RAND Review News for Spring 2011
Variations in Treating Noninvasive Breast Cancer Affect Outcomes
How physicians decide to treat the most common type of noninvasive breast cancer, known as ductal carcinoma in situ (DCIS), could determine whether the condition recurs as DCIS or evolves into invasive breast cancer in five or ten years. The health outcomes are associated in part with the treating surgeon, and the wide variability in treatment offers a potential opportunity to improve or to standardize care.
The variability might reflect differences in surgeons’ knowledge, attitudes, and beliefs.
So suggests a recent RAND study that looked at the health records of nearly 1,000 women who were diagnosed with DCIS in the United States between 1985 and 2000. The study found that the rates of recurrent DCIS or of invasive cancer stemming from DCIS could be reduced 15 to 35 percent over five years if surgeons remove at least 2 millimeters of surrounding healthy tissue when they excise tumors and if physicians put patients who receive breast-conserving surgeries on post-surgery radiation therapy.
Sometimes called “stage-zero” breast cancer, DCIS is almost never fatal. Some 96 to 98 percent of women will be alive and disease-free ten years after being diagnosed and treated. However, because physicians cannot say which DCIS cases will turn into invasive breast cancer, they treat all cases with surgery, sometimes followed by radiation.
Women diagnosed with DCIS who had mastectomies had the lowest risk of recurrence or invasive breast cancer, as long as the margins of excised tumors were at least 2 millimeters. Women who underwent breast-conserving surgeries followed by radiation therapy experienced slightly higher risks. The women with the highest risks of DCIS recurrence or of developing invasive breast cancer over five to ten years were those who had breast-conserving surgery and no radiation. In all cases, women whose surgeons removed 2 millimeters or more of healthy tissue around abnormal cells experienced lower risks of recurrence than those whose surgeons had left narrower margins (see the figure).
The Most Successful Treatments of a Common Breast Cancer Involve Excising More Tissue Around Tumors and Delivering Radiation After Breast-Conserving Surgery
SOURCE: “Comparative Effectiveness of Ductal Carcinoma in Situ Management and the Roles of Margins and Surgeons,” Journal of the National Cancer Institute, Vol. 103, No. 2, January 19, 2011, Table 5, Andrew W. Dick, Melony S. Sorbero, Gretchen M. Ahrendt, James A. Hayman, Heather T. Gold, Linda Schiffhauer, Azadeh Stark, Jennifer J. Griggs.
1 Margins of such small sizes are rare with mastectomies and always represent special cases (for example, a tumor against the chest wall).
2 DCIS = ductal carcinoma in situ.
While this study confirmed the conclusions of earlier ones in finding that larger excision margins and radiation therapy lower the risk of breast cancer recurrence, this study broke new ground in finding that these two critical determinants vary markedly from one surgeon to the next. According to the study, published in the Journal of the National Cancer Institute, the variability might reflect differences in surgeons’ knowledge, attitudes, and beliefs.
“Surgeons may play a critical role, both in the surgical treatment choices made by patients and in the receipt of radiation therapy,” said study leader Andrew Dick, a RAND economist. “Because the margin status and the receipt of radiation therapy in particular are the most important factors in predicting outcomes, the substantial variation by surgeon suggests that the quality of DCIS care could be improved.”