Background
High-dose methotrexate (HD-MTX) is used in the treatment of different childhood cancers, including leukemia, the most common cancer type and is commonly defined as an intravenous dose of at least 1 g/m2 body surface area per application. A systematic review on late effects on different organs due to HD-MTX is lacking.
Method
We conducted a systematic literature search in PubMed, including studies published in English or German between 1985 and 2020. The population of each study had to consist of at least 75% childhood cancer survivors (CCSs) who had completed the cancer treatment at least twelve months before late effects were assessed and who had received HD-MTX. The literature search was not restricted to specific cancer diagnosis or organ systems at risk for late effects. We excluded case reports, case series, commentaries, editorial letters, poster abstracts, narrative reviews and studies only reporting prevalence of late effects. We followed PRISMA guidelines, assessed the quality of the eligible studies according to GRADE criteria and registered the protocol on PROSPERO (ID: CRD42020212262).
Results
We included 15 out of 1731 identified studies. Most studies included CCSs diagnosed with acute lymphoblastic leukemia (n = 12). The included studies investigated late effects of HD-MTX on central nervous system (n = 10), renal (n = 2) and bone health (n = 3). Nine studies showed adverse outcomes in neuropsychological testing in exposed compared to non-exposed CCSs, healthy controls or reference values. No study revealed lower bone density or worse renal function in exposed CCSs. As a limitation, the overall quality of the studies per organ system was low to very low, mainly due to selection bias, missing adjustment for important confounders and low precision.
Conclusions
CCSs treated with HD-MTX might benefit from neuropsychological testing, to intervene early in case of abnormal results. Methodological shortcomings and heterogeneity of the tests used made it impossible to determine the most appropriate test. Based on the few studies on renal function and bone health, regular screening for dysfunction seems not to be justified. Only screening for neurocognitive late effects is warranted in CCSs treated with HD-MTX.
Tumors shed cell-free DNA (cfDNA) into the plasma. “Liquid biopsies” are a diagnostic test to analyze cfDNA in order to detect minimal residual cancer, profile the genomic tumor landscape, and monitor cancers non-invasively over time. This technique may be useful in patients with head and neck squamous cell carcinoma (HNSCC) due to genetic tumor heterogeneity and limitations in imaging sensitivity. However, there are technical challenges that need to be overcome for the widespread use of liquid biopsy in the clinical management of these patients. In this review, we discuss our current understanding of HNSCC genetics and the role of cfDNA genomic analyses as an emerging precision diagnostic tool.
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