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:Overall, combined with the known QOL benefits of physical activity for other cancer survivor populations (7-9), the current study results suggest that interventions that successfully promote lung cancer survivors’ engagement in physical activity may increase their QOL in several domains.
Category: