Background: The purpose of this study was to analyze the prognostic factors affecting local control and survival rates for patients with early breast cancer who received breast conserving treatment (BCT) and to find out the optimal treatment according to their risk factors.
Methods: From October 1994 to December 2001, 605 patients with 611 stage I and II breast cancers received BCT, and the results were analyzed retrospectively. BCT consists of breast conserving surgery and whole breast irradiation. All the patients underwent lumpectomy or quadrantectomy. Axillary lymph node dissection or sentinel lymph node biopsy was performed in 608 cases (99.5%). The radiation dose to the whole breast was 50.4 Gy over 5 weeks with a 1.8 Gy daily fraction and with boost doses of 9-14.4 Gy administered to the tumor bed. Adjuvant chemotherapy was performed in most of the patients with axillary lymph node metastasis or tumors larger than 1 cm. The median follow-up period was 47 months.
Results: Local relapse, regional relapse and distant metastasis occurred in 15 (2.5%), 16 (2.6%) and 43 patients (7.1%), respectively. The 5-year overall survival, local-relapse-free survival, distant-metastasis-free survival and disease-free survival rates were 95.3%, 97.2%, 91.3% and 88.5%, respectively. On multivariate analysis, age (P = 0.02), number of involved axillary lymph nodes (P = 0.01) and nuclear grade (P = 0.01) affected the local-relapse-free survival. The factors associated with disease-free survival were the T stage (P = 0.05), number of involved axillary lymph nodes (P = 0.01) and nuclear grade (P = 0.001). Overall survival was associated with the T stage (P = 0.02), number of involved axillary lymph nodes (P = 0.01) and c-erb B2 overexpression (P = 0.05). Patients with more than two factors among (i) age </=35 years, (ii) positive lymph node metastasis and (iii) high nuclear grade showed a poor 5-year local-relapse-free survival rate compared with others (P = 0.001). Also, patients with more than two factors among (i) tumor size >1 cm, (ii) positive lymph node metastasis and (iii) high nuclear grade showed an inferior 5-year disease-free survival rate compared with others (P = 0.0005).
Conclusions: The most important prognostic factor affecting local control, disease-free survival and overall survival was axillary lymph node metastasis. The nuclear grade influenced local control and disease relapse. Patients with multiple unfavorable risk factors such as positive axillary lymph nodes, high nuclear grade, young age and large tumor showed poorer local control and disease-free survival than patients without any risk factors, and so more aggressive treatment is required for these patients.