Background: The histopathological criteria for high-risk node-negative primary breast cancer stated in the National Surgical Adjuvant Study of Breast Cancer (NSAS-BC) protocol were used to grade a consecutive series of 488 cases at our hospital.
Methods: To validate the criteria retrospectively, we examined the histological features of node-negative primary breast cancers which showed early relapse within 2 years after surgical therapy.
Results: Early relapse occurred in 12 patients, distant metastases in 11, and local recurrence in one. Among 278 cases followed for up to 1.5 years or longer, early systemic relapse was detected in 10 (5.8%) of 172 higher-grade tumors (9 invasive ductal carcinomas of nuclear grade 3 and one invasive ductal carcinoma of nuclear grade 2) and one stromal cell sarcoma. Among the 115 low-risk tumors, only one case (0.9%) of invasive ductal carcinomas with nuclear grade 1 showed early local recurrence. Early relapse occurred in only one (1.5%) of 67 tumors with an invasive component of 1.0 cm but in 11 (5.2%) of 211 tumors with an invasive component of 1.1 cm. The recurrence rate increased to 9.3% (8/86) when tumor invasion was 2.1 cm. In 12 cancers showing recurrence, strand structure, large central acellular zones, and squamoid features were histologically observed in four, two, and three cases, respectively. The present results confirmed the reported tendency of correlation between strand pattern and bone metastasis, large central acellular zones and lung and brain metastasis, and squamoid features and lung metastasis. Synchronous bilateral and unilateral multiple cancers were characterized by lower nuclear grades.
Conclusions: At our hospital, the criteria used in the NSAS-BC protocol were demonstrated to identify node-negative cancers with high risk of early recurrence at a hospital level. To further identify groups prone to recurrence, longer follow-up would be necessary. In addition, the histological criteria could be improved to correlate with patient outcome more accurately.