Background: The objectives of this study were to confirm the favorable outcome of invasive breast cancer in Japanese patients without lymph node metastasis who did not receive adjuvant therapies and to validate the St-Gallen recommendations in this population.
Methods: The subjects were a consecutive series of 920 node-negative invasive breast cancer patients who underwent surgery between 1987 and 1994 at our hospital. These patients did not receive adjuvant chemotherapy. Ten-year disease-free (DFS) and overall survival (OS) rates were analyzed by the St-Gallen risk categories (Minimal/Low, Intermediate, High).
Results: The median age of the patients at surgery was 52 years and the median follow-up period of patients was 10.2 years. At 10 years, the respective DFS and OS rates of all patients were 84.6 and 86.7%. The DFS and OS of patients in the Minimal/Low risk category (25 patients) both showed 100%. The DFS and OS of patients in the Intermediate risk category (356 patients) showed 92.0 and 93.1%, respectively. The DFS and OS of patients in the High risk category (539 patients) showed 79.4 and 82.2%, respectively, indicating a significant difference between those in the Minimal/Intermediate risk category (381 patients) (p < 0.001, p < 0.001, respectively). The DFS and OS of patients who had one pathological lymph node metastasis (775 patients) showed 72.7 and 75.2%, respectively, which indicated a non-significant difference between those in the High risk category (381 patients) (p = 0.10). These data support the validation of adjuvant therapy for high-risk node-negative breast cancers in Japanese patients. However, quality control is needed to define the histological grade included in the risk categories.
Conclusion: Japanese patients with invasive breast cancer without lymph node metastasis showed a survival advantage compared with their Caucasian counterparts. However, patients in the High risk group as defined by St-Gallen recommendations should be indicated for adjuvant therapy.