Diagnostic mammography performance and race
Outcomes in Black and White women
Article first published online: 15 NOV 2005
Copyright © 2005 American Cancer Society
Volume 104, Issue 12, pages 2671–2681, 15 December 2005
How to Cite
Yankaskas, B. C. and Gill, K. S. (2005), Diagnostic mammography performance and race. Cancer, 104: 2671–2681. doi: 10.1002/cncr.21550
- Issue published online: 8 DEC 2005
- Article first published online: 15 NOV 2005
- Manuscript Accepted: 19 JUL 2005
- Manuscript Revised: 22 JUN 2005
- Manuscript Received: 10 MAR 2005
- NCI. Grant Number: U01CA70040
- diagnostic mammography;
- breast cancer
A previous study compared the performance (sensitivity, specificity, positive predictive value, and cancer detection rate) of screening mammography in Black and White women. No study, to the authors' knowledge, has evaluated the difference in the performance of diagnostic mammography between Black and White women.
Univariate analysis was used to evaluate differences in characteristics and cancers between Black and White women. Stratified and adjusted logistic regression analyses were used to test the association of Black and White race with performance measures of diagnostic mammography.
The sensitivity of diagnostic mammography was higher (91% vs. 84%) and specificity was lower (86% vs. 90%) among Black women compared with White women. After controlling for age, density, self-reported breast problems, and previous mammography, sensitivity was significantly higher (odds ratio [OR] = 1.82, 95% confidence interval [CI] = 1.22–2.80) and specificity was significantly lower (OR = 0.75, 95% CI = 0.70–0.81) among Black women. The crude cancer detection rate of mammography was higher for Black women (42.6/1000) than for White women (31.0/1000) and Black women had a higher proportion of cancers that were > 2.0 cm (57.4% vs. 46.2%) that were more often poorly differentiated (61.7% vs. 49.3%) and were more often estrogen-receptor and progesterone-receptor negative.
Black women have lower specificity of diagnostic mammography and, consequently, more unnecessary workups than White women. Black women have higher sensitivity of diagnostic mammography, with cancers that are larger and more advanced than White women. Delay in responding to signs and symptoms would explain the size and later stage. However, more research is needed to understand the biologic differences of breast cancer characteristics between Black and White women. Cancer 2005. © 2005 American Cancer Society.
Diagnostic mammography consists of extra views in addition to the standard 2-view (cranial–caudal and mediolateral view) screening study and is performed when women are seen for signs or symptoms or as continued workup after an indeterminate or positive screening study. Women may present with lump, discharge, pain, or skin changes. Because of increased scrutiny of diagnostic mammograms, and higher prevalence of signs and symptoms in the population, diagnostic mammography has been shown to have higher sensitivity and positive predictive value (PPV), and lower specificity, than screening mammography.1, 2
There have been only a few studies published on performance of diagnostic mammography.1–4 There was no published study found that compared diagnostic mammography in Black compared with White women. A previous population-based study on screening mammography performance from the Carolina Mammography Registry (CMR) found no difference in sensitivity, specificity, or PPV of screening mammography between Black and White women.5 However, the study found that Black women who reported symptoms before their screening mammograms had larger, higher grade tumors when compared with White women who reported symptoms. The authors suggest that Black women may have a longer delay in screening after the onset of symptoms than White women. We were interested in whether these findings comparing screening performance in Black and White women would persist for diagnostic mammography.
There is no reason to believe and no data to show that mammographic images of Black women differ from White women. There should be no difference in the sensitivity or specificity of diagnostic mammogram for Black women compared with White women, unless it is related to the risk of cancer or characteristics of the women themselves. In addition to examining the difference in performance of diagnostic mammograms between Black and White women, we were also interested in testing whether cancer outcomes from diagnostic mammography would differ for Black and White women, as seen previously in screening mammography.
MATERIALS AND METHODS
Data for this study came from CMR, a population based mammography registry that links prospectively collected mammography data with population-based cancer data.6 The data were limited to all diagnostic mammograms in CMR performed for Black and White women between January 1, 1994 and December 31, 2000 and were further restricted to only women who were residents of North Carolina. A mammogram was considered to be diagnostic if it was classified as symptomatic or diagnostic by the radiologist or technologist at the time of the study. Mammograms were excluded if women were younger than 25 years of age, had a history of implants, or a personal history of breast cancer. They were also excluded if a valid ACR/BI-RADS™ (American College of Radiology Breast Imaging Reporting and Data System, Reston, VA) assessment code was missing.7 The patient provided demographic information and history through a self-administered questionnaire at the beginning of the imaging visit. The technologist and radiologist, at each visit, recorded the reason for the patient visit, assessment of the diagnostic mammogram, and recommendations for future evaluations.
Patient's age was categorized into five mutually exclusive categories, 25–39 years, 40–49 years, 50–59 years, 60–69 years, and ≥ 70 years. A missing response was coded as a negative response to questions about self-reported history, including personal history of breast cancer, first-degree family history of breast cancer, history of breast problems, breast implants, or use of hormones. Self-reported breast problems included presence of lump, discharge, and other (excluding pain). When symptoms were evaluated specifically, the categories were mutually exclusive: 'lump only', 'discharge only' and 'other', which included women who had both a lump and discharge or had some other symptom. We understand that women report symptoms and signs; we use the term “symptoms” to refer to both.
Women chose one unique race from a list of racial groups. A woman's history of previous mammography was based on prior mammography present in the database. The woman's self-report was used if no record of a prior mammogram existed in the database. If there were no data present indicating previous mammography and the date of previous mammography could not be determined by self-report, it was assumed that the woman did not have previous mammography. Each woman was assigned rural or urban status based on her residential zip code, by using the Metropolitan Statistical Area score determined by the Federal Office of Management and Budget, following a set of official standards published by the interagency Federal Executive Committee on Metropolitan Areas.8 A woman's self-reported education attainment level was categorized into three groups: 1) less than high school, 2) high school graduate and/or some college, and 3) college graduate.
Breast density and assessment of diagnostic mammography were coded according to the BI-RADS assessments. Breast density was categorized into four categories: 1) extremely dense, 2) heterogeneously dense, 3) scattered fibroglandular densities, and 4) almost entirely fat. Assessments of diagnostic mammograms were categorized as follows: 0, needs further evaluation; 1, normal; 2, benign finding; 3, probably benign; 4, suspicious abnormality; and 5, suspicious for cancer. The radiologist made recommendations for additional workup based on evaluation of the diagnostic mammogram. Recommendations included ultrasound, magnetic resonance imaging (MRI), computed tomography (CT), biopsy, and surgical consult. The radiologist also made recommendations for the timing of the additional workup, either immediate, short-term (< 6 mos), or routine (1 yr, 2 yrs, or age 40 yrs).
Diagnostic mammography data were linked on a unique identifier to a database containing information about the breast cancer status of women. The assignment of identification (ID) to women in both databases was accomplished by computer software package, Matchware (MatchWare, Inc., Tampa, FL). The breast cancer database contained data compiled from three different sources, the North Carolina Central Cancer Registry, pathology labs, and from the mammography facilities. The breast cancer database contained extensive information on the pathologic characteristics of the tumors, including tumor size, grade, progesterone receptor status, estrogen receptor status, and type of cancer (invasive or ductal carcinoma in situ). Both the mammography data and the pathology data go through extensive quality control at various stages of data collection and data management. All identifying information for patients, radiologists, and facilities had been removed from the data set before any analyses were performed. Protection of identifying information was strictly adhered to, as outlined by Carney.9 CMR has been approved annually by the University of North Carolina at Chapel Hill School of Medicine Institutional Review Board (IRB) and by the IRBs of other participating hospitals. CMR also holds a Public Health Service (PHS) certificate of confidentiality.
To determine the performance of diagnostic mammography, each diagnostic mammogram was initially categorized as true positive (TP), false negative (FN), true negative (TN), and false positive (FP) according to the BI-RADS code assigned by the radiologist and the cancer outcome in the follow-up period. The follow-up period was defined as one calendar year after the date of the diagnostic mammogram. This definition corresponds to the follow-up period that is commonly used for screening mammography. A positive diagnostic mammogram was one in which the BI-RADS code assigned by the radiologist was a 0, 4, or 5, or a BI-RADS of 3, when associated with a recommendation of immediate follow-up. All other diagnostic mammograms were considered to be negative at the time of assessment. A positive diagnostic mammogram with a cancer diagnosis of ductal carcinoma in situ (DCIS) or invasive cancer in the follow-up period was considered a true positive. All other positive cancers were false positive. A negative diagnostic mammogram with no cancer in the follow-up period was categorized as a true negative; if cancer was detected in the follow-up period, the negative diagnostic mammogram was considered a false negative.
Initially, a descriptive analysis was performed of characteristics of the women associated with the diagnostic mammograms and of signs and symptoms that these women reported. Performance measures were calculated including sensitivity, specificity, cancer detection rate, and PPV. Sensitivity was calculated as the proportion of positive diagnostic mammograms among women who had a cancer diagnosis in the follow-up period [TP/(TP + FN)]. Specificity was calculated as the proportion of negative diagnostic mammograms among women who did not have a cancer diagnosis in the follow up period [TN/(TN + FP)]. The cancer detection rate was calculated as the number of true positive diagnostic mammograms divided by the total number of diagnostic mammograms [TP/(TP + FN + TN + FP)]. PPV was calculated as the proportion of diagnostic mammograms with a diagnosis of breast cancer in the follow-up period compared with all positive diagnostic mammograms [TP/(TP + FP)].
Sensitivity, specificity, and PPV were evaluated separately in logistic regression models, using the covariates of age, breast density, any self-reported breast symptoms, previous mammography, and racial group. These covariates (excluding race) have been shown to influence performance of screening mammography in previous studies.9–15 These covariates are likely to influence diagnostic mammography in a similar manner. All models were run using the PROC GENMOD procedure in SAS (SAS Institute, Cary, NC).16 For sensitivity, we restricted the data to diagnostic mammograms among women with a cancer diagnosis in the follow-up period and estimated the odds ratio (OR) for a TP diagnostic assessment versus a FN diagnostic assessment for each level of a covariate. For specificity, the data were restricted to all negative diagnostic mammograms and the OR was estimated for a TN diagnostic assessment versus a FP diagnostic assessment for each level of a covariate. For PPV, the data were restricted to all positive diagnostic mammograms, and the OR was estimated for a TP diagnostic assessment versus a FP diagnostic mammogram for each level of a covariate. An OR > 1.00 indicated better performance for any one stratum compared with the reference group. The ratio of the odds for a correct interpretation in a given variable category relative to a reference category was calculated after controlling for all other covariates in the model. Results from all logistic models were tested for significance at the 0.05 significance level.
For those women who developed cancer in the follow-up period, we described the cancer characteristics by racial group. We evaluated whether there were any differences between Black and White women in terms of type of breast cancer (DCIS or Invasive), tumor grade, estrogen receptor status, progesterone receptor status, and tumor size, by using univariate chi-square statistics.
Demographics and Health History
For the years 1994–2000, there were a total of 9488 diagnostic mammograms for 8245 Black women and 47,182 diagnostic mammograms for 37,292 White women in CMR. Restricting the data to mammograms of Black and White women 25 years of age or older with no personal history of breast cancer and no history of breast implants yielded 46,984 diagnostic mammograms from 40,751 women. The results cited for Black and White women heretofore refer to the mammograms among Black and White women. Comparing mammograms among Black to those of White women (Table 1), Black women were younger (67.8% of Black women were < 50 yrs of age compared with 52.7% of White women); they were less educated (15.6% of Black women received less than a high school education compared with 7.3% of White); they had a higher proportion living in rural locations (41.3%) compared with White women (38.2%); they had a lower proportion with a history of breast procedures (26.9% vs. 34.7%); and Black women were less likely than White women to have had a previous mammography examination (70.8% vs. 83.5%). There was little difference in reported family history of breast cancer. The numbers in this study are very large; consequently, most differences between Black and White women were statistically significant. The absolute differences should be considered.
|Characteristics||Black women||White women||Total|
|Family Hx breast cancer|
|Scat. fibrogland. dens.||3170||36.8||14,302||37.3||17,472|
|Self-reported breast problems|
The distribution of breast density among the mammograms showed only a slightly lower proportion of dense breasts for Black women (52.9%) compared with White women (55.6%) (Table 1). Symptoms were reported for 85% of Black women and 80% of White women. The proportion reporting a lump was very close for Black women (43.5%) and White women (42.2%). Reporting of discharge alone was infrequent overall (3.6%) and higher in Black women than White women (5.1%, vs. 3.3%). Rates for lump and discharge were higher for Black women in every age group.
Cancer Detection Rates
Cancer detection rates overall were 42.6/1000 for Black women and 31.0/1000 for White women. The rates were higher in Black compared with White in every subgroup evaluated (Table 2). The largest differences were in the youngest and oldest age groups: Black women younger than 40 years of age had cancer detection rates that were 1.8 times higher than White women in the same age group; Black women in the age categories 60–69 and ≥ 70 had cancer detections rates that were 1.9 and 1.8 times higher, respectively, when compared with White women in the same age categories.
|Black women||White women||Ratio B/W|
|No. cancers||Cancer detection rate/1000 mammogramsa||No. cancers||Cancer detection rate/1000 mammogramsa|
|Family Hx breast cancer|
|Scat. fibrogland. dens.||158||47.9||614||37.8||1.3|
|Self-reported breast problems|
Reporting any symptom at presentation for diagnostic mammography was associated with a significantly higher cancer detection rate for Black (47.3/1000) compared with White women (34.9/1000). The majority of cancers detected are related to presence of a lump: the cancer detection rate among the women who were positive for lump was 72.4/1000 for Black women and 51.2 for White women. Women reporting only discharge had cancer detection rates, for Black and White women of 18.1/1000 and 12.7/1000, respectively, very close to the rate in women without symptoms, 15.2/1000 and 14.5/1000. Women with no problems or discharge alone had the lowest cancer detection rates.
When there was a positive history of breast procedures associated with the mammograms, detection rates were similar (27.7/1000 for Black women and 24.2/1,000 for White women). When the history was negative for history of breast procedures, Black women had significantly higher cancer detection rates (48.1/1000) than White women (34.5/1,000). Black women in urban areas had cancer detection rates (45.0/1000) that were 5% higher than cancer detection rates for Black women in rural areas (39.3/1000). For White women, the difference in cancer detection rates between urban (31.1/1000) and rural women (30.6/1000) was only 1%.
Overall, sensitivity among diagnostic mammograms was higher for Black women (91%) than for White women (84%), specificity was lower in Black women (86%) than in White women (90%), and PPV was 25% for both Black and White women (Table 3)
|Patient characteristic||Sensitivity (95% CI)||Specificity (95% CI)||PPV (95% CI)|
|Total Age||0.91 (0.88–0.94)||0.84 (0.82–0.86)||0.86 (0.85–0.87)||0.90 (0.89–0.90)||0.25 (0.23–0.27)||0.25 (0.24–0.26)|
|< 40||0.89 (0.82–0.96)||0.88 (0.83–0.94)||0.85 (0.84–0.86)||0.88 (0.88–0.89)||0.14 (0.11–0.17)||0.10 (0.09–0.12)|
|40–49||0.90 (0.84–0.95)||0.82 (0.78–0.86)||0.86 (0.85–0.87)||0.90 (0.89–0.90)||0.19 (0.16–0.23)||0.17 (0.15–0.19)|
|50–59||0.91 (0.85–0.98)||0.83 (0.79–0.87)||0.89 (0.87–0.91)||0.91 (0.91–0.92)||0.30 (0.24–0.37)||0.27 (0.24–0.30)|
|60–69||0.89 (0.81–0.97)||0.79 (0.74–0.84)||0.89 (0.87–0.91)||0.92 (0.92–0.93)||0.43 (0.34–0.52)||0.35 (0.32–0.39)|
|≥ 70||0.96 (0.89–0.99)||0.90 (0.87–0.93)||0.85 (0.82–0.88)||0.91 (0.90–0.92)||0.53 (0.45–0.61)||0.50 (0.46–0.54)|
|Family Hx breast cancer|
|Yes||0.97 (0.85–1.00)||0.77 (0.71–0.84)||0.88 (0.86–0.90)||0.90 (0.89–0.91)||0.27 (0.19–0.36)||0.28 (0.24–0.32)|
|Noa||0.91 (0.88–0.94)||0.85 (0.83–0.87)||0.86 (0.86–0.87)||0.90 (0.90–0.91)||0.25 (0.22–0.27)||0.24 (0.24–0.26)|
|Yes||0.84 (0.76–0.92)||0.77 (0.73–0.81)||0.86 (0.86–0.87)||0.90 (0.89–0.90)||0.17 (0.14–0.22)||0.20 (0.18–0.22)|
|Noa||0.93 (0.90–0.95)||0.87 (0.85–0.89)||0.86 (0.85–0.88)||0.90 (0.90–0.91)||0.27 (0.25–0.30)||0.27 (0.26–0.29)|
|Yes||0.90 (0.87–0.94)||0.82 (0.80–0.84)||0.88 (0.88–0.89)||0.91 (0.91–0.92)||0.24 (0.21–0.27)||0.25 (0.24–0.26)|
|Noa||0.92 (0.88–0.96)||0.93 (0.90–0.95)||0.81 (0.80–0.83)||0.85 (0.84–0.86)||0.26 (0.22–0.30)||0.24 (0.22–0.27)|
|Extremely dense||0.78 (0.58–0.91)||0.76 (0.69–0.84)||0.83 (0.81–0.85)||0.88 (0.87–0.89)||0.11 (0.07–0.17)||0.15 (0.12–0.18)|
|Heterogeneously dense||0.90 (0.86–0.95)||0.82 (0.79–0.85)||0.86 (0.85–0.87)||0.90 (0.90–0.90)||0.24 (0.20–0.27)||0.22 (0.20–0.24)|
|Scat. fibrogland. dens.||0.96 (0.93–0.99)||0.88 (0.86–0.91)||0.88 (0.87–0.89)||0.92 (0.91–0.92)||0.30 (0.26–0.34)||0.32 (0.30–0.34)|
|Entirely fat||0.88 (0.62–0.98)||0.85 (0.69–0.95)||0.91 (0.89–0.94)||0.94 (0.93–0.96)||0.28 (0.16–0.42)||0.28 (0.20–0.38)|
|Missing||0.85 (0.73–0.96)||0.87 (0.79–0.95)||0.79 (0.75–0.83)||0.84 (0.82–0.86)||0.28 (0.20–0.37)||0.22 (0.17–0.27)|
|Self–reported breast problems|
|Any problem||0.91 (0.89–0.94)||0.85 (0.83–0.87)||0.86 (0.85–0.87)||0.89 (0.89–0.90)||0.26 (0.24–0.28)||0.26 (0.24–0.27)|
|Lumpb||0.92 (0.89–0.96)||0.87 (0.84–0.89)||0.82 (0.81–0.83)||0.87 (0.86–0.87)||0.31 (0.28–0.34)||0.29 (0.27–0.30)|
|Dischargeb||0.67 (0.35–0.90)||0.53 (0.35–0.71)||0.87 (0.84–0.91)||0.91 (0.90–0.93)||0.13 (0.06–0.24)||0.13 (0.08–0.20)|
|Other problemsc||0.91 (0.84–0.97)||0.83 (0.78–0.87)||0.89 (0.88–0.91)||0.93 (0.92–0.93)||0.18 (0.14–0.22)||0.20 (0.17–0.22)|
|No problema||0.86 (0.65–0.97)||0.79 (0.73–0.86)||0.91 (0.89–0.92)||0.94 (0.93–0.94)||0.14 (0.09–0.21)||0.19 (0.16–0.23)|
Sensitivity generally increased with age for Black women. In contrast, for White women, sensitivity was highest in the youngest (< 40) and oldest (≥ 70) age groups and lower in intermediate age groups (40–69 yrs). For both Black and White women, the sensitivity was higher in the presence of breast symptoms compared with no breast symptoms and was very low when the only symptom was discharge (not significantly lower in Black women, most likely because of the small number of cancers, but significantly lower in White women.) Sensitivity was higher with a negative history of previous breast procedures compared with a positive history of breast procedures.
Overall specificity of the mammograms was lower for Black women compared with White women, and this relation persisted across strata of all covariates. Overall PPV of the mammograms was similar for Black and White women and tended to be similar across strata of covariates. The PPV was lowest when the symptom was discharge, and the PPV in presence of lump was significantly higher than in presence of discharge for Black and White women.
Comparisons of sensitivity, specificity, and PPV, using logistic regression models, controlling for the covariates age, density, any self-reported breast problems, and previous mammography revealed that sensitivity was significantly higher (OR = 1.82, 95% CI = 1.22–2.80), specificity was significantly lower (OR = 0.75, 95% CI = 0.70–0.81), and PPV was marginally higher (OR = 1.12, 95% CI = 0.96–1.31) when comparing mammograms of Black women with White women (Table 4)
|Probability of (+) mammogram given disease||Probability of (−) mammogram given no disease||Probability of disease, given (+) mammogram|
|No.||OR||95% CI||No.||OR||95% CI||No.||OR||95% CI|
|White women||1338||1.00||(ref. group)||35,622||1.00||(ref. group)||4502||1.00||(ref. group)|
|Age < 40||67||0.21||0.03–0.94||2555||1.33||0.99–1.78||430||0.13||0.08–0.20|
|≥ 70||77||1.00||(ref. group)||475||1.00||(ref. group)||140||1.00||(ref. group)|
|Yes||216||1.00||(ref. group)||5576||1.00||(ref. group)||822||1.00||(ref. group)|
|Scat. fibrogland. dens.||158||5.08||0.67–26.67||3012||0.67||0.46–0.95||504||1.59||0.81–3.28|
|Entirely fat||16||1.00||(ref. group)||419||1.00||(ref. group)||50||1.00||(ref. group)|
|Any self-reported breast probs.|
|Yes||352||1.00||(ref. group)||6629||1.00||(ref. group)||1248||1.00||(ref. group)|
|Age < 40||119||0.84||0.42–1.74||8173||1.01||0.87–1.16||1057||0.10||0.08–0.13|
|≥ 70||377||1.00||(ref. group)||3919||1.00||(ref. group)||662||1.00||(ref. group)|
|Yes||1054||1.00||(ref. group)||29,828||1.00||(ref. group)||3402||1.00||(ref. group)|
|Scat. fibrogland. dens.||614||1.53||0.50–3.84||13,688||0.63||0.49–0.79||1682||1.50||0.95–2.42|
|Entirely fat||34||1.00||(ref. group)||1303||1.00||(ref. group)||104||1.00||(ref. group)|
|Any self-reported breast probs.|
|Yes||1210||1.00||(ref. group)||28,572||1.00||(ref. group)||3983||1.00||(ref. group)|
The proportion of DCIS among all cancers was only slightly lower for Black women compared with White women, with DCIS detected in 5.7% of Black women and 6.8% of White women (P = 0.43) (Table 5). Among invasive cancers however, Black women had a significantly higher proportion of higher grade cancers than White women; 61.7% had poorly differentiated tumors compared with 49.3% of White women (P < 0.001). Black women also had a higher proportion of cancers that were > 2.0 cm compared with White women, 57.4% vs.46.2%, (P = 0.015). In addition, among Black women, a significantly higher proportion of cancers were ER negative and PR negative when compared with tumors of White women.
|No.||% of nonmissinga||No.||% of nonmissinga||P value|
|Well differentiated||16||7.2||121||14.2||< 0.001b|
|Missing (% missing)||158||(41.6)||461||(35.2)|
|Estrogen receptor status|
|Not done/missing (% missing)||188||(49.5)||650||(49.6)|
|Progesteron receptor status|
|Not done/missing (% missing)||191||(50.3)||661||(50.4)|
|≤ 10 mm||51||19.4||171||18.8||0.015b|
|> 30 mm||79||30.0||206||22.7|
|Missing (% missing)||117||(30.8)||402||(30.7)|
The objective of this study was to compare performance of diagnostic mammography in Black women with White women from a large population-based mammography registry. At the time of diagnostic mammography exam, information collected included personal information about the women's medical and family histories, the results and recommendations of the imaging examinations performed, and cancer and benign outcomes. In comparing performance of diagnostic mammography, we found that mammograms of Black women, compared with White women, had higher sensitivity, lower specificity, equal PPV, and a greater proportion of larger, higher stage cancers. In our study, after controlling for previous mammography, age, breast density, and self-reported breast symptoms in the logistic models, there continued to be differences in performance of diagnostic mammography between Black and White women.
Black women also had a larger proportion of larger, higher grade, ER- and PR-tumors. There was a large amount of missing size and grade data for mammograms in both Black and White women; however, the proportion of missing data was similar for Black and White women. Other studies conducted in different populations have found similar associations of cancer characteristics comparing Black and White women. These studies also reported that cancers in Black women are larger, higher grade and have a higher proportion of ER and PR negativity when compared with White women.10, 17, 18
In our previous study of screening mammography, we found no differences in screening performance when comparing mammography between Black and White women. We did find similar but smaller differences between Black and White women in tumor characteristics such as size, stage, ER status, and PR status.5 A few studies have reported performance of diagnostic mammography but not for Black and White women separately.1, 2 These studies were undertaken in predominantly White or mixed non-Black populations. Performance estimates of diagnostic mammography in these studies are similar to performance measures of diagnostic mammography in White women in our study.
Specificity was lower for mammography in Black women compared with White women. The lack of a previous mammogram, (29.2% for Black women, 16.5% for White women) results in more false positive results. Radiologists are more likely to work up a suspicious finding when no previous films are present.19–23
Sensitivity is higher in diagnostic mammography than in screening mammography.2, 24, 25 These differences are most likely related to greater presence of symptoms and larger size of tumors that are found in diagnostic mammography.2, 26 Presence of a lump raises the probability of a cancer diagnosis27 and is one explanation for the higher sensitivity in diagnostic mammography. Another explanation for the difference in sensitivity between screening and diagnostic mammography is the difference in absolute size of the tumor. Although there were differences in tumor size in Black and White women in our previous study on screening mammography, these differences did not result in an appreciable difference in the sensitivity of screening mammography of Black and White women.5 In diagnostic mammography, where the tumors that are found are larger in size (and are larger in Black women than in White women), the sensitivity of diagnostic mammography is greater for Black women than for White women.1
Whereas Black women had slightly larger proportions of all symptoms (lump, discharge, and symptoms overall), we believe it is tumor size that drives the sensitivity and cancer detection rates in the diagnostic setting. Fifty-seven percent of Black women had invasive tumors > 2 cm, compared with 46.2% of White women. The proportion who reported lump was very similar; however, the cancer detection rate among Black women with a lump was 72.4/1000 compared with 51.2/1000 for White women. Other research in a variety of populations has also shown the relation between tumor size, grade, higher sensitivity, and cancer detection rates.28–34 Although more Black women reported discharge (the values for Black women and White women were 5.1% and 3.3%, respectively), the absolute proportions are too small to account for the difference in performance measures. Cancer detection rates in the presence of discharge were much lower than for lump and similar to detection rates that were found when no specific problem was recorded for Black and White women. The few published studies on discharge and mammography performance were conducted on case series only.35, 36
We are left with the question of why Black women present with larger tumors. Is it because they have faster growing tumors or do Black women as a group wait longer to get evaluated for their symptoms? The literature suggests that there are several factors operating. In a few studies, it has been shown that larger proportions of Black women, compared with White women, do not have a previous screening mammogram at the time of their diagnostic mammogram or are less likely to have had a screening mammogram within the previous 3 years.30, 32, 33 In addition, Black women wait longer to be seen for symptoms.28, 29, 37 As the ER and PR have a higher proportion of negativity, it is possible that there is something different about the cancers at a genetic or molecular level, which has yet to be identified. The differential roles of biologic, cultural, and other factors in the risk for and detection of breast tumors need to be further investigated.
In conclusion, in studying the performance of diagnostic mammography needs when symptoms are present, we found differences in results for mammograms of Black and White women in a community-based mammography registry. Black women have larger, higher grade tumors that lead to higher sensitivity, higher cancer detection rates, and lower specificity. Biologic contributions cannot be ruled out. In the short term, Black women need to be encouraged to respond more quickly when discovering breast signs or symptoms that need to be evaluated. Screening has been increasing among Black women, and this trend may reduce the disparities seen in this study.
- 6The Carolina Mammography Registry: A population-based mammography and cancer surveillance project. J Registry Manag. 1996; 23: 173–178., , .
- 7D'Orsi CJ, Bassett L, Feig SA, et al. editors. Breast Imaging Reporting and Database System. Reston: American College of Radiology, 1998.
- 16Categorical data analysis using the SAS system. 2nd ed. Cary, NC: SAS Institute Inc., 2000., , .