The leftover cancer cells after breast cancer surgery may play a crucial role in whether the cancer returns or not, according to a new study published in the August 1, 2006, issue of the International Journal of Radiation Oncology * Biology * Physics, the official journal of ASTRO, the American Society for Therapeutic Radiology and Oncology.
This year, more than 213,000 American women will learn they have breast cancer. Many women with early stage cancer prefer to have a lumpectomy, where only the cancerous lump is surgically removed, followed by radiation therapy and possibly chemotherapy. With a lumpectomy, the surgeon removes the tumor along with some healthy, non-cancerous tissue nearby. Doctors then examine it under a microscope. If the outside of the tumor, or margin, is free of cancer, it's considered to be a negative margin. If the outside of the tumor has cancer cells present, it's considered a positive margin. When it's unclear, or a very small distance, doctors call it a close margin. Women with a positive or close margin often require more surgery to make sure all the cancer is removed. This surgery is called a re-excision. Most patients with close or positive margins would be advised to undergo re-excision.
In this study conducted at Fox Chase Cancer Center in Philadelphia, doctors divided 1,044 patients with stage I-II breast cancer with close or positive margins into three groups. Group 1 included 199 patients who did not have additional surgery, group 2 had 546 patients who had additional surgery proving they were free from cancer and group 3 included 299 patients who had additional surgery and showed evidence of additional cancer. All patients received radiation therapy.
After 10 years, the number of local recurrences was the same for women who had re-excision and for women who did not have re-excision (group 1 versus groups 2 and 3 together). However, the result of the re-excision helped predict whether women would have their cancer return. Women with no residual disease at the time of re-excision (group 2) had a local control of 95 percent, while women found to have residual disease in the breast (group 3) had a local control of 91 percent.
"This study helps to clarify the role of a re-excision for a close or positive margin in women undergoing breast-conserving therapy for early-stage breast cancer," said Derek Chism, M.D., lead author of the study and a radiation oncologist now practicing at North Shore Medical Center in Peabody, Mass.
Contact: Julie Moore
American Society for Therapeutic Radiology and Oncology