For example , mammography screening does not seem to create anxiety in women who are given a clear result after a mammogram .
The incidence of breast cancer and mortality increases with age , and the GDG extrapolated that the absolute health benefits are greater in women aged 45 to 49 than those aged 40 to 44 years .
However , for the 45- to 49-year age group , the higher breast cancer incidence and mortality compared with women between the ages of 40 and 44 , as well as observational evidence showing a greater benefit in this age group ( 33 ) , led the GDG to judge that the balance of health effects probably favors screening , although the required re sources for screening likely differ across setting s ( 34 , 35 ) .
Other EtD criteria also were generally in favor of implementing organized mammography screening in this age group .
Despite intensified efforts by the European Council since 2003 , the implementation of organized , population -based mammography screening is not uniform across Europe and depends greatly on the policies in place in different countries , the organization of health care , and available re sources ( 1 ) .
Since the last edition of the European Guidelines on Breast Cancer Screening and Diagnosis was published in 2006 ( 2 ) , new evidence regarding breast cancer and innovation in guideline methodology prompted the European Commission Initiative on Breast Cancer ( ECIBC ) to develop new evidence -based recommendations ( in short , the European Breast Guidelines ) .
These guidelines inform women , health professionals , and policymakers about important questions related to organized mammography screening and breast cancer diagnosis , but recommendations may apply in context s in which organized screening programs are not in place .
Women generally consider these undesirable effects acceptable ( low certainty of evidence ) , and a systematic review suggested that women place a relatively low value on the psychosocial and physical effects of false-positive results and overdiagnosis ; however , some studies raised concerns about whether women fully underst and the result ing implication s ( 15 ) .
How Often Should Women Attend an Organized Mammography Screening Program ?
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
Context Seven- and 10-year results of the Canadian National Breast Screening Study ( CNBSS ) showed no reduction in breast cancer mortality from five annual mammographies and breast examinations for 40- to 49-year-old women . Some authors have argued that longer follow-up would reveal important benefits . Contribution After 11 to 16 years , the cumulative rate ratios for mammography versus usual care were 0.97 ( 95 % CI , 0.74 to 1.27 ) for breast cancer mortality without adjustment for non study mammography and 1.06 ( CI , 0.80 to 1.40 ) with adjustment . Clinical Implication s The CNBSS suggests that screening 40- to 49-year-old women is unlikely to reduce breast cancer by 20 % or more . Controversy will persist because other studies suggest that screening causes small reductions in breast cancer mortality . The Editors The Canadian National Breast Screening Study -1 ( CNBSS-1 ) , an individually r and omized trial in women 40 to 49 years of age at study entry , evaluated the efficacy of annual mammography , breast physical examination , and instruction on breast self-examination in reducing breast cancer mortality  ( 1 ) . The 7-year ( 2 ) and preliminary 10-year ( 3 ) mortality results were previously reported . At 7 years , 38 women in the mammography group and 28 women in the usual care group had died of breast cancer , for a rate ratio of 1.36 ( 95 % CI , 0.84 to 2.21 ) ( 2 ) . At 10 years , there were 82 breast cancer deaths in the mammography group and 72 in the usual care group ( rate ratio , 1.14 [ CI , 0.83 to 1.56 ] ) ( 3 ) . This article reports CNBSS-1 results after an average 13-year follow-up from study entry . Methods Patient Selection and Recruitment Participants were recruited through media publicity , personal invitation letters using population lists ( municipal registers and provincial health insurance registers ) , group mailings , and physicians ( 4 ) . Eligibility criteria were age 40 to 49 years , no previous diagnosis of breast cancer , not being pregnant , no mammography in the previous 12 months , and signed informed consent . The Human Experimentation Committee of the University of Toronto ( Toronto , Ontario , Canada ) and Human Experimentation Committees at 15 CNBSS collaborating centers approved the study . A total of 50 430 women age 40 to 49 years were enrolled from January 1980 through March 1985 . R and omization Before r and omization , all participants received an initial breast physical examination and instruction on breast self-examination . They were then immediately r and omly assigned to receive mammography and , thereafter , either annual screening with mammography and breast physical examination ( 25 214 women in the mammography group were available for analysis ) or usual care in the context of the Canadian health care system ( 25 216 women in the usual care group were available for analysis ) . Center coordinators r and omly assigned participants using prepared allocation lists , independent of breast physical examination findings . This sequence ensured that the conduct and interpretation of the breast physical examination would be unbiased by knowledge of whether mammography would follow . Intervention Screening Schedule In the mammography group , 62 % of women received five annual screenings . The remainder , recruited later , received four . Each screening examination comprised mammography , breast physical examination , and instruction and evaluation on breast self-examination . Women in the mammography group completed question naires at each rescreening visit . Women in the usual care group were not recalled for rescreening but were mailed annual question naires . We expected that these participants would continue their normal pattern of medical care as delivered through Canada 's universal health care coverage , including access to mammography for diagnosis . Study Procedures Two-view mammography was done on dedicated mammography units ( 5 ) , and second readers review ed mammograms deemed abnormal . Systematic audit procedures were used ( 6 ) . Nurses provided breast physical examination in 12 centers and physicians in 3 centers in Qubec ( 7 ) . These providers taught and evaluated breast self-examination while conducting their own examination ( 8) . If findings on breast physical examination or mammography were abnormal , participants were referred to a CNBSS review clinic . The study surgeon discussed mammography findings with the study radiologist , examined the participant , and decided whether further diagnostic procedures should be recommended to the woman 's physician . The woman 's physician determined whether and how to implement the study surgeon 's recommendations . Data Collection Protocol During the screening period , the center coordinators collected surgery and pathology reports for breast-related diagnostic and therapeutic procedures . The CNBSS pathologists review ed all slides . If the community and CNBSS pathologist disagreed , a panel of three to five CNBSS pathologists blindedly and independently review ed the slides . Extensive quality control procedures were used during data collection . After the screening centers closed in 1988 , the central CNBSS central office annually followed all women known to have breast cancer until 30 June 1996 , the cut-off for this analysis . Passive follow-up of all participants through linkage with the National Cancer Registry identified new diagnoses of breast cancer in study participants through 31 December 1993 . The central office collected pathology reports for postscreening cases of breast cancer . The community diagnosis was accepted for study purpose s. Family members responding to the annual mailed question naire identified deaths that occurred before completion of a participant 's screening schedule . Thereafter , women not known to have cancer were followed only through registry linkage ; their mammography experience was not traced . However , for women known to have breast cancer , attending physicians received annual requests for up date d clinical information , including death .  Attending physicians , who received annual requests for information on women with breast cancer , reported deaths until 30 June 1996 . Linkage with the Canadian Mortality Data base at Statistics Canada ( including deaths in Canadians who resided in the United States at the time of death ) identified causes of death in the entire cohort until 31 December 1993 . The procedures used to verify deaths from breast cancer were described previously ( 2 ) . Investigative procedures were initiated for women dying with breast cancer ; those whose death certificates mentioned breast cancer ; and those whose cause of death was described as unknown , unknown primary , lung cancer , colon cancer , or liver cancer . The review ers were blinded to study group allocation . All other causes of death were accepted as certified . For the most recent record linkage , more stringent confidentiality requirements exercised by many hospitals hindered verification . Thus , of the breast cancer deaths reported in this paper , a panel review ed 67 % in the mammography group and 77 % in the usual care group . The remaining deaths are as reported on death certificates . Study Outcomes Death due to or probably due to breast cancer was the major study outcome . A previous report of the CNBBS-1 noted axillary node status , as assessed by community pathologists , through 7 years of follow-up ( 2 ) . Subsequently ( 1993 to 1997 ) , to achieve consistent reporting of tumor size , all available material for screening-detected cancer and cancer detected between screenings was re-collected from originating institutions and review ed by one of the CNBSS pathologists or a colleague . Slides were obtained for review for nearly 80 % of requested cases . For the current analysis , pathologists measured the size of small tumors as observed on the slide or the size of the invasive component for mixed invasive and in situ tumors . Statistical Analysis Sample Size The CNBSS-1 was planned to evaluate whether breast cancer mortality would decrease by 40 % in the  mammography group compared with the usual care group after 5 years of follow-up , with a required sample size of 50 000 women ( = 0.05 ; power , 80 % ) ( 1 ) . At 5 years , however , too few women had died of breast cancer for the study to achieve the planned power . Thus , for the first report on breast cancer mortality , we extended follow-up to 7 years ( 2 ) . CNBSS Data base The data base includes records for 50 430 women , including demographic and risk factor variables and results of screening examinations , diagnostic and therapeutic procedures , pathology results , and causes of death . CNBSS Terminology The terms screen 1 , screen 2 , through screen 5 denote events associated with screening examinations in the mammography group . The initial breast physical examination received by the usual care group is called screen 1 . Screening-detected cancers are those diagnosed after a recommendation made by the study surgeon at the CNBSS review clinic . Interval cancers are cases of cancer that occurred less than 12 months after a screening examination at which no recommendation for diagnostic procedures was made . Incident cancers are cases of cancer that occurred more than 12 months after the previous CNBSS screening examination . Statistical Tests The statistical significance of differences in proportions was determined by using the chi-square test ( two-sided = 0.05 ) . For all observed-to-expected ratios , 95 % CIs were computed . Death rates were computed by using person-years based on stratification by quinquennium of age ; we assumed that all women not known to be dead are alive . Age was defined as age at entry . Because all eligible participants were included in the analysis and follow-up , this is an intention-to-treat analysis . Cox proportional-hazards regression was done to examine variables with the most significant independent influence on survival ( 9 ) , using the PHREG program in SAS software , version 6.12 ( SAS Institute , Inc. , Cary , North Carolina ) . Because the variable allocation to screening was our primary interest , it was
For example , mammography screening does not seem to create anxiety in women who are given a clear result after a mammogram .
The incidence of breast cancer and mortality increases with age , and the GDG extrapolated that the absolute health benefits are greater in women aged 45 to 49 than those aged 40 to 44 years .
However , for the 45- to 49-year age group , the higher breast cancer incidence and mortality compared with women between the ages of 40 and 44 , as well as observational evidence showing a greater benefit in this age group ( 33 ) , led the GDG to judge that the balance of health effects probably favors screening , although the required re sources for screening likely differ across setting s ( 34 , 35 ) .
Other EtD criteria also were generally in favor of implementing organized mammography screening in this age group .
Despite intensified efforts by the European Council since 2003 , the implementation of organized , population -based mammography screening is not uniform across Europe and depends greatly on the policies in place in different countries , the organization of health care , and available re sources ( 1 ) .
Since the last edition of the European Guidelines on Breast Cancer Screening and Diagnosis was published in 2006 ( 2 ) , new evidence regarding breast cancer and innovation in guideline methodology prompted the European Commission Initiative on Breast Cancer ( ECIBC ) to develop new evidence -based recommendations ( in short , the European Breast Guidelines ) .
These guidelines inform women , health professionals , and policymakers about important questions related to organized mammography screening and breast cancer diagnosis , but recommendations may apply in context s in which organized screening programs are not in place .
Women generally consider these undesirable effects acceptable ( low certainty of evidence ) , and a systematic review suggested that women place a relatively low value on the psychosocial and physical effects of false-positive results and overdiagnosis ; however , some studies raised concerns about whether women fully underst and the result ing implication s ( 15 ) .
How Often Should Women Attend an Organized Mammography Screening Program ?