Factors predicting the sentinel node metastases in T1 breast cancer tumor: an analysis of 1416 cases.

Aim: To determine the factors associated with the metastatic involvement of sentinel lymph node (SLN) biopsy in patients with early breast cancer.

Study Design: This was a retrospective study of patients with T1 invasive breast cancer who underwent SLN biopsy at Claudius Regaud Institute between January 2001 and September 2008.

Results: 1416 patients were recruited into this study. SLN metastases were detected in 368 patients (26%). Younger age, tumor size and location, histological type, nuclear grade, and lymphovascular invasion appear to be significant risk factors of SNL involvement. In multivariate analysis, tumor size, tumor location, histological type and lymphovascular invasion are significant factors. When the tumor size is >20 mm, the OR is 6.6 compared to a T1a tumor (3.145-14.175, p<0.001, confidence interval 95%). When the tumor is found in the inner quadrant, the risk of SLN involvement is reduced compared to external locations with an OR of 0.53 (0.409-0.709, p<0.001, confidence interval 95%). Non-ductal/lobular compared to infiltrative ductal cancer have a lower risk of SLN involvement with an OR of 0.423 (0.193-0.927, p<0.03, confidence interval 95%). Lymphovascular invasion increase the risk of positive SLN with an OR of 2.8 (1.9-4.1, p<0.001, confidence interval 95%).

Conclusion: It appears reasonable to avoid axillary lymph node dissection in older patients with T1a tumors of good histopathological type and in the absence of lymphovascular invasion.