BACKGROUND The increasing use of systemic therapy for women with lymph node negative breast carcinoma and earlier stage of disease at mammographic detection raises questions regarding the need for routine axillary lymph node dissection. Predictive modeling for lymph node involvement may be one way to reduce the need for axillary lymph node dissection and its morbidity. METHODS A multivariate analysis of 12 factors predictive of axillary lymph node involvement was conducted in a population‐based cohort of 4312 women with invasive breast carcinoma diagnosed between January 1. 1993 and December 31, 1996. RESULTS Clinical palpability, lymphatic or vascular invasion, lesion size, margin status, histology, and patient age were independent predictors of axillary lymph node involvement. The model correctly identified lymph node status in 76.6% of cases. Model accuracy and fit were equally high when applied to randomly selected halves of the study subjects. Approximately 32.0% of the patients in the study sample (1363/4312) were identified as having an extremely high (91%; n = 1102) or low (10%; n = 261) risk of lymph node involvement. In a second analysis, a clinically useable, three‐variable model identified a very low risk group of patients (n = 147) with a 4.8% risk of lymph node metastasis and a high risk group of patients (n = 1008) with a 74.2% risk of lymph node metastasis. Greater than 90% of subjects in the high risk group received adjuvant systemic therapy even if they were lymph node negative pathologically. CONCLUSIONS A clinically useable, three‐variable model employing tumor and lymph node palpability, size, and lymphatic or vascular invasion can identify women with invasive breast carcinoma in whom axillary lymph node dissection is very unlikely to alter recommendations regarding adjuvant systemic therapy. Cancer 1998;83:948‐955. © 1998 American Cancer Society.

The two-fold risk of relapse and breast cancer death associated with high-risk medial breast tumors may be due to occult spread to internal mammary nodes (IMNs). Enhanced local control, such as with irradiation of the IMN chain, may be one way to reduce the excess risk. Ongoing randomized controlled trials may provide prospective answers to the question of the optimal volume of radiotherapy.

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Tubular carcinoma of the breast (TCB) is a recognized histologic variant of infiltrating ductal carcinoma (IDC) and has been considered to have a comparatively favorable prognosis. However, previous studies have been based on small numbers of cases, some pure TCB and some mixed histology, or have not employed an appropriate comparison group. In this study 171 pure TCB cases and a comparison group of 386 cases with grade I (well differentiated) IDC were identified in a population-based database maintained by the British Columbia Cancer Agency (BCCA). The proportion of cases with axillary nodal involvement at presentation was lower in TCB cases than in the grade I IDC comparison group (12.9% and 23.9%, respectively; p < 0.05). Low-risk tumors (T1 and without vascular lymphatic or perineural invasion) were more prevalent in the TCB patients than in the grade I IDC patients (66.7% and 60.0%; p < 0.05). Low-risk TCB cases had a significantly lower rate of nodal metastases at presentation than low-risk grade I IDC cases (7.0% and 13.2%; p < 0.05). Kaplan-Meier and log-rank analyses indicated a statistically significantly lower rate of local recurrence in TCB cases than among IDC cases (p < 0.05) and a trend toward a lower rate of systemic relapse in TCB cases (p = 0.07). However, no difference in disease-specific survival was observed between TCB cases and grade I IDC comparisons. We conclude that the biologic behavior of TCB was more favorable than that of a comparison group of IDC cases. In view of the low incidence of axillary node metastases at presentation in the low-risk TCB subset (7%), axillary dissection may be omitted as part of the initial surgical management in these patients.