Overdiagnosis and overtreatment of breast cancer: Overdiagnosis in randomised controlled trials of breast cancer screening

Table 1 Randomised controlled trials of mammographic screening

Study	Age range at entry (years)	Screening interval (months)	Number of views	Uptake rate (%) (prevalent screen)	Relative risk of breast cancer mortality	Follow-up (years)
HIP	40–64	12	2	67	0.78	18
Two County	40–74	24–33	1	89	0.70	11
Malmö I	45–70	18–24	2	74	0.81	19
Malmö II	43–49	18–24	2	75–80	0.65	9
Stockholm	40–64	28	1	81	0.90	15
Goteborg	39–59	18	2	84	0.78	13
NBSS I^a	40–49	12	2	100	1.06	13
NBSS II^b	50–59	12	2	100	1.02	13
Edinburgh	45–64	12^c	2	61	0.78	13

^aComparison of annual mammography, clinical breast examination (CBE) and breast self-examination (BSE) instruction with a single CBE and BSE instruction. ^bComparison of annual mammography with annual CBE. ^cMammography and CBE every 24 months; CBE only in intervening years. HIP, Health Insurance Plan; NBSS, National Breast Screening Study.

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