Seventeen-years overview of breast cancer inside and outside screening in Denmark

Figures & data

Table I. Number of target population, eligible population, invited women and participants by invitation round in Copenhagen and Fyn screening programs, Denmark.

Dates for invitation round		Length of invitation round (years)	Target population	Eligible population	Eligible/target population (%)	Invited women	Invited/eligible (%)	Participant women	Participants/ invited (%)	Participants/ target (%)
Copenhagen screening program
Invitation rounds
1	4 April 1991–23 April 1993	2.05	45 151	43 092	95.44	43 092	100	30 388	70.52	67.30
2	26 April 1993–30 May 1995	2.01	42 069	41 159	97.84	38 766	94.19	26 109	67.35	62.06
3	1 June 1995–24 March 1997	1.82	41 121	40 037	97.36	36 653	91.55	25 153	68.62	61.17
4	25 March 1997–19 April 1999	2.07	41 686	40 304	96.68	36 864	91.46	25 427	68.98	61.00
5	20 April 1999–31 March 2001	1.95	42 340	40 865	96.52	37 502	91.77	25 059	66.82	59.19
6	1 April 2001–31 May 2003	2.17	43 420	41 815	96.30	33 677	80.54	25 271	75.04	58.20
7	1 June 2003–31 December 2005	2.58	45 051	42 330	93.96	35 340	83.49	26 205	74.15	58.17
8	1 January 2006–14 April 2008	2.28	52 710	50 798	96.37	41 576	81.85	30 476	73.30	57.82
Fyn screening program
Invitation rounds
1	1 November 1993–31 December 1995	2.16	56 112	49 111	87.52	49 111	100	41 519	84.54	73.99
2	1 January 1996–31 December 1997	2.00	58 009	52 870	91.14	48 057	90.90	44 117	91.80	76.05
3	1 January 1998–31 December 1999	2.00	59 697	54 577	91.42	48 712	89.25	44 892	92.16	75.20
4	1 January 2000–31 December 2001	2.00	61 247	55 968	91.38	48 839	87.26	45 817	93.81	74.81
5	1 January 2002–31 December 2003	2.00	63 049	57 685	91.49	50 134	86.91	47 458	94.66	75.27
6	1 January 2004–31 December 2005	2.00	65 212	60 233	92.36	53 485	88.80	48 831	91.30	74.88

Table II Number of breast cancers (invasive and carcinoma in situ) detected at screening in participants, diagnosed as interval cancers in participants or diagnosed in non-screened women. Proportion per 1000 women, and rate per 1000 person years. Copenhagen and Fyn screening programs, Denmark.

	Screened women								Non-screened women
	Participants	Screen-detected cancers, of which (CIS)	per 1000	per 1000 py (1)	Interval cancers, of which (CIS)	per 1000	per 1000 py (2)	False positive rate, %	Non- screened women	Diagnosed cancers, of which (CIS)	per 1000	per 1000 py (3)	Total per 1000 py (4)
Copenhagen screening program
Invitation round
1	30 388	361 (44)	11.88	5.79	58 (2)	1.93	0.97	5.6%	14 763	128 (8)	8.67	4.23	5.91
2	26 109	164 (17)	6.28	3.13	65 (6)	2.51	1.25	4.0%	15 960	62 (0)	3.95	1.96	3.45
3	25 153	156 (18)	6.20	3.41	59 (3)	2.36	1.18	2.5%	15 968	70 (3)	4.38	2.41	3.81
4	25 427	147 (18)	5.78	2.79	73 (1)	2.89	1.44	2.4%	16 260	108 (4)	6.64	3.21	3.80
5	25 059	145 (22)	5.79	2.97	66 (3)	2.65	1.32	1.8%	17 281	94 (6)	5.44	2.79	3.69
6	25 271	180 (42)	7.12	3.28	62 (1)	2.47	1.24	1.5%	18 149	109 (4)	6.01	2.77	3.73
7	26 205	227 (40)	8.66	3.36	83 (2)	3.20	1.60	1.4%	18 846	163 (5)	8.65	3.35	4.07
8	30 476	242 (47)	7.94	3.48	89 (2)	2.94	1.47	1.4%	22 234	162 (5)	7.29	3.20	4.10
Total (Rounds 1–8)	214 088	1622 (248)	7.58	3.57	555 (20)	2.61	1.31	2.6%	139 461	896 (35)	6.43	3.02	4.09
Fyn screening program
Invitation round
1	41 519	401 (59)	9.66	4.47	89 (4)	2.16	1.08	1.7%	14 593	187 (11)	12.81	5.93	5.58
2	44 117	236 (35)	5.35	2.67	124 (6)	2.83	1.41	1.1%	13 892	89 (7)	6.41	3.20	3.87
3	44 892	216 (21)	4.81	2.41	140 (4)	3.13	1.57	1.1%	14 805	90 (8)	6.08	3.04	3.74
4	45 817	273 (35)	5.96	2.98	128 (4)	2.81	1.41	1.0%	15 430	90 (1)	5.83	2.92	4.01
5	47 458	257 (19)	5.42	2.71	112 (3)	2.37	1.19	0.8%	15 591	94 (7)	6.03	3.01	3.67
6	48 831	285 (31)	5.84	2.92	109 (4)	2.25	1.12	0.8%	16 381	101 (5)	6.17	3.08	3.80
Total (Rounds 1–6)	272 634	1668 (200)	6.12	3.02	702 (25)	2.59	1.30	1.1%	90 692	651 (39)	7.18	3.54	4.10
Total	486 722	3290 (448)	6.76	3.27	1257 (45)	2.60	1.30	1.8%	230 153	1548 (74)	6.73	3.22	4.10

CIS: Carcinoma in situ.

(1) Person years at risk to develop a screen-detected cancer were estimated as number of participants multiplied by length of invitation round.

(2) Person years at risk to develop an interval cancer were estimated as number of participants, minus participants with screen-detected cancers, multiplied by 2.

(3) Person years at risk to develop a cancer outside screening were estimated as number of non-screened women multiplied by length of invitation round.

(4) For simplicity, for each invitation round based on the total of screen-detected cancers, interval cancers, and cancers in non-screened women, although part of the interval cancers were diagnosed during the next invitation round.

Figure 1. Incidence rates of breast cancer in target population in Copenhagen (1991–2008) and Fyn (1993–2005). Incidence rates of screen-detected breast cancer and interval cancer in participants, and of breast cancers in non-screened women in Copenhagen and Fyn, Denmark.

Table III. Screen-detected breast cancers and interval cancers. Proportion per 1000 participants by women’s screening round in Copenhagen and in Fyn screening programs, Denmark.

Participants		Screen-detected cancers	%	Interval cancers	%
Copenhagen screening program
Women’s screening round
1st	69 647	646	9.3	150	2.2
2nd	22 597	149	6.6	58	2.6
3rd	41 320	206	5.0	111	2.7
4th	30 466	199	6.5	86	2.8
5th	22 045	165	7.5	58	2.7
6th	15 119	137	9.1	47	3.1
7th	9053	83	9.2	32	3.6
8th	3841	37	9.6	13	3.4
Fyn screening program
Women’s screening round
1st	75 626	599	7.9	182	2.4
2nd	61 955	270	4.4	176	2.9
3rd	50 364	245	4.9	147	2.9
4th	38 735	231	6.0	86	2.2
5th	28 554	188	6.6	77	2.7
6th	17 400	135	7.8	34	2.0

Table IV. Comparison of tumor characteristics between Copenhagen and Fyn regions (Denmark), of screen-detected cancers, interval cancers and cancers detected in non-screened women.

		Screen-detected cancers		Interval cancers		Cancer in non-participants
		Copenhagen n = 1621 (%)	Fyn n = 1667 (%)	Copenhagen n = 555 (%)	Fyn n = 702 (%)	Copenhagen n = 897 (%)	Fyn n = 651 (%)
Tumor type (1)
	In situ	248 (15.3)	200 (12.0)	20 (3.6)	25 (3.6)	35 (3.9)	39 (6.0)
	Invasive	1372 (84.7)	1467 (88.0)	535 (96.4)	677 (96.4)	861 (96.1)	612 (94.0)
	Unknown (2)	1	0	0	0	1	0
Tumor’s morphology (3)
	Ductal	1045 (77.5)	1110 (77.6)	377 (70.5)	519 (76.7)	632 (73.4)	442 (72.2)
	Lobular	186 (13.8)	187 (13.1)	99 (18.5)	72 (10.6)	112 (13.0)	64 (10.5)
	Others	118 (8.8)	134 (9.4)	59 (11.3)	86 (12.7)	117 (13.6)	106 (17.3)
	Unknown (2)	23	36	0	0	0	0
Tumor’s size (3)
	0–10 mm	536 (41.1)	493 (34.6)	103 (21.7)	93 (14.9)	103 (15.1)	66 (13.1)
	11–20 mm	604 (46.3)	659 (46.3)	220 (46.3)	263 (42.1)	263 (38.5)	212 (42.0)
	21–30 mm	121 (9.3)	188 (13.2)	96 (20.2)	174 (27.9)	186 (27.2)	128 (25.4)
	> 30 mm	43 (3.3)	84 (5.9)	56 (11.8)	94 (15.1)	131 (19.2)	99 (19.6)
	Unknown(2)	68	43	60	53	178	107
Lymph node involvement (3)
	Negative	970 (74.3)	966 (68.0)	280 (58.7)	321 (51.4)	332 (48.5)	242 (47.5)
	Positive	335 (25.7)	454 (32.0)	197 (41.3)	303 (48.6)	353 (51.5)	268 (52.6)
	Unknown (2)	67	47	58	53	176	102
ER status (3)
	Negative	169 (13.0)	163 (11.5)	101 (22.4)	152 (24.5)	165 (23.6)	114 (22.9)
	Positive	1131 (87.0)	1251 (88.5)	370 (77.6)	469 (75.5)	535 (76.4)	385 (77.1)
	Unknown (2)	72	53	58	56	161	113

(1) Include in situ and invasive cancers.

(2) Tumors with missing information were excluded for calculation of percentage.

(3) Include only invasive cancers.