ProtoDrift: Evaluating the impact of small-to-big adjustments to chemotherapy protocols

Abstract Adjustments to chemotherapy protocols are common to adapt treatments to individual patient needs, yet consensus on the impact of such adjustements is lacking. We introduce ProtoDrift, a novel metric that quantifies time and dose adjustments in chemotherapies. This weighted distance enables an assessment of their impact on patient outcomes, offering more detailed analyses than the traditional Relative Dose Intensity (RDI). We compared ProtoDrift and RDI prediction performances through survival analyses on 20,808 patients across 38 groups, categorised by cancer location and treatment line at two hospitals. Without optimisation, ProtoDrift achieves either comparable or better prediction results in 71% of patient groups (27 out of 38). Once optimised, ProtoDrift surpasses the RDI C-index predictions in 89% (16 out of 18) of patient groups from the first hospital. This study confirms ProtoDrift as an advanced tool for refining chemotherapy regimen design, highlighting the critical role of time adjustments in patient outcomes.