Abstract
PurposeObesity associated fat infiltration of organ systems is accompanied by organ dysfunction and poor cancer outcomes. Obese women demonstrate variable degrees of fat infiltration of axillary lymph nodes (LNs), and they are at increased risk for node-positive breast cancer. However, the relationship between enlarged axillary nodes and axillary metastases has not been investigated. The purpose of this study is to evaluate the association between axillary metastases and fat-enlarged axillary nodes visualized on mammograms and breast MRI in obese women with a diagnosis of invasive breast cancer.MethodsThis retrospective case–control study included 431 patients with histologically confirmed invasive breast cancer. The primary analysis of this study included 306 patients with pre-treatment and pre-operative breast MRI and body mass index (BMI) > 30 (201 node-positive cases and 105 randomly selected node-negative controls) diagnosed with invasive breast cancer between April 1, 2011, and March 1, 2020. The largest visible LN was measured in the axilla contralateral to the known breast cancer on breast MRI. Multivariate logistic regression models were used to assess the association between node-positive status and LN size adjusting for age, BMI, tumor size, tumor grade, tumor subtype, and lymphovascular invasion.ResultsA strong likelihood of node-positive breast cancer was observed among obese women with fat-expanded lymph nodes (adjusted OR for the 4th vs. 1st quartile for contralateral LN size on MRI: 9.70; 95% CI 4.26, 23.50; p < 0.001). The receiver operating characteristic curve for size of fat-enlarged nodes in the contralateral axilla identified on breast MRI had an area under the curve of 0.72 for predicting axillary metastasis, and this increased to 0.77 when combined with patient and tumor characteristics.ConclusionFat expansion of axillary lymph nodes was associated with a high likelihood of axillary metastases in obese women with invasive breast cancer independent of BMI and tumor characteristics.
Highlights
Obesity affects more than 30% of adult women worldwide, and obese women have an increased risk of breast cancer with increased risk of axillary node metastases and breast1 3 Vol.:(0123456789)Breast Cancer Research and Treatment (2021) 189:257–267 cancer-specific mortality compared to normal-weight women [1, 2]
We found that enlarged fat expanded axillary lymph nodes were strongly associated with node-positive breast cancer in obese women despite age, body mass index (BMI), and tumor characteristics
Previous studies have shown that obesity is associated with an increased size of axillary lymph nodes (LNs) due to hilar fat expansion without associated increase in cortical size, a finding demonstrated by increased hilo-cortical ratio in enlarged nodes of obese women [10]
Summary
Obesity affects more than 30% of adult women worldwide, and obese women have an increased risk of breast cancer with increased risk of axillary node metastases and breast1 3 Vol.:(0123456789)Breast Cancer Research and Treatment (2021) 189:257–267 cancer-specific mortality compared to normal-weight women [1, 2]. Studies have reported that there are no appreciable differences in mammography screening rates and screening intervals among obese women and normal-weight women suggesting that biologic factors are likely responsible for higher breast cancer risk and mortality [2,3,4,5]. Axillary lymph node (LN) status is one of the most important independent prognostic indicators of survival, with reports of up to 14% decrease in 5-year survival associated with a single metastatic axillary node [8, 9]. These findings suggest that targeting nodal metastases in breast cancer treatment may significantly impact breast cancer mortality
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