Radiation recall reaction induced by gemcitabine/docetaxel in children: A retrospective study on risk factors and outcomes

IntroductionRadiation recall reaction (RRR) is a rare inflammatory reaction developing in a previously irradiated field after a triggering agent. In pediatric patients, it is poorly understood and deficiently studied. Gemcitabine-docetaxel (G/D) in childhood cancer is mainly used as a salvage regimen for sarcomas. We aim to describe RRR triggered by G/D in children.Patients and methodsRetrospective review of 21 patients receiving G/D along with radiotherapy at two hospitals from 2010 until 2022. RRR was considered as any toxicity occurring after G/D administration in a previously irradiated field. RRR features were described. Fisher's and Mann-Whitney tests were utilized to analyze the risk factors involved.ResultsSixteen episodes of RRR developed in 16 (76.2%) patients. RRR mainly involved deep layers of the skin (58%) and occurred predominantly after two G/D cycles. The mean time between radiotherapy and chemotherapy was 28.5 days (0-1359 days), and the mean radiation volume 391 mL (157-1810 mL) for RRR. RRR treatment was mainly systemic steroids, with partial responses in six of 11 (58%) patients. Re-exposure to G/D was associated with a high rate of recurrence in nine of 15 (56.2%), prompting drug discontinuation. The major risk factors for RRR after G/D include, without statistical significance, a larger volume of the irradiated field and a shorter interval between chemotherapy and radiotherapy.ConclusionsThe incidence of RRR after G/D in the pediatric population is higher than previously reported. Drug re-exposure is usually followed by recurrence. Higher irradiated volumes and a shorter time to the start of chemotherapy could be related with an increased risk of RRR.