Purpose: The selective treatment of internal mammary lymph nodes (IMNs) in breast cancer is controversial. The purpose of this research was to determine the subpopulation patients with high risk of internal mammary lymph nodes metastasis who received extended radical mastectomy without any preoperative treatment from 1956 to 2003 in China.
Patients and methods: 1,679 Chinese patients were underwent extended radical mastectomy (ERM) between 1956 and 2003. Four individual variables were selected (tumor site, tumor size, the number of ALNs involvement, patient age),then classified by following standards: tumor site(lateral, central, medial),tumor size(T1:<or=2 cm; T2:2 < T <or= 5 cm, T3:>5 cm), ALNs(0,1-3,4-6, >or=7), age(<or=35 y, 36-50 y, >50 y). Chi-square and binary logistic regression were used to analysis relationship of these variable and IMMs.
Results: The four individual variables were significantly associated with IMNs metastasis using univariate analysis. However, three individual variables except for tumor size independently impact the IMNs metastasis using multivariate analysis. The incidence of IMNs metastasis in patients with 4-6 and >or=7 positive ALNs was 28.1%, 41.5%. Within subgroup patients with medial tumor and positive ALNs, the incidence of IMNs metastasis was 23.6% for patients with 1-3 positive ALNs, and 47.5% for 4-6 positive ALNs, 38.7% for patients with >or=7 positive ALNs. The incidence of IMNs metastasis was 25.4% for patients with T3 tumor and younger than 35 y.
Conclusion: Patients with following conditions had high risk of IMNS metastasis: (1) patients with 4 or more positive ALNs. (2) patients with medial tumor and positive ALNs.(3) patients with T3 tumor and younger than 35 y. (4) patients with T2 tumor and positive ALNs.(5) patients with T2 tumor and medial tumor .The incidences of IMNS metastasis for those patients were more than 20%.