Pathological approach to breast conserving therapy.

There is no uniformly accepted definition of a positive margin in breast conserving surgery. In 1999, the Japanese Breast Cancer Society created the Guidelines for Breast-Conserving Treatment (GBCT). At that time, we did a questionnaire survey about the definition of margin status. Although 57.1% of hospitals/institutes used the definition of cancer cells present at the surface, the GBCT adopted the definition of cancer cells present within 5 mm of the surface. Moreover, the GBCT required that the distance between the edge of the cancer cells and the surface be recorded in millimeters when cancer cells were present within 5 mm of the surface. The risk factors for local recurrence after breast-conserving treatment were studied. From 1986 to 1995, 391 patients were treated with breast-conserving surgery at Osaka Medical Center for Cancer and Cardiovascular Diseases. Of these, 35 patients developed local recurrence. Multivariate analysis showed that positive margin (p=0.0002), high degree of ductal proliferative change around the tumor (p=0.0035) and high histological grade (p=0.0041) were significant independent risk factors for local recurrence, while radiation therapy (p=0.0327) significantly reduced local recurrence. There was no significant difference in the risk of local recurrence between the two different definitions of positive margin (tumor present at the surface and tumor present within 5 mm from the surface). It is hoped that more hospitals/institutes will adopt the definition of margin positivity presented by the GBCT and that a practical definition of margin positivity will be established.