Prediction of Late Distant Recurrence in Estrogen Receptor–Positive Breast Cancer After 5 Years of Endocrine Therapy
As reported in the Journal of Clinical Oncology, Dowsett et al have developed a clinicopathologic tool for predicting risk of late distant recurrence in estrogen receptor (ER)-positive breast cancer treated with 5 years of endocrine therapy.
Study Details
In the study, a prognostic score for post–5-year risk of distant recurrence (CTS5) was developed using clinicopathologic variables in the data set from the phase III ATAC trial (n = 4,735). The model was validated using the data set from the phase III BIG 1-98 trial (n = 6,711). The final model derived in the ATAC population included age (continuous variable), tumor size (continuous variable), quadratic tumor size, nodal status (five groups: negative, 1, 2–3, 4–9, and > 9 positive nodes), and tumor grade (three groups: low, intermediate, and high). Separate models developed for patients receiving or not receiving chemotherapy did not perform significantly better for either group vs a single model including all patients.
Prognostic Ability
The CTS5 model was significantly prognostic for late distant recurrence in the ATAC population (hazard ratio [HR] = 2.47, P < .001) and BIG 1-98 population (HR = 2.07, P < .001). Risk stratification for years 5 to 10 defined in the ATAC cohort as low (< 5%), intermediate (5%–10%), or high (> 10%) identified 43% of the BIG 1-98 cohort as low-risk, with a distant recurrence rate of 3.6% during years 5 to 10. During years 5 to 10, 63% of node-negative patients were at low risk, with a distant recurrence rate of 3.9%, and 24% with 1 to 3 positive nodes were at low risk, with a distant recurrence rate of 1.5%. A final CTS5 model was derived using pooled data from ATAC and BIG 1-98.
The investigators concluded, “CTS5 is a simple tool based on information that is readily available to all clinicians. CTS5 was validated as highly prognostic for late [distant recurrence] in the independent BIG 1-98 study. The final CTS5 algorithm identified 42% of women with < 1% per-year risk of [distant recurrence] who could be advised of the limited potential value of extended endocrine therapy.”
The study was supported by grants from the Royal Marsden National Institute of Health Biomedical Research Centre, Breast Cancer Now, Cancer Research UK, and Susan G. Komen for the Cure.
Mitch Dowsett, PhD, of the Ralph Lauren Centre for Breast Cancer Research, Royal Marsden Hospital, is the corresponding author for the Journal of Clinical Oncology article.
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