Biobanking of Fresh-Frozen Gastric Cancer Tissues: Impact of Long-Term Storage and Clinicopathological Variables on RNA Quality.

BACKGROUND: Molecular research is increasingly dependent on high-quality biobanked biospecimens. Preanalytical variables in tissue processing and preservation may influence the RNA quality and research results. Hence, the effect of long-term storage and clinicopathological parameters on RNA quality needs to be elucidated.

METHODS: Ninety gastric cancer tissue samples were collected and fresh-frozen in a -80°C freezer for 12 years (2006-2017). The histology was assessed and RNA integrity number (RIN) was detected by an Agilent 2100 Bioanalyzer. The impact of storage duration on RNA integrity and histomorphology was analyzed. The difference between RIN values and clinical variables was analyzed. Correlations between pathological parameters such as tumor cell percentage, stroma percentage, necrosis extent, cellularity, and RIN were assessed, respectively.

RESULTS: Long-term storage at -80°C for 12 years did not adversely affect RNA integrity and histomorphology. RNA integrity was also not influenced by tumor location, estimated blood loss, cold/warm ischemia time, and surgical approach. However, RIN values were significantly correlated with the tumor cell percentage and stroma percentage. Gastric cancer tissues with higher tumor cell percentage or lower stroma percentage had higher RIN values.

CONCLUSIONS: RNA quality of fresh-frozen gastric cancer tissues is influenced by clinical and histological parameters. Standard tissue collection procedure and histological quality control remain essential for tissue biobanking.