Abstract P2-09-11: Uptake of risk-reducing strategies and related challenges among carriers of breast cancer-associated germline pathogenic variants in Mexico

Background: Genetic cancer risk assessment is a multidisciplinary approach that enables the invaluable opportunity to recommend measures aimed at decreasing the risk of recurrence and new cancer diagnoses in individuals with inherited cancer predisposition. However, different challenges may limit the uptake of risk-reducing (RR) strategies among patients in underserved settings. This study describes the implementation of RR surgeries or surveillance studies and related barriers among carriers of breast cancer-associated germline pathogenic variants (PV). Methods: PV carriers were identified at two referral cancer centers in Mexico ≥6 months after receiving test results and genetic counseling. From October 2020 to June 2021, participants were invited to answer a multiple-choice survey assessing their uptake rate of RR measures according to NCCN guidelines by type of PV, as well as the challenges that had hindered this uptake. Descriptive statistics and Chi-squared or Fisher’s exact tests were used for data analysis. Results: In total, 162 carriers (median age: 42.5 years [range 21-73]) answered the survey. Most were women (89%), lived in an urban setting (91%), were married/in domestic partnership (72%), had at least high school education (69%), and were employed (51%). Monthly household income was lower than the minimum wage in 25% of cases and most patients had public (53%) or no (32%) healthcare coverage. Overall, 105 (65%) had a personal history of cancer, most commonly unilateral (77%) or bilateral (13%) breast cancer. PV were found in BRCA1/BRCA2 (75%), CHEK2 (11%), PALB2 (6%), ATM (4%), RAD51C (3%), and less frequently (3%) in TP53, NF1 or PTEN. Carriers underwent at least one of the recommended RR surgeries and surveillance studies in 61% and 69% of cases, respectively. Specifically, 52/124 (42%) of female BRCA1/BRCA2, PALB2, PTEN or TP53 PV carriers had undergone RR mastectomy, while 45/77 (58%) of eligible BRCA1/BRCA2 or RAD51C PV carriers had RR salpingo-oophorectomy. As for surveillance studies, carriers performed all, some and none of the recommended examinations according to their PV in 34%, 35% and 31% of cases, respectively. When an annual mammogram was recommended, 69/109 (63%) underwent the study in the previous year; in the case of breast MRI, only 23/103 (22%) had performed it in the last year. Notably, 132 (81%) carriers reported ≥1 challenge that hindered the uptake of RR strategies (median: 2 [range 0-10]). The main barriers were lack of insurance coverage of the recommended interventions (60%), financial limitations (50%), belief that their physician had not requested the studies or procedures (36%), and fear (25%). Uptake of RR strategies was not associated with carriers’ age, education level, employment status, income, place of residence, or type of mutation (high-risk vs moderate- or low-risk PV). Significant associations are reported in the Table. Conclusion: An important proportion of PV carriers in this resource-constrained setting underwent all or some of the recommended RR strategies, with the most cited uptake challenges being financial barriers and lack of endorsement by their physician. Targeted interventions to reduce out-of-pocket expenses and improve patient-physician communication and patients’ understanding of the implications of carrying a genetic mutation are warranted to enhance the uptake of RR surgeries and surveillance strategies among PV carriers.

Variables associated with the uptake of RR strategiesVariableUnderwent ≥1 RR surgeryDid not undergo any RR surgeryp-valueVariableUnderwent all or some surveillance studiesDid not undergo any surveillance studiesp-valueMarital status.012Gender<.001Married/Domestic partnership6532Female10133Single/Divorced/Widowed1419Male313Personal cancer history<.001Personal cancer history.002Yes6923Yes7521No1028No2925Attendance to follow-up appointments<.001Attendance to follow-up appointments<.001Yes6225Yes7916No1726No2530Knowledge that a genetic mutation conveys a greater risk of new cancer diagnoses.001Knowledge that a genetic mutation conveys a greater risk of cancer recurrence.012Yes7336Yes7423No615No3023Knowledge of carrier status.044Yes9436No1010Recent cancer diagnosis in a relative.017Yes2922No7524

Citation Format: Cynthia Villarreal-Garza, Fernanda Mesa-Chavez, Yanin Chavarri-Guerra, Dione Aguilar y Mendez, Andrea Becerril-Gaitan, Bryan F Vaca-Cartagena, Salvador G Santiesteban, Alejandro Aranda-Gutierrez, Daniela Obregon-Leal, Melina Miaja-Avila, Maria F Ochoa Chavez, Andres Rodriguez-Faure, Hermes J Franco Jimenez, Jeffrey N Weitzel. Uptake of risk-reducing strategies and related challenges among carriers of breast cancer-associated germline pathogenic variants in Mexico [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P2-09-11.

Abstract PS8-15: The spectrum of germline susceptibility gene variants in Mexican patients with breast cancer (BC): A Prospective Multicenter study

Background: BRCA mutations are responsible for a significant proportion of hereditary breast and ovarian cancers. However, other cancer susceptibility genes are also associated with an increased risk of developing breast cancer (BC). In Mexico, approximately 15% of patients with BC have been identified with BRCA mutations. Despite our growing understanding of BRCA mutations, the contribution and characterization of non-BRCA mutations in Mexican patients with a BC diagnosis remains unknown. We aimed to investigate the spectrum of BC-associated mutations among Mexican patients with BC referred for genetic cancer risk assessment (GCRA) in the multinational Clinical Cancer Genomics Community Research Network (CCGCRN). Methods: Mexican patients with a primary BC who were enrolled in the IRB-approved CCGCRN registry protocol and underwent genetic counseling and multigene panel testing (MGPT) were included. Pathogenic and likely pathogenic variants (PV) in genes associated with increased BC risk were used for analyses. Clinical and demographic characteristics of BRCA and non-BRCA carriers were compared. Results: From December 2012 to February 2020, 725 Mexican patients with BC who had MGPT results with a median age (years) of 41 (range 25-76) were included. 142 (19.6%) patients carried a BC-associated PV. Of these, 98 (69.0%) carried BRCA PVs: 58 in BRCA1 (41.5%) and 40 in BRCA2 (26.7%). PVs in other BC-associated genes (n = 42) accounted for 29.5% of all observed PVs and were distributed as follows: PALB2 (n = 13), CHEK2 (n = 11), RAD51C (n = 6), ATM (n = 3), PTEN (n = 3), TP53 (n = 3), BRIP1 (n = 2), and CDH1(n = 1). Other actionable genes represented 3.5% of all PVs (PMS2 [n = 3]; MSH6 [n = 1]; MSH2 [n = 1]). Suspected founder mutations in Latinas, PALB2 c.2167_2168delAT (n = 5) and CHEK2 c.707T>C (n = 9), represented 33.3% (n = 14/42) of the detected non-BRCA PVs. Mean age at first cancer diagnosis (years) for BRCA and non-BRCA carriers was: 37 (range 26-58) and 42 (range 25-76) (p<0.05), respectively. Among carriers, those with BRCA PVs had a significantly greater proportion of triple-negative (TN) tumors compared to non-BRCA PVs (45.2% vs 9.5%; p<0.05). Conclusion: A significant proportion of Mexican women carried a BC-associated mutation and a third were non-BRCA PVs. Among non-BRCA PVs, recurrent PALB2 and CHEK2, which had previously been characterized in BRCA-negative US Latinas with BC, were the most common and confirms their presence and clinical impact in Mexico. BRCA carriers were younger and more commonly had the TN molecular subtype.

Citation Format: Yanin Chavarri-Guerra, Cynthia Villarreal-Garza, Gubidxa Gutierrez Seymour, Dione Aguilar y Mendez, Jazmin Arteaga-Vazquez, Servando Cardona-Huerta, Adrian Daneri-Navarro, Azucena del Toro Valero, Alejandro Mohar-Betancourt, Andrés Rodríguez-Faure, Jose Luis Rodriguez-Olivares, Gregorio Quintero Beulo, Danielle Castillo, Kai Yang, Joseph Herzog, Rosa Mejia, Sharon Sand, Jeffrey N Weitzel. The spectrum of germline susceptibility gene variants in Mexican patients with breast cancer (BC): A Prospective Multicenter study [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 PS8-15.