Loss of nuclear p27KIP1 (p27) expression as a predictor of lymph node spread in T1 breast cancer

e11010 Background: We originally reported that p27 loss in T1a/b breast carcinomas was associated with lack of estrogen and progesterone (ER/PR) hormone receptors, but not in T1c node negative tumors (Mirchandani et al, Anticancer Research 2011). The current study explored the association of p27 expression with lymph node (N) status. Methods: 217 consecutive patients with T1 tumors were identified from 2001-2003. All patients underwent sentinel node biopsy (and complete lymphadenectomy when positive on frozen section): 111 were N0 and 106 were N+. Immunohistochemistry was performed for ER/PR, Her2, and nuclear p27 (low vs normal) and tumors were graded (well, moderate, and poorly differentiated). Analysis was conducted to define associations between standard variables and p27 expression among node positive and node negative tumor carriers (Table). Results: Low p27 expression was found in 21% of N0 and 36% of N+ T1 breast cancer patients (Chi-square=6.14, p-value=0.01). However from a series of multivariable analyses, only tumor size was significantly associated with node positivity. Conclusions: Poorly differentiated tumors, T1c tumors, and low p27 expression were associated with lymph node positivity, but only tumor size was significant in multivariable analysis. Contrary to our prior report, the relationship between low p27 and ER/PR- is strongest in the T1c subset (data not shown). Future studies will expand study cohorts to explore whether low p27 expression is a biomarker of poor outcome at 10 years in patients with T1 tumors treated with antiestrogens. [Table: see text]