The added value of mammography in different age-groups of women with and without BRCA mutation screened with breast MRI

Table 4 Number of screens needed (NSN) for one additional mammography-only detected cancer

	Age group (years)	Number of breast cancers	Number of screens	Breast cancers detected by mammography only	NSN for mammography to detect breast cancer missed by MRI
Overall	< 40 years	26	1829	1	1829
	40–50 years	32	2050	2	1025
	50–60 years	45	1833	8	229
	≥ 60 years	22	841	2	421
BRCA	< 40 years	17	1113	0	N/A
	40–50 years	14	737	0	N/A
	50–60 years	26	568	3	189
	≥ 60 years	4	190	0	N/A
No BRCA	< 40 years	9	716	1	716
	40–50 years	18	1313	2	657
	50–60 years	19	1265	5	253
	≥ 60 years	18	651	2	326
Follow up	< 40 years	17	1112	1	1112
	40–50 years	20	1447	2	724
	50–60 years	28	1342	8	168
	≥ 60 years	11	626	2	313
BRCA	< 40 years	12	725	0	N/A
	40–50 years	9	554	0	N/A
	50–60 years	18	433	3	144
	≥ 60 years	0	152	0	N/A
No BRCA	< 40 years	5	387	1	387
	40–50 years	11	893	2	447
	50–60 years	10	909	5	182
	≥ 60 years	11	474	2	237

MRI magnetic resonance imaging, N/A not applicable, the first round was not shown in the table as no mammography-only cancers were detected in the first round