Abstract P4-17-04: Male breast cancer: Clinico-pathological characteristics from the national cancer database (NCDB)
Authors: Elimimian Elizabeth Blessing , Elson Leah , Liang Hong , Nahleh Zeina 
Published: March 2020

Background: Male breast cancer (BC) is a rare clinical diagnosis, representing &lt;1% of all cancers, with an incidence rate of approximately 1% in western countries (1). There is a paucity of data from large cohorts describing the prevalence, demographics, mortality, incidence, and changes over time of male BC (2).

Objective: This study aimed to describe the demographic and pathologic characteristics associated with a very large database of men treated for BC in the United States over the course of 12 years, using the National Cancer Database (NCDB), and to identify any significant disparities in demographic and clinical characteristics, between male and female breast cancer patients.

Methods: We analyzed all male BC cases, diagnosed between the years 2004-2016, from the NCDB, that estimated to capture 70% of all diagnosed malignancies from all regions of the United States. Univariate and descriptive analyses were conducted in order to identify any epidemiologic trends over time, and to identify demographic characteristics associated with this population. Any significance was determined by a threshold of α &lt; 0.05. Chi-squared analyses were performed to determine any significance in disparities observed between the gender sample groups.

Results: A total of n= 23,990 men were included in the analysis and were compared to a total sample of n=2,672,744 female patients with breast cancer. The mean age was 65 ±13.0 years for men and 61 ±13.3 years for women (distribution: 13% &lt;50 years; 52% 51-70 years old; 35 % 71+ years). Race and Ethnicity were reported as follows: White (non-Hispanic) n=19,034 (79.3%); Black n=3,125 (13.0%); Hispanic n=807 (3.4%); Asian n=477 (2.0%); Native American n=37 (0.2%); Pacific Islander n=31 (0.1%); other n=190 (0.8%); Unknown n=289 (1.2%). Clinical stages for men were as follows: 2,385 (9.9%) presented with Stage 0 disease; 6,630 (27.6%) presented with Stage I disease; 5,946 (24.8%) presented with Stage II disease; 1,561 (6.5%) presented with Stage III disease; 1,407 (5.9%) presented with Stage IV disease. Grade distribution for most tumors was moderate or poorly differentiated (74.5%). The primary cancer subtypes were: ductal carcinoma (86.9%), lobular carcinoma (6.4%), and other invasive carcinoma (5.1%). Ductal carcinoma was diagnosed significantly more frequently than all other subtypes (p&lt;0.001) Men were older at diagnosis, exhibited more comorbidities, presented with a larger proportion of disease metastasis, with a trend towards more poorly differentiated tumor grades (P&lt;0.005) than women. The annual prevalence of male BC diagnoses increased by over 48%, from 2004 (n=1,416) to 2016 (n=2,101) compared to a rate increase of 42% for women between 2004 and 2016.

Conclusion: This study reports the clinical and pathological characteristics of a large cohort of male BC in the United States. Patients with male BC present at an older age, with more comorbidities, and exhibit later stages of disease compared to women. The data also suggests the annual diagnosis rate of male breast cancer has increased over time. These results may indicate an increased need for clinical education regarding the continued risks of breast cancer in the men.

Citation Format: Elizabeth Blessing Elimimian, Leah Elson, Hong Liang, Zeina Nahleh. Male breast cancer: Clinico-pathological characteristics from the national cancer database (NCDB) [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 P4-17-04.