Background: The incidence of axillary lymph node metastases from infiltrating breast carcinomas measuring 1.0 cm or smaller reported in the literature varies from 0% (for tumors measuring < or =0.5 cm) to 27.1% (for all tumors < or =1 cm).
Methods: The authors examined all infiltrating breast carcinomas measuring 1.0 cm or smaller with axillary lymph node dissections in patients seen at their institution between January 1990 and March 1997 (117 cases) to determine the incidence of axillary lymph node metastases. All tumors were evaluated for patient age, histologic type of tumor, modified Bloom-Richardson grade, estrogen and progesterone receptor status, ploidy, S-phase fraction, and angiolymphatic vessel invasion, to determine whether there was a relation between the indicators and axillary lymph node metastases. The authors also performed immunohistochemical stains for the basement membrane components laminin and Type IV collagen on the tumors demonstrating metastases and on an equal number of size- and date-matched tumors not demonstrating metastases.
Results: Twelve cases of infiltrating carcinoma with axillary lymph node metastases were identified (a 10.3% overall incidence of metastases). Lymph node metastases were not identified in any of the cases with tumors measuring < or =0.5 cm (24 cases). The incidence of axillary lymph node metastases for carcinomas 0.6-1.0 cm was 12.9% (12 of 93 cases). High nuclear grade was found to correlate with the presence of lymph node metastases (P = 0.007). No statistically significant correlation was found between the other indicators examined and axillary lymph node metastases or between basement membrane staining and axillary lymph node metastases.
Conclusions: The authors concluded that infiltrating breast carcinomas measuring < or =0.5 cm are unlikely to have demonstrable axillary lymph node metastases. Lymph node dissections in these women may be unnecessary. Nuclear grade may be the best predictor of lymph node metastases in T1b tumors.