Judith A. Malmgren, PhD
In a study reported in Cancer, Judith A. Malmgren, PhD, and colleagues found marked regional differences in improvements in breast cancer–specific survival among women diagnosed with metastatic breast cancer between 1990 and 2011, with the best rates found in an institutional cohort.
Study Details
The study involved data from patients diagnosed with first primary de novo stage IV breast cancer at ages 25 to 84 years between 1990 to 2011. The change in 5-year breast cancer–specific survival was compared using the Surveillance, Epidemiology, and End Results (SEER) 9 registries (Connecticut, Detroit, Atlanta, San Francisco/Oakland, Hawaii, Iowa, New Mexico, Seattle-Puget Sound, and Utah) without the SEER 9 Seattle–Puget Sound region (n = 12,121), the SEER Seattle–Puget Sound region alone (1,931), and a Seattle–Puget Sound institutional cohort (n = 261).
The SEER 9 without Seattle–Puget Sound population and the SEER Seattle–Puget Sound region populations were both older than the institutional cohort patients (mean age = 61 vs 55 years) and more patients in the institutional and Seattle–Puget Sound cohorts identified as white (81% and 89%) than the SEER 9 without Seattle–Puget Sound patients cohort (75%).
Breast Cancer–Specific Survival
Between 1990 and 2011, 5-year breast cancer–specific survival improved by:
- 7% (from 19% to 26%) in the SEER 9 regions not including the Seattle–Puget Sound region
- 14% (from 21% to 35%) in the Seattle–Puget Sound region
- 27% (from 29% to 56%) in the Seattle–Puget Sound institutional cohort.
Multivariate analysis in the institutional cohort indicated that more recent diagnosis year, receipt of chemotherapy, receipt of surgery, and age < 70 years were significantly associated with improved 5-year breast cancer–specific survival (all P < .05). In the entire SEER 9 cohort, in addition to the significant factors in the institutional cohort, hormone receptor–positive status and white race were significantly associated with improved outcomes. In the Seattle–Puget Sound region, differences from the entire SEER 9 region were absence of significant effects of receipt of chemotherapy and white race as significant factors.
KEY POINTS
- Improvements in 5-year breast cancer–specific survival were smallest in the SEER 9 region excluding Seattle–Puget Sound, intermediate in the Seattle–Puget Sound region, and greatest in a Seattle–Puget Sound institutional cohort.
- Improvements in 5-year breast cancer–specific survival were greater in all three cohorts between 2005 and 2011.
In an adjusted model, breast cancer–specific survival increased by greater amounts in all three cohorts between 2005 and 2011—by 28% in SEER 9 without Seattle–Puget Sound, 43% in the Seattle–Puget Sound region, and 45% in the institutional cohort.
The investigators concluded, “Over 2 decades, the survival of patients with metastatic breast cancer improved nationally, but with regional survival disparity and differential improvement. To achieve equitable outcomes, access and treatment approaches will need to be identified and adopted.”
Dr. Malmgren, of HealthStat Consulting, Seattle, and of the Department of Epidemiology, University of Washington, Seattle, is the corresponding author for the Cancer article.
Disclosure: The study was supported by the Kaplan Cancer Research Fund, Metastatic Breast Cancer Alliance, and SEER Cancer Surveillance System program of the National Cancer Institute. For full disclosures of the study authors, visit onlinelibrary.wiley.com.
