1. Comparison on proportions of early-stage breast cancer between cancer cohorts with and without mammographic screening.

Age (year)	1973−1976 cancer cohort (no screening)				1999 cancer cohort (screening)			Excessive proportion of early-stage cancer (%)	P
	Number of cancers	Number of early-stage cancers	Proportion of early-stage cancers (%)		Number of cancers	Number of early-stage cancers	Proportion of early-stage cancers (%)
40−49	6,401	3,493	54.6		4,201	2,853	67.9	13.3	<0.001
50−59	9,018	4,561	50.6		5,618	3,957	70.4	19.9	<0.001
60−69	8,055	4,041	50.2		4,801	3,529	73.5	23.3	<0.001
70−74	3,261	1,709	52.4		2,575	1,990	77.3	24.9	<0.001
≥75	5,708	3,087	54.1		4,830	3,692	76.4	22.4	<0.001
Total	32,443	16,891	52.1		22,025	16,021	72.7	20.7	<0.001
50−74 in total	20,334	10,311	50.7		12,994	9,476	72.9	22.2	<0.001