Background: The purpose was to determine the rate of local breast relapse in patients with breast cancer uniformly treated with partial mastectomy but without postoperative radiotherapy and without systemic adjuvant therapy. We also systematically examined the factors associated with local recurrence to determine whether a low-risk subgroup existed.
Methods: A retrospective review of a prospectively followed (median, 8 years) cohort of 293 patients was performed. The end-point was ipsilateral local breast cancer recurrence. The patient's age, tumor size, nodal status, estrogen and progesterone receptor status, histology, and tumor and nuclear grade were studied, as were the presence and amount of carcinoma in situ and the presence of tumor emboli using univariate Kaplan-Meier and Cox step-wise multivariate analyses.
Results: The overall local relapse rate was 26% (77 recurrences). Univariate factors significantly associated with decreased local relapse included older age, negative nodes, small tumor size, positive estrogen receptor status, and absence of tumor emboli. Significant multivariate variables were age, nodal status, estrogen receptor status, absence of comedo carcinoma in situ, and tumor emboli. A low-risk subgroup of 66 patients was defined with a 6% 10-year local recurrence rate.
Conclusion: Important patient and tumor variables associated with local breast cancer relapse after breast-conserving surgery can define a low-risk subgroup.