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 40% of A-T patients develop malignant disease over the course of their lives [1,8,9] and 10–15% of them develop a lymphoid malignancy (leukemia or lymphoma) in childhood or early adulthood [1].
Category: