Table 1.

Attributes of combined case-control studies

CambridgeNorwich
Cancers/controls (n)140/140494/1,740
    Screen-detected cancers/controls (n)94/94334/1,161
    Interval cancers/controls (n)46/46160/579
Mean age (y)57.657.4
Age range (y)50-7550-75
Period of selection1995-20031998-2004