Abstract P6-08-06: Characteristics of ductal carcinoma in situ (DCIS) in patients who underwent multigene panel testing for hereditary breast cancer

Abstract

Abstract Background: Multigene panel testing (MPG) for hereditary breast cancer has recently increased significantly. While clinical and pathological characteristics for invasive breast cancer in patients with non BRCA germline mutations is emerging, there is very limited data in patients with ductal carcinoma in situ (DCIS). This study evaluates the clinical and pathological characteristics of patients with DCIS who underwent MPG testing for hereditary breast cancer. Methods: Patients with DCIS who underwent MPG testing between 2014-2019 were identified from our prospectively maintained and IRB-approved research registry study and included in this analysis. Clinical and tumor characteristics were analyzed using descriptive statistics. Variables included in the analysis included: Age at diagnosis, family history of breast and ovarian cancer, tumor characteristics including ER/PR and nuclear grade and genetic testing results. Results: In this prospective cohort, 324 patients with DCIS underwent multigene panel testing. Age of diagnosis was 50.5 years (range: 18-86), a family history of breast and/or ovarian cancer was positive in 283 (87.3%) patients. Genetic testing results were as follows: Pathogenic or likely pathogenic mutations were found in 28 (8.6%) patients: BRCA1 2 (7.1%), BRCA2 6 (21.4%), PALB2 6 (21.4%), CHEK2 5 (17.9%), ATM 3 (10.7%), APC 2 (7.1%), BARD1 1 (3.6%), BRIP1 1 (3.6%), MSH2 1 (3.6%), MUTYH 1 (3.6%). The variant of uncertain significance rate was 16% (52): 7 (13.5%) in BRCA1 or 2 and 45 (86.5%) in other genes. 244 (75.3%) of patients had negative results. Conclusion: Our data demonstrates that, in addition to BRCA 1 and 2 genes, patients with DCIS have other hereditary genes involved. In fact, 71.4% of the germline mutations were in non-BRCA genes. Regardless of gene status, most patients had ER positive disease, this can have implications for chemopreventive therapy. Furthermore, patients with germline mutations have a higher percentage of nuclear grade III DCIS than gene negative patients. Larger studies are needed to evaluate the clinical implications of these findings. Genetic testing with a larger panel, other than BRCA1 and BRCA2 genes only, should be considered for patients with DCIS. NegativeBRCA1+BRCA2+PALB2+CHEK2+ATM+Variablesn%n%n%n%n%n%ERpositive17471.32100.0583.3350.0480.03100.0negative187.400.000.0116.7120.000.0unknown5120.900.0116.7233.300.000.0PRpositive15262.3150.0583.3350.0480.03100.0negative3815.6150.000.0116.7120.000.0unknown5422.100.0116.7233.300.000.0NGI187.4150.000.000.0240.000.0II10041.000.0116.7350.0240.0133.3III8534.8150.0466.7233.300.0266.7unknown4116.800.0116.7116.7120.000.0Totals244100.02100.06100.06100.05100.03100.0 Citation Format: Loredana Militello, Angelica M Gutierrez Barrera, Henry Kuerer, Constance Albarracin, Banu K Arun. Characteristics of ductal carcinoma in situ (DCIS) in patients who underwent multigene panel testing for hereditary breast cancer [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 P6-08-06.