Vitamin C and DMSO for Skin Cancer: What the Studies Found

What is the vitamin C and DMSO skin cancer study?

The figure spreading online, 56 percent, comes from the second study (medRxiv, 2025). It is a real number from a real study. It is also one open-label study of 17 people, posted as a preprint, which means no journal's reviewers have checked it yet. The first study, a randomised trial against a standard prescription cream, is the stronger of the two and got less attention (Biomedicine & Pharmacotherapy, 2022).

What the 2025 squamous cell study found

Squamous cell carcinoma in situ is a skin cancer confined to the top layer of skin. In the preprint, 19 patients were enrolled, 2 were lost to follow-up, and the 17 who finished, with 27 biopsy-confirmed lesions, applied 30 percent ascorbic acid in 95 percent DMSO twice daily for 12 weeks, and every lesion was biopsied again at week 12 (medRxiv, 2025).

The authors report no pain, itching, burning or ulceration, only mild redness, and no loss of skin colour. Most of the lesions that did not fully clear showed sun-damage changes without cancer on the second biopsy, and were then treated with freezing (cryotherapy). The authors list their own limits: a small sample, no placebo or comparison group, DMSO alone never tested, little ethnic diversity, and no long-term data yet on whether the cancers come back.

What the 2022 basal cell trial found

Basal cell carcinoma is the most common skin cancer. The 2022 trial randomly assigned 25 patients with 29 biopsy-confirmed nodular or superficial lesions to the vitamin C solution twice daily for 8 weeks or to imiquimod, a standard prescription cream. At 8 weeks, biopsy showed complete resolution in 86.7 percent of vitamin C lesions against 57.1 percent of imiquimod lesions. The authors call vitamin C superior at 8 weeks and non-inferior at 12 weeks (Biomedicine & Pharmacotherapy, 2022).

This is the more important of the two studies because it has a comparison group: people were randomly assigned, and the comparison was a real treatment, not nothing. It is still 29 lesions, and the lesions were low risk by design.

Who ran these studies, and who paid?

Both papers come from the same group. Briant Burke, of Boise, Idaho, is the corresponding author on both. On ClinicalTrials.gov, the 2022 trial's lead sponsor is the Center for Biomedical Research, Inc., classed as industry, the authors' own organisation (NCT04279535). The 2025 preprint declares no outside funding and no competing interests, and its review board was the Institute for Biomedical Sciences in Boise, the corresponding author's own institute.

Three things in the public record are worth knowing. First, the 2022 trial was registered on 19 February 2020, after it finished in June 2019. Registering before a trial starts is what stops researchers from changing the goal after seeing the results. Second, the squamous cell study was registered on time, in June 2023, as NCT05932511, sponsored by the same company. That registration names the main result as lesions free of tumour on biopsy at 8 weeks, in an estimated 15 people. The preprint reports its main result at 12 weeks, in 17, and does not explain the change. Third, the preprint prints NCT04279535 as its registration, which is the 2022 basal cell trial's number, not its own.

Is this the same as a vitamin C serum?

DMSO, dimethyl sulfoxide, is the part of the formula people tend to skip past. It carries what is dissolved in it through the outer layer of skin. The preprint's authors note that DMSO alone was never tested, so the studies cannot say how much of the effect is vitamin C and how much is DMSO.

What does the wider research say?

A 2026 scoping review in Dermatologic Surgery searched the major medical databases for topical vitamin C in the prevention and treatment of actinic keratoses (precancerous sun spots) and nonmelanoma skin cancers. It found four studies: two randomised trials, one observational study and one case report, covering 40 people with actinic keratoses, 21 with basal cell carcinoma and 1 with squamous cell carcinoma. It concluded that highly concentrated vitamin C may have some benefit for actinic keratoses and low-risk nonmelanoma skin cancers, but that too few studies exist to make clinical recommendations (Dermatologic Surgery, 2026).

What these studies do not show

• Anything about melanoma, the most dangerous skin cancer. Neither study included it.
• Anything about high-risk, deep or large skin cancers. Both studies enrolled low-risk or in situ lesions.
• Long-term results. The 2025 preprint reports no recurrence data yet.
• That it works without a biopsy. Every result here was confirmed by looking at tissue under a microscope before and after.
• Any effect of an over-the-counter vitamin C serum.

The bottom line

Two small studies from one group found that a 30 percent vitamin C solution in DMSO cleared many low-risk skin cancers on biopsy, with fewer side effects than imiquimod in the one randomised comparison. That is worth a larger, independent trial, which is what the authors themselves call for. It is not yet evidence that vitamin C treats skin cancer, and it says nothing at all about vitamin C serums.