Evaluate the collective function of references cited together in a given text segment.
Classify their combined role into one of the following categories: 'method', 'background', or 'result'.

Text:Despite a study performed by Cancer and Leukemia Group B (CALGB) did not demonstrate superior activities by higher doses of CrEL-based paclitaxel [18], data from several other phase II studies in MBC suggest a dose-response relationship.
Category: