Abstract PS14-10: Trends in incidence and stage of male breast cancer, 2004-2016: An analysis from the national cancer database
Authors: Cao Lifen , Singh Rashi , Sarode Anuja L , Kharouta Michael , Shenk Robert , Miller Megan E 
Published: February 2021

Abstract
Background: Male breast cancer has been less well studied due to the rarity of this condition compared with female breast cancer. Men have traditionally presented at later stages than women, leading to disparities in outcomes. Our aim was to identify the incidence of male breast cancer in recent years and determine trends in clinical and pathologic stage that could be utilized to improve breast cancer care. Methods: Patients diagnosed with primary breast cancer between 2004 and 2016 were identified using the National Cancer Database (NCDB), which collects hospital registry data from over 1,500 Commission on Cancer (CoC)-accredited facilities and represents more than 70% of newly diagnosed cancer cases in the United States. Patient, tumor, treatment, and facility data was compared between male and female patients. Incidence of male and female breast cancer was stratified by both AJCC clinical stage and pathologic stage (I-IV) and evaluated over the study period. Results: 17,814 male breast cancer patients and 2,001,551 female patients with breast cancer were identified. The incidence of male breast cancer increased by 1.5-fold from 1044 cases per year in 2004 to 1565 cases per year in 2016. The number of female breast cancer cases was 123,799 in 2004 and reached the highest annual volume of 184,718 in 2015. In 2010 incident male breast cancer cases rose by nearly 100% compared with the prior year, the majority of which represented early stage disease. In that year alone, for males there was a 99.6% increase (276 vs. 556 cases) in pathologic stage I disease, 89% increase (200 vs. 378 cases) in pathologic stage II disease and 94.7% increase (68 vs. 132 cases) in patients diagnosed with in situ disease. After 2010, incidence patterns for male breast cancer stabilized with ratio changes for Stage I or II at the level of only 1% to 7.3% per year. Interestingly, the proportion of male to female breast cancer incident cases remained constant over the study period, with males representing 0.8-0.9% of the total cases. Overall, a minority of patients presented with Stage III (6.6%) and Stage IV (4.6%) disease, though a greater proportion of males than females had advanced stage disease at diagnosis (16.88% of males vs. 11.14% females, p&lt; 0.001). The incidence of clinical Stage I and II disease increased over time for both genders, though a greater proportion of female breast cancer was Stage I (43.2% female vs. 35.93% male, p&lt;0.001), and Stage II disease was more common in men (33.83% male vs 24.22% female, p&lt;0.001). When pathologic stage was considered, Stage I and II represented the majority of male breast cancer cases, 74.7% to 80% per year, and was slightly higher than the combination of Stage I and II at clinical diagnosis, 65.7% to 78.7% per year. Conclusions: Over past 15 years, the incidence of male breast cancer has increased substantially, yet remains a stable proportion of total breast cancer cases. The greater frequency of Stage II, III and IV disease in men likely reflects the difference in diagnosis by clinical exam or symptoms in men vs. screening programs in women. Education to increase awareness of male breast cancer, promote symptom recognition, and encourage appropriate use of genetic testing should be emphasized to improve early diagnosis of breast cancer in men.
Citation Format: Lifen Cao, Rashi Singh, Anuja L Sarode, Michael Kharouta, Robert Shenk, Megan E Miller. Trends in incidence and stage of male breast cancer, 2004-2016: An analysis from the national cancer database [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS14-10.