Abstract P3-10-04: Obesity and adipose inflammation in men with breast cancer

Abstract

Background: Elevated body mass index (BMI) is associated with increased risk of hormone receptor (HR)-positive breast cancer in postmenopausal women and worsened outcomes after breast cancer diagnosis. These observations may be partly attributable to adipose inflammation, which is prevalent in the breasts of obese women and is associated with worsened breast cancer survival. In men, some studies have reported obesity to be a risk factor for breast cancer, however the biologic links are not well characterized. Whether adipose inflammation occurs in male breast tissue has not been previously reported. Here we examined the relationships among pre-diagnosis BMI, adipose inflammation, and breast cancer features in men. Methods: Males diagnosed with stage 0 – III breast cancer who underwent mastectomy at Memorial Sloan Kettering (MSK) between August 1991 – November 2011 were included in this retrospective cohort study. Pre-operative BMI was categorized as normal or underweight (<25), overweight (25 – 29.9), obese (≥30), or morbidly obese (≥40 or ≥35 + co-morbidity). Archived breast tissue was subjected to CD68 immunohistochemistry to detect adipose inflammation, defined by the presence of dead or dying adipocytes surrounded by macrophages – known as crown-like structures of the breast (CLS-B). Clinicopathologic associations with BMI and CLS-B were analyzed by logistic regression and Fisher's exact test. Results: A total of 141 men were included; median age 63 (range 23 – 96). By BMI category, 25 were normal or underweight, 65 overweight, and 51 obese – of which 19 were morbidly obese. Only 11 men had known BRCA1/2 mutations. Median age at diagnosis was 69 in normal/underweight men versus 63 in obese men and 51 in morbidly obese men (P≤0.05). Among those with invasive tumors, average tumor size was 1.50 cm (± 0.84) in normal/underweight men versus 2.04 (±0.81) in morbidly obese men (P≤0.05). Archived breast tissue was available from 92 (65%) men. Breast adipose inflammation was present in 55 (60%) men, and average BMI was 31 (±8) versus 28 (±5) in men with versus without inflammation, respectively (P=0.07). Conclusions: Obesity is associated with early onset breast cancer in men. Morbidly obese men were diagnosed with breast cancer at an even younger age and had larger tumors than normal weight individuals. These findings support further studies to investigate mechanisms, such as adipose inflammation, through which obesity may promote breast cancer in men. Citation Format: Williams S, Parrish JC, Zhou XK, Wang H, Dierickx A, Gucalp A, Dannenberg AJ, Iyengar NM. Obesity and adipose inflammation in men with breast cancer [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 P3-10-04.