Table 5. Results of Mammography Trials Among Women Younger Than 50

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Studies of Mammography Alone

Study (reference)	Ages	Median followup (years)	Number of breast cancer deaths/ total number of women (Screened)	Number of breast cancer deaths/ total number of women (Control)	Breast cancer death rate per 1,000 women (Screened)	Breast cancer death rate per 1,000 women (Control)	Relative risk for breast cancer death (95% Confidence Interval)	Absolute risk reduction per 1,000 women	Number needed to invite^a	Followup year controls screened
Stockholm²³	40-49	14.3	34/14,842	13/7,103	2.29	1.83	1.52 (0.8-2.88)	No reduction	-	5
Gothenburg²³	39-49	12.7	22/11,724	46/14,217	1.88	3.24	0.58 (0.35-0.96)	1.36	736	7
Malmö²³	45-50	13.3	53/13,568	66/12,279	3.91	5.38	0.73 (0.51-1.04)	1.47	681	4
Swedish Two-County Trial¹⁶	40-49	13	45/19,844	39/15,604	2.27	2.50	0.87 (0.54-1.41)	0.23	4316	7-8

Studies of Mammography Plus CBE

Study (reference)	Ages	Median followup (years)	Number of breast cancer deaths/ total number of women (Screened)	Number of breast cancer deaths/ total number of women (Control)	Breast cancer death rate per 1,000 women (Screened)	Breast cancer death rate per 1,000 women (Control)	Relative risk for breast cancer death (95% Confidence Interval)	Absolute risk reduction per 1,000 women	Number needed to invite^a	Followup year controls screened
CNBSS-1²²	40-49	13	105/25,214	108/25,216	4.16	4.28	0.97 (0.74-1.27)	0.12	-	-
HIP^19,27	40-49	14	64/13,740	82/13,740	4.66	5.97	0.78 (0.56-1.08)	1.31	763	-
Edinburgh¹⁸	45-49	13	49/11,749	53/10,267	4.17	5.16	0.75 (0.48-1.18)	0.99	1008	6-10

^aNumber needed to invite for screening to prevent one breast cancer death after 11-16 years.

Note: CBE indicates clinical breast examination; CNBSS, Canadian National Breast Screening Study; HIP, Health Insurance Plan of Greater New York.