Evaluating the Utility of Fresh Tissue in Molecular Diagnostics of Colorectal Cancer

<b>Background:</b> Molecular diagnostics has become a critical component of precision oncology in solid tumors, including colorectal cancer, yet the use of formalin-fixed, paraffin-embedded (FFPE) tissue often suffers from DNA degradation that compromises sequencing quality. This study aimed to evaluate the feasibility and effectiveness of using fresh, intraoperatively collected tumor tissue for next-generation sequencing-based molecular diagnostics in colorectal cancer. <b>Methods:</b> Tissue samples from 24 patients undergoing colorectal tumor resection were obtained based on macroscopic evaluation and tested with a custom gene panel. Sequencing metrics, mutation profiles, and correlations with clinical and pathological features were analyzed. <b>Results:</b> All samples yielded high-quality sequencing data. Oncogenic or likely oncogenic variants were detected in 21 out of 24 samples (87.5%), predominantly affecting genes frequently involved in colorectal cancer carcinogenesis, including <i>APC</i>, <i>TP53</i>, and <i>KRAS</i>. In three cases, no typical mutations were found despite visual confirmation of tumor tissue during surgery, which may be attributed to insufficient tumor cellularity or molecular alterations beyond the panel's scope. <b>Conclusions:</b> The results support the use of fresh tissue as a high-quality source for molecular diagnostics, capable of reducing turnaround time and avoiding formalin-induced artifacts. However, the findings also highlight the diagnostic risk of relying solely on macroscopic tumor assessment without histological confirmation. Overall, fresh tissue-based testing represents a promising yet currently investigational approach that can enhance molecular diagnostics in colorectal cancer.