Abstract PO5-15-08: Role of next-generation sequencing testing in metastatic breast cancer
Authors: Wani Kashmira , Godbole Manasi , Jacob Brigid , Springer Kylie , Dabak Vrushali 
Published: May 2024

Background: With recent advances in therapy, patients with metastatic breast cancer have been living longer. Treatment has previously largely depended on the subtypes of breast cancer (ER/PR positive, HER2 positive, triple negative). In recent years, testing metastatic breast cancer samples for somatic and germline mutations has revealed additional therapeutic targets which could help patients further than standard therapeutic options. Recent evidence has demonstrated that targeted therapy may offer an advantage in overall survival in patients with metastatic breast cancer. However, data regarding the use of targeted therapy is still sparse and its overall impact on metastatic breast cancer patients needs to be further investigated. We wanted to study genomic testing in such patients and see how often it leads to new therapy recommendations beyond standard of care as we move towards the era of precision medicine.

Methods: Patients who were diagnosed with metastatic breast cancer between 2015-2020 were screened and a total of 193 patients were identified. Baseline characteristics, treatment/outcome and NGS testing information was collected. Univariate two group comparisons were performed using t-tests for continuous variables, and using chi-square, or Fisher’s tests if cell counts were &lt; 5 for categorical variables. Survival analysis for progression free survival (PFS) and overall survival (OS) were done using log rank tests.

Results: Out of 193 patients, the majority (189) were female. There were 121 (62.7%) White patients, 69 (35.8%) Black patients, and 3 (1.6%) patients that were another race. 30.6 % of patients received next-generation sequencing (NGS) testing, 68.4% of patients did not, and 1% were unknown. Patients that received NGS testing were on average younger than those that did not receive NGS testing (53.24 years old vs 65.17 years old, respectively). Patients that received NGS testing were more likely to be premenopausal (p &lt; .0001). Patients without NGS testing were more likely to die than those with NGS testing (p=.0327). There were no statistically significant differences observed in percentage of patients getting NGS testing done and whether patients were triple negative, HER2 positive with hormone receptor positive or negative, and HER2 negative with hormone receptor positive. As the year of metastatic breast cancer diagnosis advanced from 2015-2020, a high percentage of patients received NGS testing (i.e. 20% diagnosed in 2015 received NGS testing, whereas 50% diagnosed in 2020 received NGS testing). As the number of years between diagnosis and last follow-up increased, the probability of progression decreased for patients that had NGS testing done. Patients with NGS testing did better than those without NGS testing, but patients with no treatment change had the lowest probability of progression.

Conclusion: On average, only 30% of patients are receiving NGS testing, however it is being done more often in recent years than ever before. There is a clear progression free survival benefit seen in patients who received NGS testing. It is interesting to note that those who did not receive any changes in treatment based on NGS testing have the lowest probability of progression, but overall survival was not different for any of the different groups studied. This could be related to the low number of patients with NGS testing in our analysis. Further studies are warranted to understand this association.

Table. Summary of NGS testing data in various demographic categories There was a statistically significant difference in whether NGS testing was obtained or not and age, menopausal status and current status. There was no statistically significant difference in whether NGS testing was obtained or not and gender or race.

Citation Format: Kashmira Wani, Manasi Godbole, Brigid Jacob, Kylie Springer, Vrushali Dabak. Role of next-generation sequencing testing in metastatic breast cancer [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 PO5-15-08.