Predictive Accuracy of Chemotherapy Toxicity Tools in Older Adults with Cancer: A Systematic Review and Diagnostic Test Accuracy Meta-Analysis

Background: Older adults with cancer are at increased risk of severe treatment-related toxicity. CARG, CRASH, and CARG-BC were developed as toxicity-risk prediction models, whereas G8 was developed as a geriatric screening instrument but has also been evaluated as a predictor of treatment-related toxicity. This study aimed to assess, separately for each instrument, the accuracy with which these tools identify older adults who develop severe chemotherapy-related toxicity. Methods: A systematic review and meta-analysis were conducted in accordance with PRISMA 2020 guidelines. Seven databases were searched through May 2026 for observational studies evaluating the predictive accuracy of the CARG, CRASH, CARG-BC and G8 tools in patients aged ≥65 years initiating chemotherapy. Pooled sensitivity and specificity with 95% confidence intervals (CIs) were calculated, and ROC curves were constructed. Risk of bias was assessed using QUADAS-2 and certainty of evidence was evaluated using GRADE. Results: Twenty-one studies were included, with an overall toxicity prevalence of 52.6%. CARG demonstrated a pooled sensitivity of 79.7% and specificity of 38.3% (AUC = 0.632). CRASH showed sensitivity of 86.9% and specificity of 68.2% (AUC = 0.866), but estimates were based on only four studies. CRASH hematological toxicity showed sensitivity of 75.9% and specificity of 53.1% (AUC = 0.694), with substantial heterogeneity. G8 yielded sensitivity of 69.5% and specificity of 41.5% (AUC = 0.666). CARG-BC showed sensitivity of 83.3% and specificity of 54.4% (AUC = 0.763), based on two breast cancer studies. Certainty of evidence ranged from low to very low. Conclusions: The instruments have distinct purposes and were not pooled against one another. CARG and G8 may be useful for initial risk screening, whereas CRASH showed a more balanced profile but remains supported by limited evidence. None should be used as a stand-alone basis to withhold or modify treatment.