Abstract PD10-03: Triple-negative breast cancer (TNBC) risk with pathogenic variants (PV) in hereditary cancer predisposition genes
Authors: Hall Michael J , Rosenthal Eric , Roman Susana San , Bernhisel Ryan , Kidd John , Hughes Elisha , Slavin Thomas , Kurian Allison 
Published: February 2021

Abstract
BACKGROUND: TNBC is among the most aggressive subtypes of invasive breast cancer (BC), and accounts for approximately 10-15% of incidental BC diagnoses. TNBC is associated with early age of onset (median age of diagnosis &lt;50) and disproportionately affects African American women. Breast MRI is currently recommended to screen for BC in women with at least a moderate-to-high lifetime risk of BC (a 2-fold or higher increased risk), and may also be superior to mammogram to screen for TNBC. TNBC has been most closely associated with germline PVs in BRCA1. However, recent studies have suggested that PVs in other genes previously associated with invasive BC may specifically confer high risks of the TNBC subtype. METHODS: Results were analyzed from 627,219 women undergoing clinical multi-gene panel testing at a single US-based commercial laboratory between 5/2013 and 2/2020, including genes associated with hereditary BC and other cancers. Demographic and personal/family history data were collected on a test requisition form. Individuals who had single- or founder-site testing, or prior BRCA1 or BRCA2 testing, were excluded. Multivariable regression analysis was used to examine the association between PVs/suspected PVs and personal history (PHx) of TNBC. Models were adjusted for age, personal/family cancer history, and ancestry. Odds ratios (OR) with 95% confidence intervals (CI) excluding 1.0 were considered significant. RESULTS: In total, 22.4% (140,467/627,219) of women tested reported PHx of BC, of whom 12.8% (17,951/140,467) reported PHx of TNBC. Elevated risks of TNBC were identified in carriers of PVs in 10 genes (see Table). While the highest TNBC risk was associated with PVs in BRCA1 (OR 21.24, 95% CI 19.71-22.88), high risks were also seen for BARD1 (OR 7.05, 95% CI 5.71-8.71), TP53 (OR 5.64, 95% CI 3.08-10.33), PTEN (OR 5.52, 95% CI 2.35-13.00) and PALB2 (OR 5.27, 95% CI 4.55-6.10). Moderate-to-high risks (2-5-fold increased risk) of TNBC were also seen for carriers of PVs in RAD51C, RAD51D, BRCA2, and CDKN2A/P16. By contrast, PVs in NBN, ATM, and CHEK2 were all associated with an apparent decreased risk of TNBC. CONCLUSIONS: PVs in several hereditary cancer genes routinely tested on multi-gene panel tests are associated with high risks (OR&gt;5.0) and moderate-to-high risks (OR 2.0-5.0) of TNBC. These findings can inform practice guidelines about which genes to test when evaluating breast cancer risk and which PV carriers may benefit from intensive breast screening with magnetic resonance imaging (MRI).
Odds ratios for TNBC in germline carriers of PV in hereditary cancer risk genesRisk GenePV Positive with TNBCOR95% CIp-valueHigh RiskBRCA1119321.2419.71-22.88&lt;0.001BARD11257.055.71-8.71&lt;0.001TP53125.643.08-10.33&lt;0.001PTEN65.522.35-13.00&lt;0.001PALB22315.274.55-6.10&lt;0.001Moderate-to-High RiskRAD51C864.923.86-6.26&lt;0.001RAD51D454.643.34-6.45&lt;0.001BRCA24884.434.02-4.89&lt;0.001CDKN2A (p16)172.521.52-4.18&lt;0.001Moderate-to-Low RiskBRIP1771.921.51-2.44&lt;0.001Protective EffectNBN140.550.32-0.940.030ATM400.510.37-0.70&lt;0.001CHEK2490.440.33-0.58&lt;0.001HOXB1350.330.14-0.810.015
Citation Format: Michael J Hall, Eric Rosenthal, Susana San Roman, Ryan Bernhisel, John Kidd, Elisha Hughes, Thomas Slavin, Allison Kurian. Triple-negative breast cancer (TNBC) risk with pathogenic variants (PV) in hereditary cancer predisposition genes [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 PD10-03.