(292) Claims-Based Algorithm to Define Breast Cancer Recurrence in SEER-Medicare Data

Publication Number: 966

Background: Breast cancer (BC) is the most common cancer among women with approximately half diagnosed after age 65. While recurrence is one of the major clinical concerns after cancer treatment, no validated algorithm exists to define BC recurrence.

Objectives: To apply a claims-based algorithm to identify BC recurrence and estimate the claims-defined BC recurrence incidence rate.

Methods: Among older women ≥ 66 years with incident stage I-III BC in SEER-Medicare data (2007-2017), we identified a cohort who received 1) surgery and no further treatment for 210 days or 2) radiation therapy (RT) or chemotherapy (CTX) for no more than 180 days and a 90-day treatment-free interval, 3) no other signs of progressive BC (metastatic diagnosis or hospice admission). After patients complete their cancer treatment and have at least 90 days of recurrence-free survival without losing eligibility, we followed them to assess for BC recurrence, which was defined as: (a) repeat or new use of RT/CTX , (b) metastatic BC diagnosis, (c) BC hospice, or (d) BC death. We described the patient-level characteristics, initial treatment regimen for incident BC, subsequent treatment for BC recurrence, and incidence rates (IR) of recurrence with 95% confidence intervals (CIs).

Results: Among 66,376 women initially identified with stage I-III BC and surgery within 90 days, 9.4% were excluded based on above pre-specified treatment and diagnostic parameters. The final cohort consisted of 60,159 women (median age 74, 83% white, 64% stage I, 31% stage II, and 5% stage III, 87% hormone receptor positive, median Charlson score of 3). Initial treatment regimens included 40% with surgery only, 47% with radiation only, and 13% with chemotherapy. We observed 6,700 episodes of recurrence (11.1%) during 295,000 person-years (py) with a median-time-to-recurrence of 26 months (IQR 14-51 months). The recurrence IR per 1,000py was 11.9 (95%CI: 11.4-12.4), 35 (95%CI: 33.8-36.3), and 114 (95%CI: 107-120) in women with stage I, II, and III BC, respectively. Among women whose initial treatment was surgery then subsequently developed a treatable recurrence, common treatments included radiation 84%, paclitaxel 15%, and trastuzumab 9.6%..

Conclusions: We were able to identify signs of recurrence and describe cancer-directed treatments among a real-world cohort of patients. The recurrence algorithm should be refined to consider other treatment time windows, other available data in Medicare, such as cancer screenings and oral cancer treatments, and be validated against clinically identified recurrence.