The vertebral 3′-deoxy-3′-${}^{18}$F-fluorothymidine uptake predicts the hematological toxicity after systemic chemotherapy in patients with lung cancer

Although hematological toxicities (HT) are the leading adverse events of systemic chemotherapy, the estimation of severe HT is challenging. Recently, 3′-deoxy-3′-[${}^{18}$F]-fluorothymidine (${}^{18}$F-FLT) accumulation with PET has been considered a biomarker of the cell proliferation. This study aims to elucidate whether the vertebral accumulation of ${}^{18}$F-FLT could estimate severe HT during platinum-doublet chemotherapy. In this Institutional Review Board–approved retrospective study, 50 patients with primary lung cancer underwent ${}^{18}$F-FLT PET scan before platinum-doublet chemotherapy. We evaluated the standardized uptake value, total vertebral proliferation (TVP), and TVP/body surface area (TVP/BSA) of the vertebral body (Th4, Th8, Th12, and L4), and then the associations between those parameters and frequency of severe HT during platinum-doublet chemotherapy were assessed. Severe HT (grade 3/4) was observed in 40.0% of patients during the first cycle. The ROC curve analyses revealed that the TVP/BSA of L4 was the most discriminative parameter among PET parameters for the prediction of severe HT. The multivariate logistic regression analysis revealed the TVP/BSA of L4 (odds ratio [OR], 0.94; p = 0.0036) and the frequency of the grade 3/4 hematological toxicity in previous clinical trials (OR, 1.03; p = 0.023) were independent predictors. Furthermore, the sensitivity, specificity, and accuracy of the TVP/BSA of L4 cut-off of 68.7 to predict grade 3/4 HT were 80.0%, 86.7%, and 84.0%, respectively. A low TVP/BSA of L4 (< 68.7) as a binary variable was a significant indicator of severe HT (OR, 26.0; p = 0.000026). The low ${}^{18}$F-FLT uptake in the lower vertebral body is a predictor of severe HT in patients with lung cancer who receive platinum-doublet chemotherapy.