Radiosensitivity Index is Not Fit to be Used for Dose Adjustments: A Pan-Cancer Analysis

• DOI: 10.1016/j.clon.2023.02.018
• Publication Date: 2023-03-08T06:57:06Z
• Authors: H.B. Mistry
• Keywords: radiosensitivity index; Lung Neoplasms; Leukemia; genomic adjusted radiation dose; Glioma; Biostatistics; Radiation Tolerance; 3. Good health; 03 medical and health sciences; 0302 clinical medicine; Humans; Melanoma; radiotherapy

Radiotherapy has been striving to find markers of radiotherapy sensitivity for decades. In recent years the community has spent significant resources on exploring the wide range of omics data-sets to find that elusive perfect biomarker. One such candidate termed the Radiosensitivity Index, RSI for short, has been heavily publicized as a marker suitable for making dose-adjustments in the clinical setting. However, none of the analyses conducted, thus far, has assessed whether RSI explains enough of the outcome variance to elucidate a dose-response empirically. Here we re-analyze a pan-cancer data-set and find that RSI is no better than random chance at explaining outcome variance, overall survival times. For completeness, we then assessed whether RSI captured a sufficient amount of outcome variance to elucidate a dose-response, it did not. These results suggest that like the initial in-vitro analysis 12 years previously RSI is not a marker of radiotherapy sensitivity and is thus not fit to be used in any dose-adjustment algorithms.