A simple way to measure the burden of interval cancers in breast cancer screening

BMC Cancer

Table 1 Screened women, screen detected cancers, interval cancers and background annual incidence by screening location in primarily initial screening rounds

Reference	Screening program location	Year (of invitation)	Age	Screened women	Screen-detected cases	Interval cancers	Pct. of initial screens	[Screen-detected per 10.000]	[Interval cancers per 10.000]	Background annual incidence rate per 10.000	$[\frac{Total I C rate}{background rate}]$	$[\frac{Interval cancers}{total cancers}] ((, 95 % C I))$
Mammography screening evaluation group [5]	Copenhagen, Denmark	1991-‘93	50-69	30,362	360	52	100	118.6	17.3	25.4	0.34	0.13 (0.10-0.16)
Njor et al. [6]	Funen, Denmark	1993-‘95	50-69	41,480	398	87	100	95.9	21.2	24.2	0.43	0.18 (0.15-0.21)
Törnberg et al. [7]	Stockholm, Sweden	1989-‘97	50-69	188,032	1,108	382	100	58.9	20.4	25.8	0.40	0.26 (0.24-0.28)
Törnberg et al. [7]	Four counties, Norway	1996-‘97	50-69	126,779	852	207	100	67.2	16.4	20.0	0.41	0.20 (0.18-0.22)
Hofvind et al. [4]	NBCSP, Norway	1996-‘05	50-69	367,428^a	2,351	669	100	64.0	18.3	18.0	0.51	0.22 (0.21-0.23)
Törnberg et al. [7]	Marseille, France	1993-‘98	50-69	103,946	483	179	100	46.5	17.3	20.1	0.43	0.27 (0.24-0.30)
Törnberg et al. [7]	Strasbourg, France	1989-‘97	50-65	63,235	328	129	100	51.9	20.5	22.6	0.45	0.28 (0.24-0.32)
Törnberg et al. [7]	Florence, Italy	1990-‘94	50-69	35,754	325	47	100	90.9	13.3	22.2	0.30	0.13 (0.10-0.16)
Törnberg et al. [7]	Turin, Italy	1992-‘96	50-69^b	28,804	248	40	100	86.1	14.0	20.2^c	0.35	0.14 (0.10-0.18)
Vettorazzi et al. [8]	Veneto Region, Italy	1999-‘02	50-69	94,874^d	683	154	73	72.0	16.3	27.8	0.29	0.18 (0.15-0.21)
Törnberg et al. [7]	Navarra, Spain	1990-‘96	45-65	40,665	256	29	100	63.0	7.2	16.2	0.22	0.10 (0.07-0.13)

^aOnly 367,428 prevalent screens from a total of 467,343 women had 2 years of follow-up.
^bAlthough the age group targeted in Turin is 50-69 years, during the period of the study, invitations were restricted to women aged 50-59. A few women had the test shortly after they turned 60.
^cBased on the ages 50-64.
^dWomen-Years at risk. Follow-up was not complete in the second year of the interval resulting in only 77,979 women-years.

ISSN: 1471-2407