An evaluation of breast cancer screening in the South Thames (West) Region of the UKNHS Breast Screening Programme: the first 10 years

We have determined the progress of breast canter screening in the South Thames (West) region of the UK National Health Service Breast Screening Programme (NHSBSP) from the start of screening in 1987 to 31 March 1997, by evaluating uptake, cancer detection rates, and interval cancer rates. Regional performance measures have been compared with NHSBSP targets. Uptake rates have been consistently close to the target of 70%, although marginally lower than the national average. Between 1 April 1990 and 31 March 1997 the region detected 1161 invasive cancers at prevalent (brst) screen compared with a calculated age standardized expected number of 1164.2, a Standardised Detection Ratio (SDR) of 1.00 (95% CI 0.94-1.06). During the same period, for incident (subsequent) screens, the region detected 640 invasive cancers compared with an expected 602.6, an SDR of 1.06 (95% CI 0.98-1.15). The target SDR for both prevalent and incident screen is 1. The interval cancer rates over the period I April 1990 to 31 March 1994 for 0-23 months after a negative screen were 1.23 per 1000 (95% CI 1.06-1.42) compared with a current national target of 1.20 per 1000. The evidence presented suggests that NHSBSP targets for both invasive cancer detection and interval cancer rates can be achieved.