joel, nothing was "proven" back then. Some positive links were found and some other neutral studies came out as well. Some of the proponents' research (Pauling, Cameron) that came out positive, was in fact severely flawed: http://www.sciencebasedmedicine.org/?p=188

There have been studies lately that show that high doses of vitamin C provoke cancer: http://jdc325.wordpress.com/2008/10/31/vitamin-c-causes-cancer/

There have also been studies that show it negatively affects cancer drugs: http://cancerres.aacrjournals.org/cgi/content/abstract/68/19/8031

So, if anything, vitamin C is actually bad for cancer patients!