Abstract PS14-12: Trends in breast and axillary surgery for T1-T2 male breast cancer: A study from the national cancer database
Authors: Singh Rashi , Cao Lifen , Sarode Anuja L , Kharouta Michael , Shenk Robert , Miller Megan E 
Published: February 2021

Abstract
Introduction: Due to the low incidence of male breast cancer, large scale prospective trials to guide therapy are lacking. Historically males with breast cancer present at more advanced stages than females and have been surgically treated with modified radical mastectomy. Recent studies suggest that breast-conserving therapy for early-stage male breast cancer yields similar outcomes as for female patients, and that sentinel lymph node biopsy (SLNB) can be used in place of axillary lymph node dissection (ALND) for appropriate clinically node-negative patients. Our study investigates trends in breast and axillary surgery for male breast cancer patients, focusing specifically on the treatment of early-stage disease. Methods: The National Cancer Database (NCDB) was utilized to identify male and female patients diagnosed with clinical T1-2 breast cancer from 2004-2016. Patient, tumor, facility, and surgical treatment factors were examined. Patients were stratified by surgery type: partial, unilateral, and bilateral mastectomy; simple versus modified radical mastectomy; SLNB (removal of ≤ 5 lymph nodes) and ALND (&gt;5 lymph nodes). Trends in surgery type were compared between male and female patients and over the study period for each gender. Results: 9,782 males and 1,078,105 females with T1-2 breast cancer were identified. Men were significantly older at diagnosis than women (31.4% vs. 23.6% age &gt;70, p&lt;0.0001), were more often insured by Medicare (44.5% vs. 35.3%, p&lt;0.0001), and had greater co-morbidity (21.9% vs. 15.6% Charlson Deyo Score &gt;0). ER/PR+ disease (94.2% vs. 84.1%, p&lt;.0001), moderate/high grade histology (85.4% vs. 77.8%, p&lt;.0001) and lymphovascular invasion (24% vs. 15.3%, p&lt;.0001) were also more common in males vs. females. The majority of all patients were clinically node negative (80.4% of males, 85% of females) and had AJCC clinical stage I or II disease (92.3% men, 95.2% women). Unilateral mastectomy was performed most commonly for men (67.1% men vs. 24.1% women, p&lt;0.001), while women more frequently underwent partial mastectomy (64.7% women vs. 26.4% men, p&lt;0.001). The rates of each surgery type remained disparate by gender and stable over the study period: male unilateral mastectomy rate 59.8% in 2004 and 66.1% in 2016; female partial mastectomy rate 65.9% in 2004, 68.4% in 2016. Modified radical mastectomy rates decreased in favor of simple mastectomy for both genders, 61.8% to 24.1% in males and 58.7% to 20.2% in females, 2004 to 2016. There was a similar overall increase in SLNB vs. ALND for all patients, though SLNB was not adopted as the more common procedure in male patients until 2009. In 2016, 78.2% of females and 65.3% of males underwent SLNB vs. 51.1% and 39.8% in 2004, respectively. Conclusions: Although breast-conserving therapy is the treatment of choice for female patients with early-stage breast cancer and could be similarly used to treat men with T1-T2 disease, the majority of male breast cancer patients continue to undergo unilateral mastectomy for early-stage disease. In more recent years, SLNB has surpassed ALND for men, mirroring the trend for women, though in a more delayed and gradual fashion. Partial mastectomy and SLNB warrant consideration for men with T1 and T2 breast cancer, in particular since male breast cancer patients present at older ages and with more co-morbidity than their female counterparts, and may benefit from de-escalation of surgical treatment.
Citation Format: Rashi Singh, Lifen Cao, Anuja L Sarode, Michael Kharouta, Robert Shenk, Megan E Miller. Trends in breast and axillary surgery for T1-T2 male breast cancer: A study 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 PS14-12.