Canadian National Breast Screening Study Research Articles

Does This Patient Have Breast Cancer? The Screening Clinical Breast Examination: Should It Be Done? How?

The authors conducted an extensive search of the literature and investigation of many published studies to collect information on the optimal use of clinical breast examinations (CBEs). All published clinical screening programs that used CBEs as part of the screening process were analyzed to determine the effectiveness of clinical examinations in screening for breast cancer. There were no published reports of screening with CBEs alone. Studies that investigated the use of silicone breast models, as well as those of actual clinical techniques, were included in the investigation of optimal CBE methods. A meta-analyses of studies found that, in women aged 50 to 69 years, screening with either CBE, mammography, or both methods reduces deaths due to breast cancer by one-fourth. For women in their 40s, deaths were reduced by 18 percent. In the Canadian study, women in their 50s were screened yearly for 5 years with either yearly mammography and CBE or CBE only. Over a 7-year period, deaths due to breast cancer were similar in the two groups. The Health Insurance Plan study, which found CBE to be superior to early forms of mammography at detecting breast tumors, was conducted in the 1960s when mammography techniques and interpretation were not well developed. Mammography seems to be more sensitive than CBE alone, but the greatest sensitivity is achieved when both methods are used (Table 1). No evidence could be found in these studies that screening with both CBE and mammography ultimately reduces the rate of death due to breast cancer more than mammography alone. Women whose cancer was found by breast examination but missed by mammography had a higher mortality rate than women whose cancers were detected by mammography. In these studies, CBE had a high false-positive rate and a higher false-negative rate for detecting breast cancers. The overall sensitivity for CBE was 54 percent. Specificity was 94 percent. Table 1: Proportion of cancers detected by clinical breast examination (CBE) and mammography screeningThe studies did show, however, that sensitivity increased with the length of the breast examination. Examiners who spent the most time on examinations consistently had the highest sensitivity rates. In the Canadian National Breast Screening Study, examiners who spent between 5 and 10 minutes on the complete examination achieved a sensitivity of 69 percent. Only one investigation made any attempt to use a standard method for the CBE, and other studies indicated that the findings of clinicians using nonstandardized breast examination methods agree only slightly better than chance. The technique used had an impact on the sensitivity of the examination. When a thorough, systematic search pattern with varying palpation pressures, using the pads of three fingers in a circular motion, was used to examine silicone models, sensitivity increased. Experience and training increased the effectiveness of the examiner. In tests with silicone models, residents were better than untrained lay women at finding suspicious lumps. With training, the women improved almost to the level of the residents, and with experience, the sensitivity of the residents further increased. There was little information in the studies to support recommendations for careful visual inspection of the breast in various positions. Visual inspection while performing the examination seemed to be sufficient. Nor was there any evidence that squeezing the nipple to check for discharge was valuable in detecting breast tumors. In women with otherwise normal findings, spontaneous discharge was associated with the presence of breast tumor in only 2 percent of patients. There was no cancer found in women with expressed discharge. JAMA 1999;282:1270–1280

Mammographic densities and risk of breast cancer among subjects with a family history of this disease.

A family history of breast cancer is known to increase risk of the disease, but other genetic and environmental factors that modify this risk are likely to exist. One of these factors is mammographic density, and we have sought evidence that it is associated with increased risk of breast cancer among women with a family history of breast cancer. We used data from a nested case-control study based on the Canadian National Breast Screening Study (NBSS). From 354 case patients with incident breast cancer detected at least 12 months after entry into the NBSS and 354 matched control subjects, we analyzed subjects who were identified as having a family history of breast cancer according to one of three, nonmutually exclusive, criteria. We compared the mammographic densities of case patients and control subjects by radiologic and computer-assisted methods of measurement. After adjustment for other risk factors for breast cancer, the relative risks (RRs) between the most and least extensive categories of breast density were as follows: For at least one first-degree relative with breast cancer, RR = 11.14 (95% confidence interval [CI] = 1.54-80.39); for at least two affected first- or second-degree relatives, RR = 2.57 (95% CI = 0.23-28.22); for at least one first- or second-degree relative with breast cancer, RR = 5.43 (95% CI = 1.85-15.88). These results suggest that mammographic density may be strongly associated with risk of breast cancer among women with a family history of the disease. Because mammographic densities can be modified by dietary and hormonal interventions, the results suggest potential approaches to the prevention of breast cancer in women with a family history of breast cancer.

Hormone replacement therapy and risk of benign proliferative epithelial disorders of the breast.

Use of hormone replacement therapy (HRT) has been associated with increased risk of breast cancer, and it is possible that this reflects a positive association between HRT use and risk of proliferative forms of benign breast disease (BBD), conditions which are thought to have pre-malignant potential. The purpose of the present investigation was to study the association between HRT use and risk of benign proliferative epithelial disorders of the breast (BPED). The study was undertaken using the 56,837 women within the Canadian National Breast Screening Study (NBSS) who completed self-administered lifestyle and dietary questionnaires. (The NBSS is a randomized controlled trial of screening for breast cancer in women aged 40-59 at recruitment.) During the course of the follow-up period, a total of 691 women in the dietary cohort were diagnosed with biopsy-confirmed incident BPED. For comparative purposes, a sub-cohort consisting of a random sample of 5681 women (including 65 of the subjects with BPED) was selected from the full dietary cohort. After exclusions for various reasons, the analyses were based on 691 cases and 5443 non-cases. In post-menopausal women, in whom most of the reported use occurred, there was a positive association between duration of HRT use and risk of BPED, the adjusted incidence rate ratio (95% confidence interval) in those who had used HRT for more than 8 years being 1.70 (1.06-2.72). There were too few cases of atypical BPED for meaningful analysis, but results for those whose BPED showed no atypia were similar to the overall results. Further analyses conducted separately in the screened and control arms of the NBSS were similar to those observed overall, as were those conducted separately for screen-detected and interval-detected BPED.

Cigarette smoking and risk of benign proliferative epithelial disorders of the breast.

Benign proliferative epithelial disorders (BPED) of the breast are conditions which are thought to have premalignant potential. The purpose of the present investigation was to study the association between cigarette smoking and risk of BPED. The study was undertaken within the 56,837 women within Canadian National Breast Screening Study (NBSS) who completed self-administered lifestyle and dietary questionnaires. (The NBSS is a randomized controlled trial of screening for breast cancer in women aged 40-59 at recruitment.) During the course of the follow-up period, a total of 691 women in the dietary cohort were diagnosed with biopsy-confirmed incident BPED. For comparative purposes, a subcohort consisting of a random sample of 5681 women (including 65 of the subjects with BPED) was selected from the full cohort. After exclusions for various reasons, the analyses were based on 691 cases and 5443 non-cases. Overall, the results of the present study are almost uniformly null, and provide little support for an association between cigarette smoking and risk of BPED. Analyses conducted separately in the screened and control arms of the NBSS also failed to provide strong support for associations, and there was little difference between the results for screen-detected and interval-detected BPED. There was some suggestion of an increase in risk in post-menopausal ex-smokers, but the trend in risk with cigarette-years of exposure in this group was not statistically significant. Risk in ex-smokers varied little by years since smoking cessation. There was little evidence for associations with either atypical or non-atypical forms of BPED.

Assessing the extent of contamination in the Canadian National Breast Screening Study

Objective: To estimate the proportion of Canadian National Breast Screening Study (NBSS) participants who went outside the trial for a mammogram, based on health insurance claims data. Method: Prospective cohort study linking trial subjects with population-based administrative data. Subjects: All NBSS participants enrolled in the Winnipeg screening center who had health insurance claims to Manitoba Health ( n = 9,780). Analysis: Claims for bilateral mammograms were compared by screening arm allocation and age group at enrollment. Mammograms likely to be “screening” were defined based on prior claim history. Results: For women aged 40 to 49 at enrollment, 5.3% in the intervention group and 21.8% in the control group had a claim for at least one bilateral mammogram. After excluding nonscreening mammograms these proportions fell to 2.2% and 14.1% ( P < 0.0001). For women aged 50 to 59, 4.5% in the intervention group and 16.7% of the control group had at least one claim for a bilateral mammogram. These proportions were 2.1% and 10.5% for screening ( P < 0.0001). Conclusion: Health care utilization data can be used to estimate contamination in a screening trial. The levels of contamination resulting from participants going outside the study for a screening test can have an impact on the power of the study and need to be considered when interpreting results and planning future screening studies.

Alcohol consumption and risk of benign proliferative epithelial disorders of the breast: a case-cohort study.

To study the association between alcohol consumption and risk of benign proliferative epithelial disorders (BPED) of the breast (conditions which are thought to have premalignant potential). Case-cohort study. The study was undertaken within the 56,537 women in the Canadian National Breast Screening Study (NBSS) who completed self-administered dietary questionnaires. (The NBSS is a randomized controlled trial of screening for breast cancer in women aged 40-59 years at recruitment.) The study subjects were the 657 women in the dietary cohort who were diagnosed with biopsy-confirmed incident BPED. For comparative purposes, a subcohort consisting of a random sample of 5681 women was selected from the full dietary cohort. After exclusions for various reasons, the analyses were based on 557 cases and 5028 non-cases. When compared to non-drinkers, rate ratios (95% CI) for those consuming > 0 and < or =10 g of ethanol day(-1), >10 and < or =20 g day(-1), >20 and < or =30 g day(-1) and >30 g day(-1) were 0.35 (0.27-0.45), 0.26 (0.18-0.39), 0.29 (0.18-0.48), and 0.23 (0.13-0.40), respectively (the associated P value for the trend was 0.089). Similar findings were obtained from analyses conducted separately in the screened and control arms of the NBSS, in premenopausal and postmenopausal women, and for non-atypical and atypical forms of BPED, and there was little difference between the results for screen-detected and interval-detected BPED. Alcohol consumption was associated with a non-dose-dependent reduction in risk of BPED.

A case-cohort study of diet and risk of benign proliferative epithelial disorders of the breast (Canada).

A case-cohort analysis of the association between diet and risk of benign proliferative epithelial disorders (BPED) of the breast was undertaken within a cohort of 56,537 women who were enrolled in the Canadian National Breast Screening Study (NBSS) and who completed a self-administered dietary questionnaire. (The NBSS is a randomized controlled trial of screening for breast cancer in women aged 40 to 59 years.) BPED are thought to have premalignant potential. Specific hypotheses were that risk of BPED would increase with increasing energy-adjusted fat intake and decrease with increasing energy-adjusted vitamin A and fiber intake. Additionally, we explored the association between calcium intake and risk of BPED. During the active follow-up phase of the NBSS, 657 women in the dietary cohort were diagnosed with biopsy-confirmed incident BPED. For comparative purposes, a subcohort consisting of a random sample of 5,581 women was selected from the full dietary cohort. After exclusions for various reasons, the analyses were based on 545 cases and 4,921 non-cases. Overall, the results were almost uniformly null, and provided little support for the study hypotheses. Rate ratios (95 percent confidence intervals [CI]) for the highest cf the lowest quintile levels for total fat, retinol, beta-carotene, fiber, and calcium were 0.88 (CI = 0.65-1.20), 0.97 (CI = 0.71-1.31), 0.94 (CI = 0.70-1.27), 1.11 (CI = 0.82-1.50), and 0.81 (CI = 0.60-1.07), respectively. There were too few cases of atypical BPED for meaningful analysis, but results for those whose BPED showed no atypia were similar to the overall results. Further analyses conducted separately in the screened and control arms of the NBSS also failed to provide strong support for dietary associations, as did those conducted separately for screen-detected and interval-detected BPED.

Impact of menstrual phase on false-negative mammograms in the canadian national breast screening study

The efficacy of breast carcinoma screening should be enhanced if false-negative mammography were reduced. Prospectively collected data from the Canadian National Breast Screening Study were used to examine whether menstrual cycle phase was associated with false-negative outcomes for mammographic screening. Of 8887 women ages 40-44 years at the onset of screening, randomized to receive annual mammography and clinical breast examination, reporting menstruation no more than 28 days prior to their screening examination, and with a valid radiologic report, 1898 had never used oral contraceptives or replacement estrogen with or without progesterone. The remainder were past (6573) and current (416) estrogen users. Similar selection criteria were applied at subsequent screens. The distribution of false-negative and false-positive mammography in relation to true-negative and true-positive mammography was examined with respect to the follicular (Days 1 to 14) and luteal (Days 15-28) menstrual phases. Comparing luteal with follicular mammograms in 6989 patients who ever used estrogen, the unadjusted odds ratio (2-sided P-values) for false-negatives versus true-negatives was 2.16 (0.05) and the adjusted odds ratio was 1.47 (0.05). In 1898 never-users, parallel odds ratios for luteal false-negatives were 0.55 (1.0) and 0.74 (1.0), respectively. These results suggest that menstruating women who have used hormones may have an increased risk of false-negative results for screening mammograms performed in the luteal phase of the menstrual cycle. An increased risk of false-negative mammography might adversely affect screening efficacy. The impact of menstrual phase on mammographic interpretation, especially for women who ever used hormones, requires further investigation.

Impact of menstrual phase on false‐negative mammograms in the canadian national breast screening study

Impact of menstrual phase on false‐negative mammograms in the canadian national breast screening study

Automated analysis of mammographic densities and breast carcinoma risk.

There is considerable evidence that one of the strongest risk factors for breast carcinoma can be assessed from the mammographic appearance of the breast. However, the magnitude of the risk factor and the reliability of the prediction depend on the method of classification. Subjective classification requires specialized observer training and suffers from inter- and intraobserver variability. Furthermore, the categoric scales make it difficult to distinguish small differences in mammographic appearance. To address these limitations, automated analysis techniques that characterize mammographic density on a continuous scale have been considered, but as yet, these have been evaluated only for their ability to reproduce subjective classifications of mammographic parenchyma. In this study, using a nested case-control design, the authors evaluated the direct association between breast carcinoma risk and quantitative image features derived from automated analysis of digitized film mammograms. Two parameters, one describing the distribution of breast tissue density as reflected by brightness of the mammogram (regional skewness) and the other characterizing texture (fractal dimension), were calculated for images from 708 subjects identified from the Canadian National Breast Screening Study. These parameters were evaluated for their ability to distinguish cases (those women who developed breast carcinoma) from controls. It was found that both the skewness and fractal parameters were significantly related to risk of developing breast carcinoma. Although the relative risk estimates were moderate (typically > 2.0) and less than those from subjective classification or for an interactive computer method the authors have previously described, they are comparable to other risk factors for the disease. The observer independence and reproducibility of the automated methods may facilitate their more widespread use.

Using an alternative data source to examine randomization in the Canadian National Breast Screening Study

Criticisms of the Canadian National Breast Screening Study (NBSS) assert that reported findings (more deaths in women aged 40–49 allocated to mammography versus no mammography and no difference in mortality between women who had mammography and physical examination versus physical examination alone for those aged 50–59) may be due to more women with prior breast disease being allocated to the mammography arms of the study. The possibility that allocation was not random was examined for NBSS participants in Manitoba, Canada, using health insurance data that were external to and independent of the NBSS. The study design consisted of a retrospective observation study using health insurance (claims) data to construct health histories of breast disease prior to NBSS entry. Self-reported breast disease from the NBSS entry questionnaires was compared to breast disease histories on the basis of health insurance claims. The setting consisted of one NBSS screening center in Winnipeg, Canada. The patient population consisted of 9477 women with at least one health insurance claim in the 24 months prior to NBSS entry. We determined the proportions of women within each study arm who had claims for breast disease, breast disease investigation, or xeromammograms in the 24 months prior to NBSS entry, and compared the proportion of women's self-reports of breast disease or xeromammography with the presence/absence of a claim prior to NBSS entry for breast disease or xeromammography. No significant differences in the proportion of women with prior histories of benign breast disease, investigation, or xeromammograms ( p > 0.05) were found across the study arms. Nine women in the mammography group versus one in the no mammography group had one prior health insurance claim for breast cancer, but eight of these women had no subsequnt claims for breast cancer. There were no differences across the study arms in the proportion of women who reported a prior history of breast disease or a prior xeromammogram for whom an insurance claim was found. Using data external to the NBSS for Manitoba participants, the study found no definitive evidence to support a nonrandom allocation of women with prior breast disease to the mammography arms of the study. However, generalizability to the other NBSS centers cannot be assured.

The Canadian national breast screening study. Why? what next? and so what?

Why the National Breast Screening Study (NBSS)? In 1979, after reviewing the Breast Cancer Detection Demonstration Projects (BCDDP), the Beahrs Working Group made 11 recommendations. The NBSS protocol reflected a number of these recommendations, particularly the evaluation of screening women age 40-49 and the still unanswered question of the incremental benefit of mammography versus physical examination of the breasts among women age 50-59. Three years after publication of NBSS's 7-year results and in light of other published evidence from screening trials (as opposed to observational studies), it is reasonable to recommend screening with mammography and physical examination every 2 years for women age 50-59. In contrast, it is not reasonable to offer screening mammography to women age 40-49 other than in the context of a controlled trial, an opportunity currently available in the United Kingdom. The Beahrs recommendation, that "physical examinations should be continued in the Breast Cancer Detection Demonstration Projects as a routine screening modality for all ages," remains justifiable as long as so many women age 40-49 are having mammograms performed, given the relatively poor sensitivity of mammography in this age group. Criticism of the NBSS, mainly by radiologists, will continue until the NBSS yields results that support its critics' belief in the efficacy of screening. To date, responses to critics of the NBSS have focused on correcting misinformation and clarifying NBSS procedures. Useful critical commentary should await the results of a 10-year NBSS follow-up and the U.S. National Cancer Institute-sponsored meta-analysis of screening trials. Rigorous critical scrutiny should be directed at all trials.

Controversies in breast cancer screening

Because breast cancer is the most common cancer occurring in women in the United States, early detection of breast cancer through screening mammography, physician clinical examination, and breast self-examination has been recommended. However, despite admonitions to physicians and patients to be aggressive in their screening efforts, there has been continued controversy regarding appropriate guidelines for screening. In December 1993, the National Cancer Institute announced that it could no longer recommend routine mammographic screening for women age 40-49 years, which it had previously supported along with other medical organizations. This change in policy, along with data from the Canadian National Breast Screening Study showing an increased mortality rate for screened women, created confusion for physicians and patients alike. The controversy about screening guidelines has created many practical concerns for the physicians involved in the primary health care of women. In the current paper, the author discussed the development of screening guidelines and the current recommendations of various medical organizations and reviewed the data from studies supporting and challenging the current guidelines, with a focus on screening guidelines for women age 40-49 and the elderly. Recommendations are made for physicians on how to communicate with patients regarding screening controversies.

Screening Women Aged 40-49 Years: Where Are We Today?

The fact that mammographic screening can reduce deaths from breast cancer is well established and is unarguably true for women aged 50-69 years (12)- While the unique value of mammography in the early detection of breast cancer is also well established, it is less certain if early detection results in similar mortality reductions for women diagnosed with breast cancer between the ages of 40 and 49 years compared with women aged 50 years and older. This uncertainty is, at the outset, the result of an inadequate base of scientific data. Specifically, no trial to date, with the exception of the Canadian National Breast Screening Study (NBSS-1), was designed to have adequate statistical power to test the hypothesis of a benefit from mammography for women aged 40^9 years, and the results are not universally accepted due to concerns about study methodology. While the majority of these trials suggest a benefit for women aged 40-49 years, none of the observed mortality differences in individual studies has achieved conventional criteria for statistical significance (3). Periodic updates of trial data have been published, but small sample sizes in individual studies remain a limiting factor. However, there are other limiting factors that potentially influence trial results, and these factors may have been especially influential on outcomes for women aged 40-49 years. These factors include mammographic technique, one versus two views, and the interval between screenings. To address the limitations of small sample sizes and these quality-assurance

Screening mammography and public health policy: the need for perspective

SummaryThe early trials of screening mammography, reporting 30% relative reduction in mortality from breast cancer in women over 50 years of age, led to strong professional and public demand for screening programmes. There has been little publicity about the subsequent trials showing no significant benefit in any age group, or about the harm and costs associated with screening mammography. For women under 50, there is a reluctant consensus that screening is not beneficial, but there is increasing pressure for publicly funded programmes for older women.When analysed in terms of population benefit, the randomised controlled prospective trials showed that the numbers of women screened to achieve one less death per year ranged from 7086 (Health Insurance Plan of New York), to 63264 (Malmo), to infinity (Canadian National Breast Screening Study). About 5% of screening mammograms are positive or suspicious, and of these 80-93% are false positives that cause much unnecessary anxiety and further procedures including surgery. False reassurance by negative mammography occurs in 10-15% of women with breast cancer that will manifest clinically within a year. Our calculations confirm others that the mean annual cost per life "saved" is around $1·2 million (£558 000).In the allocation of limited resources, public health policy on a proposed mass population intervention must be based on a critical analysis of benefits, harm, and cost. Since the benefit achieved is marginal, the harm caused is substantial, and the costs incurred are enormous, we suggest that public funding for breast cancer screening in any age group is not justifiable.

Quantitative Classification of Mammographic Densities and Breast Cancer Risk: Results From the Canadian National Breast Screening Study

The radiographic appearance of the female breast varies from woman to woman depending on the relative amounts of fat and connective and epithelial tissues present. Variations in the mammographic density of breast tissue are referred to as the parenchymal pattern of the breast. Fat is radiologically translucent or clear (darker appearance), and both connective and epithelial tissues are radiologically dense (lighter appearance). Previous studies have generally supported an association between parenchymal patterns and breast cancer risk (greater risk with increasing densities), but there has been considerable heterogeneity in risk estimates reported. Our objective was to determine the level of breast cancer risk associated with varying mammographic densities by quantitatively classifying breast density with conventional radiological methods and novel computer-assisted methods. From the medical records of a cohort of 45,000 women assigned to mammography in the Canadian National Breast Cancer Screening Study (NBSS), a multicenter, randomized trial, mammograms from 354 case subjects and 354 control subjects were identified. Case subjects were selected from those women in whom histologically verified invasive breast cancer had developed 12 months or more after entering the trial. Control subjects were selected from those of similar age who, after a similar period of observation, had not developed breast cancer. The mammogram taken at the beginning of the NBSS was the image used for measurements. Mammograms were classified into six categories of density, either by radiologists or by computer-assisted measurements. All radiological classification and computer-assisted measurements were made using one craniocaudal view from the breast contralateral to the cancer site in case subjects and the corresponding breast of control subjects. All P values represent two-sided tests of statistical significance. For all subjects, there was a 43% increase in the relative risk (RR) between the lower and the next higher category of density, as determined by radiologists, and there was a 32% increase as determined by the computer-assisted method. For all subjects, the RR in the most extensive category relative to the least was 6.05 (95% confidence interval [CI] = 2.82-12.97) for radiologists and 4.04 (95% CI = 2.12-7.69) for computer-assisted methods. Statistically significant increases in breast cancer risk associated with increasing mammographic density were found by both radiologists and computer-assisted methods for women in the age category 40-49 years (P = .005 for radiologists and P = .003 for computer-assisted measurements) and the age category 50-59 years (P = .002 for radiologists and P = .001 for computer-assisted measurements). These results show that increases in the level of breast tissue density as assessed by mammography are associated with increases in risk for breast cancer.

Benefit of mammography screening in women ages 40 to 49 years. Current evidence from randomized controlled trials.

Eight randomized controlled trials (RCTs) of screening mammography were conducted involving women ages 40 to 49 years at entry. Current data gathered for periods ranging from 7 to 18 years of follow-up are available from these trials. Meta-analyses were performed using a Mantel-Haenszel estimator method to combine current follow-up data from the eight RCTs of mammography that included women ages 40 to 49 years. Combining all current data on women ages 40 to 49 years at entry into the trials yielded a 16% [corrected] benefit from screening mammography, without statistical significance at the 95% confidence level. Combining all data on women ages 40 to 49 years at entry, excluding results from the Canadian National Breast Screening Study, yielded a 24% [corrected] benefit to women invited for screening, with statistical significance at the 95% confidence level. These results suggest that screening mammography in women ages 40 to 49 years at entry can reduce mortality from breast cancer when combined with adequate follow-up.

The excess of patients with advanced breast cancer in young women screened with mammography in the Canadian National Breast Screening Study

An unexpected excess of patients with breast cancer with four or more positive lymph nodes was observed in mammographically screened women who were younger than the age of 50 years at enrollment into the Canadian National Breast Screening Study (NBSS). It has been suggested that this excess is consistent with prior screening trials evaluating mammography. A quantitative evaluation of the distribution of patients with breast cancer with four or more positive lymph nodes in the NBSS was undertaken, and the percentages of patients with breast cancer who were at an advanced state at diagnosis in the NBSS and in previous randomized screening trials were compared. The validity of mortality analyses after eliminating advanced cases detected by physical examination at the initial screening visit is examined. The excess of patients with cancer with four or more positive lymph nodes in the 40-49-year mammography age group of the NBSS was statistically significant, even when expressed as a percentage of all invasive cancers diagnosed. Such an excess is inconsistent with published data on extent of disease at diagnosis from previous studies. Analysis of NBSS mortality data after eliminating advanced cases detected by physical examination at the initial visit should result in minimal, if any, bias. Mortality analyses eliminating advanced cases detected by physical examination at the initial screening visit may be less susceptible to bias caused by possible nonrandom allocation of study participants and should be considered in future evaluations of the NBSS cohort after longer follow-up periods and in meta-analyses that may include the NBSS in assessments of the efficacy of mammography.

Determination of mammographic screening intervals with surrogate measures for women aged 40-49 years.

HomeRadiologyVol. 193, No. 2 PreviousNext Determination of mammographic screening intervals with surrogate measures for women aged 40-49 years.S A FeigS A FeigS A FeigPublished Online:Nov 1 1994https://doi.org/10.1148/radiology.193.2.7972732MoreSectionsPDF ToolsImage ViewerAdd to favoritesCiteTrack CitationsPermissionsReprints ShareShare onFacebookTwitterLinked In Article HistoryPublished in print: 1994 FiguresReferencesRelatedDetailsCited ByEvidence to Support Screening Women in Their 40sKimberly M.Ray, Elissa R.Price, Bonnie N.Joe2017 | Radiologic Clinics of North America, Vol. 55, No. 3Personalized Screening for Breast Cancer: A Wolf in Sheep's Clothing?Stephen A.Feig2015 | American Journal of Roentgenology, Vol. 205, No. 6Screening Mammography Benefit ControversiesStephen A.Feig2014 | Radiologic Clinics of North America, Vol. 52, No. 3Breast ImagingStephen A.Feig, Stephen W.Duffy20114–9 Breast cancer mortality after screening mammography in British Columbia womenS.A.Feig2008 | Breast Diseases: A Year Book Quarterly, Vol. 18, No. 4Auditing and Benchmarks in Screening and Diagnostic MammographyStephen A.Feig2007 | Radiologic Clinics of North America, Vol. 45, No. 5Factors Contributing to Mammography Failure in Women Aged 40–49 YearsStephen A.Feig2006 | Breast Diseases: A Year Book Quarterly, Vol. 16, No. 44–8 A Basal Epithelial Phenotype Is More Frequent in Interval Breast Cancers Compared With Screen Detected TumorsS.A.Feig2006 | Breast Diseases: A Year Book Quarterly, Vol. 16, No. 4Screening Mammography Controversies: Resolved, Partly Resolved, and UnresolvedStephen A.Feig2005 | The Breast Journal, Vol. 11, No. s1Current status of breast ultrasoundGeorgian-SmithDianne M2004 | Applied RadiologyRecent Results in Cancer ResearchStephen A.Feig2003 | , Vol. 163Screening strategy for breast cancerStephen A.Feig2003 | Seminars in Breast Disease, Vol. 6, No. 4Breast Cancer Screening for High-Risk Women: Too Little, Too Late?KatrinaArmstrong, Barbara L.Weber2001 | Journal of Clinical Oncology, Vol. 19, No. 4Medical RadiologyS. M.Ascher2000Medical RadiologyI.Schreer, H.-J.Frischbier2000Medical RadiologyL. J. WarrenBurhenne2000Role and evaluation of mammography and other imaging methods for breast cancer detection, diagnosis, and stagingStephen A.Feig1999 | Seminars in Nuclear Medicine, Vol. 29, No. 1BREAST CANCER SCREENINGBrenda E.Sirovich, Harold C.Sox1999 | Surgical Clinics of North America, Vol. 79, No. 5Prognosis, treatment, and recurrence of breast cancer for women attending or not attending the Screening Mammography Program of British ColumbiaIvo A.Olivotto, DonnaMates, LisaKan, JonathanFung, RajivSamant, Linda J. WarrenBurhenne1999 | Breast Cancer Research and Treatment, Vol. 54, No. 1The benefits of mammography are not limited to women of ages older than 50 yearsRuthHeimann, JeffreyBradley, SamuelHellman1998 | Cancer, Vol. 82, No. 11American College of Radiology guidelines for breast cancer screening.S AFeig, C JD'Orsi, R EHendrick, V PJackson, D BKopans, BMonsees, E ASickles, C BStelling, MZinninger, PWilcox-Buchalla1998 | American Journal of Roentgenology, Vol. 171, No. 1Survival of women ages 40-49 years with breast carcinoma according to method of detectionCarol P.McPherson, Karen K.Swenson, GailJolitz, Charles L.Murray1997 | Cancer, Vol. 79, No. 10Increased benefit from shorter screening mammography intervals for women ages 40-49 yearsStephen A.Feig1997 | Cancer, Vol. 80, No. 11National Institutes of Health Consensus Development Conference Statement: Breast Cancer Screening for Women Ages 40-49, January 21-23, 19971997 | JNCI Journal of the National Cancer Institute, Vol. 89, No. 14Mammography Outcomes in a Practice Setting by Age: Prognostic Factors, Sensitivity, and Positive Biopsy RateMichael N.Linver, Stuart B.Paster1997 | JNCI Monographs, Vol. 1997, No. 22Breast Cancer Screening Outcomes in Women Ages 40-49: Clinical Experience With Service Screening Using Modern MammographyEdward A.Sickles1997 | JNCI Monographs, Vol. 1997, No. 22Assessment of radiation risk from screening mammographyStephen A.Feig1996 | Cancer, Vol. 77, No. 5Screening Mammography in Women Under Fifty Years of AgeStephen A.Feig1996 | The Breast Journal, Vol. 2, No. 3Estimation of currently attainable benefit from mammographic screening of women aged 40-49 yearsStephen A.Feig1995 | Cancer, Vol. 75, No. 10Mammographic screening of women aged 40–49 years. Benefit, risk, and cost considerationsStephen A.Feig1995 | Cancer, Vol. 76, No. S10The Canadian national breast screening study. Why? what next? and so what?Cornelia J.Bathes1995 | Cancer, Vol. 76, No. S10MAMMOGRAPHY SCREENING OF WOMEN AGED 40 TO 49 YEARSStephen A.Feig1994 | Obstetrics and Gynecology Clinics of North America, Vol. 21, No. 4Recommended Articles RSNA Education Exhibits RSNA Case Collection Vol. 193, No. 2 Metrics Altmetric Score PDF download

Screening mammography: interpretation of the data

The literature on screening mammography includes a plethora of conflicting articles. More recently, individuals and various medical organizations have recommended and established their own guidelines for screening mammography. A review of salient breast screening randomized clinical trials in women over and under the age of 50 years is provided and compared with the more recent results of the Canadian National Breast Screening Study. In women under the age of 50 years, screening mammography cannot be supported from the results of these trials. In women over the age of 50 years, screening mammography leads to a significant reduction in breast cancer mortality and should be strongly recommended.