SAN ANTONIO--Final excisional margin status proved to be the strongest predictor of local recurrence in a study of more than 300 breast cancer patients treated with breast-conserving surgery and radiation, Melanie C. Smitt, MD, said at the opening general session of the San Antonio Breast Cancer Symposium.
Five- and 10-year freedom from local recurrence was 98% among patients who had negative final margins, compared with 90% and 82%, respectively, for patients with non-negative excisional margins.
The combination of re-excision and negative final margin was associated with 100% local control versus 78% for patients who did not achieve negative final margins after re-excision.
Use of adjuvant chemotherapy was the only other significant predictor of local control, said Dr. Smitt, assistant professor of radiation oncology, Stanford University Medical Center.
The study involved 303 women with stage I or II invasive breast cancer. All patients were treated with lumpectomy and radiation. Adjuvant chemotherapy or tamoxifen(Drug information on tamoxifen) (Nolvadex) was limited to patients with positive lymph nodes and other high-risk features.
A surgical margin was defined as negative if a tumor-free zone of greater than 2 mm was achieved. A close margin was less than 2 mm. Positive margins were defined as focal or diffuse. Re-excision was performed as deemed appropriate.
Initially, only 17% of patients had a tumor-free margin. More than 40% had indeterminate margins after primary excision (see table). Following re-excision, final margins were negative in half the patients and indeterminate in 35%.