Effects of High-Dose Intravenous Vitamin C on Colorectal Cancer Recurrence: The Retrospective Study by Medical Records for 23 Years

Background: Among the complementary and alternative therapies used to treat cancer, studies have reported since the late 1960s that the intravenous administration of high-dose vitamin C had an anticancer effect. As the incidence of colorectal cancer has recently increased, interest in treating and preventing its recurrence has also increased. Therefore, this study investigated whether the intravenous administration of high-dose vitamin C to patients with colorectal cancer who received chemotherapy after radical resection would reduce recurrence rates.Methods: One hundred eighty patients who were diagnosed with colorectal cancer and received chemotherapy after surgery at a university hospital in Busan for a total of 23 years from January 2000 to March 2023 were retrospectively studied. Of them, 30 were administered high-dose (1 g/kg) intravenous vitamin C injections twice weekly for more than 5 weeks in addition to standard treatments, while the remaining 150 patients who received only standard treatments were assigned to the control group. In both groups, a thorough examination was performed every year after surgery. The chi-squared test was performed to compare 5-year recurrence rates.Results: The control group had higher recurrence and mortality rates than the experimental group; however, the differences were not statistically significant. The recurrence rate was 28.1% in the stage 2 and 3 control groups, non-significantly higher than that in the experimental group (18.8%; P>0.05).Conclusions: There was no statistically significant difference in recurrence among patients with colorectal cancer who received chemotherapy, although the 5-year recurrence rate was decreased in the experimental versus control group.