Six-year follow-up of patients with microinvasive, T1a, and T1b breast carcinoma

Background: Management of patients with breast cancers ≤ 1 cm remains controversial. Reports of infrequent nodal metastases in tumors ≤5 mm has led to suggestions that axillary dissection should be selective, and that tumor characteristics should guide adjuvant therapy. Methods: A retrospective review of 290 patients with breast cancer 1 cm in size or smaller from 1989 to 1991 was done. Distant disease-free survival (DDFS) was the primary outcome measure. Results: There were 95 T1a (≤5 mm) and 196 T1b (6-10 mm) cancers. Nodal metastases were found in 8 T1a and 26 T1b tumors. Larger size, poorer differentiation, and lymphovascular invasion (LVI) were associated with more nodal metastases, but none of these trends reached statistical significance. The 6-year DDFS was 93 % for node-negative and 87% for node- positive patients (P = .02). Overall, breast cancers with poorer differentiation and LVI trended toward a poorer outcome. For patients with node-negative tumors, LVI was associated with a poorer outcome (P = .03). The size of the primary tumor was not predictive of outcome. There were no nodal metastases or recurrences in the 18 patients with microinvasive breast cancer. Conclusions: Lymph node status is the major determinant of outcome in breast cancers 1 cm in size or smaller. Accurate axillary assessment remains crucial in management of small breast cancer.