Lymph node negative invasive breast carcinoma 1 centimeter or less in size (T1a,bN0M0)

BACKGROUND: Patients with lymph node negative invasive breast carcinomas < or = 1 cm in size have a low recurrence rate and may be spared adjuvant therapy. Reliable prognostic features will help physicians design appropriate treatment for these patients. METHODS: The clinicopathologic features, prognostic marker profiles, and clinical outcomes of 88 T1a,bN0M0 carcinomas in 87 patients who presented between 1975 and 1990 were studied. The size of each tumor was determined by direct measurement of histologic sections. The median follow-up was 7.8 years (range, 4-15 years). The characteristics of tumors diagnosed between 1975 and 1983 and between 1984 and 1990 were also compared. RESULTS: Before 1984, the majority of patients presented with palpable mass lesions, whereas from 1984 on, more patients presented with mammographic abnormalities. However, no significant differences in the pathologic features of tumors were observed between the two periods. There were only 3 locoregional recurrences (3%) and 4 distant recurrences (5%). Palpable tumors had worse prognoses than mammographically detected lesions (P = 0.02). Histologic grade, lymphatic invasion, hormone receptors, Ki-67 antigen, and bcl-2 expression were significant univariate prognostic indicators. The small number of patients in the series precluded multivariate analysis. None of the 43 patients (49%) with tumors < or = 0.5 cm, or of histologic and nuclear Grade 1, or of favorable histologic types developed recurrences; and their outcomes were significantly better than those of other patients (P = 0.013). Tumors originally classified as T1b, but which exceeded 1 cm on review and were excluded from the study, had a significantly higher distant recurrence rate (23%) than bona fide T1a,b carcinomas (P = 0.03). CONCLUSIONS: T1a,bN0M0 carcinomas have a low recurrence rate, especially those tumors < or = 0.5 cm, or of low histologic or nuclear grade, or of favorable histologic type. The high recurrence among patients with tumors initially understaged as T1a,b carcinoma underscores the importance of accurately determining tumor size.