Electronic searches including MEDLINE, PubMed and trial registries and manual searches of references in published studies or abstracts published in proceedings of meetings were used to identify the relevant literature. Search terms included squamous cell carcinomas of head and neck, clinical trial, metastatic or advanced cancers. The articles were selected for inclusion if they met the following criteria: randomized controlled trials (RCTs) with appropriate control groups. Some single arm trials were included if there was no evidence from phase III clinical trials.
We prioritized for randomized trials. To select studies for inclusion in our analysis, we checked for the study status entered in the trial registries, and included only the trials that were completed or currently recruiting studies. For some novel drugs, active, but not recruiting or of other status were also included.
In the case of Cetuximab, because of more than 160 studies were found, we only included completed, and trials with results or published studies.