Axillary lymph node metastases associated with small invasive breast carcinomas

BACKGROUND. Over the past 20 years the proportion of invasive breast carcin omas measuring less than or equal to 1 cm has increased progressively. Info rmation regarding the effect of clinical and histologic characteristics on the frequency of lymph node metastases associated with small invasive breas t carcinomas is limited. METHODS. A review of Surveillance, Epidemiology, and End Results data was p erformed using cases diagnosed between January 1988 through December 1993. A total of 12,950 patients with invasive breast carcinomas measuring less t han or equal to 1 cm undergoing a resection of the primary tumor and an axi llary lymph node dissection were included in this study. The effect of clin ical and histologic characteristics on the frequency of lymph node metastas es was reviewed. RESULTS, The frequency of lymph node metastases associated with Tla tumors was less than that observed from T1b tumors (9.6% vs. 14.3%; P < 0.001). Tu mors with favorable histology (mucinous, papillary, and tubular carcinomas) had a lower frequency of lymph node metastases compared with all other his tologic types (3.9% vs. 13.9%; P < 0.001). Increasing histologic grade was associated with an increased risk of lymph node metastases ranging from 7.8 % in Grade 1 tumors to 21.0% in Grade 4 turners (P < 0.001), Increasing pat ient age was associated with a progressively decreasing frequency of associ ated axillary lymph node metastases ranging from 22.6% in women age < 40 ye ars to 10.2% in women age greater than or equal to 70 years (P < 0.001). CONCLUSIONS. Cases in which an axillary lymph node dissection can be avoide d are those with an associated frequency of lymph node metastases less than or equal to 5%, including Tla and T1b mucinous and tubular carcinomas, Tla papillary carcinomas, and Tla Grade 1 carcinomas. (C) 1999 American Cancer Society..