Using the Cell-Cycle Risk Score to Predict the Benefit of Androgen-Deprivation Therapy Added to Radiation Therapy in Patients With Newly Diagnosed Prostate Cancer

Abstract

PURPOSE Guidelines recommend adding androgen-deprivation therapy (ADT) to radiation therapy (RT) in certain patients with localized prostate cancer. Individualized genomic testing may improve the prognostic accuracy of risk assessments. Herein, we describe a mathematical model of the benefit of adding ADT to RT as a function of the personalized clinical cell-cycle risk (CCR) score to inform 10-year metastasis risk. METHODS A model of absolute risk reduction (ARR) was built using a retrospective cohort of men tested with Prolaris who received RT alone (N = 467). The relative benefit of ADT added to RT to reduce distant metastasis was estimated at 41% on the basis of a meta-analysis of randomized trials. The ARR and number needed to treat (NNT) were computationally derived in patients clinically tested with Prolaris between January 1, 2020, and October 31, 2022 (N = 56,485). Risks were predicted using a cause-specific Cox proportional hazards model with CCR score predicting time to metastasis. A CCR score of 2.112 represents the validated multimodal treatment (MMT) threshold. RESULTS The ARR from ADT increased from almost zero at low CCR scores to 17.1% at CCR = 3.690 with the corresponding NNT = 6, indicating that adding ADT to RT would prevent metastasis within 10 years for one of every six treated individuals. In the clinical cohort, the average ARR was 0.86% in individuals under the MMT threshold (NNT = 116). The average ARR was 8.19% in individuals above the MMT threshold (NNT = 12). Broad ranges of ADT benefit were observed within National Comprehensive Cancer Network risk categories. CONCLUSION The precise and personalized risk estimate of metastasis provided by the CCR score can help inform patients and physicians when considering treatment intensification.