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William E Barlow

Publications and source records attributed to William E Barlow.

At least 19 recordsLinked to original sources
PubMed2007

Reoperation as a quality indicator in colorectal surgery: a population-based analysis.

OBJECTIVE: To describe unplanned procedures following colorectal cancer surgery that might be used as intermediate outcome measures, and to determine their association with mortality and length of stay. SUMMARY BACKGROUND: Variation in the quality of surgical care, especially for common illnesses like colorectal cancer, has received increasing attention. Nonfatal complications resulting in procedural interventions are likely to play a role in poor outcomes but have not been well explored. METHODS: Cohort analysis of 26,638 stage I to III colorectal cancer patients in the 1992 to 1996 SEER-Medicare database. INDEPENDENT VARIABLES: sociodemographics, tumor characteristics, comorbidity, and acuity. PRIMARY OUTCOME: postoperative procedural intervention. ANALYSIS: Logistic regression identified patient characteristics predicting postoperative procedures and the adjusted risk of 30-day mortality and prolonged hospitalization among patients with postoperative procedures. RESULTS: A total of 5.8% of patients required postoperative intervention. Patient characteristics had little impact on the frequency of postoperative procedures, except for acute medical conditions, including bowel perforation (relative risk [RR] = 3.0, 95% confidence interval [CI] = 2.5-3.6), obstruction (RR = 1.6; 95% CI = 1.4-1.8), and emergent admission (RR = 1.3; 95% CI = 1.1-1.4). After a postoperative procedure, patients were more likely to experience early mortality (RR = 2.4; 95% CI = 2.1-2.9) and prolonged hospitalization (RR = 2.2; 95% CI = 2.1-2.4). The most common interventions were performed for abdominal infection (31.7%; RR mortality = 2.9; 95% CI = 2.3-3.7), wound complications (21.1%; RR mortality = 0.7; 95% CI = 0.4-1.3), and organ injury (18.7%; RR mortality = 1.6; 95% CI = 1.1-2.3). CONCLUSIONS: Postoperative complications requiring additional procedures among colorectal cancer patients correlate with established measures of surgical quality. Prospective tracking of postoperative procedures as complication markers may facilitate outcome studies and quality improvement programs.

Aged↗
PubMed2006

p27(Kip1) and cyclin E expression and breast cancer survival after treatment with adjuvant chemotherapy.

BACKGROUND: Abnormal expression of the cell cycle regulatory proteins p27(Kip1) (p27) and cyclin E may be associated with breast cancer survival and relapse. We studied these markers in a clinical trial setting with patients with breast cancer treated by a uniform drug regimen so that treatment was not associated with variability in outcome. METHODS: We used tissue microarrays to evaluate the expression of p27 and cyclin E proteins by immunohistochemistry in tumor tissue from 2123 (68%) of 3122 patients with moderate-risk primary breast cancer who were enrolled in Southwest Oncology Group-Intergroup Trial S9313, in which patients were assigned to receive doxorubicin and cyclophosphamide administered concurrently (n = 1595) or sequentially (n = 1527). Disease-free and overall survival were equivalent in the two arms. Expression of the proteins was rated on a scale of 1-7, and the median value was used as the cut point. Log-rank tests and Cox regression analyses were used to assess associations with survival. Overall survival was defined as time to death from all causes; disease-free survival was defined as time to recurrence or death. All P values were from two-sided statistical tests. RESULTS: Lower p27 expression was associated with worse overall survival (unadjusted hazard ratio [HR] = 1.50, 95% confidence interval [CI] = 1.21 to 1.86) and disease-free survival (unadjusted HR = 1.31, 95% CI = 1.10 to 1.57) than higher p27 expression. Among hormone receptor-positive patients, lower p27 expression was associated with worse overall survival (HR = 1.42, 95% CI = 1.05 to 1.94) and worse disease-free survival (HR = 1.27, 95% CI = 0.99 to 1.63) than higher p27 expression after adjustment for treatment, menopausal status, tumor size, and number of positive lymph nodes. Among these patients, 5-year overall survival associated with higher p27 expression (0.91, 95% CI = 0.89 to 0.93) was similar to that associated with lower p27 expression (0.85, 95% CI = 0.82 to 0.87). No association between p27 expression and survival was found in hormone receptor-negative patients. Cyclin E expression was not statistically significantly associated with overall survival (HR = 1.12, 95% CI = 0.91 to 1.38) or disease-free survival (HR = 1.09, 95% CI = 0.92 to 1.29). CONCLUSIONS: Low p27 expression appears to be associated with poor prognosis, especially among patients with steroid receptor-positive tumors.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2006

Prospective breast cancer risk prediction model for women undergoing screening mammography.

BACKGROUND: Risk prediction models for breast cancer can be improved by the addition of recently identified risk factors, including breast density and use of hormone therapy. We used prospective risk information to predict a diagnosis of breast cancer in a cohort of 1 million women undergoing screening mammography. METHODS: There were 2,392,998 eligible screening mammograms from women without previously diagnosed breast cancer who had had a prior mammogram in the preceding 5 years. Within 1 year of the screening mammogram, 11,638 women were diagnosed with breast cancer. Separate logistic regression risk models were constructed for premenopausal and postmenopausal examinations by use of a stringent (P<.0001) criterion for the inclusion of risk factors. Risk models were constructed with 75% of the data and validated with the remaining 25%. Concordance of the predicted with the observed outcomes was assessed by a concordance (c) statistic after logistic regression model fit. All statistical tests were two-sided. RESULTS: Statistically significant risk factors for breast cancer diagnosis among premenopausal women included age, breast density, family history of breast cancer, and a prior breast procedure. For postmenopausal women, the statistically significant factors included age, breast density, race, ethnicity, family history of breast cancer, a prior breast procedure, body mass index, natural menopause, hormone therapy, and a prior false-positive mammogram. The model may identify high-risk women better than the Gail model, although predictive accuracy was only moderate. The c statistics were 0.631 (95% confidence interval [CI] = 0.618 to 0.644) for premenopausal women and 0.624 (95% CI = 0.619 to 0.630) for postmenopausal women. CONCLUSION: Breast density is a strong additional risk factor for breast cancer, although it is unknown whether reduction in breast density would reduce risk. Our risk model may be able to identify women at high risk for breast cancer for preventive interventions or more intensive surveillance.

Adult↗
PubMed2006

Does utilization of screening mammography explain racial and ethnic differences in breast cancer?

BACKGROUND: Reasons for persistent differences in breast cancer mortality rates among various racial and ethnic groups have been difficult to ascertain. OBJECTIVE: To determine reasons for disparities in breast cancer outcomes across racial and ethnic groups. DESIGN: Prospective cohort. SETTING: The authors pooled data from 7 mammography registries that participate in the National Cancer Institute-funded Breast Cancer Surveillance Consortium. Cancer diagnoses were ascertained through linkage with pathology databases; Surveillance, Epidemiology, and End Results programs; and state tumor registries. PARTICIPANTS: 1,010,515 women 40 years of age and older who had at least 1 mammogram between 1996 and 2002; 17,558 of these women had diagnosed breast cancer. MEASUREMENTS: Patterns of mammography and the probability of inadequate mammography screening were examined. The authors evaluated whether overall and advanced cancer rates were similar across racial and ethnic groups and whether these rates were affected by the use of mammography. RESULTS: African-American, Hispanic, Asian, and Native American women were more likely than white women to have received inadequate mammographic screening (relative risk, 1.2 [95% CI, 1.2 to 1.2], 1.3 [CI, 1.2 to 1.3], 1.4 [CI, 1.3 to 1.4], and 1.2 [CI, 1.1 to 1.2] respectively). African-American women were more likely than white, Asian, and Native American women to have large, advanced-stage, high-grade, and lymph node-positive tumors of the breast. The observed differences in advanced cancer rates between African American and white women were attenuated or eliminated after the cohort was stratified by screening history. Among women who were previously screened at intervals of 4 to 41 months, African-American women were no more likely to have large, advanced-stage tumors or lymph node involvement than white women with the same screening history. African-American women had higher rates of high-grade tumors than white women regardless of screening history. The lower rates of advanced cancer among Asian and Native American women persisted when the cohort was stratified by mammography history. LIMITATIONS: Results are based on a cohort of women who had received mammographic evaluations. CONCLUSIONS: African-American women are less likely to receive adequate mammographic screening than white women, which may explain the higher prevalence of advanced breast tumors among African-American women. Tumor characteristics may also contribute to differences in cancer outcomes because African-American women have higher-grade tumors than white women regardless of screening. These results suggest that adherence to recommended mammography screening intervals may reduce breast cancer mortality rates.

Adult↗
PubMed2006

Pathologic findings from the Breast Cancer Surveillance Consortium: population-based outcomes in women undergoing biopsy after screening mammography.

BACKGROUND: To the authors' knowledge, a comprehensive analysis of pathology outcomes after screening mammography, as it is practiced clinically in the U.S. general population, has not been performed. METHODS: Breast Cancer Surveillance Consortium data from 1996-2001 were used to identify pathology specimens that were obtained within 1 year of screening mammograms performed on 786,846 women ages 40-89 years. The pathology results were classified as invasive carcinoma, ductal carcinoma in situ (DCIS), or benign. The associations between overall pathology outcomes and invasive tumor size and lymph node status were analyzed by age and mammography assessment category. RESULTS: The rates of both recommending and performing a biopsy varied little with age. The 1,664,032 screening mammograms were followed by 26,748 known biopsies (1.6%) and 8815 diagnoses of breast carcinoma (0.53%). Overall, 81% of carcinomas were invasive, and 78% of those were pathologically lymph node-negative tumors, in contrast to the 66% prevalence observed in the Surveillance, Epidemiology, and End Results (SEER) data during the same period. Most invasive tumors measured between 0 mm and 10 mm (35%) or between 11 mm and 20 mm (36%) in greatest dimension, and 92% and 78% were lymph node-negative tumors, respectively: Biopsy results that were classified as malignant increased with age (P < 0.0001) and were most likely to follow Breast Imaging, Reporting, and Diagnosis System Category 5 and 4 assessments, respectively. Ductal hyperplasia (19.6%), fibroadenoma (18.5%), and other benign findings (56.1%) were the most common benign diagnoses. CONCLUSIONS: Pathologically negative lymph nodes were more prevalent in this mammographically screened population than in the overall SEER population. The prevalence of invasive carcinoma, DCIS, and benign findings presented herein establish a range of expected biopsy outcomes for women after screening mammography in the general U.S. population.

Adult↗
PubMed2006

Performance benchmarks for screening mammography.

PURPOSE: To retrospectively evaluate the range of performance outcomes of the radiologist in an audit of screening mammography by using a representative sample of U.S. radiologists to allow development of performance benchmarks for screening mammography. MATERIALS AND METHODS: Institutional review board approval was obtained, and study was HIPAA compliant. Informed consent was or was not obtained according to institutional review board guidelines. Data from 188 mammographic facilities and 807 radiologists obtained between 1996 and 2002 were analyzed from six registries from the Breast Cancer Surveillance Consortium (BCSC). Contributed data included demographic information, clinical findings, mammographic interpretation, and biopsy results. Measurements calculated were positive predictive values (PPVs) from screening mammography (PPV(1)), biopsy recommendation (PPV(2)), biopsy performed (PPV(3)), recall rate, cancer detection rate, mean cancer size, and cancer stage. Radiologist performance data are presented as 50th (median), 10th, 25th, 75th, and 90th percentiles and as graphic presentations by using smoothed curves. RESULTS: There were 2 580 151 screening mammographic studies from 1 117 390 women (age range, <30 to >/=80 years). The respective means and ranges of performance outcomes for the middle 50% of radiologists were as follows: recall rate, 9.8% and 6.4%-13.3%; PPV(1), 4.8% and 3.4%-6.2%; and PPV(2), 24.6% and 18.8%-32.0%. Mean cancer detection rate was 4.7 per 1000, and the median [corrected] mean size of invasive cancers was 13 mm. The range of performance outcomes for the middle 80% of radiologists also was presented. CONCLUSION: Community screening mammographic performance measurements of cancer outcomes for the majority of radiologists in the BCSC surpass performance recommendations. Recall rate for almost half of radiologists, however, is higher than the recommended rate.

Adult↗
PubMed2005

Efficacy of breast cancer screening in the community according to risk level.

BACKGROUND: The efficacy of breast cancer screening in the community may differ from that suggested by the results of randomized trials, and no data have been available on efficacy among women who have different levels of breast cancer risk. METHODS: We conducted a matched case-control study among women enrolled in six health plans in Washington, Oregon, California, Massachusetts, and Minnesota. We examined the efficacy of screening by mammography and/or clinical breast examination among women in two age cohorts (40-49 years and 50-65 years) and in two breast cancer risk levels (average and increased risk). Women who died from breast cancer from January 1, 1983, through December 31, 1998, (N = 1351; case subjects) were matched to control subjects (N = 2501) on age and risk level. Increased risk was defined as a family history of breast cancer or a breast biopsy noted in the medical records before the index date (defined as date of first suspicion of breast abnormalities in case subjects, with the same date used for matched control subjects). Data on screening, risk status, and other variables were abstracted from medical records. Conditional logistic regression was used to examine the association between breast cancer mortality and receipt of screening. All statistical tests were two-sided. RESULTS: There were small, non-statistically significant associations between breast cancer mortality and receipt of screening during the 3 years prior to the index date for both the younger women [odds ratio (OR) = 0.92; 95% confidence interval (CI) = 0.76 to 1.13] and the older women (OR = 0.87; 95% CI = 0.68 to 1.12). The association among women at increased risk (OR = 0.74; 95% CI = 0.50 to 1.03) was stronger than that among women at average risk (OR = 0.96; 95% CI = 0.80 to 1.14), but the difference was not statistically significant (P = .17). CONCLUSIONS: In this community-based study, screening history was not associated with breast cancer mortality. However, potential limitations of this study argue for a cautious interpretation of these findings.

Adult↗
PubMed2005

Current realities of delivering mammography services in the community: do challenges with staffing and scheduling exist?

PURPOSE: To evaluate the current (2001-2002) capacity of community-based mammography facilities to deliver screening and diagnostic services in the United States. MATERIALS AND METHODS: Institutional review board approvals and patient consent were obtained. A mailed survey was sent to 53 eligible mammography facilities in three states (Washington, New Hampshire, and Colorado). Survey questions assessed equipment and staffing availability, as well as appointment waiting times for screening and diagnostic mammography services. Criterion-related content and construct validity were obtained first by means of a national advisory committee of academic, scientific, and clinical colleagues in mammography that reviewed literature on existing surveys and second by pilot testing a series of draft surveys among community mammography facilities not inclusive of the study facilities. The final survey results were independently double entered into a relational database with programmed data checks. The data were sent encrypted by means of file transfer protocol to a central analytical center at Group Health Cooperative. A two-sided P value with alpha = .05 was considered to show statistical significance in all analyses. RESULTS: Forty-five of 53 eligible mammography facilities (85%) returned the survey. Shortages of radiologists relative to the mammographic volume were found in 44% of mammography facilities overall, with shortages of radiologists higher in not-for-profit versus for-profit facilities (60% vs 28% reported). Shortages of Mammography Quality Standards Act-qualified technologists were reported by 20% of facilities, with 46% reporting some level of difficulty in maintaining qualified technologists. Waiting times for diagnostic mammography ranged from less than 1 week to 4 weeks, with 85% performed within 1 week. Waiting times for screening mammography ranged from less than 1 week to 8 weeks, with 59% performed between 1 week and 4 weeks. Waiting times for both diagnostic and screening services were two to three times higher in high-volume compared with low-volume facilities. CONCLUSION: Survey results show shortages of radiologists and certified mammography technologists.

Breast Neoplasms↗
PubMed2005

Efficacy of prophylactic mastectomy in women with unilateral breast cancer: a cancer research network project.

PURPOSE: We investigated the efficacy of contralateral prophylactic mastectomy (CPM) in reducing contralateral breast cancer incidence and breast cancer mortality among women who have already been diagnosed with breast cancer. METHODS: This retrospective cohort study comprised approximately 50,000 women who were diagnosed with unilateral breast cancer during 1979 to 1999. Using computerized data confirmed by chart review, we identified 1,072 women (1.9%) who had CPM. We obtained covariate information for these women and for a sample of 317 women who did not undergo CPM. RESULTS: The median time from initial breast cancer diagnosis to the end of follow-up was 5.7 years. Contralateral breast cancer developed in 0.5% of women with CPM, metastatic disease developed in 10.5%, and subsequent breast cancer developed in 12.4%; 8.1% died from breast cancer. Contralateral breast cancer developed in 2.7% of women without CPM, and 11.7% died of breast cancer. After adjustment for initial breast cancer characteristics, treatment, and breast cancer risk factors, the hazard ratio (HR) for the occurrence of contralateral breast cancer after CPM was 0.03 (95% CI, 0.006 to 0.13). After adjustment for breast cancer characteristics and treatment, the HRs for the relationship of CPM with death from breast cancer, with death from other causes, and with all-cause mortality were 0.57 (95% CI, 0.45 to 0.72), 0.78 (95% CI, 0.57 to 1.06), and 0.60 (95% CI, 0.50 to 0.72), respectively. CONCLUSION: CPM seems to protect against the development of contralateral breast cancer, and although women who underwent CPM had relatively low all-cause mortality, CPM also was associated with decreased breast cancer mortality.

Breast Neoplasms↗
PubMed2005

A population-based study of bilateral prophylactic mastectomy efficacy in women at elevated risk for breast cancer in community practices.

BACKGROUND: Findings from several studies suggest that bilateral prophylactic mastectomy reduces breast cancer incidence by 90% or more, but the studies used highly selected patients from referral centers, and the comparison groups were not population based. We studied the efficacy of bilateral prophylactic mastectomy in women with elevated breast cancer risk cared for in community practices. METHODS: We conducted a retrospective case-cohort study of women aged 18 to 80 years with 1 or more breast cancer risk factors (family history of breast cancer, history of atypical hyperplasia, or > or =1 breast biopsies with benign findings). Using computerized data and medical records, we identified 276 women with bilateral prophylactic mastectomy and a stratified random sample of 196 women representing an underlying cohort of 666 800 women with elevated breast cancer risk without prophylactic mastectomy, and then we determined who developed breast cancer. RESULTS: Breast cancer developed in 1 woman (0.4%) after bilateral prophylactic mastectomy vs 26 800 women (4.0%) without prophylactic mastectomy. Stratifying by birth year, the hazard ratio for breast cancer occurrence after bilateral prophylactic mastectomy was 0.005 (95% confidence interval, 0.001-0.044). No woman with bilateral prophylactic mastectomy died of breast cancer vs a calculated 0.2% of women without prophylactic mastectomy. CONCLUSIONS: Bilateral prophylactic mastectomy reduced breast cancer incidence in women at elevated risk for breast cancer cared for in community-based practices. However, the absolute risk of breast cancer incidence and death in women who did not undergo the procedure in these settings was relatively low.

Adolescent↗
PubMed2005

Residual tumor uptake of [99mTc]-sestamibi after neoadjuvant chemotherapy for locally advanced breast carcinoma predicts survival.

BACKGROUND: Studies utilizing serial [99mTc]-sestamibi (MIBI) scintimammography have reported accurate prediction of tumor response in patients with locally advanced breast carcinoma (LABC) undergoing neoadjuvant chemotherapy. The pathologic response of LABC to presurgical treatment regimens is a prognostic indicator of survival. The authors tested whether MIBI uptake posttherapy predicted survival. METHODS: Sixty-two patients with LABC underwent MIBI scintimammography just before chemotherapy and 2 months after treatment initiation. An additional MIBI scan was performed if treatment lasted >3 months. The affected breast was imaged within 10 minutes after injection to reflect early uptake, which the authors have shown to be related to tumor blood flow. MIBI uptake was quantified using the lesion-to-normal breast (L:N) ratio. Most patients (93%) received weekly dose-intensive doxorubicin-based treatment. Disease-free survival (DFS) and overall survival (OS) were compared with posttherapy primary MIBI uptake and with other established prognostic factors for neoadjuvantly treated LABC, namely, primary tumor pathologic response and posttherapy axillary lymph node status. RESULTS: Patients with high uptake on the last observed MIBI scan (i.e., the L:N ratio was greater than the median value) had poorer DFS and OS (P<0.01 and P=0.01, respectively). Residual MIBI uptake retained independent prognostic significance in preliminary multivariate analysis that included other established prognostic markers. CONCLUSIONS: High primary breast tumor MIBI uptake after neoadjuvant chemotherapy predicted poor survival, suggesting serial MIBI imaging may provide a useful quantitative surrogate end point for neoadjuvant chemotherapy trials. Given the association between MIBI uptake and tumor blood flow, this prognostic capability may be related to retained tumor vascularity after treatment.

Adult↗
PubMed2005

Change in bone mineral density among adolescent women using and discontinuing depot medroxyprogesterone acetate contraception.

BACKGROUND: Several studies report an association between depot medroxyprogesterone acetate (DMPA) injectable contraception and decreased bone mineral density. Adolescents, who are still gaining bone, may be particularly affected, but there has been little study of the association in adolescent users and none following discontinuation. OBJECTIVE: To evaluate bone mineral density changes in adolescents using and discontinuing use of DMPA contraception. DESIGN: A population-based prospective cohort study. PARTICIPANTS: One hundred seventy adolescent women, aged 14 to 18 years; 80 baseline DMPA users and 90 age-similar, unexposed comparison women. Sixty-one participants discontinued DMPA use during follow-up. MAIN OUTCOME MEASURE: Bone mineral density, measured every 6 months for 24 to 36 months at the hip, spine, and whole body, comparing mean bone mineral density changes in DMPA users and discontinuers with nonusers. RESULTS: Among DMPA users, bone mineral density declined significantly relative to nonusers at the hip and spine but not the whole body. Annualized mean percentage changes, adjusted for covariates, were hip, -1.81% vs -0.19%; P<.001; spine, -0.97% vs 1.32%; P<.001, and whole body, 0.73% vs 0.88%; P = .78 for DMPA users vs nonusers, respectively. New users lost bone mineral density more rapidly than prevalent users. Discontinuers experienced significantly increased bone mineral density relative to nonusers at all anatomical sites; annualized mean percentage changes were hip, 1.34% vs -0.19%; P = .004; spine, 2.86% vs 1.32%; P = .004; and whole body, 3.56% vs 0.88%; P<.001. CONCLUSIONS: Use of DMPA contraception in adolescents was associated with significant continuous losses of bone mineral density at the hip and spine. However, significant gains postdiscontinuation provide evidence that the loss of bone mass is apparently reversed.

Absorptiometry, Photon↗
PubMed2005

Characteristics of women refusing follow-up for tests or symptoms suggestive of breast cancer.

BACKGROUND: Delay in diagnosis of breast cancer can occur at several points on the diagnostic pathway. We examined characteristics of women with breast cancer who before diagnosis actively refused recommended follow-up of tests or symptoms suggestive of breast cancer. METHODS: We identified women aged 50 years or older diagnosed with late-stage (metastatic disease or tumors > or = 3 cm at diagnosis) and a matched sample of women with early-stage (tumors < 3 cm) breast cancer from 1995 to 1999. Using medical records, we investigated clinical characteristics, use of health care, and documentation of care refusal during the 3 years before diagnosis. We used logistic regression models to compare refusers to nonrefusers. RESULTS: Of the 2694 women studied, 7.2% refused provider follow-up advice during the 3 years. These women were more likely to have late-stage breast cancer at diagnosis than were nonrefusers (odds ratio [OR] = 1.9, 95% confidence interval [CI] = 1.4 to 2.6). They were more likely to be aged 75 years or older (OR = 1.9, 95% CI = 1.4 to 2.7 compared with age 50-64) or to have six or more children (OR = 2.3, 95% CI = 1.3 to 4.2 compared to women with one to two children). Clinical factors associated with refusal included low use of mammography, high use of clinical breast exam, and missed appointments. A minority of women who refused had a reason documented in the medical record; the most frequent reasons were avoidance-denial-fatalism, fear of diagnostic tests, and fear of surgery or disfigurement. CONCLUSIONS: Our results suggest that certain demographic and clinical characteristics are associated with women's refusal of diagnostic testing for breast cancer. Further study is needed on refusers' characteristics and on how such refusals affect outcomes. Efforts aimed at identifying and counseling women with abnormal results who refuse follow-up are warranted.

Aged↗
PubMed2005

Late-stage breast cancer among women with recent negative screening mammography: do clinical encounters offer opportunity for earlier detection?

BACKGROUND: Opportunities to prevent late-stage breast cancer within the course of usual care are needed. We evaluate whether clinical encounters offer such opportunities. METHODS: Within seven health care plans, we identified 1298 women aged more than 50 years with early (<3 cm), late-stage (> or = 3 cm), or metastatic invasive breast cancer diagnosed during 1995-1999, whose first screening mammogram 13-36 months prior to the diagnosis (index) was negative. We audited all care occurring in the health plans up to 36 months prior to the cancer diagnoses. Ordinal logistic regression compared the frequency of events by disease category. We hypothesized that during the 13-36 months prior to diagnosis, women with late-stage or metastatic breast cancer would have more symptoms and be more likely to have breast-related clinical visits but have less breast screening (clinical breast examination [CBE] or mammography) than women with early-stage disease, thereby indicating clinical opportunities for earlier detection. RESULTS: We found no differences in demographic characteristics across breast cancer stage among the 1298 women. Both before and after the negative index mammogram but during the 13-36 months prior to diagnosis, few women had breast symptoms (5% before index, 8% after), but many sought breast care (86% before index, 90% after) and screening CBE (62% before index, 43% after). Only the occurrence of screening CBE (odds ratio [OR] = 0.73, 95% confidence interval [CI] = 0.56 to 0.95) or screening mammograms (OR = 0.74, 95% CI = 0.57 to 0.97) after the negative index mammogram reduced odds of more severe disease at diagnosis. CONCLUSION: Although the mortality benefit of CBE, or one compared to two year mammography has not been established, we found that women with late-stage breast cancers undetected by screening mammography did not experience opportunities for earlier detection except through CBE or additional screening mammography.

Aged↗
PubMed2005

Screening clinical breast examination: how often does it miss lethal breast cancer?

BACKGROUND: Although most American women regularly receive screening clinical breast examination (CBE), little is known about CBE accuracy in community practice. We sought to estimate the rate of cancer detection (sensitivity) of screening CBE performed by community-based clinicians on women who ultimately died of breast cancer, as well as to identify factors associated with accurate detection. SUBJECTS AND METHODS: We evaluated CBE accuracy among asymptomatic female health plan enrollees in five states (WA, OR, CA, MA, and MN) who received a CBE within 1 year of breast cancer diagnosis and who died of breast cancer within 15 years of diagnosis (N = 485). Sensitivity was estimated as the proportion whose exam was abnormal. Bivariate and logistic regression analyses identified patient characteristics associated with cancer detection. RESULTS: An abnormality was noted on screening CBE in one of five women who ultimately succumbed to breast cancer (sensitivity = 21.6%; 95% confidence interval [CI] = 18.1% to 25.6%). The odds of a true-positive screening CBE (sensitivity) were decreased among women using estrogen (odds ratio [OR] = 0.23; 95% CI = 0.07 to 0.80), receiving a Pap smear during the same visit as CBE (OR = 0.45; 95% CI = 0.27 to 0.72), and with increasing chronic disease comorbidity (P(trend) = .08). CONCLUSION: Screening CBE as performed in the community may be insufficiently sensitive to detect most lethal breast cancers. Low sensitivity of screening CBE in community practice may be partly attributable to its performance alongside time-consuming clinical tasks such as Pap smear screening or chronic illness care.

Adult↗
PubMed2005

Assessing accuracy of mammography in the presence of verification bias and intrareader correlation.

The performance of a medical diagnostic test is often evaluated by comparing the outcome of the test to the patient's true disease state. Receiver operating characteristic analysis may then be used to summarize test accuracy. However, such analysis may encounter several complications in actual practice. One complication is verification bias, i.e., gold standard assessment of disease status may only be partially available and the probability of ascertainment of disease may depend on both the test result and characteristics of the subject. A second issue is that tests interpreted by the same rater may not be independent. Using estimating equations, we generalize previous methods that address these problems. We contrast the performance of alternative estimators of accuracy using robust sandwich variance estimators to permit valid asymptotic inference. We suggest that in the context of an observational cohort study where rich covariate information is available, a weighted estimating equations approach may be preferable for its robustness against model misspecification. We apply the methodology to mammography as performed by community radiologists.

Bias↗
PubMed2005

Association between mammography timing and measures of screening performance in the United States.

PURPOSE: To evaluate whether there is an association between the number of months since previous mammography (MSPM) and performance measures (sensitivity, specificity, recall rate, cancer detection rate, and positive predictive value) in women who underwent U.S. community-based screening mammography. MATERIALS AND METHODS: Data from seven registries (Breast Cancer Surveillance Consortium) and mammographic data and cancer outcome in regard to 1 213 754 screening mammographic examinations performed in 680 641 women who were 40-89 years old for the years 1996-2000 were used in this study. These data are submitted annually in a standard format to a central statistical coordinating center that is subject to institutional review board approval, quality control, and confidentiality standards. Performance measures were calculated for first and subsequent screening mammography. For subsequent mammography, performance measures were calculated according to categories of MSPM (9-15, 16-20, 21-27, and >/=28 months). Receiver operating characteristic and multivariable logistic regression analyses were conducted to test the association between the number of MSPM and performance measures. RESULTS: With increasing MSPM in each category from 9-15 to 28 months or more and for first mammographic examinations, respectively, there was increased sensitivity (70.9%, 75.7%, 85.4%, 82.5%, and 88.6%), decreased specificity (93.3%, 92.7%, 91.6%, 91.0%, and 85.9%), increased recall rate (7.0%, 7.6%, 8.8%, 9.4%, and 14.7%), and increased cancer detection rates (3.2, 3.5, 4.5, 4.6, and 6.1 per 1000 mammographic examinations). When the category of 9-15 MSPM was compared with that of 21-27 MSPM, there was a slight increase in positive predictive value from 4.6% to 5.1%. Confidence intervals were narrow and did not overlap. Age affected these associations for all performance measures except sensitivity. CONCLUSION: Performance measures increased as MSPM increased, except for specificity, which decreased. Time between mammograms is an important factor to consider when audits are reviewed or screening performance measures are compared.

Adult↗