In a study reported in the Journal of Clinical Oncology, Jennifer K. Plichta, MD, MS, and colleagues formulated a novel prognostic staging system for de novo metastatic breast cancer.
The staging system was developed using data from 42,467 patients from the National Cancer Database (NCDB) who had metastatic breast cancer at the time of their initial diagnosis in 2010 to 2016. Recursive partitioning analysis was used to categorize patients with similar overall survival on the basis of clinical T category, grade, estrogen receptor status, progesterone receptor status, HER2 status, histology, organ system site of metastasis (bone-only/brain-only/visceral), and number of organ systems involved. Final stages were based on median 3-year overall survival rates as follows: IVA = > 70%, IVB = 50% to 70%, IVC = 25% to < 50%, and IVD = < 25%.
The staging model was assessed in two validation cohorts consisting of 20,469 patients from the Surveillance, Epidemiology, and End Results (SEER) registry diagnosed in 2010 to 2018 and a separate NCDB cohort of 14,958 patients diagnosed in 2017 or 2018.
Jennifer K. Plichta, MD, MS
In the NCDB discovery cohort of 42,467 patients, median follow-up was 52.9 months (95% confidence interval [CI] = 52.4–53.5 months) and median overall survival in the total cohort was 35.4 months (95% CI = 34.8–35.9 months). Patients were segregated into four stage groups based on median 3-year overall survival as follows: IVA (n = 2,962) = 73.2%; IVB (n = 21,118) = 61.9%; IVC (n = 12,117) = 40.1%; and IVD (n = 6,270) = 17% (overall P < .001).
In the SEER validation cohort, median follow-up was 47 months (95% CI = 46–48 months). Application of the staging model showed four distinct stage groups with significantly different median 3-year overall survival: IVA = 72.5%, IVB= 58.4%, IVC = 35.7%, and IVD = 14.6% (overall P < .001).
In the NCDB validation cohort, median follow-up was 32.7 months (95% CI = 32.4–33.0 months). Application of the staging model again showed four distinct stage groups with significantly different median 3-year overall survival: IVA = 76.6%, IVB = 64.2%, IVC = 43.5%, and IVD = 21.1% (overall P < .001).
The investigators concluded, “Our findings regarding the heterogeneity in outcomes for patients with de novo metastatic breast cancer could guide future revisions of the current American Joint Committee on Cancer staging guidelines for patients with newly diagnosed stage IV disease. Our findings should be independently confirmed.”
Dr. Plichta, of Duke University Medical Center, is the corresponding author for the Journal of Clinical Oncology article.
Disclosure: The study was supported by the National Institutes of Health and National Cancer Institute. For full disclosures of the study authors, visit ascopubs.org.The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.