Abstract P1-07-26: Clinicopathological predictors of axillary lymph node metastasis in early breast cancer patients
Authors: Satish M , Walters R , Silberstein PT 
Published: February 2018

Axillary lymph node (ALN) status is key in the prognosis of early breast cancer. Sentinel lymph node biopsy (SLNB) is the standard treatment in determining ALN status in clinically node negative patients with early breast cancer, but nearly 70% exhibit no ALN metastasis (a regional lymph node (RLN) metastasis). Likewise, selective use of SLNB has engendered modeling ALN metastasis. Using the National Cancer Database (NCDB), this study aimed to evaluate clinicopathological factors to help predict first and subsequent RLN metastasis in patients with early breast cancer.

Methods: We identified 660,258 women from 2004-2013 with early breast cancer stage (cT1-T3, cN0-N1, and M0). A two-part model was estimated using multivariable logistic regression to evaluate 1) predictors, by odds (OR), of having at least one RLN metastasis, and 2) predictors, by rate difference (RD), of having additional RLN metastasis relative to women with only one RLN metastasis. The same set of predictor variables were included in both parts of the model. All analyses were conducted using SAS v. 9.4 with p &lt;.05 indicating statistical significance.

Results: Adjusted ORs and RDs of RLN metastasis for selected variables from the model are shown in Table 1. Increased likelihood of at least one RLN metastasis was significantly associated with the presence of larger tumor size (p &lt;0.0001), a primary tumor in the nipple region (p &lt;0.0001) of the left breast (p &lt;0.0001), lobular or ductal type histology (p &lt;0.001, and p &lt;0.0001, respectively), positive estrogen (ER) and progesterone (PR) receptor statuses (p &lt;0.0001 for both), younger age (p &lt;0.0001), being white (p &lt;0.0001), and greater comorbidity (Charlson/Deyo - CD) (p &lt; 0.0001). Predictors of at least one RLN metastasis were also significantly associated with higher adjusted rates of further metastasis, except age, tumor size, ductal type histology, ER, and PR. However, a primary tumor in the central region (p =0.037), not the nipple region, was most associated with additional metastasis.

Table 1. Adjusted OR/RD (95% CI) for RLN Metastasis Events≥1 event &gt;1 event0.99 (0.99-0.99)Age (continuous)1.00 (-)1.10 (1.05-1.14)White vs. Other1.02 (1.00-1.04)0.98 (0.95-1.00)CD = 0 vs. 10.98 (0.97-0.99)0.89 (0.85-0.93)CD = 0 vs. ≥20.97 (0.95-0.99)1.02 (1.02-1.02)Tumor Size (continuous)1.00 (-) Primary Tumor Site - Nipple vs. (left), Central vs. (right) 1.80 (1.61-2.02)Overlap1.02 (1.01-1.04)1.87 (1.59-2.20)Tail0.98 (-)1.64 (1.46-1.84)LOQ1.00 (-)1.71 (1.53-1.92)UOQ1.02 (1.00-1.03)2.07 (1.84-2.33)LIQ1.07 (1.04-1.09)2.73 (2.43 -3.07)UIQ1.11 (1.09-1.13)1.44 (1.28 -1.63)Central (left), Nipple (right)1.06 (1.02-1.11) Histological Type - Lobular vs. 4.00 (3.72-4.30)Other1.52 (1.46-1.57)0.99 (-)Ductal1.18 (1.17-1.19)1.04 (1.04-1.04)ER (Positive vs. Negative)1.00 (-)1.02 (1.02-1.02)PR (Positive vs. Negative)1.00 (-)1.06 (1.05-1.08)Laterality (Left vs. Right)1.02 (1.01-1.02)≥1 event (vs. 0): OR; &gt;1 event (vs. 1): RD; (-) = insignificant

Conclusion: Utilizing a large dataset, several clinicopathological factors emerged from the NCDB as independent predictors of at least one, or additional RLN metastasis, supporting their weighted inclusion in prediction tools for ALN metastasis. Notably, different primary tumor sites of the breast predicted the two events modeled.

Citation Format: Satish M, Walters R, Silberstein PT. Clinicopathological predictors of axillary lymph node metastasis in early breast cancer patients [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P1-07-26.