Re-Assessment Urged for Intravenous Vitamin C and Cancer
By Michael Smith, MedPage Today Staff Writer
Reviewed by Zalman S. Agus, MD; Emeritus Professor at the University of Pennsylvania School of Medicine.
March 27, 2006
MedPage Today Action Points
BETHESDA, Md., March 27 - Three case reports of benefit from intravenous use of high-dose vitamin C for cancer are being promoted here as a sign that perhaps a reassessment of the long-discredited approach is in order.
For years high-dose vitamin C as a treatment for cancer was banished to the category of alternative therapy, after clinical trials of oral vitamin C showed no benefit.
But the three case studies, as well as new pharmacological evidence, suggest that the role of high-dose vitamin C administered intravenously should be re-assessed, according to Sebastian Padayatty, M.D., of the National Institute of Diabetes and Digestive and Kidney Diseases here.
The three case reports increase the "clinical plausibility" that vitamin C may have a benefit, Dr. Padayatty and colleagues wrote in the March 28 issue of the Canadian Medical Association Journal.
It is now known, they said, that high-dose intravenous -- but not oral -- vitamin C therapy results in plasma concentrations of about 14,000 micromole per liter. Oral doses result in plasma concentrations of at best 220 micromole per liter.
At those concentrations in vitro, Dr. Padayatty and colleagues said, the vitamin is toxic to some cancer cells, but not to normal cells -- a finding that increases the "biological plausibility" of a beneficial effect.
Early studies of high-dose oral and intravenous vitamin C appeared to show a benefit, but a randomized controlled trial of oral vitamin C failed to confirm the finding, the researchers noted, and the idea was abandoned.
The three case studies -- of patients whose disease had a poor prognosis but an unusually favorable outcome -- can't be regarded as conclusive, but they "were analyzed in accordance with the National Cancer Institute's Best Case Series process, which reports and interprets apparent responses to alternative therapies," the researchers noted.
In the first study, a 51-year-old woman was found to have a tumor involving her left kidney, shown after nephrectomy to be a renal cell carcinoma. CT scans of the chest and abdomen showed no evidence of metastatic disease. However, six months later, CT chest scans showed new small rounded and well-defined soft tissue masses that were judged consistent with metastatic cancer. After another seven months, multiple cannonball lesions were seen.
The patient refused conventional therapy and opted instead for high-dose intravenous vitamin C -- 65 grams twice a week for 10 months -- as well as a range of other alternative therapies, including thymus protein extract, N-acetylcysteine, niacinamide, and whole thyroid extract.
Seven months after the cannonball lesions were seen, chest radiography was normal, except for a possible pulmonary scar in the left lung.
The conclusion that the vitamin C had a beneficial effect would be strengthened, the researchers noted, if there had been histological proof that the cannonball lesions were actually malignant - evidence that does not exist. However, the researchers said, the clinical characteristics and evolution of the pulmonary lesions "make any other diagnosis unlikely."
Unfortunately, the woman -- a long-time smoker -- was diagnosed four years later with small-cell lung cancer. She again opted for vitamin C treatment, but the second cancer did not respond.
In the second case, a 49-year-old man was found to have a primary bladder tumor with multiple satellite tumors. Transurethral resection of the primary and satellite tumors was carried out. Histopathologic review at the NIH revealed a grade 3/3 papillary transitional cell carcinoma invading the muscularis propria.
The patient declined chemotherapy and radiotherapy, opting instead for 30 grams of vitamin C twice a week for three months, followed by 30 grams once every one to two months for four years, interspersed with periods during which he had more frequent infusions. He also used supplements including botanical extract, chondroitin sulfate, chromium picolinate, flax oil, glucosamine sulfate, a-lipoic acid, Lactobacillus acidophilus, L. rhamnosus, and selenium.
Nine years after diagnosis, the patient is in good health with no symptoms of recurrence or metastasis, the researchers reported.
The outcome would have been unexpected, Dr. Padayatty and colleagues noted. With only local treatment, as in this case, invasive transitional cell bladder cancer "almost invariably develops into clinically apparent local or metastatic disease within a short period."
In the third case, a 66-year-old woman was found to have a large left paraspinal mass medial to the iliopsoas muscle at the L4-5 level, with evidence of extension into the posterior paraspinal muscle and bone invasion, although chest radiography results were normal. A biopsy was diagnostic of a diffuse large B-cell lymphoma. Later histopathologic analysis at the NIH confirmed the diagnosis.
The patient agreed to a five-week course of radiation, but refused chemotherapy, opting instead for 15 grams of intravenous vitamin C twice weekly for two months, 15 grams once to twice a week for seven months, and then 15 grams once every two to three months for about a year. The patient also used additional products: beta-carotene, bioflavonoids, chondroitin sulfate, coenzyme Q10, dehydroepiandrosterone, a multiple vitamin supplement, N-acetylcysteine, a botanical supplement, and bismuth tablets.
Over the year following diagnosis and the beginning of treatment, the patient had several occasions when axillary, cervical, sub-mandibular, or supraclavicular lymph nodes were palpable, but at the end of that time -- and for the 10 years since -- the patient was in normal health, with no signs of B-cell lymphoma.
The three cases "do not provide grounds for advocating intravenous vitamin C therapy as a cancer treatment," the researchers said. These patients received other alternative medicine therapies and spontaneous remission of some tumors is known to occur rarely.
On the other hand, Dr. Padayatty and colleagues said, they "increase the clinical plausibility of the notion that vitamin C administered intravenously might have effects on cancer under certain circumstances."
Primary source: Canadian Medical Association
Sebastian J. Padayatty, et al "Intravenously administered vitamin C as cancer therapy: three cases" CMAJ 2006;174(7):937-42.
© 2004-2006 MedPage Today, LLC. All Rights Reserved.
0.244 sec, (5)