medwireNews: A prognostic tool that integrates clinicopathologic and genomic data provides more information on distant recurrence risk than either feature alone, and can estimate absolute chemotherapy benefit in individual patients with node-negative breast cancer, say researchers.
The details of the RSClin tool were simultaneously presented at the 2020 San Antonio Breast Cancer Symposium and published in the Journal of Clinical Oncology.
Joseph Sparano (Albert Einstein College of Medicine, New York, USA) and colleagues developed RSClin using a patient-specific meta-analysis of data for 10,004 women with hormone receptor-positive, HER-2 negative, node-negative breast cancer.
The tool integrates the 21-gene recurrence score with age, and tumor grade and size.
Using a likelihood ratio test, the researchers found that RSClin provides significantly more prognostic information for distant recurrence than the 21-gene recurrence score or clinicopathologic factors alone.
They also used the tool to show that not all patients with unfavorable traditional risk factors have a large absolute chemotherapy benefit and not all patients with favorable traditional risk factors have minimal chemotherapy benefit.
Furthermore, when the study authors compared the estimates of absolute chemotherapy benefit provided by RSClin with estimates in which the relative chemotherapy benefit is held constant they found that the recurrence score “prediction contributes substantially to differentiation of treatment effect over and above the effect of increasing recurrence risk.”
For example, RSClin predicts that a 55-year-old woman with a clinical low-risk 1.5 cm intermediate-grade tumor would derive a 0–15% absolute benefit from chemotherapy as the recurrence score increases from 11 to 50. By contrast, the absolute chemotherapy benefit would be estimated at 2–8% if the relative chemotherapy benefit was held constant, rather than varying by recurrence score.
“This indicates that incremental chemotherapy benefit observed with higher recurrence score is driven not only by a higher underlying recurrence risk but also by prediction of greater relative risk reduction with chemotherapy,” Sparano and co-authors remark.
When the investigators validated RSClin in 1098 women with node-negative breast cancer from the Clalit Health Registry, they found that the RSClin risk estimate was significantly associated with distant recurrence risk (standardized hazard ratio=1.73).
Sparano et al say their findings show that patient-specific meta-analysis methods “may be used in conjunction with randomized clinical trials to develop tools that facilitate more effective application of precision medicine in cancer therapy.”
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SABCS 2020: 8–11 December
J Clin Oncol 2020; doi:10.1200/JCO.20.03007