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:Up to now, several studies [21-26] and one meta-analyses [15] have investigated the relationship of CCND1 rs9344 G>A polymorphism with GC; however, the results were inconclusive and ambiguous.
Category: