Mammographic features and risk of breast cancer death among women with invasive screen-detected cancer in BreastScreen Norway 1996-2020.

OBJECTIVES: We explored associations between mammographic features and risk of breast cancer death among women with small (<15 mm) and large (≥15 mm) invasive screen-detected breast cancer. METHODS: We included data from 17,614 women diagnosed with invasive breast cancer as a result of participation in BreastScreen Norway, 1996-2020. Data on mammographic features (mass, spiculated mass, architectural distortion, asymmetric density, density with calcification and calcification alone), tumour diameter and cause of death was obtained from the Cancer Registry of Norway. Cox regression was used to estimate hazard ratios (HR) with 95% confidence intervals (CI) for breast cancer death by mammographic features using spiculated mass as reference, adjusting for age, tumour diameter and lymph node status. All analyses were dichotomised by tumour diameter (small versus large). RESULTS: Mean age at diagnosis was 60.8 (standard deviation, SD=5.8) for 10,160 women with small tumours and 60.0 (SD=5.8) years for 7454 women with large tumours. The number of breast cancer deaths was 299 and 634, respectively. Mean time from diagnosis to death was 8.7 (SD=5.0) years for women with small tumours and 7.2 (4.6) years for women with large tumours. Using spiculated mass as reference, adjusted HR for breast cancer death among women with small tumours was 2.48 (95% CI 1.67-3.68) for calcification alone, while HR for women with large tumours was 1.30 (95% CI 1.02-1.66) for density with calcification. CONCLUSIONS: Small screen-detected invasive cancers presenting as calcification and large screen-detected cancers presenting as density with calcification were associated with the highest risk of breast cancer death. CLINICAL RELEVANCE STATEMENT: Small tumours (<15 mm) presented as calcification alone and large tumours (≥ 15 mm) presented as density with calcification were associated with the highest risk of breast cancer death among women with screen-detected invasive breast cancer diagnosed 1996-2020. KEY POINTS: • Women diagnosed with invasive screen-detected breast cancer 1996-2020 were analysed. • Small screen-detected cancers presenting as calcification alone resulted in the highest risk of breast cancer death. • Large screen-detected cancers presenting as density with calcification resulted in the highest risk of breast cancer death.

Does it matter for the radiologists' performance whether they read short or long batches in organized mammographic screening?

OBJECTIVE: To analyze the association between radiologists' performance and image position within a batch in screen reading of mammograms in Norway. METHOD: We described true and false positives and true and false negatives by groups of image positions and batch sizes for 2,937,312 screen readings performed from 2012 to 2018. Mixed-effects models were used to obtain adjusted proportions of true and false positive, true and false negative, sensitivity, and specificity for different image positions. We adjusted for time of day and weekday and included the individual variation between the radiologists as random effects. Time spent reading was included in an additional model to explore a possible mediation effect. RESULT: True and false positives were negatively associated with image position within the batch, while the rates of true and false negatives were positively associated. In the adjusted analyses, the rate of true positives was 4.0 per 1000 (95% CI: 3.8-4.2) readings for image position 10 and 3.9 (95% CI: 3.7-4.1) for image position 60. The rate of true negatives was 94.4% (95% CI: 94.0-94.8) for image position 10 and 94.8% (95% CI: 94.4-95.2) for image position 60. Per 1000 readings, the rate of false negative was 0.60 (95% CI: 0.53-0.67) for image position 10 and 0.62 (95% CI: 0.55-0.69) for image position 60. CONCLUSION: There was a decrease in the radiologists' sensitivity throughout the batch, and although this effect was small, our results may be clinically relevant at a population level or when multiplying the differences with the number of screen readings for the individual radiologists. KEY POINTS: • True and false positive reading scores were negatively associated with image position within a batch. • A decreasing trend of positive scores indicated a beneficial effect of a certain number of screen readings within a batch. • False negative scores increased throughout the batch but the association was not statistically significant.

Time of day and mammographic reader performance in a population-based breast cancer screening programme.

OBJECTIVES: To analyse how reader performance varied by time during the day in a population-based breast cancer screening programme. METHODS: A total of 2,937,312 readings from 148 radiologists and 1,468,656 women were included in this study from Norway. Number and percentages of mammographic readings, positive scores, true and false positive readings, true and false negative readings, sensitivity and specificity were presented for categories of time of day and for each day of the week. Multilevel mixed effect logistic regression models with restricted cubic splines were fitted to the data, and used to predict the odds ratio of the different performance measures. RESULTS: The following distribution was found for the performance measures during the study period: true positive: 12,463 (0.4%); false positive: 128,419 (4.4%); true negative: 2,794,636 (95.1%); and false negative: 1794 (0.06%). The percentage of positive readings (true positive and false positive) was highest before lunch and in the early afternoon (4.9%): false positive was highest in both periods (4.5%) and true positive was highest in the early afternoon (0.5%). The percentage of true negative was highest in the evening (95.6%), and of false negative was highest at lunchtime (0.07%). This corresponds to a gradually decreasing predicted sensitivity throughout the day. The opposite was observed for specificity. CONCLUSIONS: Screen-reading early versus late during the day resulted in higher sensitivity, although at the cost of specificity. Despite small differences in the performance measures during the day, the results may be important in the discussion of optimal management of screening programmes.