Breast conservation therapy: local tumor control in patients with pathologically clear margins who receive 5000 cGy breast irradiation without local boost.

A retrospective study was performed to determine the value of pathological evaluation of inked primary tumor specimen margins in the local control of patients with stage I and II breast cancer. In 150 patients with 153 invasive breast cancers, treatment involved surgical resection of the primary tumor, pathological determination of tumor-free inked specimen margins, and 5000 cGy whole breast radiation therapy (RT) without tumor bed RT local boost. This approach yielded an actuarial five-year local control rate of 95%. The local control rate was 96% for T-1 cases and 93% for T-2 cases. The local control rate was 96% for patients with clear margins achieved at initial resection and 94% for patients with clear margins achieved at re-excision. Among patients with clear margins at re-excision, the local control rate was 97% for those with no residual cancer and 88% for those with residual cancer. Patients with surgical margins clear by 3 mm or less had a local control rate of 92% at five years. Local control rates appear to be comparable to other breast conservation approaches which routinely employ local RT boosts. In omitting the local RT boost in patients with clear margins, the overall RT course will be briefer and the cosmetic changes associated with high-dose, large volume local RT boosts can be avoided.