Abstract P1-08-22: Adenosquamous carcinoma of the breast, an uncommon diagnosis with poor prognosis – Lessons learned from analysis of the National Cancer Data Base 2004-2015
Authors: Cochrane K , Heidel RE , Bell JL , Orucevic A 
Published: May 2019

Abstract
Background
Adenosquamous carcinomas (ASQ) of the breast is rare, with a reported incidence of &lt;1%. This tumor is considered to belong to the metaplastic breast carcinoma category and is commonly low grade. It has a distinct adenocarcinomatous component comprised of infiltrating small glands with varying degrees of squamous differentiation. The significance of ASQ differentiation and its impact on diagnosis, treatment and prognosis is based primarily on results from small retrospective case series reports. The objective of our study is to define prevalence, clinicopathologic characteristics, treatment patterns and prognosis of ASQ and compare these to the most frequent invasive breast carcinoma (BC), ductal (IDC), through analysis of the National Cancer Data Base (NCDB).
Methods
A retrospective observational study of NCDB patients (pts) compared all ASQ pts to the same number of randomly selected IDC pts (ICD-O-3 diagnosis codes 8560 and 8500, respectively) using SPSS software. Patients' clinicopathologic characteristics, treatment, and overall survival (OS) were analyzed using frequency statistics, t-tests, Mann-Whitney U tests, chi-square, Kaplan-Meier and logistic regression.
Results
From 1,932,688 female pts with invasive BC, 1,421,250 had IDC (73.5%); 453 had ASQ (0.0002%). ASQ pts were significantly (p&lt;0.05) more likely to be: older, have grade 1 tumors, negative lymph nodes, ER, PR, and HER2-negative tumors when compared to IDC. No significant difference was found in tumor size, TNM stage, or treatment. ASQ pts had significantly worse 5-year OS than IDC pts (p&lt;0.025; 73% vs 82% at 60 months, respectively).
Conclusion
Our study is the largest study to date on ASQ revealing that this unique disease is an aggressive carcinoma and carries a significantly worse prognosis than IDC. Since prospective randomized clinical trial(s) are unlikely, further studies on the genomic make-up of ASQ are needed in order to understand biology and personalize treatment of pts with this uncommon BC.
Clinicopathologic characteristics of pts with ASQ & IDC - NCDB analysis (2004-2015)DemographicsASQIDC (random sample)Adjusted Odds Ratio95% CI Lower95% CI Upper N=453N=453 N%N% Age Average63.50*60.62 Tumor Size (mm) Median18.018.0 Interquartile Range2419 Grade 1202*88Referent 44.619.4 271*185.17.12.24 15.740.8 3136*147.40.29.57 3032.5 Unknown4433 9.77.3 # of node(s) positive 0296*267Referent 65.358.9 1 to 350*72.63.42.93 11.015.9 4 to 914*31.41.21.78 3.16.8 &gt;10910.81.332.02 2.02.2 Unknown8473 18.516.1 TNM Stage I227223Referent 50.250.2 II1461301.1.821.49 32.329.3 III3855.68.431.07 8.412.4 IV1622.71.371.40 3.55.0 Unknown2514 5.53.2 ER (+)135*359 31.481 (-)295*849.36.812.8 68.619 PR (+)61*313 14.371.1 (-)367*12714.810.520.8 85.728.9 HER2 (+)8*44 3.218 (-)240*2016.63.014.3 96.882 Surgery Yes427424 94.794.2 No2426.92.521.62 5.35.8 Chemotherapy No199206 51.751.8 Yes1861921.00.761.33 48.348.2 Hormone Therapy No308131 76.832.7 Yes93270.15.11.2 23.267.3 Radiation No210200 46.944.3 Yes238251.90.71.17 53.155.7 5-year Overall Survival Alive137*165.65.43.98 64.974 Dead74*58 35.126 *Significant (p&lt;.05)
Citation Format: Cochrane K, Heidel RE, Bell JL, Orucevic A. Adenosquamous carcinoma of the breast, an uncommon diagnosis with poor prognosis – Lessons learned from analysis of the National Cancer Data Base 2004-2015 [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P1-08-22.