Abstract PO4-08-05: Disparities in Genetic Testing Patterns and Positivity Among Patients with Breast Cancer in the CancerLINQ Real-World Oncology Database
Authors: Kantor Olga , Jones Alyssa , Bychkovsky Brittany , Laws Alison , Weiss Anna , Rana Huma , Garber Judy , Scheib Rochelle , Chavez Marianna , Mayer Erica , King Tari , Mittendorf Elizabeth 
Published: May 2024

Introduction:

Indications for hereditary genetic testing (GT) continue to expand among breast cancer patients (pts), with some guidelines suggesting offering germline GT to all pts diagnosed with breast cancer. The objective of this study was to explore patterns of germline GT and prevalence of pathogenic and likely pathogenic variant (PV) frequency by age, sex, race and ethnicity, and stage at diagnosis within a large, real world oncology database.

Methods:

The American Clinical Society for Oncology CancerLINQ Discovery breast dataset was used to identify pts with a stage 0-III breast cancer diagnosis who underwent breast surgery at initial diagnosis from 1990-2022. Genetic testing was identified as an available test result from at least one of the following genes: BRCA1/2, ATM, CHEK2, PALB2, TP53, BARD1, BRIP1, CDH1, MHL1, MSH2, MSH6, NF1, RAD51C, or RAD51D. Descriptive statistics were used for comparisons, and adjusted multivariable regression predicting receipt of GT was performed.

Results:

Overall, 76,978 pts with breast cancer were identified. Of these, 16,284 (21.1%) underwent GT. There were differences in the proportion of pts that underwent GT by age, sex, self-reported race and ethnicity, and stage at diagnosis (Table). Genetic testing decreased with increasing age (59.2% in &lt; 40 vs 7.5% in &gt;=70, p&lt; 0.001) and was more common in men (45.9% vs 21.1% of women, p&lt; 0.001). Genetic testing rates ranged from 18.1-27.7% by race and ethnicity (p&lt; 0.001), with the lowest rates in Non-Hispanic Black (18.1%) and American Indian/Alaskan Native pts (18.2%) and the highest rate in Hispanic pts (27.7%). Genetic testing also differed by stage at diagnosis, with 19.3% of stage I pts vs 25.7% of stage III pts having genetic testing (p&lt; 0.001). On multivariable analysis adjusted for age, sex, race and ethnicity, and stage, male sex was associated with increased likelihood of GT (OR 5.12, 95% CI 4.04-6.49 compared to female sex, p&lt; 0.001) while increasing age (OR 0.05, 95% CI 0.04-0.06 in age &gt;=70 compared to age &lt; 40, p&lt; 0.001) and Non-Hispanic Black or American Indian/Alaskan Native race and ethnicity were associated with decreased likelihood of GT (OR 0.69, 95% CI 0.65-0.73 for Non-Hispanic Black and OR 0.71, 95% CI 0.50-1.00 for American Indian/Alaskan Native pts, compared to Non-Hispanic White pts, p&lt; 0.001); stage was not independently associated with GT.

Among those that had GT, PVs were detected in 2,974 (18.3%) pts. PVs were more common in pts &lt; 40 years (27.3% vs 15.0-17.6% in pts &gt;=40, p&lt; 0.001) and in men (26.4% vs 18.2% in women, p&lt; 0.001). Compared by race and ethnicity, PVs were highest among American Indian/Alaskan Native patients (30.2%) and lowest in Non-Hispanic White and Asian/Pacific Islander patients (18.6% and 17.0%, respectively, p&lt; 0.001). There was also a higher prevalence PVs with increasing stage (16.5% for stage 0 and 23.8% for stage III, p&lt; 0.001). Among those with PVs, the distribution was as follows: BRCA1 n=937 (31.5%), BRCA2 n=1176 (39.5%), TP53 n=315 (10.6%), CHEK2 n=238 (8.0%), ATM n=214 (7.2%), and PALB2 n=200 (6.7%).

Conclusions:

Differences in patterns of GT and PV frequency by age, sex, race and ethnicity, and stage were prevalent. Importantly, despite lower rates of GT, PV frequencies were similar or higher among minority patients and similar among all pts aged 40 and older. Inclusive testing practices and expansion of genetic testing coverage are needed to work towards equitable access to and acceptance of genetic testing.

Table. Genetic Testing And Positivity Rates

Citation Format: Olga Kantor, Alyssa Jones, Brittany Bychkovsky, Alison Laws, Anna Weiss, Huma Rana, Judy Garber, Rochelle Scheib, Marianna Chavez, Erica Mayer, Tari King, Elizabeth Mittendorf. Disparities in Genetic Testing Patterns and Positivity Among Patients with Breast Cancer in the CancerLINQ Real-World Oncology Database [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO4-08-05.