectomy. Choosing a treatment depends on clinical factors, the treating surgeon, and patient preferences. Long-term health outcomes depend on which treatment is received. According to a new study, health outcomes are also associated with the treating surgeon.

To figure out the effectiveness of each treatment strategy, Andrew W. Dick, Ph.D., of the RAND Corporation and colleagues conducted a retrospective study of women diagnosed with DCIS between 1985 and 2000 with as many as 18 years of follow-up. They identified the women through two large tumor registries: the Monroe County (New York) tumor registry and the tumor registry at the Henry Ford Health System in Detroit.

The researchers collected extensive data on the patients, including the rate of ipsilateral recurrence (or recurrent breast cancer in the same breast); whether the women had been treated with mastectomy or breast conserving surgery (with or without radiation therapy); and their margin status (margin of tissue surrounding their resected tumors).

They defined margins as positive (in which cancer cells extend to the edge of the resected tissue), negative (cancer cells are more than 2 millimeters away from the edge of the tissue), or close (in which cancer cells are present within 2 millimeters of the edge).

The two most important determinants of breast cancer recurrence are the tumor margins and whether or not the women received radiation therapy following breast-conserving surgery.

"BCS in the absence of radiation therapy resulted in substantially lower ipsilateral event-free survival than either BCS followed by radiation therapy or mastectomy," Dr. Dick was quoted as saying, "Regardless of treatments, positive or close margins following the last surgical treatment substantially compromised ipsilateral event-free survival."

Both of these important determinants of outcomes, however, varied markedly by the treating surgeon.

Wide variability in treatment by surgeons may reflect differences in surgeons' knowledge, attitudes and beliefs, especially given the lack of consensus on what constitutes a negative margin, the authors believe.

"Lack of knowledge about the importance of margins, and differences in beliefs about the role of radiation therapy in local control, together with differences in physician-patient communication during the decision-making process could explain the substantial variation in the acceptance of positive margins and the determination not to proceed to mastectomy," the authors write.

They estimate that with modest reductions in variation by surgeon, based only on changes among those surgeons with low rates of radiation therapy and high rates of positive or close margins, ipsilateral five- and 10-year event rates could be reduced by 15 percent to 30 percent.

In an accompanying editorial, Beth A. Virnig, Ph.D., and Todd M. Tuttle, M.D., of the University of Minnesota, explain that the study poses a perplexing question. They write, "How should women select a provider knowing that up to 35 percent of the variation in outcomes is based on their choice of physician but that there are no actionable characteristics that can be taken into account?"

They suggest one solution could be publishing the scores for all physicians performing breast cancer surgery in a particular area. In any case, the variability in surgeons' treatment choice provides a potential opportunity to improve or standardize DCIS care.

"The challenge is then for the professional community to identify factors that are associated with the currently unexplained physician variability and to use that information to promote identification of high-quality providers or quality improvement activities," Dr. Virnig and Tuttle were quoted as saying.

SOURCE: The Journal of the National Cancer Institute, published online January 3, 2010