Yes, if you believe the result of a recent review, published in the Annals of Oncology recently. The authors surveyed a large number of clinical trial reports and found out that researchers tended to downplay the seriousness of side effects, even omitting any mention of them in some instances. Investigators also tended to exaggerate secondary findings, which were not part of the study design and could be traced to chance.

http://well.blogs.nytimes.com/2013/01/14/clinical-trials-flawed-by-biased-reporting/