DNA polymerase gamma variants and hepatotoxicity during maintenance therapy of childhood acute lymphoblastic leukemia: is there a causal relationship?

Hepatotoxicity is a frequent complication during maintenance therapy of acute lymphoblastic leukemia (ALL) with 6-mercaptopurine and methotrexate. Elevated levels of methylated 6-mercaptopurine metabolites (MeMP) are associated with hepatotoxicity. However, not all mechanisms are known that lead to liver failure in patients with ALL. Variants in the POLG gene, which encodes the catalytic subunit of mitochondrial DNA polymerase gamma (POLG1), have been related to drug-induced hepatotoxicity, for example, by sodium valproate. The association of common POLG variants with hepatotoxicity during maintenance therapy was studied in 34 patients with childhood ALL. Of the screened POLG variants, four different variants were detected in 12 patients. One patient developed severe hepatotoxicity without elevated MeMP levels and harbored a heterozygous POLG p.G517V variant, which was not found in the other patients.

Late effects and survival of children with malignant solid tumours in northern Finland: a single-centre cohort study.

The global survival rates for childhood cancers are high: approximately 80% of affected children will survive. Nevertheless, the burden of treatment for survivors is also high as three-quarters experience late effects of varying severity following cancer treatment. The aims of this study were to evaluate the treatment-related late effects of patients with childhood solid tumour in northern Finland and to report their survival rates. Our study included 104 patients treated for malignant solid tumours, excluding central nervous system tumours and lymphomas, between 1990 and 2015. Information regarding the type of late effects as well as other clinical data were obtained from the patients' medical records. Late effects were observed in 65 (63%) patients, and almost half (40%) of the patients displayed more than one late effect. The most common late effect was hearing loss (n = 20). The 5-year survival rate in our study was 75%.   Conclusion: Our results highlight the importance of long-term follow-up for childhood cancer survivors. As survivors age and survival rates improve, late effects and their impact on patient health as well as the value of surveillance must be considered. What is Known: • Up to three-quarters of childhood cancer survivors experience treatment-related late effects. What is New: • The 5-year survival rate and the prevalence of late effects amongst childhood solid tumour patients treated in northern Finland are in line with findings from previous studies.