Removing Tissue Surrounding Breast Cancer Tumors Prevents Residual Disease

The researchers carried out further excision specimens on 31% of the women who had received breast-conserving surgery to check for residual disease, obtaining 139 samples from 93 patients. Of these, 52 samples were from patients who had received surgery for noninvasive cancer (tumor confined to the milk ducts or lobules), and 87 were from patients who had received treatment for invasive cancer that had spread to the surrounding breast tissue.

The researchers found that in the women who had received surgery for invasive cancer, the amount of residual disease, defined as the presence of invasive or noninvasive cancer, reduced as the free margin increased – from 35.3% with no margin to 2.4% with a margin of more than two mm. However, when it came to the women who had received surgery for noninvasive cancer, residual disease was higher and the pattern was less than clear. Incidence ranged from 0% at more than 5 mm to 57% when the margin was between 0.1 mm to 0.9 mm, but at 44% where no margin was involved.

The researchers also looked at the characteristics of the 202 women who had had a close free margin of less than two mm and the 101 women who had had a clear free margin of two mm or more.

They found that women with a close margin of less than two mm were more likely to be associated with large grade three tumors than the clear margin group (46% vs. 42%), lymphovascular invasion (52% vs. 40%), and nodal involvement (48% vs. 33%). In addition to the women who underwent wider reexcision to determine any residual disease, 13% went on to have a mastectomy, and the remaining 56% did not have further surgery. The study was published in the November 2010 issue of the International Journal of Clinical Practice.

"Based on these results, we feel confident that a free margin of two mm from the area of invasive cancer is adequate to minimize residual disease, but the equivalent free margin for noninvasive cancer remains unclear,” concluded lead author Stephen Ward, M.D., and colleagues of the department of breast surgery. "Eliminating the possibility of residual disease during breast conserving surgery is very important as nearly 50% of patients with local recurrence go on to develop secondary breast cancer, which is a progressive incurable disease.”

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