Although conference proceedings are not indexed in MEDLINE and a number of other major databases, they are indexed in the BIOSIS databases (http://www.biosis.org/). Over one-half of trials reported in conference abstracts never reach full publication, and those that are eventually published in full have been shown to be systematically different from those that are never published in full (Scherer 2007). It is, therefore, important to try to identify possibly relevant studies reported in conference abstracts through specialist database sources and by handsearching or electronically searching those abstracts that are made available in print form, on CD-ROM or on the internet. Many conference proceedings are published as journal supplements. Specialist conference abstract sources are listed in Box 6.2.f.
Many conference abstracts are published free of charge on the internet, such as those of the American Society of Clinical Oncology (ASCO):