This one is controversial. Early studies in the 80s showed no change in outcomes in patients, but they were orally administering the ascorbate. IV is a whole other story, but it just doesn't seem there are many studies. That said, the risk is low, cost is manageable, and there do seem to be some benefits shown in vitro. Here's one of the more recent papers I could find on the topic: [Parenteral Ascorbate As a Cancer Therapeutic: A Reassessment Based on Pharmacokinetics - PMC](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3869468/) And of course MSKCC has a good write up and references: [Vitamin C | Memorial Sloan Kettering Cancer Center](https://www.mskcc.org/cancer-care/integrative-medicine/herbs/vitamin-c#references-28)