(P03-020-24) The Potential Predictive Value of Antioxidant Enzyme Activity on the Recurrence of Colorectal Cancer

Objectives: Imbalanced oxidative stress and antioxidant capacity have been suggested to cause the development of colorectal cancer (CRC); however, it remains unclear whether the status of oxidative stress or antioxidant capacity indicators play a role in predicting the prognosis of CRC. We aimed to compare changes in oxidative stress and antioxidant capacity indicators before, one month and one year after tumor resection between patients with recurrent and non-recurrent CRC, and to evaluate the correlation of these indicators with recurrence of CRC.

Methods: This cross-sectional and follow-up study involved 95 patients who underwent CRC tumor resection. Patients were followed from one day before tumor resection (pre) through one month (1-mo post) and one year (1-y post) after resection until recurrence or the end of this study, and were assigned to the recurrent and non-recurrent group. Fasting blood specimens were drawn at pre, 1-mo post and 1-y post. Tumor and its adjacent normal tissues were collected. Malondialdehyde (MDA) and advanced oxidation protein products (AOPP) as oxidative stress indicators, superoxide dismutase (SOD), glutathione (GSH), glutathione peroxidase (GPx), glutathione reductase (GR) and glutathione S-transferase (GST) as indicators of antioxidant capacity were measured.

Results: 11 patients experienced CRC recurrence during the median follow-up time of 931 days. Plasma or serum levels of MDA, AOPP, GSH, and activities of SOD, GPx, GR, and GST at 1-mo post were slightly or significantly higher than pre-levels, and remained steady at 1-y post in both recurrent and non-recurrent groups. Tumor tissues exhibited higher levels of MDA, AOPP, GSH, and activities of GPx, GR as well as GST than in their adjacent normal tissue. The decrease in SOD activities at pre (HR = 0.224, p = 0.011) and the increase in MDA levels in tumor tissue (HR = 5.069, p = 0.032) were significantly associated with a higher recurrence of CRC.

Conclusions: Recurrent and non-recurrent patients showed similar fluctuation patterns in indicators of oxidative stress and antioxidant capacity within one year after tumor resection. Patients with CRC had higher SOD activities before tumor resection likely decreased the CRC recurrence.

Funding Sources: The study was supported by a grant from the National Science and Technology Council, Taiwan.