Abstract P4-03-13: AN EVALUATION OF BREAST CANCER RECURRENCE DATA REPORTED TO THE NCI SEER PROGRAM
Authors: Ramirez-Pena Esmeralda , Negoita Serban 
Published: March 2023

Abstract
Background: There are currently 18.1 million cancer survivors in the U.S. and the number is expected to increase to 22.5 million in the next ten years. The increasing number of survivors also means that the population at risk for cancer recurrence will increase. Recurrence significantly impacts patients’ health outcomes because there are limited treatment options. Currently, there are limited population level recurrence data in cancer registries world-wide. Most recurrence estimates have been derived from randomized clinical trials (RCTs) where the patient population only represents 4% of all cancer patients. Since 2018 the National Cancer Institute’s Surveillance, Epidemiology and End Results (SEER) program has been collecting abstract-based recurrence information. Our goal is to use the SEER recurrence data sources to develop a high-quality population-based recurrence database to disseminate to the public for future research. Measuring recurrence from population-based cohorts can enhance our understanding of what clinical, demographic, and geographic factors impact the risk of recurrence and can inform researchers on developing prevention strategies. Methods: In November 2021 we obtained a dataset that included recurrence information such as type of first recurrence (defined by the Standard for Oncology Registry Entry manual) and date of first recurrence. To evaluate the burden of breast cancer recurrence in the U.S. SEER population, we described the cohort of women diagnosed with breast cancer from 2010 to 2019. We then evaluated the patients with information on the status of recurrence including those that never experience recurrence and those that were never disease free (NDF). We measured frequencies of recurrence by multiple clinical variables such as age at diagnosis, race, stage at diagnosis, and tumor subtype. We followed patients from their date of diagnosis to the event defined by first recurrence, second primary, death, or last contact. We used the Kaplan-Meier method to estimate DFS. Results: The analytic dataset included 412,920 female breast cancer cases diagnosed between 2010 and 2019. Most women diagnosed with breast cancer were between 40 and 64 years old (53%, n=218,760), were White (78%, n= 320,555), were diagnosed with localized tumors (52%, n=213,824), were HER2 negative (HER2-) hormone receptor positive (HR+) (56%, n=230,874), and received treatment (95%, n=390,959). During the observation period, 67% (n = 278,098) of women did not have a recurrence, 3% (n=10,922) had a recurrence, and 16% (n=66,319) were NDF. After excluding patients with NDF status, we observed that the age group with the highest frequency of recurrence was 20-39 (9%). For reference, 4% of women in the 40 to 64 age group has a recurrence event during the observation period. Black women had higher recurrence (6%) compared to white women (3%). Triple negative breast cancers had the highest recurrence (9%) out of all subtypes. When we measured DFS, we observed significant differences by race, independent of tumor subtype. For example, in patients with HER2+/HR+ tumors, the percentage of patients at 120 months who did not experience a DFS event were 73.6% (95% CI, 72.3% to 74.9%) in white women and 67.5% (95% CI, 63.9% to 70.8%) in black women. Discussion & Conclusion: We are reporting population-based recurrence estimates for breast cancer obtained through the SEER program. This is the largest breast recurrence database in North America. The size of the database allowed precise estimation of recurrence stratified by demographics, subtype, and extent of disease. We observe trends consistent with previous reports and have identified some novel findings that warrant further study. Our long-term goal is to assess how DFS estimates derived from a population-based cohort compares to previously published estimates which are largely derived from RCTs.
Citation Format: Esmeralda Ramirez-Pena, Serban Negoita. AN EVALUATION OF BREAST CANCER RECURRENCE DATA REPORTED TO THE NCI SEER PROGRAM [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P4-03-13.