Intratumor heterogeneity has attracted more and more attention in recent years. Heterogeneity is the driving force of tumor clone evolution. Chromosomal instability, somatic mutation, epigenetic modification and extrachromosomal DNA (ecDNA) contribute to tumor heterogeneity. The degree of such heterogeneity is extremely high.

Over the years, several ablation techniques, such as radiofrequency ablation (RFA), microwave ablation, and cryoablation, have been developed and implemented in the treatment of different cancers. Of these ablation technologies, RFA is the most widely used. RFA is a form of thermal ablation that relies on radio waves to produce an electrical current at the tip of an inserted electrode, thus allowing for heat production at the site of the tumor.

Radiation therapy (RT) is one of the pillars of locally advanced head and neck cancer (HNSCC) treatment in combination with cisplatin or epidermal growth factor receptor inhibitors. Despite a very high local tumor control rate, approximately 50% of patients with locally advanced disease will develop a recurrence.

Gastrointestinal stromal tumors are mesenchymal tumors which predominantly originate from the interstitial cells of Cajal in the intestinal lining. Around ~85% of malignant GISTs possess activating mutations in the tyrosine kinase receptors KIT or PDGFRA. The driver mutations in genes other than KIT or PDGFRA account for around 15% GISTs and belong to highly heterogeneous groups called wild-type GISTs. Around 20–40% of WT-GISTS are deficient for the succinate dehydrogenase complex (SDHA, SDHB, SDHC, SDHD). 

Congenital adrenal hyperplasia (CAH) is a disorder affecting cortisol biosynthesis in the adrenal cortex [1]. 21-hydroxylase deficiency is the most frequent reason for CAH, with an incidence between 1:10.000 and 1:20.000 [2]. Due to the lack of enzyme function, patients with any enzyme deficiency cannot synthesize cortisol effectively.