The CHTN mission is to provide prospectively procured biospecimens to scientific investigators with the ability to modify procurement and specimen processing procedures to suit the individual protocol of each investigator. Basic demographic information and clinicopathologic data abstracted from pathology reports are provided to investigators. More detailed clinical annotation may be obtained by arrangement.
Most tissue specimens procured by the CHTN are distributed to investigators as fresh/viable aliquots or snap-frozen. Quality control (QC) for all tissue samples consists of histologic analysis of a paired formalin-fixed paraffin-embedded (FFPE) tissue segment that is examined by a board-certified anatomic pathologist ensuring the delivery of correct tissue type and the elimination of highly necrotic specimens (Fig. A).
For tumor specimens, tumor cellularity, percent stroma and percent necrosis are also recorded (Fig. B). The histologic QC procedures created by the CHTN have been widely adopted and have served as the basis for biorepository best practice documents created by the NCI and the International Society for Biological and Environmental Repositories (ISBER). Prior network-wide surveys from procured tissue have shown that the CHTN procedures lead to most specimens having good-quality RNA1.
If a neoplasm (tumor) is present in the tissue section, an assessment is made of what percentage of the entire tissue area is involved by the tumor. Separate assessments are then made just on the area involved by tumor. Tumors are comprised of neoplastic cells, non-neoplastic tumor stromal cells and residual normal tissue cells that have been infiltrated by the tumor. The term “tumor cellularity” refers to the percentage of neoplastic cell nuclei as a total of all cell nuclei in the tumor area. Tumor attributes that are assessed include:
- % of nuclei that are neoplastic cells (tumor cellularity)
- % tumor necrosis by cellularity using only tumor cells as denominator
- % non-neoplastic stroma by area using only tumor area as denominator
- % acellular mucin by area using only tumor area as denominator
1Am J Clin Pathol 2002;118:733-41