Search tips
Search criteria 


Logo of cmajCMAJ Information for AuthorsCMAJ Home Page
CMAJ. 1992 November 15; 147(10): 1459–1476.
PMCID: PMC1336543

Canadian National Breast Screening Study: 1. Breast cancer detection and death rates among women aged 40 to 49 years.


OBJECTIVES: To evaluate the efficacy of the combination of annual screening with mammography, physical examination of the breasts and the teaching of breast self-examination in reducing the rate of death from breast cancer among women aged 40 to 49 years on entry. DESIGN: Individually randomized controlled trial. SETTING: Fifteen urban centres in Canada with expertise in the diagnosis and treatment of breast cancer. PARTICIPANTS: Women with no history of breast cancer and no mammography in the previous 12 months were randomly assigned to undergo either annual mammography and physical examination (MP group) or usual care after an initial physical examination (UC group). The 50,430 women enrolled from January 1980 through March 1985 were followed for a mean of 8.5 years. DATA COLLECTION: Derived from the participants by initial and annual self-administered questionnaires, from the screening examinations, from the patients' physicians, from the provincial cancer registries and by record linkage to the Canadian National Mortality Data Base. Expert panels evaluated histologic and death data. MAIN OUTCOME MEASURES: Rates of referral from screening, rates of detection of breast cancer from screening and from community care, nodal status, tumour size, and rates of death from all causes and from breast cancer. RESULTS: Over 90% of the women in each group attended the screening sessions or returned the annual questionnaires, or both, over years 2 to 5. The characteristics of the women in the two groups were similar. Compared with the Canadian population, the participants were more likely to be married, have fewer children, have more education, be in a professional occupation, smoke less and have been born in North America. The rate of screen-detected breast cancer on first examination was 3.89 per 1000 in the MP group and 2.46 per 1000 in the UC group; more node-positive tumours were found in the MP group than in the UC group. During years 2 through 5 the ratios of observed to expected cases of invasive breast cancer were 1.26 in the MP group and 1.02 in the UC group. Of the women with invasive breast cancer through to 7 years, 191 and 157 women in the MP and UC groups respectively had no node involvement, 55 and 43 had one to three nodes involved, 47 and 23 had four or more nodes involved, and 38 and 49 had an unknown nodal status. There were 38 deaths from breast cancer in the MP group and 28 in the UC group. The ratio of the proportions of death from breast cancer in the MP group compared with those in the UC group was 1.36 (95% confidence interval 0.84 to 2.21). The survival rates were similar in the two groups. The highest survival rate occurred among women whose cancer had been detected by mammography alone. CONCLUSION: The study was internally valid, and there was no evidence of randomization bias. Screening with yearly mammography and physical examination of the breasts detected considerably more node-negative, small tumours than usual care, but it had no impact on the rate of death from breast cancer up to 7 years' follow-up from entry.

Full text

Full text is available as a scanned copy of the original print version. Get a printable copy (PDF file) of the complete article (3.0M), or click on a page image below to browse page by page. Links to PubMed are also available for Selected References.

Selected References

These references are in PubMed. This may not be the complete list of references from this article.
  • Miller AB, Howe GR, Wall C. The National Study of Breast Cancer Screening Protocol for a Canadian Randomized Controlled trial of screening for breast cancer in women. Clin Invest Med. 1981;4(3-4):227–258. [PubMed]
  • Léger JL, Naimark AP, Béique RA, McFarlane DV, Miller S, Miller AB. Report of the "ad hoc" committee on mammography rapport du comite "ad hoc" sur la mammographie. J Can Assoc Radiol. 1974 Mar;25(1):3–21. [PubMed]
  • Miller AB. Is routine mammography screening appropriate for women 40-49 years of age? Am J Prev Med. 1991 Jan-Feb;7(1):55–62. [PubMed]
  • Chu KC, Smart CR, Tarone RE. Analysis of breast cancer mortality and stage distribution by age for the Health Insurance Plan clinical trial. J Natl Cancer Inst. 1988 Sep 21;80(14):1125–1132. [PubMed]
  • Miller AB, Chamberlain J, Day NE, Hakama M, Prorok PC. Report on a Workshop of the UICC Project on Evaluation of Screening for Cancer. Int J Cancer. 1990 Nov 15;46(5):761–769. [PubMed]
  • Tabàr L, Fagerberg G, Duffy SW, Day NE, Gad A, Gröntoft O. Update of the Swedish two-county program of mammographic screening for breast cancer. Radiol Clin North Am. 1992 Jan;30(1):187–210. [PubMed]
  • Baines CJ. Impediments to recruitment in the Canadian National Breast Screening Study: response and resolution. Control Clin Trials. 1984 Jun;5(2):129–140. [PubMed]
  • Baines CJ, To T. Changes in breast self-examination behavior achieved by 89,835 participants in the Canadian National Breast Screening Study. Cancer. 1990 Aug 1;66(3):570–576. [PubMed]
  • Baines CJ, Miller AB, Wall C, McFarlane DV, Simor IS, Jong R, Shapiro BJ, Audet L, Petitclerc M, Ouimet-Oliva D, et al. Sensitivity and specificity of first screen mammography in the Canadian National Breast Screening Study: a preliminary report from five centers. Radiology. 1986 Aug;160(2):295–298. [PubMed]
  • Baines CJ, McFarlane DV, Miller AB. Sensitivity and specificity of first screen mammography in 15 NBSS centres. Can Assoc Radiol J. 1988 Dec;39(4):273–276. [PubMed]
  • Baines CJ, McFarlane DV, Wall C. Audit procedures in the National Breast Screening Study: mammography interpretation. Can Assoc Radiol J. 1986 Dec;37(4):256–260. [PubMed]
  • Baines CJ, McFarlane DV, Miller AB. The role of the reference radiologist. Estimates of inter-observer agreement and potential delay in cancer detection in the national breast screening study. Invest Radiol. 1990 Sep;25(9):971–976. [PubMed]
  • Miller AB, Baines CJ, Turnbull C. The role of the nurse-examiner in the National Breast Screening Study. Can J Public Health. 1991 May-Jun;82(3):162–167. [PubMed]
  • Baines CJ, Miller AB, Kopans DB, Moskowitz M, Sanders DE, Sickles EA, To T, Wall C. Canadian National Breast Screening Study: assessment of technical quality by external review. AJR Am J Roentgenol. 1990 Oct;155(4):743–749. [PubMed]
  • Baines CJ, Christen A, Simard A, Wall C, Dean D, Duncan L, Edward P, Fryer ML, Grégoire LB, May C, et al. The National Breast Screening Study: pre-recruitment sources of awareness in participants. Can J Public Health. 1989 May-Jun;80(3):221–225. [PubMed]
  • Morrison AS, Brisson J, Khalid N. Breast cancer incidence and mortality in the breast cancer detection demonstration project [published errtum appears in J Natl Cancer Inst 1989 Oct 4;81(19):1513]. J Natl Cancer Inst. 1988 Dec 7;80(19):1540–1547. [PubMed]
  • CUTLER SJ, EDERER F. Maximum utilization of the life table method in analyzing survival. J Chronic Dis. 1958 Dec;8(6):699–712. [PubMed]
  • Peto R, Pike MC, Armitage P, Breslow NE, Cox DR, Howard SV, Mantel N, McPherson K, Peto J, Smith PG. Design and analysis of randomized clinical trials requiring prolonged observation of each patient. II. analysis and examples. Br J Cancer. 1977 Jan;35(1):1–39. [PubMed]
  • Schechter MT, Miller AB, Baines CJ, Howe GR. Selection of women at high risk of breast cancer for initial screening. J Chronic Dis. 1986;39(4):253–260. [PubMed]
  • Simard A, Paquette L, Baillargeon J, Falardeau M. Perception of cancer detection and early treatment in a population participating in the National Breast Screening Study in Canada. Can J Public Health. 1989 May-Jun;80(3):226–227. [PubMed]
  • Day NE, Baines CJ, Chamberlain J, Hakama M, Miller AB, Prorok P. UICC project on screening for cancer: report of the workshop on screening for breast cancer. Meeting held in Helsinki, Finland, on April 7-9, 1986. Int J Cancer. 1986 Sep 15;38(3):303–308. [PubMed]
  • Howe GR, Friedenreich CM, Jain M, Miller AB. A cohort study of fat intake and risk of breast cancer. J Natl Cancer Inst. 1991 Mar 6;83(5):336–340. [PubMed]
  • Brisson J, Verreault R, Morrison AS, Tennina S, Meyer F. Diet, mammographic features of breast tissue, and breast cancer risk. Am J Epidemiol. 1989 Jul;130(1):14–24. [PubMed]
  • Shapiro S, Strax P, Venet L, Fink R. The search for risk factors in breast cancer. Am J Public Health Nations Health. 1968 May;58(5):820–835. [PubMed]
  • Baker LH. Breast Cancer Detection Demonstration Project: five-year summary report. CA Cancer J Clin. 1982 Jul-Aug;32(4):194–225. [PubMed]
  • Miller AB, Baines CJ, Sickles EA. Canadian National Breast Screening Study. AJR Am J Roentgenol. 1990 Nov;155(5):1133–1134. [PubMed]
  • Tabár L, Akerlund E, Gad A. Five-year experience with single-view mammography randomized controlled screening in Sweden. Recent Results Cancer Res. 1984;90:105–113. [PubMed]
  • Tabár L, Faberberg G, Day NE, Holmberg L. What is the optimum interval between mammographic screening examinations? An analysis based on the latest results of the Swedish two-county breast cancer screening trial. Br J Cancer. 1987 May;55(5):547–551. [PubMed]
  • Verbeek AL, Hendriks JH, Holland R, Mravunac M, Sturmans F. Mammographic screening and breast cancer mortality: age-specific effects in Nijmegen Project, 1975-82. Lancet. 1985 Apr 13;1(8433):865–866. [PubMed]
  • Andersson I, Aspegren K, Janzon L, Landberg T, Lindholm K, Linell F, Ljungberg O, Ranstam J, Sigfússon B. Mammographic screening and mortality from breast cancer: the Malmö mammographic screening trial. BMJ. 1988 Oct 15;297(6654):943–948. [PMC free article] [PubMed]
  • Tabár L, Fagerberg CJ, Gad A, Baldetorp L, Holmberg LH, Gröntoft O, Ljungquist U, Lundström B, Månson JC, Eklund G, et al. Reduction in mortality from breast cancer after mass screening with mammography. Randomised trial from the Breast Cancer Screening Working Group of the Swedish National Board of Health and Welfare. Lancet. 1985 Apr 13;1(8433):829–832. [PubMed]
  • Frisell J, Eklund G, Hellström L, Lidbrink E, Rutqvist LE, Somell A. Randomized study of mammography screening--preliminary report on mortality in the Stockholm trial. Breast Cancer Res Treat. 1991 Mar;18(1):49–56. [PubMed]
  • Palli D, Del Turco MR, Buiatti E, Carli S, Ciatto S, Toscani L, Maltoni G. A case-control study of the efficacy of a non-randomized breast cancer screening program in Florence (Italy). Int J Cancer. 1986 Oct 15;38(4):501–504. [PubMed]
  • Roberts MM, Alexander FE, Anderson TJ, Chetty U, Donnan PT, Forrest P, Hepburn W, Huggins A, Kirkpatrick AE, Lamb J, et al. Edinburgh trial of screening for breast cancer: mortality at seven years. Lancet. 1990 Feb 3;335(8684):241–246. [PubMed]

Articles from CMAJ : Canadian Medical Association Journal are provided here courtesy of Canadian Medical Association