Targeted sequencing based on NGS offers new perspectives in drug selection for cancer patients. The accuracy of mutation analysis relies on the tumor content of the tissue samples.
Download the recent application note by Dr. Hatakeyama et al. (Shizuoka Cancer Center, Japan) and learn more about:
- How to improve the accuracy of mutation detection in FFPE tissue sections of gastric cancers
- How our FFPE Tissue Dissociation Kit, together with the gentleMACS™ Technology, enables the preparation of single-cell suspensions to separate tumor cells from healthy cells
- How this helps to increase the sequencing sensitivity for FFPE samples
Background Targeted sequencing using next generation sequencing (NGS) offers new prospects for drug selection for cancer patients based on alterations in their genome.¹–³ The accuracy in the mutation analysis using NGS relies on the tumor content of the tissue samples, which are commonly formalin-fixed paraffinembedded (FFPE) tissues. FFPE tissue samples with low tumor cell content are typically subjected to tumor cell enrichment using macrodissection. This technique consists of isolating the tumor-specific areas within the sample. However, this is often unsuitable for samples containing diffused-tumor cells, such as diffuse-type gastric cancer or lobular breast cancer. In those cases alternative methods for tumor cell isolation are necessary to enable the accurate detection of mutations in the sequencing of target gene panels. This application note summarizes some of the findings observed in the study performed by Hatakeyama et al.⁴ to investigate the effect of tumor cell isolation from FFPE tissue sections of diffusetype and intestinal gastric cancers on the detection of mutaResults Efficient tumor cell isolation from FFPE tissue sections of diffuse and intestinal gastric cancers of varying thickness FFPE tissue sections of 10, 20, and 50 µm in thickness were obtained from two diffuse-type (D1 and D2) and two intestinal (S1 and S2) gastric cancers. The tumor cellularity estimated by a pathologist was of 20% tumor content for both diffuse-type samples, and 60% and 50% in the intestinal-type samples. After dissociation of the FFPE sections, tumor cells were efficiently isolated using automated magnetic cell separation from both gastric cancer types based on the expression of cytokeratin. The population considered to be of tumor cells (cytokeratin-positive, vimentin-negative) were increased in the tumor fractions compared to the unseparated samples, whereas in the residual fraction, these populations were decreased (fig. 1). No differences in tumor cell isolation due to the thickness of the FFPE tissue sec