Association between radiologists' and facilities' characteristics and mammography screening detection of ductal carcinoma in situ.

PURPOSE: The aim of our study was, first, to measure association between radiologists and facilities characteristics and DCIS detection. Second, to assess whether those characteristics affect differently the likelihood of detection of DCIS versus invasive breast cancer. When applicable, we examined whether the identified characteristics were similarly associated with low-grade and high-grade DCIS detection. METHODS: This retrospective cohort study included 1,750,002 digital screening mammograms (2145 screen-detected DCIS) performed in the Quebec breast cancer screening program between 2007 and 2015 inclusively. The associations between radiologists' and facilities' characteristics and (1) the DCIS detection rate, (2) the invasive detection rate, and (3) the odds of DCIS on invasive detection were assess. For statistically significant associations in the latter analysis, analyses stratified by DCIS grade were performed. Multivariable logistic regression with generalized estimating equations estimates to account for correlation among mammograms was used. RESULTS: Compared to radiologists with recall rate between 5.0 and 9.9%, radiologists with recall rate between 15.0-19.9% and ≥ 20% reached a higher DCIS detection rate, with adjusted detection ratios of, respectively, 1.33 (95% confidence interval = 1.15-1.53) and 1.43 (95% confidence interval = 1.13-1.81). Increase in radiologist' recall rate was statistically significantly associated with an increase in detection of low/intermediate-grade DCIS (P < 0.001), while not in high-grade DCIS (P = 0.15). CONCLUSIONS: A major determinant of DCIS detection is the radiologists' recall rate. Abnormalities referred by radiologists with higher recall rates should be identified in order to understand how to decrease recall rate while keeping an optimal DCIS and invasive detection rate.

The mammography screening detection of ductal carcinoma in situ and invasive breast cancer according to women's characteristics: is it the same?

PURPOSE: Detection of ductal carcinoma in situ (DCIS) has increased with the mammography dissemination. Given the potential role of DCIS as a precursor of invasive breast cancer (IBC), we aimed to assess whether women's characteristics have a different effect on the DCIS compared to IBC detection rate. METHODS: This study included 3,609,569 screening mammograms performed from 2002 to 2015 in our organized breast cancer screening program, which actively invites women 50-69 years of age. The association between women's characteristics and the DCIS detection rate, the IBC detection rate and the odds ratio of DCIS among screen-detected cancers was assessed by logistic regression and generalized estimating equations with independent correlation matrix and sandwich estimator. RESULTS: A total of 4173 DCIS and 15,136 IBC were screen-detected. Increasing women's age, current hormone replacement therapy use and higher body mass index were less associated with the DCIS than with IBC detection rates (p value for the odds of DCIS among screen-detected cancers of, respectively, < 0.0001, 0.0244 and < 0.0001). In contrast, having a previous breast aspiration or biopsy and increasing breast density were more strongly associated with DCIS than with IBC detection rates (p value of, respectively, 0.0050 and < 0.0001). CONCLUSION: The results suggest that some women's characteristics could be playing a role in the initiation and other in the progression from in situ to invasive breast cancer. These characteristics can also affect the screening sensitivity, and this effect may differ depending on whether screen-detected cases were DCIS or IBC.

Screening Sensitivity According to Breast Cancer Location.

PURPOSE: To examine the relation between breast cancer location and screening mammogram sensitivity, and assess whether this association is modified by body mass index (BMI) or breast density. METHODS: This study is based on all interval cancers (n = 481) and a random sample of screen-detected cancers (n = 481) diagnosed in Quebec Breast Cancer Screening Program participants in 2007. Film-screening mammograms, diagnostic mammograms, and ultrasound reports (when available) were requested for these cases. The breast cancer was then localised in mediolateral oblique (MLO) and craniocaudal (CC) projections of the breast by 1 experienced radiologist. The association between cancer location and screening sensitivity was assessed by logistic regression. Adjusted sensitivity and sensitivity ratios were obtained by marginal standardisation. RESULTS: A total of 369 screen-detected and 268 interval cancers could be localised in MLO and/or CC projections. The 2-year sensitivity reached 68%. Overall, sensitivity was not statistically associated with location of the cancer. However, sensitivity seems lower in MLO posterior inferior area for women with BMI ≥ 25 kg/m2 compared to sensitivity in central area for women with lower BMI (adjusted sensitivity ratio: 0.58, 95% confidence interval [CI]: 0.17-0.98). Lower sensitivity was also observed in subareolar areas for women with breast density ≥ 50% compared to the central areas for women with lower breast density (for MLO and CC projections, adjusted sensitivity ratio and 95% CI of, respectively, 0.54 [0.13-0.96] and 0.46 [0.01-0.93]). CONCLUSIONS: Screening sensitivity seems lower in MLO posterior inferior area in women with higher BMI and in subareolar areas in women with higher breast density. When interpreting screening mammograms, radiologists need to pay special attention to these areas.

Clinical Image Quality and Sensitivity in an Organized Mammography Screening Program.

PURPOSE: The study sought to examine the association between clinical image quality of mammograms and screening sensitivity. METHODS: Four radiologists evaluated the clinical image quality of 374 invasive screen-detected cancers and 356 invasive interval breast cancers for which quality evaluation of screening mammograms could be assessed from cancers diagnosed among participants in the Quebec Breast Cancer Screening Program in 2007. Quality evaluation was based on the Canadian Association of Radiologists accreditation criteria, which are similar to those of the American College of Radiology. The association between clinical quality and screening sensitivity was assessed by logistic regression. Adjusted sensitivity and adjusted sensitivity ratios were obtained through marginal standardization. No institutional review board approval was required. RESULTS: A proportion of 28% (206 of 730) of screening mammograms had lower overall quality for the majority of assessments. Positioning was the quality attribute that was the most frequently deficient. The 2-year screening sensitivity reached 68%. Sensitivity of screening was not statistically associated with the overall quality (ratio of 2-year sensitivity = 1.03; 95% confidence interval: 0.93-1.15) or with any quality attributes (positioning, exposure, compression, sharpness, artifacts, contrast). Results were similar for the 1-year sensitivity. CONCLUSIONS: Although not all mammograms in the Quebec screening program met the optimum quality required by the Canadian Association of Radiologists or American College of Radiology accreditation, the screening mammograms produced in this population-based organized screening program reached a high enough level of quality so that the remaining variation in quality is too little to impair screening sensitivity.

Detection Rate, Recall Rate, and Positive Predictive Value of Digital Compared to Screen-Film Mammography in the Quebec Population-Based Breast Cancer Screening Program.

PURPOSE: The study sought to compare performance indicators of computed radiography (CR) using different plate readers, digital direct radiography (DR), and screen-film mammography (SFM) in a population-based screening program. METHODS: This analysis involved women 50-69 years of age who participated in the breast screening program of Quebec (Canada) and who had screening mammogram between January 1, 2007, and September 30, 2012. The detection rate, recall rate, and positive predictive value of CR (n = 672,125 mammograms) and DR (n = 60,023) were compared to SFM (n = 782,894) using mixed-effect logistic regression, adjusting for potential confounders. No institutional review board approval was required. RESULTS: CR was not associated with change in cancer detection rate (odds ratio [OR]: 0.95; 95% confidence interval [CI]: 0.88-1.03), but with a small increase in recall rate (OR: 1.03; 95% CI: 1.01-1.06) compared to SFM. The association of CR with recall rate varies with the CR plate reader manufacturer (P < .0001). DR was not associated with change in detection rate (OR: 1.06; 95% CI: 0.89-1.25), but with an increase in the recall rate (OR: 1.25; 95% CI: 1.19-1.30) compared to SFM. CONCLUSIONS: In our screening program, digital mammograms gave detection rates equivalent to those of SFM, but with an increase of recall rate, particularly for DR. If this situation persists, the adoption of DR may increase the adverse effects of screening with little or no benefit for women.

Variance estimation and confidence intervals for the standardized mortality ratio with application to the assessment of a cancer screening program.

The effect of a cancer screening program can be measured through the standardized mortality ratio (SMR) statistic. The numerator of the SMR is the observed number of deaths from the screened disease among participants in the screening program, whereas the denominator of the SMR is an estimate of the expected number of deaths in these participants under the assumption that the screening program has no effect. In this article, we propose a variance estimator for the denominator of the SMR when this expected number of deaths is estimated with Sasieni's method. We give both a general formula for this variance as well as formulas for specific disease incidence and survival estimators. We show how this new variance estimator can be used to build confidence intervals for the SMR. We investigate the coverage properties of various types of confidence intervals by simulation and find that intervals that make use of the proposed variance estimator perform well. We illustrate the method by applying it to the Québec Breast Cancer Screening program.

The economic consequences of obesity and overweight among adults in Quebec.

OBJECTIVES: This article presents the first study of the economic consequences of obesity and overweight in the Canadian province of Quebec. The article examines three types of direct costs: hospitalizations, medical visits and drug consumption; and one type of indirect cost: productivity loss due to disability. METHODS: The National Population Health Survey, conducted in all Canadian provinces by Statistics Canada between 1994 and 2011, provides self-reported longitudinal data for body mass index and the frequency of health care utilization and disability. RESULTS: When we compared obese adults in Quebec to those with a normal weight at the beginning of the follow-up period, we observed that the former had significantly more frequent visits to the physician, more frequent hospital stays and higher consumption of drugs between 1994 and 2011. We estimated the annual cost of the excess health care utilization and excess disability at more than CAD $2.9 billion in 2011. CONCLUSION: The results confirm that, similar to what had been found elsewhere in Canada and abroad, there are important economic consequences associated with overweight and obesity in Quebec.

Radiologist interpretive volume and breast cancer screening accuracy in a Canadian organized screening program.

BACKGROUND: To strengthen evidence on which radiologist mammography interpretive volume requirements can be based, we assessed the relation of volume to accuracy in the Quebec Breast Cancer Screening Program. METHODS: Annual interpretive volume (total, screening, and diagnostic) for all 340 radiologists who interpreted 1315327 screening examinations in the period from 2000 to 2006 was obtained using provincial databases. The association of volume to sensitivity, false-positive rate, and accuracy (sensitivity/false-positive rate) was assessed by multivariable Poisson regression with robust error variance. All statistical tests were two-sided. RESULTS: Radiologists consistently interpreting less than 500 mammograms annually experienced a 58% reduction in accuracy (adjusted accuracy ratio = 0.42; 95% confidence interval [CI] = 0.24 to 0.74) compared with those who consistently interpreted at least 500 mammograms annually. Moreover, accuracy increased progressively as total annual volume increased (P trend = .0005). Radiologists interpreting at least 4000 mammograms annually experienced a 32% increase in accuracy (adjusted accuracy ratio = 1.32; 95% CI = 1.13 to 1.54) compared with those interpreting 500 to 999 mammograms annually. This increase in accuracy is attributable to a reduction in false-positive rate as total volume increased (P trend = .001). Sensitivity changed little with total volume (P trend = .68). Gains in accuracy were greater up to approximately 3000 mammograms interpreted annually. CONCLUSIONS: The minimum annual volume of 500 mammograms required in North America is justified; radiologist accuracy may be compromised if interpretive volume is consistently less than this requirement. Raising interpretive volume may help to reduce the frequency of false positives without loss of sensitivity. Possible gains in accuracy may be greater with increases in volume of up to approximately 3000 mammograms interpreted annually.