Until recently, cancer-related health services and economics research has depended heavily on retrospective data
obtained from administrative databases or surveys conducted at the national level. More detailed, prospective
studies have usually been limited to small studies conducted at single institutions, or from highly selected
convenience samples. To address this problem, NCI has begun to sponsor national research networks, supported
through cooperative agreement grants. The networks listed here provide direct access to prospective and
retrospective information and allow active collaboration between network members and NCI research staff.