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

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.