Clinical significance of tumor mutation burden in patients after R 0 resection of colorectal cancer and capecitabine-based adjuvant chemotherapy / 中华普通外科杂志

ABSTRACT

Objective:To investigate the clinical significance of TMB among CRC patients after R 0 resection and capecitabine-based adjuvant chemotherapy. Methods:Data of 82 CRC patients were reviewed retrospectively. Tumor tissue specimens were collected for DNA extraction . Somatic mutation detection and TMB analysis were performed using next-generation sequencing (NGS) of tumor-related genes. The univariate analysis between TMB status and prognosis was carried out by Kaplan-Meier survival analysis and adjusted by multivariate COX regression analysis subsequently.Results:In these 82 cases,with the median follow-up period was 5.5 years the median disease-free survival (DFS) was 4.5 years, and the median overall survival (OS) was 5.7 years. The most common mutated somatic genes were TP53, APC, KRAS and PIK3CA, with the mutation frequencies of 68.3%, 64.6%, 46.3% and 29.3%, respectively. Other somatic mutant genes were of a relatively low frequency (<25%). The overall somatic mutation burden was relatively low. TMB status was divided into TMB-L (≤3.6/Mb) and TMB-H (>3.6/Mb) according to the median TMB threshold. And the patients with TMB-L and TMB-H were 42 cases and 40 cases, respectively. The median OS in patients with TMB-L and TMB-H was 6.5 and 4.7 years, respectively (χ 2=6.59, P=0.010). TMB status was an independent factor for OS ( HR=0.73, P=0.021). Conclusion:TMB is a biomarker for evaluating the prognosis of CRC patients after surgical resection and receiving capecitabine-based adjuvant chemotherapy .