Abstract P6-08-11: Regional variation in de novo metastatic breast cancer survival improvement over time using an institutional registry to support SEER analysis: 1990-2010
Authors: Malmgren JA , Calip GS , Atwood MK , Kaplan HG 
Published: February 2018

Background: It is not known how much de novo MBC (dnMBC) survival varies by where one lives and receives treatment in the US. Variation could exist depending on access to care, insurance availability, geographic area, and treatment options (urban vs. rural). Our objective is to measure variance in survival by Surveillance, Epidemiology, and End Results (SEER) region and compared to a non-academic institutional cohort.

Methods: We compared change in disease specific survival (DSS) over time intervals1990-1998, 1999-2004 and 2005-2010, following diagnosis of first primary dnMBC among women in the SEER 9 population-based cancer registry using SEER 9 without Seattle-Puget Sound (S-PS) (n = 11,139) and Seattle Puget Sound separately (n = 1787). In a separate analysis we calculated and compared dnMBC DSS in our community-based cancer center registry located in the Seattle-Puget Sound region (n = 247) for the same time intervals. For the institutional cohort time to event used the outcome death from breast cancer confirmed from the patient chart or death certificate if information on cause of death was not available in the chart. For SEER data we used the SEERstat calculation for cause-specific survival as equivalent for disease specific survival (DSS). We estimated 5-year DSS cumulative incidence with 95% confidence intervals using the Kaplan-Meier method and compared survivor function equality by diagnosis years with log-rank tests. SEER*stat 8.3.4 was used for the SEER regional comparison and SPSS 24 for the institutional.

Results: Patient age in the SEER registry population ranged from 18-93 years. The institutional cohort patient age range was 24-94 years. DSS improved over time for SEER 9 without Seattle-Puget Sound [1990-1998: 18.8% (95% CI: 17.6%, 20.0%);1999-2004; 22.0% (95% CI: 20.5%, 23.4%); 2005-2010: 24.6% (95% CI: 23.2%, 26.0%) (log-rank test=61.59, p&lt;0.001)]. DSS for SEER Seattle-Puget Sound had a similar significant improvement gradient over time [1990-1998: 20.1% (95% CI: 17.1%, 23.2%)]; 1999-2004: 25.6% (95% CI: 21.9%, 29.4%); 2005-2010: 33.4% (95% CI: 29.7%, 37.1%) (log-rank test=42.46, p&lt;0.001)]. DSS was significantly better in the Seattle-Puget Sound region in 2005-2010 (33.4%) compared to SEER9 without Seattle-Puget Sound (24.6%) (p=.017). Among dnMBC cases at the non-academic community cancer center, five year dnMBC DSS improved over time as well and by a larger margin [1990-1998: 28%, 95% CI: 18.2%, 37.8%; 1999-2004: 48%, 95% CI: 33.9%, 58.9%; 2005-2010: 55%, 95% CI: 45.3%, 64.5% (log rank test=9.65, p=.008)].

Conclusions: The SEER regional comparison indicates a significant regional survival difference for breast cancer patients with de novo stage IV metastatic breast cancer. Better survival in the Seattle-Puget Sound region is supported by the retrospective cohort analysis results from a center with a more detailed registry and complete follow up in the same region. Supplementation of regional survival SEER analysis with detailed analysis from an embedded institutions' dedicated registry could be used to enhance evaluation of factors such as standard of care that impact survival improvement.

Citation Format: Malmgren JA, Calip GS, Atwood MK, Kaplan HG. Regional variation in de novo metastatic breast cancer survival improvement over time using an institutional registry to support SEER analysis: 1990-2010 [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P6-08-11.