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

BMC Cancer

Table 2 Screened women, screen detected cancers, interval cancers and background annual incidence by screening location in primarily subsequent 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	1993-‘95	50-69	26,063	163	53	18	62.5	20.5	25.4	0.40	0.25 (0.19-0.31)
Njor et al. [6]	Funen, Denmark	1996-‘97	50-69	43,543	227	105	19	52.1	24.2	26.0	0.47	0.32 (0.27-0.37)
Törnberg et al.[7]	Stockholm, Sweden	1989-‘97	50-69	270,260	1,075	584	0	39.8	21.7	23.7	0.46	0.35 (0.33-0.37)
Hofvind et al.[4]	NBCSP, Norway	1998-‘05	50-69	336,323^a	1,648	610	0	49.0	18.2	18.2	0.51	0.27 (0.25-0.29)
Törnberg et al.[7]	Pirkanmaa, Finland	1988-‘97	50-69	75,927	235	121	42	31.0	16.0	13.1^b	0.61	0.34 (0.29-0.39)
Törnberg et al.[7]	Marseille, France	1993-‘98	50-69	36,140	171	65	0	47.3	18.1	20.1	0.45	0.28 (0.22-0.34)
Törnberg et al.[7]	Strasbourg, France	1989-‘97	50-65	104,951	390	230	0	37.2	22.0	22.6	0.49	0.37 (0.33-0.41)
Törnberg et al.[7]	Florence, Italy	1990-‘94	50-69	13,394	54	28	0	40.3	21.0	22.2	0.47	0.34 (0.24-0.44)
Törnberg et al.[7]	Turin, Italy	1992-‘96	50-69^c	13,117	82	25	0	62.5	19.2	20.2^d	0.47	0.23 (0.15-0.31)
Törnberg et al.[7]	Navarra, Spain	1990-‘96	45-65	85,653	268	77	0	31.3	9.0	16.2	0.28	0.22 (0.18-0.26)

^aOnly 336,323 prevalent screens from a total of 467,343 women had 2 years of follow-up.
^bbased on the ages 50-59 years.
^cAlthough 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. and all women invited for the first time in their 50s received their subsequent invitations even after they turned 60.
^dBased on the ages 50-64.

ISSN: 1471-2407