Triple-Negative Receptor Status and Other Predictors of Lymph Node Positivity in Small (T1) Breast Cancers: A National Registry Study

Abstract

Purpose/Objective(s): With increased early detection of breast cancers (BC), the understanding of prognostic factors associated with small tumors becomes important in management. This study examined the effects of various tumor characteristics on positive lymph nodes (LN) and N staging through review of the Surveillance, Epidemiology, and End Results (SEER) database. Materials/Methods: Women who had stage T1N0-3M0 BC over the age of 30 who were treated in 2010 were identified using the SEER database. Patients underwent either lumpectomy or mastectomy with axilla evaluation. The incidence of LN+ and N staging were compared based on tumor grade, size, quadrant, and receptor status. Chi-square test, KruskalWallis test, and multivariable logistic regression were used, as appropriate. Results: A total of 14301 patients were included. The median age group was 60-64 years old. The median tumor size was 12 mm (2-20 mm). There were 31% grade I, 45% grade II, and 24% grade III tumors. LNs were negative in 81%, while N1, 2, 3 diseases were 16%, 2%, and 1%, respectively. Hormone receptor status was positive for estrogen (ER) in 86.5%, progesterone (PR) in 76%, and HER 2 for 12% of the cases, resulting in 15.6% triple negative (TNBC) and 6.1% triple positive (TPBC). The LN+ patients had larger primary tumor size (median: 15 mm) compared to LN(median: 11 mm) (p < 0.0001). Tumor grade was strongly associated with the likelihood of LN+ as well as higher N stage (p < 0.0001). Higher prevalence of N2/N3 disease was found in ERtumors (p Z 0.04) and PRtumors (p < 0.001) compared to ER+ and PR+. HER 2+ tumors were associated with higher likelihood of LN+ disease (p < 0.0001). TNBC was less likely to be associated with +LN (p Z 0.03). In multivariable logistic regression analysis, TNBC (vs TPBC) remained a predictor for fewer LN+ disease (adjusted OR Z 0.66; 95% CI Z 0.52, 0.84; P Z 0.001) and N2/3 stage (adjusted OR Z 0.62; 95% CI Z 0.39, 0.99; P Z 0.048). Tumor location (central and quadrants) was not a predictor of +LN and N staging except for a small number of patients coded to have tumor involving the nipple (0.4%) and axillary tail (0.8%) (p < 0.0001). Conclusions: This review of the SEER data suggests that grade, tumor size, and HER 2 were strong predictors of +LN in T1 breast cancer patients. TNBC had a negative association with likelihood and number of positive LN as compared to other receptor types. These factors should be considered when deciding on management of axilla for T1 BC patients. Author Disclosure: J.C. Ye: None. W. Yan: None. P. Christos: None. D. Nori: None. K.C. Chao: None. A. Ravi: None.