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Table 3. Estimated Benefits and Harms of Mammography Screening for 10,000 Women Who Undergo Annual Screening Mammography Over a 10-Year Perioda

Age, y No. of Breast Cancer Deaths Averted With Mammography Screening Over Next 15 yb No. (95% CI) With ≥1 False-Positive Result During the 10 yc No. (95% CI) With ≥1 False Positive Resulting in a Biopsy During the 10 yc No. of Breast Cancers or DCIS Diagnosed During the 10 y That Would Never Become Clinically Important (Overdiagnosis)d 
401–166,130 (5,940–6,310)700 (610–780)?–104e
503–326,130 (5,800–6,470)940 (740–1,150)30–137
605–494,970 (4,780–5,150)980 (840–1,130)64–194

No. = number; CI = confidence interval; DCIS = ductal carcinoma in situ.
aAdapted from Pace and Keating.[1]
bNumber of deaths averted are from Welch and Passow.[2] The lower bound represents breast cancer mortality reduction if the breast cancer mortality relative risk were 0.95 (based on minimal benefit from the Canadian trials [3,4]), and the upper bound represents the breast cancer mortality reduction if the relative risk were 0.64 (based on the Swedish 2-County Trial [5]).
cFalse-positive and biopsy estimates and 95% confidence intervals are 10-year cumulative risks reported in Hubbard et al. [6] and Braithwaite et al.[7]
dOverdiagnosed cases are calculated by Welch and Passow.[2] The lower bound represents overdiagnosis based on results from the Malmö trial,[8] whereas the upper bound represents the estimate from Bleyer and Welch.[9]
eThe lower-bound estimate for overdiagnosis reported by Welch and Passow [2] came from the Malmö study.[8] The study did not enroll women younger than 50 years.


  1. Pace LE, Keating NL: A systematic assessment of benefits and risks to guide breast cancer screening decisions. JAMA 311 (13): 1327-35, 2014.  [PUBMED Abstract]

  2. Welch HG, Passow HJ: Quantifying the benefits and harms of screening mammography. JAMA Intern Med 174 (3): 448-54, 2014.  [PUBMED Abstract]

  3. Miller AB, To T, Baines CJ, et al.: The Canadian National Breast Screening Study-1: breast cancer mortality after 11 to 16 years of follow-up. A randomized screening trial of mammography in women age 40 to 49 years. Ann Intern Med 137 (5 Part 1): 305-12, 2002.  [PUBMED Abstract]

  4. Miller AB, To T, Baines CJ, et al.: Canadian National Breast Screening Study-2: 13-year results of a randomized trial in women aged 50-59 years. J Natl Cancer Inst 92 (18): 1490-9, 2000.  [PUBMED Abstract]

  5. Tabár L, Vitak B, Chen TH, et al.: Swedish two-county trial: impact of mammographic screening on breast cancer mortality during 3 decades. Radiology 260 (3): 658-63, 2011.  [PUBMED Abstract]

  6. Hubbard RA, Kerlikowske K, Flowers CI, et al.: Cumulative probability of false-positive recall or biopsy recommendation after 10 years of screening mammography: a cohort study. Ann Intern Med 155 (8): 481-92, 2011.  [PUBMED Abstract]

  7. Braithwaite D, Zhu W, Hubbard RA, et al.: Screening outcomes in older US women undergoing multiple mammograms in community practice: does interval, age, or comorbidity score affect tumor characteristics or false positive rates? J Natl Cancer Inst 105 (5): 334-41, 2013.  [PUBMED Abstract]

  8. Zackrisson S, Andersson I, Janzon L, et al.: Rate of over-diagnosis of breast cancer 15 years after end of Malmö mammographic screening trial: follow-up study. BMJ 332 (7543): 689-92, 2006.  [PUBMED Abstract]

  9. Bleyer A, Welch HG: Effect of three decades of screening mammography on breast-cancer incidence. N Engl J Med 367 (21): 1998-2005, 2012.  [PUBMED Abstract]