OBJECTIVETo study the clinical significance of extracapsular extension (ECE) of axillary lymph node metastases in breast cancer.

METHODSThe clinicopathological data of 1230 cases of nodal positive breast cancer treated in our department from 1989 to 1995 were analyzed retrospectively.

RESULTS486 (39.5%) from the 1230 cases were ECE positive. There was a higher incidence of ECE in postmenopausal women than premenopausal ones (47.5% versus 35.5%, respectively, P < 0.001). The patients in ECE positive group had a larger tumor size (5.11 +/- 2.53 cm versus 3.90 +/- 1.80 cm, P < 0.001). 18.3% of patients with stage T1 were ECE positive, stage T2 were 36.4%, and stage T3 were 54.4%, and the difference was significant (P < 0.001). ECE was correlated with the number of positive axillary lymph nodes. The ECE positive group had more positive nodes than ECE negative group (16.96 +/- 12.16 versus 5.24 +/- 6.60, P < 0.001). 6.1% of patients with 1 positive node were ECE positive, 13.5% with 2 - 3, 35.8% with 4 - 9, 62.3% with 10 - 19, and 84.0% with more than 20 positive axillary nodes, and there was a significant difference among those groups (P < 0.001). ECE had no association with ER/PR status (P = 0.706). ECE was a risk factor of local-regional recurrence, but the relapse time had no significant difference (P = 0.559). ECE was also a risk factor of distant metastasis, and the relapse time had a significant difference (P < 0.001). The median metastasis free time was 30.0 (2 approximately 172) months in ECE positive group, while 37.5 (2 approximately 170) months in ECE negative group (P = 0.006). CE occurred in 60.4% of the patients with firstly diagnosed bone, skin and distant lymph node metastasis, but in 42.0% of the patients with firstly diagnosed visceral metastasis (P = 0.001). The metastasis-free survival rate, locoregional recurrence-free survival rate and overall survival rate of the ECE positive group were much shorter than that of the ECE negative group. COX proportional hazard regression single factor analysis and multi-factor analysis suggested that ECE is an independent factor of metastasis-free survival, locoregional free recurrence and overall survival.

CONCLUSIONThe presence of ECE in breast cancer is positively related with tumor size and the number of positive lymph nodes. It is also a risk factor of locoregional recurrence and distant metastasis. ECE positive group has a much shorter metastasis-free survival, locoregional recurrence-free survival and overall survival. ECE is a risk factor of those three indexes.