Measurement of Nucleic Acid Metabolizing Enzymes in Stage III Colorectal Cancer Adds Precision to Adjuvant Fluorouracil and Leucovorin Therapy

Abstract

1. Abstract 1.1. <span style=font-size:10.0pt;mso-fareast-font-family: ms= mincho=>Background <span style=font-size:10.0pt;mso-fareast-font-family: ms= mincho=>: Recurrence of colorectal cancer has been shown to be inhibited by adjuvant chemotherapy. To achieve effective adjuvant chemotherapy, a target molecule is necessary . Therefore, we performed a prospective clinical trial to determine the relationship between adjuvant chemotherapy outcomes and prognostic factors in colorectal cancer based on nucleic acid metabolizing enzyme levels. 1.2. Methods: A total of 147 patients with stage IIIA, IIIB, and IIIC cancer were selected for adjuvant chemotherapy. We analyzed Disease-Free Survival (DFS) as the primary endpoint and Overall Survival (OS) as the secondary endpoint in relation to the Thymidylate Synthase (TS) and Dihydropyrimidine Dehydrogenase (DPD) levels as measured by enzyme-linked immunosorbent assay. According <span style=letter-spacing: -.15pt>to the levels of the mean preliminary TS of 21.0 ng/mg protein and DPD of 115 ng/mg protein, the patients were divided into 4 groups. They were then administered postoperative adjuvant chemotherapy that primarily included fluorouracil and Leucovorin (FL) or Uracil/Tegafur (UFT) and Leucovorin (UZEL) for 6 months. 1.3. Results: The 5-year DFS in advanced stage III cancer was 63.9%. A significant difference was observed between the LL (low TS and low DPD levels) and HL (high TS and low DPD levels) groups and the LH (low TS and high DPD levels) and HH (high TS and high DPD levels) groups. Multivariate<span style=letter-spacing: -.5pt> analysis revealed a significant difference<span style=letter-spacing: -.1pt> in stage, TS level, and TS and DPD levels. The OS was 79.6% for all the groups. A significant difference was observed between the LL, LH, and HL groups and the HH groups. Multivariate analysis revealed a significant difference<span style=letter-spacing: -.5pt> in the stage, age, TS level, and<span style=letter-spacing: -.55pt> TS and DPD levels. <span style=font-size:10.0pt;letter-spacing: -.15pt>1.4. Conclusions: Measurement of the TS and DPD levels of a primary colorectal cancer lesion as target molecules may be helpful for achieving an effective postoperative adjuvant chemotherapy. TS and DPD can potentially serve as more accurate predictors of OS than age and cancer stage. 2. Keywords: Adjuvant Chemotherapy; Colorectal Cancer; Metabolizing <span style=font-size: 10.0pt;mso-fareast-font-family: ms= mincho=> <span style=font-size: 10.0pt>Enzyme; Precision Medicine