Effects of age, breast density, ethnicity, and estrogen replacement therapy on screening mammographic sensitivity and cancer stage at diagnosis: review of 183,134 screening mammograms in Albuquerque, New Mexico.

PURPOSE: To examine how common patient factors affect screening mammographic sensitivity and cancer stage at diagnosis. MATERIALS AND METHODS: The authors used a population-based database of 183,134 screening mammograms and a statewide tumor registry to identify 807 breast cancers detected at screening mammography. RESULTS: Sensitivity varied significantly with ethnicity, use of estrogen replacement therapy, mammographic breast density, and age. Sensitivity was 54% (13 of 24) in women younger than 40 years, 77% (121 of 157) in women aged 40-49 years, 78% (224 of 286) in women aged 50-64 years, and 81% (277 of 340) in women older than 64 years. Sensitivity was 68% (162 of 237) for dense breasts and 85% (302 of 356) for nondense breasts and 74% (180 of 244) in estrogen replacement therapy users and 81% (417 of 513) in nonusers. Sensitivity was most markedly reduced with the combination of dense breasts and estrogen replacement therapy use; there was little difference when only one factor was present. Median cancer size and the percentage of early cancers showed little change with any factors. CONCLUSION: Age is a minor determinant of mammographic sensitivity in women aged 40 years or older. Sensitivity is substantially decreased with the combination of higher breast density and estrogen replacement therapy use. There was not a notable shift in cancer outcomes in the groups with lower mammographic sensitivity. These data do not support different screening recommendations in women aged 40-49 years or in estrogen replacement therapy users.

Mammography outcomes in a practice setting by age: prognostic factors, sensitivity, and positive biopsy rate.

The separate unplanned analysis of women ages 40-49 in population-based randomized controlled trials has resulted in demonstration of statistically significant breast cancer mortality reduction due to screening mammography in only two of the individual trials, and in all such trials only through meta-analysis. Therefore, many researchers have utilized the surrogate endpoints of tumor size and axillary lymph node status to evaluate screening efficacy. For the present study, these endpoints were evaluated in an audit of 854 screen-detected cancers found in 147,125 mammographic examinations performed in women over 40 between 1988 and 1994 in a community practice setting. The concerns that mammography in the 40-49 group has a lower sensitivity and higher biopsy rate were also addressed. Median invasive tumor size and lymph node positivity were found to be equally small (1.0-1.1 cm and 13.5-12.2%, respectively), and the sensitivity and overall biopsy rate were found to be constant over all ages 40 and above. Positive biopsy rate (PBR) varied directly with increasing age, paralleling the measured cancer detection rate in each decade, with no abrupt change at age 50. We conclude that modern mammography in a community practice setting can successfully detect breast cancers with favorable prognostic factors and achieve constant sensitivity and acceptable PBRs in all women over 40. Our data also suggest that many of the large differences seen by inappropriately dividing data at age 50 decrease or disappear when analysis is performed by decade.

The New Mexico Mammography Project. Screening mammography performance in Albuquerque, New Mexico, 1991 to 1993.

BACKGROUND: This project was designed to collect and link population-based mammography and breast carcinoma data to assess the performance of community mammography screening. METHODS: Computerized data were collected from all radiology practices in Albuquerque, New Mexico. The data were linked by computer match to breast carcinomas in a statewide cancer registry. Analysis is based on 126,466 screening mammogram studies performed on 87,443 female residents of New Mexico between the ages of 35 and 84 by 5 radiology groups. Sensitivity, specificity, positive predictive value, and call back rates were calculated as indicators of the discriminative performance of mammography. Carcinoma size and stage distribution were analyzed as outcome measurements. RESULTS: The computer match linked 634 breast carcinomas to the 126,466 screening mammogram series. The community-wide sensitivity was 79.9%, and specificity was 90.5%. The predictive value of an abnormal screen was 4.3%, and that of a biopsy recommendation result was 16.9%. The call back rate was 11.4%. The median invasive breast carcinoma size was 15 mm, 20.3% of carcinomas were in situ, 18.3% were lymph node positive, and 68.1% were Stage 0 or Stage 1. CONCLUSIONS: Mass screening mammography as practiced in Albuquerque, New Mexico, is able to detect breast carcinomas at early, treatable stages. The stage distribution of carcinomas is similar to that seen in successful clinical trials. However, measures of mammography performance show lower sensitivity, more additional studies, and more biopsy recommendations in this community setting than have been reported by expert mammographers.

Mammography outcomes analysis: potential panacea or Pandora's box?

As a consequence of the demand for and perceived value of mammography outcomes analysis, collection of community-based mammography data by the NHMN and others has begun and is supported by the radiologists involved. Radiologists are increasing their use of standardized coding of report data necessary for clear communication and data collection but remain justifiably concerned about the confidentiality of these data. If stronger protection of these data is forthcoming, more radiologists will be encouraged to perform practice audits. The pooling of community-based data as exemplified by NHMN will create statistics that measure the actual practice of mammography and estimate its impact on breast cancer. For individual radiologists, the audit process will improve their mammography skills through direct feedback of results and provide important information about their patterns of interpretation. Although this approach will create community standards, comparisons with such standards may be more applicable among various communities than among individual radiologists because of the statistical variation created by the relatively small numbers of cancers found by individual radiologists, the differences in populations served by these radiologists, and the variability in reproducing the audit by individuals or groups. Pooled community data, however, will still be useful to community radiologists as general standards toward which to strive. We believe that medical audits offer important potential public health benefits for breast cancer control. Insofar as confidentiality issues cannot be effectively addressed by individual radiologists, institutions in a position to be advocates should immediately explore how legal underpinnings can be put in place to protect the audit process from disclosure. With such protection, the audit process may fulfill its potential for the radiologist's pivotal role in breast cancer control; without it, the process may prove to be a Pandora's box for the community radiologist.

Benefits versus risks from mammography: a critical reassessment.

BACKGROUND: The use of mammography has increased rapidly over the last decade. The justification for mammographic examinations is the potential benefit they provide in detecting breast cancer at an early stage and reducing mortality. However, this benefit must be balanced against the associated potential risk of radiation carcinogenesis, economic costs, and a number of other factors. Most publications to date have used radiation risk factors and data from studies that were published over a decade ago, which now have been superseded by the results of more recent epidemiological studies. METHODS: This report examines the current literature regarding the benefits of cancer detection and the risk of radiation carcinogenesis, and calculates the ratio of benefit and risk for women who begin annual mammography screening at different ages. We have used current data to calculate the expected individual benefits and radiation risks associated with annual mammographic screening. RESULTS: It now appears that there is little risk of breast cancer associated with radiation exposure from annual mammography in women over the age of 35, although there is some indication that exposure of younger women may pose a risk for those women in a genetically sensitive subgroup. CONCLUSIONS: New data document that for a woman beginning annual mammographic screening at age 50 and continuing until age 75, the benefit exceeds the radiation risk by a factor of almost 100. Even for a woman who begins annual screening at age 35 and continues until age 75, the benefit of reduced mortality is projected to exceed the radiation risk by factor of more than 25.

A national breast cancer database.

The medical audit of technical and interpretive aspects of mammography has been recommended by a number of expert panels and as part of some regulations that govern the oversight of mammography. The value of the medical audit is to aid practitioners in the performance evaluation of mammography in their facilities. Collection and analysis of audit data at a regional or national level have the potential to allow for the comparison of practice-level performance with regional and national-level performance and to provide a public health tool for the evaluation and improvement of breast cancer detection. In addition, a regional and national-level breast cancer database has the potential for allowing monitoring and tracking of women participating in a screening program. Prior to establishing such a database, data must be protected from discovery and disclosure, and patient and physician confidentiality must be ensured.

The mammography audit: a primer for the mammography quality standards act (MQSA).

The medical audit of a mammography practice is a recognized method for evaluating mammography and the accuracy of mammographic interpretation [1-4]. As such, portions of the audit will become integral to the quality assurance activities of every mammography practice under the Mammography Quality Standards Act (MQSA) of 1992, administered by the Food and Drug Administration (FDA). The FDA Interim Rules, which became effective October 1, 1994, state that "each facility shall establish a system for reviewing outcome data from all mammography performed, including follow-up on the disposition of positive mammograms and correlation of surgical biopsy results with mammogram reports" [5]. It is expected that the proposed final rules, due to be released for public comment in 1995, will require collection of additional data for medical audits (public meeting of the National Mammography Advisory Committee, May 3, 1994). Although most mammography practices are now collecting clinical outcomes data on abnormal mammographic examinations, very few have established an organized and deliberate system of data collection necessary for a more complete mammography audit [6]. A detailed discussion of and recommendations for such an audit were recently published as part of the Quality Determinants of Mammography Guideline by the Agency for Healthcare Policy and Research (AHCPR) [7]. As members and consultants on the multidisciplinary panel that produced the guideline, we offer the following review of the various elements, definitions, and processes of the mammography audit. This is intended as a primer for all radiologists who will be performing some of the same audit activities for the MQSA.

Improvement in mammography interpretation skills in a community radiology practice after dedicated teaching courses: 2-year medical audit of 38,633 cases.

The authors conducted a complete audit of results of 38,633 mammographic examinations performed by 12 general radiologists during a 2-year period with a computerized reporting system. During this period, 11 group members attended 17 dedicated mammography courses. Audit results were analyzed for each radiologist and the entire group. In the 2nd year, the number of breast cancers diagnosed increased 50% (from 121 to 181), with a 6.5% increase in patient volume. Sensitivity increased from 80% to 87%, and there was no change in the positive predictive value of 32%. Median tumor size and node positivity decreased. Most major variables of population and technical factors were unchanged. Diagnostic approach was altered during the 2nd year, as shown by a 50% increase in the use of spot compression, magnification views, and sonography. Analysis of each radiologist's performance before and after attending mammography courses showed similar changes. These data suggest that dedicated mammography courses can help improve radiologists' performance and alter their interpretive approach.