Channing J. Paller, MD, on vitamin C and prostate cancer

In this video, Channing J. Paller, MD, discusses vitamin C’s role in prostate cancer management. She is the senior author of the recent Urologic Oncology paper, “Harnessing nature's therapeutic potential: A review of natural products in prostate cancer management.” Paller is an associate professor of oncology at the Johns Hopkins University School of Medicine, director of Prostate Cancer Clinical Research, and associate director of oncology, Johns Hopkins Clinical Research Network, Baltimore, Maryland.

Transcription:

What are the most promising natural products with the strongest preclinical evidence for their potential anticancer effects?

There are so many, it's hard to pick. This review looked at vitamin C, curcumin, lycopene, green tea, soy isoflavones. If I had to pick one, I'd pick vitamin C. That has a fun story. It was studied many, many years ago by Linus Pauling to figure out about scurvy, and he also studied it in cancer. What he figured out was, if he gave it intravenously, it prolonged the survival of cancer patients compared to not giving it. Later, it was studied orally by Mayo, and unfortunately, that study was negative. But what one scientist, Mark Levine [MD], figured out was that if you take it orally, it is an antioxidant. You can only absorb so much of it in your intestines, but if you take it intravenously at higher doses, you can get to super high levels that become an oxidant and have a different mechanism of action. So what we've seen pre clinically is that ascorbic acid has an ability to induce oxidative stress in cancer cells selectively and not in our normal cells, unless you have something called G6PD deficiency, which not that many people have. So this study that I just finished, in [patients with] metastatic castrate-resistant prostate cancer who were eligible for docetaxel chemotherapy, we gave them placebo with their chemotherapy, or ascorbic acid, and it was actually negative. And this is the second trial that was negative. The first trial was just once-a-week ascorbic acid, and it was also negative. And this was at high doses intravenously, a couple times a week with my trial. So what we noticed was there was not an improvement in overall survival, there was not an improvement in progression-free survival or any difference in PSA response. What we're wondering, though, is a few patients more in the vitamin C group did have more PSA responses, but it was not significant. The reason I point that out is before I write off all of vitamin C for prostate cancer, I want to point out there was another study just published around the same time in pancreas cancer that was positive. So adding ascorbic acid intravenously to chemotherapy improved their survival. It was so positive, the data safety monitoring board shut down their trial to close it because so many patients were benefiting. So what I'm telling you here is, I think we're learning slowly—I hope faster—how to use these agents as any other drug that a pharmaceutical company would study. So our first agents, like Taxol, came from natural products. And so we are figuring out, even though you can't patent these natural products, some of them have really incredible activity.

This transcript was AI generated and edited by human editors for clarity.