The following is from http://www4.dr-rath-foundation.org/Newsletter/archive/newsletter_2008_09_sep_23.html
Concern Raised about 'Cancer Publication Bias'
Less than 20 percent of registered clinical trials of cancer treatment are eventually published in medical journals, according to a study published online by the journal "The Oncologist."
Read article at marketwatch.com
Comment: The publication rate was particularly low for "industry-sponsored" studies, such as those funded by pharmaceutical companies -- just 5.9 percent, compared to 59 percent for studies sponsored by collaborative research networks. The researchers suspect that the rate of negative results is much higher in the studies that have gone unpublished.