Who is included in the study?

375,744 men and women who were assessed for eligibility for the UKFSST trial included:

• were registered at a participating GP practice between November 1994 and March 1999; and
• were aged 55–64 years between November 1994 and March 1999

Of these, 170,432 people indicated in the study questionnaire or letter sent between September 1994 and March 1999 that they would take up the offer of screening if invited; and were assessed as being eligible for the study; and were randomised. 40,674 of these 170,432 people were screened.

The remaining 205,312 men and women included those who were sent a study questionnaire or letter between September 1994 and March 1999 asking whether they would take up the offer of screening if invited and

• indicated that they would take up the offer of screening if invited and were eligible for the study but were not randomised as 40,000 people had already been screened (funding was given to screen 40,000 people); or
• indicated that they would take up the offer of screening if invited, but were subsequently assessed as not eligible for the study; or
• did not respond to the study questionnaire or letter; or
• responded to the study questionnaire or letter that they would not take up the offer of screening if invited.