Table 3.

Estimation of overdiagnosis in women aged 50-74 years in the Netherlands, 2009-11

Parameters	Estimate	Row	Comments
No of breast cancers diagnosed in women aged 50-74 in 2009-11*:
In situ	4422	(1)
Stage 1	12 804	(2)
Stage 2+	10 270	(3)
Not staged	186	(4)
Total	27 682	(5)
No of screen detected breast cancers†	16 965	(6)
% of screen detected breast cancers	61	(7)	(6)/(5)
Estimation of overdiagnosed in situ and stage 1 breast cancers:
No of extra cancers, considering 57% extra cancers	9819	(8)	((1)+(2))×0.57 (extra cancer proportion of 57% from supplementary table S2)
No of screen detected breast cancers representing clinical lead time	960	(9)	612 breast cancer deaths avoided because of screening (from row 10 of table 2 multiplied by 3/2)
No of overdiagnosed breast cancers	8859	(10)	(8)−(9)
Breast cancers overdiagnosed among women invited to screening (%)	32	(11)	(10)/(5)
Breast cancers overdiagnosed among women with screen detected breast cancer (%)	52	(12)	(10)/(6)
Overdiagnosed in situ and stage 1 cancer among women invited to screening (%)	51	(13)	(10)/((1)+(2))

^*Source: Integraal Kankercentrum Nederland.

^†Source: Dutch National Evaluation Team, 2014.