Factors affecting nodal involvement in mucinous breast cancer.

124 Background: Mucinous carcinoma of the breast is a rare type of invasive ductal breast cancer that accounts for 2-5% of all primary breast cancers. Axillary lymph node involvement for mucinous breast carcinoma is rare and correlated with a poor prognosis. However, the relation of lymph node involvement to certain factors is unknown, hence the purpose of our study. Methods: Retrospective chart review of patients diagnosed with mucinous breast carcinoma from 2004 to 2014 from the local tumor registry. Variables include age, tumor size, lymph node metastasis, diagnosis type (pure/mixed), and hormone status of patients. Chi square and T-test was performed. Results: 45 female patients were included in the study with the age range of 35 to 97 years old. 39 patients were diagnosed with mixed mucinous carcinoma and 6 had pure mucinous carcinoma. 9 patients had positive axillary lymph node involvement. 78% of patients with positive lymph node had mixed mucinous carcinoma and 22% had pure mucinous carcinoma. There is no statistical significance (p > 0.05) between lymph node involvement and diagnosis type. Tumor size ranged from 4 to 120 mm, with a mean of 28 mm. 78% of patients with positive lymph node had a tumor size smaller than 60 mm. The other two had a tumor size of 65 mm. and 120 mm. There is no statistical significance (p > 0.05) in the proportion of people who are lymph node positive to tumor size less than 60 mm. Out of the 45 patients, 42 patients expressed ER receptors, 36 expressed PR receptors, and 12 expressed HER2 receptors. 89% of positive lymph node patients express ER hormone receptors, 78% expressed PR receptors, and 56% expressed HER2 receptors. No correlation between ER/PR status and lymph node involvement (p > 0.05) was found but there was a positive correlation between HER2 receptor status and lymph node involvement (p < 0.05). Conclusions: No significant difference between diagnosis type/tumor size in relation to lymph node involvement. Although there is a trend between small tumor size to positive lymph node, it is not significant enough. There is a significant relationship between HER2 positive receptors and lymph node involvement. This is suggestive that the biological nature of the tumor has a larger influence on lymph node involvement than the physical nature.