Long-term risk of false-positive screening results and subsequent biopsy as a function of mammography use.

PURPOSE: To retrospectively determine the long-term risk of false-positive mammographic assessments and to evaluate the effect of screening regularity on the risk of false-positive events. MATERIALS AND METHODS: Institutional review board approval was obtained, and informed consent was waived. Retrospective analysis was performed for the occurrence of false-positive assessments among 83,511 women who underwent 314,185 mammographic examinations from January 1, 1985, to February 19, 2002. Data were collected from a database that had been assembled prospectively. Two categories of false-positive events were examined: biopsies that did not reveal cancer and false-positive mammographic assessments. Rates of false-positive events were compared by using a chi2 analysis, and 95% confidence limits were calculated. Because comparisons of multiple pairs were considered, all P values that demonstrated statistical significance exceeded the requirement of the Bonferroni correction. RESULTS: While the overall rates of biopsies that did not reveal cancer and of false-positive mammographic assessments were similar to those found in other studies, most of the burden of false-positive events was borne by women who underwent intermittent screening. Long-term rates of false-positive events were lower among women who underwent regular screening than among those who underwent intermittent screening. In the 5-year group, 2.9% of women who underwent five mammographic examinations over the next 5 years had biopsy results that did not reveal cancer, whereas 4.6% of women who underwent three mammographic examinations over the next 5 years had biopsy results that did not reveal cancer. For women who underwent regular screening, the risk of undergoing biopsies that did not reveal cancer declined over time to 0.25% per year after several years of screening, a value that is lower than the risk of these events among women who did not undergo screening. The rate of false-positive mammographic assessments was also lower for women who underwent regular screening than for those who underwent intermittent screening. CONCLUSION: Prompt annual attendance for mammographic screening reduces the occurrence of false-positive mammographic results.

Mammographic screening: patterns of use and estimated impact on breast carcinoma survival.

BACKGROUND: Although many studies support the life-saving potential of screening mammography, the actual utilization of screening and the impact of the actual pattern of screening use on the breast carcinoma death rate, remain incompletely understood. In the current report, the authors describe patterns of screening use among women who were examined at a large screening and diagnostic service and estimate the added mortality associated with missed screening mammograms. METHODS: Mammography use was assessed in a population of 72,417 women who received a total of 254,818 screening mammograms at the Massachusetts General Hospital (MGH) Avon Comprehensive Breast Center (Boston, MA) between January 1, 1985, and February 19, 2002. A computer simulation of breast carcinoma growth, spread, and detection of breast carcinoma was used to estimate the likely health consequences of various types of screening use. RESULTS: Both prompt return for annual screening and full use of screening over extended periods of time were rare, and comparison of the MGH population with other populations revealed that the low level of use observed in the MGH population was not atypical. Only 6% of women who received a mammogram in 1992 received all annual mammograms that were available over the next 10 years; the mean number of mammograms received during this period was 5.06, or 51% of the number recommended by the American Cancer Society. Computer simulation results indicate that this underutilization of screening should result in higher mortality levels. Women from traditionally underserved socioeconomic, racial, and ethnic groups, women without insurance, and women who did not speak English had lower levels of use compared with other women. Lower levels of use also were observed among women receiving their first mammogram or who in the past had not returned promptly. Women ages 55-65 years had higher levels of use than did younger or older women. Women who previously had breast carcinoma also had higher levels of screening use. Nonetheless, none of the subpopulations of women stratified by age, race, ethnicity, zip code, income,language, insurance, status, previous screening use, or medical history exhibited a widespread propensity to promptly return for annual screening over an extended period of time. CONCLUSIONS: By many measures, the current analysis is one of the most detailed descriptions of screening use to date. The authors observed a level of screening use that was disappointingly low, with potentially negative health-related consequences, among women across categories defined by racial, ethnic, socioeconomic, and geographic characteristics; insurance status; language; age; medical history; and previous screening use. Improvements in the promptness with which women return to screening appear to have the potential to lead to considerable reductions in breast carcinoma death.