Enhancing Tumor Content through Tumor Macrodissection

Abstract

The presence of contaminating non-tumor tissues in formalin-fixed paraffin-embedded (FFPE) tissues can greatly undermine genomic studies. Herein we describe macrodissection, a method designed to augment the percentage tumor content of a tissue specimen by removing and eliminating unwanted tissue prior to performing downstream nucleic acid extractions. FFPE tissue blocks were sectioned to produce 4-5 µm slide-mounted tissue sections. A representative section was submitted for hematoxylin and eosin (H&E) staining and subsequently reviewed by a boardcertified pathologist. During the review, the pathologist identified and marked the regions of tumor tissue in the H&E. Once complete, the demarked H&E was used to guide resection of the serial unstained sections from the same tissue block. To demonstrate the effects of macrodissection, RNA extracted from matched macrodissected and non-dissected Diffuse Large B-Cell Lymphomas (DLBCL) were run on a digital gene expression assay capable of determining DLBCL subtype and BCL2 translocation status. The results showed that macrodissection changed the subtype or BCL2 translocation status calls in 60% of the samples examined.In conclusion, macrodissection is a simple and effective method for performing tumor enrichment prior to nucleic acid extractions, the product of which can then be confidently used in downstream genomic studies.

Suitability of respiratory endoscopy for sampling malignant thoracic tumors for comprehensive genomic profiling

“…These cases may have influenced the results, thus precluding a statistically significant difference between the conventional bronchoscopy cases with and without cryobiopsy. Although the proportion of tumor cell content may be reduced by the presence of a certain amount of non‐neoplastic tissues in cryobiopsy specimens, it can be controlled to some extent through macro/microscopic dissection 34 as long as tumor tissues can be collected, because the specimens usually have a clear boundary between normal lung parenchyma and tumor tissues. Therefore, it is important to perform cryobiopsy on target lesions; however, conventional 1.9‐mm cryoprobes are thick and stiff and have poor operability in PPLs.…”