Vitamin C trial yields exploratory survival signal in pre-cancer blood disorders

A randomized, double-blind, placebo-controlled phase 2 clinical trial found that daily oral vitamin C was associated with favorable changes in inflammatory signaling, fewer selected clinical complications and an exploratory survival advantage in people with clonal cytopenia of undetermined significance or lower-risk myeloid malignancies. The EVITA trial enrolled 109 patients in Denmark and the United States and compared 1,000 mg of daily vitamin C with placebo for 12 months. Its primary endpoint, the growth rate of precancerous or cancerous cells, was similar between the groups, so the findings do not establish vitamin C as an effective treatment or show that it prevents leukemia.

Investigators randomly assigned 55 participants to oral vitamin C and 54 to placebo. Patients entered the study with either clonal cytopenia of undetermined significance, a blood condition that can turn cancerous, or a low-risk form of blood cancer. Although participants taking vitamin C experienced changes in inflammatory signaling that aligned with better outcomes, anemia, pneumonia, acute aseptic arthritis and internal bleeding were less frequent than among those taking placebo.

Gastrointestinal problems, meanwhile, were more frequent in the vitamin C group. These differences were reported as observations from the phase 2 trial rather than definitive proof of a treatment effect. Decreased function of TET enzymes is a common driver of certain forms of blood cancer, the research team reported, providing the rationale for testing vitamin C in patients whose disorders may progress to malignancy.

The randomized trial was designed to evaluate whether supplementation could influence disease-related cellular growth and produce other changes associated with better outcomes in this at-risk population. The primary endpoint did not distinguish the treatment groups: the growth rate of precancerous or cancerous cells was similar among participants receiving vitamin C and those receiving placebo. That result means the study did not answer its main question about abnormal cell growth.

The investigators nevertheless identified several other differences between the groups, including changes in inflammatory signaling, lower frequencies of four clinical complications and more gastrointestinal problems with vitamin C. The release did not provide numerical estimates, confidence intervals or statistical significance for these individual clinical comparisons, limiting the precision with which their size or certainty can be assessed from the available report. Death outcomes provided the trial’s most prominent exploratory finding. At a median follow-up of 33.6 months, or nearly three years, 35 deaths were recorded in the intention-to-treat population: 24 in the placebo group and 11 in the vitamin C group.

An exploratory analysis found that participants assigned to vitamin C were more likely to survive during follow-up than those assigned to placebo. The survival comparison was not the primary endpoint, and the research release did not state the numerical effect estimate, confidence interval or statistical significance. The investigators consequently said the finding requires confirmation in a larger phase 3 clinical trial.

“The EVITA trial gives us a strong rationale to continue exploring if and how vitamin C might benefit people with certain pre-cancer or early-stage blood cancers,” said Peter A. Jones, co-senior author of the study and co-leader of the Van Andel Institute–Stand Up To Cancer Epigenetics Dream Team, which led EVITA. “More work is needed but we are cautiously optimistic that these findings could inform future strategies to intercept leukemia development.” The researchers presented the survival result as a reason to continue investigating vitamin C, not as evidence that the supplement prevents leukemia or improves survival for all people with blood disorders. Kirsten Grønbæk, the trial’s other co-senior author and a longtime member of the Van Andel Institute–Stand Up To Cancer Epigenetics Dream Team, also emphasized the limits of the findings.

“We are encouraged by our findings and what they ultimately could mean for people with these early-stage blood disorders,” she said. “Although it is too soon to make recommendations based on our results, we are hopeful that a larger study will give us more definitive answers.” The report did not recommend vitamin C supplementation or identify it as a clinical standard of care, and the trial did not test whether it could treat established leukemia or reverse an advanced blood cancer. Several features limit the conclusions that can be drawn from EVITA.

The intervention also involved one fixed dose of 1,000 mg per day over 12 months, while survival was assessed over a median of 33.6 months. The findings concern people with clonal cytopenia of undetermined significance or lower-risk myeloid malignancies in Denmark and the United States, so they do not directly address other blood cancers, advanced disease or the general population. The results also require careful separation of the trial’s primary, secondary and exploratory measures.

The primary cellular-growth endpoint did not differ between vitamin C and placebo. Other reported findings included favorable changes in inflammatory signaling, fewer instances of anemia, pneumonia, acute aseptic arthritis and internal bleeding, and more gastrointestinal problems in the supplement group. The apparent survival advantage emerged from an exploratory analysis and had not been established as the primary test.

The absence of a difference in the main endpoint therefore remains central to interpreting the study, even as the other observations support further research. EVITA provides a rationale for a larger phase 3 trial, but it does not resolve whether vitamin C meaningfully improves outcomes in people with these pre-cancer or early-stage blood disorders. The results were published online on September 21, 2026, in CANCER , a peer-reviewed journal of the American Cancer Society, under the title “Oral vitamin C supplementation in patients with clonal cytopenia of undetermined significance or lower-risk myeloid malignancies: Results from EVITA, a phase 2 randomized placebo-controlled trial.” A larger study would be needed to test whether the biological, clinical and exploratory survival findings are reproducible, estimate any benefit more precisely and determine whether vitamin C has a meaningful role in intercepting progression to leukemia.

Subject of Research: Phase 2 randomized trial of oral vitamin C in clonal cytopenia and lower-risk myeloid malignancies

Article Title: Can vitamin C improve outcomes in people with pre-cancer blood disorders?

Article References: Can vitamin C improve outcomes in people with pre-cancer blood disorders?. Original publication (Bibliographic details unavailable.)

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Keywords: vitamin C, clonal cytopenia, myeloid malignancies, blood cancer, TET enzymes, leukemia prevention, randomized trial, survival, phase 2 trial, clinical outcomes, vitamin, improve