Clinicopathologic predictors of lymph node metastasis in breast cancer patients according to molecular subtype

We present a large institutional study to determine factors predictive of axillary lymph node (LN) metastasis in breast cancer according to molecular subtype.

We conducted a retrospective analysis of our prospectively maintained breast cancer database study using data from of women managed from January 2009 through December 2013. Clinicopathologic characteristics were correlated with lymph node status and outcome according to breast cancer molecular subtyping.

LN metastases were detected in 464 (32.1%) of 1444 women with breast cancer. By multivariate analysis, independent factors predictive of LN involvement were: for the luminal A subtype (n=776): tumour size: OR=1.05 [95% CI: 1.03-1.07] P<0.0001; lymphovascular invasion: OR=3.06 [95% CI: 1.80-5.20] P<0.0001 and tumour grade: OR=1.65 [95% CI: 1.07-2.58] P=0.026. For luminal B subtype (n=441): age: OR=0.97 [95% CI: 0.95-0.99] P=0.004; tumour size: OR=1.03 [95% CI: 1.01-1.05] P=0.002; lymphovascular invasion: OR=3.21 [95% CI: 1.92-5.44] P<0.0001; inflammatory breast cancer: OR=12.36 [95% CI: 2.18-243.3] P=0.019. For the HER2 subtype (n=72): lymphovascular invasion: OR=7.87 [95% CI: 2.10-35.2] P=0.003. For the triple negative subtype (n=155): parity: OR=1.53 [95% CI: 1.10-2.25] P=0.02; tumour size: OR=1.03 [95% CI: 1.01-1.05] P=0.002 and lymphovascular invasion: OR=7.13 [95% CI: 2.46-22.8] P=0.00048.

This retrospective study provides valuable insight into LN involvement of patients with primary breast cancer according to molecular subtyping.