. Author manuscript; available in PMC: 2013 Aug 23.

Published in final edited form as: Breast Cancer Res Treat. 2012 Jul 26;135(1):291–299. doi: 10.1007/s10549-012-2162-x

Table 1.

Stage-specific incidence rate, tumor size, lymph node involvements, and distant metastasis of breast tumors diagnosed in invited participants and invited non-participants in the Norwegian Breast Cancer Screening Program 1996–2007

All tumors	1,925,725 biennial invitations sent to 640,347 women between 1996 and 2007
	All invitations n = 1,925,725		Invited participants n = 1,475,978		Invited non-participants n = 449,747		Rate ratio
	N	Rate per 100,000 invitations	N	Rate per 100,000 invitations	N	Rate per 100,000 invitations	Participants/non- participants
Stage
0 (DCIS)	1,670	86.7	1,517	102.8	153	34.0^a	3.0
I	5,885	305.5	5,105	345.9	780	173.4^a	2.0
II	3,552	184.4	2,845	192.8	707	157.2^a	1.2
III	173	9.0	108	7.3	65	14.5^a	0.5
IV	272	14.1	134	9.1	138	30.7^a	0.3
Missing/not available	17	0.9	17	1.1	–	–	–
All	11,569	600.6	9,726	659.0	1,843	409.8^a	1.6

Invasive tumors	n = 9,899		n = 8,209		n = 1,690

Tumor size
≤20 mm	6,364	330.5	5,573	377.6	791	175.9^a	2.1
>20 and ≤50 mm	1,854	96.3	1,431	97.0	423	94.1	1.0
>50 mm	334	17.4	198	13.4	136	30.2^a	0.7
Missing/ not available	1,347	69.9	1,007	68.2	340	75.6	–
Lymph node involvements
No	6,158	319.8	5,331	362.2	827	183.9^a	2.0
Yes	3,013	156.5	2,376	161.0	637	141.6^a	1.1
Missing/not available	728	37.8	502	34.0	226	50.3	–
Distant metastasis
No	7,465	387.6	6,370	431.6	1,095	243.2^a	1.8
Yes	267	13.9	132	8.9	135	30.0^a	0.3
Missing/ not available	2,167	112.5	1,707	115.7	460	102.3	–

p value <0.05 for Chi-squared between the groups “Invited Participants” and “Invited Non-participants”