Multiple Breath Washout and Imaging to Detect Early Pulmonary Toxicity in Paediatric Cancer Patients and Survivors: First Results of a Systematic Review

Introduction: Conventional pulmonary function tests in asymptomatic patients are not sensitive enough to detect early pulmonary dysfunction after pulmotoxic cancer treatment. Washout tests are more sensitive for small airway disease and imaging can detect structural and functional changes. Their use for early detection of pulmonary dysfunction in paediatric cancer patients remains unknown. Aims and objectives: We investigate the use of washout tests and lung imaging for detecting pulmotoxic treatment effects in children undergoing cancer treatment. Method: We addressed two examination modalities to detect functional and structural lung damage 1.) washout test and 2.) lung imaging. We registered the review in PROSPERO (CRD42022348624) and systematically searched Medline, Embase and Cochrane Library for the period 1995-2022. Two reviewers checked title, abstract, full text, extracted data and performed quality control. Results: For both research questions combined, we identified 6512 studies. We screened 109 full-texts and included 20 publications (7 washout, 12 imaging, 1 with both). From the 8 studies on washout, 4 covered stem cell transplantation (HSCT) patients. Computed tomography images were used in 12 out of 13 studies, of which 9 covered HSCT patients. We did not conduct a meta-analysis because of study heterogeneity. Conclusion: Few studies used washout tests in HSCT and oncology patients to assess pulmonary dysfunction. Lung imaging was mainly done in HSCT patients, using computed tomography. Longitudinal studies, including radiation-free imaging, not only after HSCT but also in childhood cancer patients are needed.