False-Positive Mammograms: A Barrier to Annual Screening?

Institution: Cancer Prevention Institute of California
Investigator(s): Phillip Gardiner, DrPH -
Award Cycle: 1995 (Cycle I) Grant #: 1KB-0124 Award: $117,783
Award Type: New Investigator Awards
Research Priorities
Detection, Prognosis and Treatment>Imaging, Biomarkers, and Molecular Pathology: improving detection and diagnosis



Initial Award Abstract (1995)
This research proposes to measure the extent and assess the psychological and behavioral impacts of false-positive mammography results among underserved African American women. Studies continue to show that African American women have a lower incidence of breast cancer but a disproportionately high rate of mortality from this disease compared to white women. Late stage at diagnosis has been one of the main factors cited for this disparity. Evidence suggests that even though African American women have increased use of initial mammography screening, they may not adhere to recommended annual screening over time. Additionally, the low incidence of breast cancer, combined with greater use of initial screening is expected to yield numerous false-positive results among African American women. Due to the problems poor women encounter in trying to obtain medical care, it is the hypothesis of this study that the experience of a false-positive mammogram combined with all that is involved in resolving the abnormality is a deterrent to subsequent screening, and thus may be a factor in disproportionate mortality among African American women.

This study seeks to: 1) analyze the distribution of false-positive mammography results across racial/ethnic groups of underserved women; 2) establish the positive predictive value (PPV) of the BCCCP (Breast and Cervical Cancer Control Program) mammography screening (PPV is the likelihood that an abnormal mammogram has actually detected cancer); 3) assess the relationship between false-positive results and subsequent screening practices; and 4) identify the psychological and behavioral impact of false-positives in African American women.

Using data from the State of California's BCCCP, a cross-sectional analysis (i.e., assessment of data at one point in time) will compare rates of false positive mammograms across race/ethnic groups for the period 1992 to 1997. Second, a cohort study of BCCCP participants who have had false positive mammograms will be followed up for a period of three years to assess the relationship of the false-positive and subsequent screening. Third, a telephone interview of 100 African American women who had a false-positive and a matched sample of 100 whose results were normal will be conducted to compare the attitudes, intentions, and behaviors of these two groups and to further illuminate the potential impact of the result on routine screening.

Innovative interventions directed at populations most at risk for false-positives can improve and expand the early detection of breast cancer. This intervention can lay the basis for the development of educational material about false-positive mammography screening. Better informed and educated women can improve and expand their cancer screening practices. Research that addresses the racial disparity in breast cancer mortality can be instrumental in reducing human toll and misery from this disease.


Final Report (1998)
The specific aims of this study were to: 1 ) analyze the distribution of false-positive mammography results across racial/ethnic groups of underserved women; 2) establish the positive predictive value (PPV) of the State of California Breast and Cervical Cancer Control Program's (BCCCP) mammography screening test (PPV is the total number of true positives (cancers) divided by all positive mammogram test results); 3) assess the relationship between false-positive results and subsequent screening practices; and 4) identify the psychological and behavioral impact of false-positives in African American women. This study was terminated after 18 months, because the Principal Investigator changed jobs and was unable to continue research on this grant.

However, BCCCP mammography screening records (n=26,019) for the years 1992-1995 for women 18 years of age and older were analyzed. The racial composition of the sample was: 42% Latina; 29% white: 16% Asian American; 7% African American; 3% Native American; and 3% "other." The data set showed that 2012 women (7.73%) had had a false-positive mammogram. Analyzing women returning for routine mammograms, showed that a prior false-positive result did not predict subsequent screening; there was no significant difference in women returning for mammograms when women with false-positives were compared to women without. Additionally, we have found that the positive-predictive value of the BCCCP mammography test, the distribution of false-positives, and the proportion of women returning for annual screening differed by race/ethnicity.

Since, the study was terminated after 18 months there is only cursory data to assess the psychological and behavioral impact of false-positives among African American women. Our original hypothesis stated that false-positive mammograms might decrease adherence to cancer screening guidelines, especially among underserved women. The findings for this study show that women, who received abnormal mammography results, but did not have cancer, were just as likely as women with negative results to return for subsequent non-diagnostic mammograms. In a previous progress report we stated that women with false-positives were returning more often and sooner for regular screening. But on closer data analysis we find no statistical difference between the two groups. Mammography is not an exact science; for every 1000 women age 50 and older screened for the first time, 71 examinations will be abnormal, yet only 10 cancers will be found. Clearly, better tests need to be developed for the early detection of breast cancer. But until more exact tests are developed, our investigation shows that false positive mammograms do not necessarily deter women from returning for regular mammograms.