Significance of lymphatic invasion combined with size of primary tumor for predicting sentinel lymph node metastasis in patients with breast cancer.

Lymphatic invasion (ly) may mainly reflect the selective affinity of breast cancer cells for lymph nodes. We conducted the present study to investigate whether the presence of lymphatic invasion is a predictor of sentinel lymph node (SLN) metastasis in clinically node-negative breast cancer.We retrospectively evaluated the cases of 202 consecutive female patients with clinically node-negative primary breast cancer who underwent a radical breast operation with SLN biopsy. We examined the relationship between SLN metastasis and the significance of clinicopathological factors, including lymphatic invasion.Among the 202 patients, 49 (24.3%) had SLN metastasis. The univariate and multivariate analyses revealed that the size of the tumor and lymphatic invasion were independent risk factors for SLN metastasis. Among the 96 patients who were ly-negative and had a tumor size of less than 20 mm, only 5 (5.2%) had 1-2 metastases within the SLN. Among the 34 patients who were ly-negative and had a tumor size of less than 10 mm, there were no patients with SLN metastasis.Our results suggest that the presence of lymphatic invasion combined with the size of the primary cancer could be considered a strong risk factor for SLN metastasis in clinically node-negative breast cancer, and patients with a tumor size of less than 20 mm and clinically node-negative breast cancer may avoid axillary lymph node dissection after SLN biopsy. There is also a possibility that SLN biopsy could be unnecessary for patients with clinically node-negative breast cancer who are ly-negative and have a tumor size of less than 10 mm.