I'm studying med. We are certainly taught of the existence of ascorbic acid megadosing and other "alternative" therapies.
We're also taught that *all* therapies have to be approached with scepticism.
Can we be sure that a particular treatment does what it is supposed to?
Has it been fairly tested? (This can be a very difficult question.)
What other effects does it have?
Were the people it was tested on similar to the person we're considering treating?
The information used to answer those questions can come from anywhere. We're not limited to information that the med school chooses to make available. A good rule of thumb is that a book promoting a product sold by the author might not be the most reliable source of information.
As for Vitamin C's effect on cancer, the Wikipedia page (
Vitamin C megadosage) is an obvious starting place:
In 1976 Linus Pauling and Ewan Cameron published a trial of 100 cancer patients which suggested that treatment with intravenous vitamin C significantly increased lifespans.[11] Three large, placebo-controlled trials of only oral (not intravenous absorbic acid, as with Paulings' study) vitamin C in 1979, 1983 and 1985[12][13][14] did not find a positive effect of vitamin C in cancer patients and a re-analysis of Pauling and Cameron's initial data found that the comparison groups were not adequately controlled or randomized, with the vitamin C group being less sick than controls when entering the study.[15][16] More recent Phase I clinical trial studies, which were limited in scope to a "dose-finding phase," have confirmed that while vitamin C is not necessarily toxic to cancer patients,[17] it is not useful as a treatment for cancer in humans when doses do not exceed 1.5 grams ascorbic acid/kg body weight.[18] In vitro tests on cell lines indicate that dehydroascorbic acid (DHA), an oxidized form of ascorbic acid may interfere with the effectiveness of chemotherapy.[19] A systematic review of the use of vitamin C and other antioxidants as part of a chemotherapeutic regimen found no significant difference between groups.[20] A 2010 review of 33 years of research on vitamin C to treat cancer stated "we have to conclude that we still do not know whether Vitamin C has any clinically significant antitumor activity. Nor do we know which histological types of cancers, if any, are susceptible to this agent. Finally, we don't know what the recommended dose of Vitamin C is, if there is indeed such a dose, that can produce an anti-tumor response."[21]
QuackWatch.com is also very useful resource when figuring out whether a promoted health remedy has value or not.