Abstract PO5-10-07: Risk factors associated with secondary cancers in AYA patients with breast cancer. A SEER database study

Abstract Background Adolescents and young adults (AYA) diagnosed with breast cancer face unique challenges and have distinct characteristics compared to older patients. While primary breast cancer remains a significant concern, the risk of developing secondary cancers in this population is also of great importance. This study aimed to identify these risk factors by analyzing a large cohort of AYA breast cancer patients using SEER (Surveillance Epidemiology and End Result) Database. Methods Patients were identified from SEER Research Data 17, from 2000 to 2019. Patients aged 18-39 years with breast cancer and at least 1 year of survival were identified. Secondary cancers were then identified and included any disease site. Patient demographic and clinical characteristics were summarized by secondary cancer status using Mann-Whitney U and Fisher’s exact tests. Overall survival from the initial breast cancer diagnosis was summarized by secondary cancer status using standard Kaplan-Meier methods, where the median and 3/5-year rates were estimated with 95% confidence intervals. Comparisons were made using the log-rank test. SAS v9.4 (Cary, NC) was used at a significance level of 0.05. Results A total of 47,912 AYA breast cancer patients were identified, of which 2,886 (6.0%) developed a secondary cancer at least 1 year after the initial breast cancer diagnosis. When comparing patients with and without secondary cancers, we observed significant differences with respect to age at initial breast cancer diagnosis, race, stage, nodal status, surgical procedure, ER status, PR status, Her2 status, and sub-type (Table 1). The analysis of overall survival showed that, from the time of breast cancer diagnosis, there was no statistically significant difference between patients with and without secondary cancers. However, this may be due to an immortal time bias. Breast was the most common site of secondary cancer (67%) followed by gynecological (7%), colorectal (3.7%), skin (3.4%) lung and hematologic (2.7%) Compared to other subtypes, TNBC patients were found to have much shorter time to secondary cancer development of 38 months compared to Her2+ and ER/PR+ (40 and 45 months respectively, P 0.001). Black and Hispanic individuals were found to have higher rates (7.4% and 6.3%) and earlier development of secondary cancer (76 months and 74 months) as compared to whites and Asians (5.9% and 5%, 88 months and 81 months, P 0.001 and P 0.002 respectively). Conclusion This study identified several risk factors associated with the development of secondary cancers in AYA breast cancer patients such as age at initial breast cancer diagnosis, race, stage, nodal status, surgical procedure and sub-type. Higher rates and early development of secondary cancer were observed among TNBC subtype and Black and Hispanic races that calls for further investigation and tailored interventions to improve outcomes in specific patient populations. Table 1 showing significant differences in characteristics AYA breast cancer patients who developed secondary breast cancer compared to those who did not Citation Format: Sheeba Ba Aqeel, Alankrita Taneja, Shipra Gandhi. Risk factors associated with secondary cancers in AYA patients with breast cancer. A SEER database study 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 PO5-10-07.