Age in Years (n) 1991 Size  mm (n) P 1987 Size  mm (n) P 1997/98 Size mm (n)
<50 (96) 19.4±12.6  (80) ns 22.0±13.8  (98) ns 22.8±13.5 (67)
50-59 (102) 19.3±13.6 (96) ns 21.6±11,9  (79) ns 18.5±12,9 (119)
60-69 (142)  17.7±13.8 (130) <0.001 23.5±13,3 (120) p<0.0005 15.4±12.4  (70)
≥70 (169) 21.8±11.5 (108) ns 22.5±13.3  (103) ns 20.4±14.2 (89)
Tumors from a control sample from 1987 and samples from 1991 and 1997/98 are sorted to four age intervals. The two screened age groups are flanked by those younger than 50 years of age and those older than 70 years, neither of which were invited to the screening. The results shows a significant reduction of mean tumor size related to screening only for women aged 60 to 69 years for both 1991 and 1997/98-samples.
Table 2: Tumor size in four age intervals in comparison of two screened cohorts against controls.