Another example of the potential benefits, but also the pitfall of using case reports of
unconventional approaches to justify the initiation of prospective cancer clinical trials is the
PC-SPES story. PC-SPES is a proprietary formulation that was marketed as a dietary
supplement by Botanic Lab (Brea, CA) from 1996 through 2002.63 PC-SPES apparently
came to the attention of cancer researchers through reports of use by prostate cancer
patients.64 Several articles published between 1999 and 2003 described the results of
observational studies and clinical trials conducted before adulteration with warfarin,
indomethacin and diethystilbesterol was identified in several PC-SPES lots.65 These
findings led the National Center for Complementary and Alternative Medicine in 2002 to
place a hold on ongoing studies of PC-SPES and a moratorium on further research with the
compound.66 After several years, two recent reports indicate the reemergence of research
with mixtures of the extracts of the herbs from the PC-SPES formula, hopefully, without the
adulterants.67,6