Thesis Nathalie Lak

Summary

In the Netherlands, more than 500 children are diagnosed each year with a pediatric malignancy, of which 33% with a solid tumor. Treatment for these solid tumors is intensive and has a great impact on quality of life. Additionally, it is hard to identify patients upfront with therapy resistant disease which can lead to recurrent disease and is associated to high mortality.

Currently, treatment stratification and response monitoring is based on analysis of tumor material and imaging studies, which can be a burden for the patients and have limited sensitivity. Minimally invasive sampling of blood to detect circulating tumor material using molecular analysis, i.e. liquid biopsies, can form an additional modality to improve current risk stratification at diagnosis and response monitoring during treatment. In the first part of this thesis, we demonstrated that presence of tumor-specific material in small volumes of blood from patients with rhabdomyosarcoma (tumor of the muscles) can predict clinical outcome. Furthermore, we showed that it is feasible to design patient-specific assays suitable for clinical application and different liquid biopsy-based techniques can be complementary.

In the second part of this thesis, we also investigated further novel molecular techniques for liquid biopsy analysis of patients with different types of solid tumors, such as neuroblastoma and Ewing sarcoma. 
In conclusion, analysis of liquid biopsies can be of added value to current clinical methods and ultimately help to improve outcome for children with solid tumors.