Correlation of dynamic blood dose with clinical outcomes in radiotherapy for head-and-neck cancer

Background and purpose: Radiation-induced lymphopenia (RIL) during cancer radiotherapy is receiving growing attention due to its association with adverse clinical outcomes. Correlations between RIL and poorer locoregional control (LRC), distant-metastasis-free survival (DMFS), and overall survival (OS) have been demonstrated across multiple treatment sites. Estimates of radiation delivered to circulating blood or lymphocytes have been shown to be correlated with severe RIL. This study aims to evaluate whether blood dose estimates are equally correlated with patient outcomes directly.

Materials and methods: For 298 head-and-neck cancer patients, blood dose was estimated via the total body dose (D_body), a static blood dose model considering the mean dose to relevant organs and tissues (D_static), and a dynamic model which further included temporal aspects such as blood flow and treatment delivery time (D_dynamic). The latter utilized hematological dose (HEDOS), an open-source computational tool for blood dose simulations. Survival analysis was performed to evaluate potential correlations between blood dose and LRC, DMFS, and OS.

Results: Multivariable Cox regression analysis found a statistically significant (p < 0.05) correlation between various dynamic blood dose metrics and clinical outcomes. D_body and D_static did not correlate with any of the outcomes considered.

Conclusion: A statistically significant correlation between the dynamic blood dose model and adverse clinical outcomes was observed. During multivariable regression analysis, neither static blood dose model exhibited a statistically significant correlation with any of the outcomes studied.