Iris Noordhoek1,2, Erik J Blok3, Elma Meershoek-Klein Kranenbarg1, Hein Putter4, Marjolijn Duijm-de Carpentier1, Emiel J T Rutgers5, Caroline Seynaeve6, John M S Bartlett7,8, Jean-Michel Vannetzel9, Daniel W Rea10, Annette Hasenburg11, Robert Paridaens12, Christos J Markopoulos13, Yasuo Hozumi14, Johanneke E A Portielje2, Judith R Kroep2, Cornelis J H van de Velde1, Gerrit-Jan Liefers1. 1. Department of Surgery, Leiden University Medical Center, Leiden, the Netherlands. 2. Department of Medical Oncology, Leiden University Medical Center, Leiden, the Netherlands. 3. Department of Internal Medicine, Erasmus Medical Center, Rotterdam, the Netherlands. 4. Department of Medical Statistics, Leiden University Medical Center, Leiden, the Netherlands. 5. Department of Surgery, Netherlands Cancer Institute, Amsterdam, the Netherlands. 6. Department of Medical Oncology, Erasmus Medical Center, Rotterdam, the Netherlands. 7. Diagnostic Development Program, Ontario Institute for Cancer Research, Toronto, Ontario, Canada. 8. Edinburgh Cancer Research Centre, University of Edinburgh, Edinburgh, UK. 9. Department of Radiation Oncology, Clinique Hartmann, Neuilly-sur-Seine, France. 10. Department of Medical Oncology, University of Birmingham, Birmingham, UK. 11. Department of Gynecology and Obstetrics, University Hospital Mainz, Mainz, Germany. 12. Department of Medical Oncology, University Hospitals Leuven, Leuven, Belgium. 13. Medical School, National and Kapodistrian University of Athens, Athens, Greece. 14. Department of Breast and Endocrine Surgery, University of Tsukuba Hospital, Ibaraki, Japan.
Abstract
PURPOSE: Most distant recurrences (DRs) in women with hormone receptor-positive breast cancer occur after 5 years from diagnosis. The Clinical Treatment Score post-5 years (CTS5) estimates DRs after 5 years of adjuvant endocrine therapy (AET). The aim of this study was to externally validate the CTS5 as a prognostic/predictive tool. METHODS: The CTS5 categorizes patients who have been disease free for 5 years into low, intermediate, and high risk and calculates an absolute risk for developing DRs between 5 and 10 years. Discrimination and calibration were assessed using data from the TEAM and IDEAL trials. The predictive value of the CTS5 was tested with data from the IDEAL trial. RESULTS: A total of 5,895 patients from the TEAM trial and 1,591 patients from the IDEAL trial were included. When assessing the CTS5 discrimination, significantly more DRs were found at 10 years after diagnosis in the CTS5 high- and intermediate-risk groups than in the low-risk group (hazard ratio, 5.7 [95% CI, 3.6 to 8.8] and 2.8 [95% CI, 1.7 to 4.4], respectively). In low- and intermediate-risk patients, the CTS5-predicted DR rates were higher, although not statistically significantly so, than observed rates. However, in high-risk patients, the CTS5-predicted DR rates were significantly higher than observed rates (29% v 19%, respectively; P < .001). The CTS5 was not predictive for extended AET duration. CONCLUSION: The CTS5 score as applied to patients treated in the TEAM and IDEAL cohorts discriminates between risk categories but overestimates the risk of late DRs in high-risk patients. Therefore, the numerical risk assessment from the CTS5 calculator in its current form should be interpreted with caution when used in daily clinical practice, particularly in high-risk patients.
PURPOSE: Most distant recurrences (DRs) in women with hormone receptor-positive breast cancer occur after 5 years from diagnosis. The Clinical Treatment Score post-5 years (CTS5) estimates DRs after 5 years of adjuvant endocrine therapy (AET). The aim of this study was to externally validate the CTS5 as a prognostic/predictive tool. METHODS: The CTS5 categorizes patients who have been disease free for 5 years into low, intermediate, and high risk and calculates an absolute risk for developing DRs between 5 and 10 years. Discrimination and calibration were assessed using data from the TEAM and IDEAL trials. The predictive value of the CTS5 was tested with data from the IDEAL trial. RESULTS: A total of 5,895 patients from the TEAM trial and 1,591 patients from the IDEAL trial were included. When assessing the CTS5 discrimination, significantly more DRs were found at 10 years after diagnosis in the CTS5 high- and intermediate-risk groups than in the low-risk group (hazard ratio, 5.7 [95% CI, 3.6 to 8.8] and 2.8 [95% CI, 1.7 to 4.4], respectively). In low- and intermediate-risk patients, the CTS5-predicted DR rates were higher, although not statistically significantly so, than observed rates. However, in high-risk patients, the CTS5-predicted DR rates were significantly higher than observed rates (29% v 19%, respectively; P < .001). The CTS5 was not predictive for extended AET duration. CONCLUSION: The CTS5 score as applied to patients treated in the TEAM and IDEAL cohorts discriminates between risk categories but overestimates the risk of late DRs in high-risk patients. Therefore, the numerical risk assessment from the CTS5 calculator in its current form should be interpreted with caution when used in daily clinical practice, particularly in high-risk patients.