Abstract P4-17-10: Obesity increases the risk of male breast cancer and protects against triple negative male breast cancer
Authors: Restrepo Nicolas , Vatcheva Kristina , Moreno Katia , Trejo Aimee , Restrepo Alvaro 
Published: March 2020

Abstract
Introduction: Male breast cancer (MaBC) is an uncommon disease that represents less than 1% of all breast cancers. Obesity has been associated with increased breast cancer incidence in post-menopausal women. Overweight and obese rates have almost tripled since the 1990’s in the U.S. In 2016, 68% of Texas adults were classified as overweight or obese. The Rio Grande Valley (Cameron, Hidalgo, Starr and Willacy counties) is one of the areas with the highest levels of obesity in the country (37% of the population). The aim of this exploratory retrospective population-based study is to analyze the incidence of MaBC in Texas and the Rio Grande Valley (RGV), as well as to compare the association of obesity with triple negative MaBC. Methods: Retrospectively, we reviewed available data from the Texas Cancer Registry, Cancer Epidemiology and Surveillance Branch, and Texas Department of State Health Services from the years 2011-2016 of patients with a diagnosis of invasive MaBC. The incidence of MaBC was examined according to sex, stage, tumor subtypes (HR+, HER2-Neu, Triple Negative) and BMI in Texas and the RGV. Some cases were excluded due to issues with data quality regarding BMI. Results: Between 2011-2016, there were 869 patients diagnosed with MaBC in Texas. The incidence of MaBC almost doubled during this time period. MaBC with distant metastasis had a downward trend (&lt; 10% of cases). Evaluating MaBC tumor markers, there was no increase in the number of triple negative MaBC cases in Texas or the RGV despite a dramatic increase in MaBC cases. Furthermore, the number of triple negative MaBC cases in the RGV was significantly less than Texas’s, despite the RGV having higher levels of obesity (see table 1).A total of 495 cases of MaBC in Texas and 18 cases in the RGV had good quality data regarding BMI for analysis. There was a significant increase in the incidence of MaBC associated with obesity (BMI &gt;30), which almost tripled in Texas and the RGV during the years studied. In the RGV, there was a trend to zero cases of MaBC in patients who were underweight and normal weight, see table 2. Conclusion: (1)There is a significant increase in MaBC, as well as in MaBC associated with obesity between the years 2011-2016 in Texas and the RGV. (2)There is no increase in the incidence of triple negative MaBC in Texas or the RGV despite a significant increase in obesity associated MaBC. (3)There is no increase in the incidence of MaBC in patients who are underweight or normal weight in the RGV. (4)Obesity appears to be a protective factor for the development of triple negative MaBC.
Table 1. Male Breast Cancer Cases between 2011-2016 in Texas and the RGV201120122013201420152016Incidences of MaBC (Texas)104117121133202192MaBC Triple Negative (Texas)511556Incidences of MaBC (RGV)434366MaBC Triple Negative (RGV)001000
Table 2. Male Breast Cancer Cases by BMI between 2011-2016 in Texas and the RGVTexas Statewide2011-2016201120122013201420152016Underweight (&lt;18.5)7111211Normal Weight (18.5–24.9)98768202928Overweight (25–29.9)167101617225547Obese (≥30)223151921416562Total49533424785150138Rio GrandeValley2011-2016201120122013201420152016Underweight (&lt;18.5)0000000Normal Weight (18.5–24.9)3111000Overweight (25–29.9)4020011Obese (≥30)11002234Total18133245
Citation Format: Nicolas Restrepo, Kristina Vatcheva, Katia Moreno, Aimee Trejo, Alvaro Restrepo. Obesity increases the risk of male breast cancer and protects against triple negative male breast cancer [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P4-17-10.