Breast Cancer Screening Controversies

Article Figures & Data

Table 1.

Summary of Key Characteristics of Randomized Controlled Trials of Mammography Screening.

Study (year began)	Age (yr)	Screening Provided	Rounds (of Mammography) (No)	Screening Interval (mo)	Views	Compliance Rounds (%)	Crossovers (Controls Who Had Mammography) (%)	Follow-up (yr)	Breast Cancer Mortality^* RR	Absolute Risk Reduction in Breast Cancer Mortality (per 1,000)	Number Needed to Screen 10 yr^†
HIP11 ,12 (1963)	40–64	M + CBE vs UC	4	12	2	1 = 67	Data not available	13	0.83	1.4193	916
N = 61,000	40–64	M + CBE vs UC	4	12	2	2–4 = 54–46	Data not available	13	(0.7–1.0)
Malmo13 (1976)	45–70	M vs UC	9	18–24	1–2	1 = 74	25	11–13	0.81	1.0127	1,185
N = 68,000						2–5 = 70			(0.62–1.07)
Two-Country14 (1977)	40–74	M vs UC	3	24–33	1	1 = 89	13	10	0.68	1.8095	553
N = 126,000						2–3 = 83–84			(0.5–0.93)
Stockholm15 ,16 (1981)	40–64	M vs UC	2	24–28	1	1 = 81	Controls offered screening yr 5	7.4	0.71	0.5369	1,378
N = 60,000						2 = 81			(0.4–1.2)
Gothenburg17 (1982)	39–59	M vs UC	5	18	1–2	1 = 85	20	8	0.86	0.3286	2,435
N = 40,000						2–5 = 77–78			(0.54–1.37)
Edinburgh18 ,19 (1979)	45–64	M + CBE vs UC	4	24	1–2	1 = 66	Data not available	14	0.71	0.945	1,482
N = 45,000						7 = 44			(0.53–0.95)
Canada 120 ,21 (1980)	40–49	M + CBE vs single CBE	4–5	12	2	1 = 100	25	13	0.98	No reduction	Not applicable
N = 50,000						2–4 = 85–89			(0.73–1.31)
Canada 221 ,22 (1980)	50–59	M + CBE vs CBE	4–5	12	2	1 = 100	16	10.5	1.14	No reduction	Not applicable
N = 40,000						2–5 = 87–90			(0.83–1.56)

RR = relative risk, N = number of participants, M = screening mammography, CBE = clinical breast examination, UC = usual care.
* Length of follow-up reported for various times up to 20 years. Data estimates were closest to 10-year point.
† Number needed to screen corrected for 10 years of screening.

Table 2.

Test Performance of Clinical Breast Examinations at Group Health Cooperative from 1992–1994.

Age	Sensitivity^* (%)	Specificity^† (%)	Positive Predictive Value^‡ (%)	Incremental Increase in Case Finding^§ (%)
40–49 yr	37.5	96.5	2.1	8.3
50–64 yr	36.0	97.3	8.8	9.6
65–74 yr	23.6	97.3	9.3	3.7
75+ yr	30.6	97.5	9.9	8.1
All ages combined	30.6	97.1	7.1	7.0

Note: all clinical breast examinations (CBEs) were performed by registered nurses in screening centers. Only invasive breast cancers were analyzed. A total of 42,647 women had CBEs and 297 cases of invasive breast cancer were diagnosed, screened and nonscreened.
* Sensitivity—percent of invasive breast cancers detected by CBE, unrelated to mammography.
† Specificity—percent of women without invasive breast cancer with normal findings on CBE.
‡ Positive predictive value—percent of positive CBEs that were invasive breast cancer.
§ Percent of cases of breast cancer found by CBE alone, eg, mammography negative and CBE.