Comparing Interval Breast Cancer Rates in Norway and North Carolina: Results and Challenges

Abstract

Objective To compare interval breast cancer rates (ICR) between a biennial organized screening programme in Norway and annual opportunistic screening in North Carolina (NC) for different conceptualizations of interval cancer. Setting Two regions with different screening practices and performance. Methods 620,145 subsequent screens (1996–2002) performed in women aged 50–69 and 1280 interval cancers were analysed. Various definitions and quantification methods for interval cancers were compared. Results ICR for one year follow-up were lower in Norway compared with NC both when the rate was based on all screens (0.54 versus 1.29 per 1000 screens), negative final assessments (0.54 versus 1.29 per 1000 screens), and negative screening assessments (0.53 versus 1.28 per 1000 screens). The rate of ductal carcinoma in situ was significantly lower in Norway than in NC for cases diagnosed in both the first and second year after screening. The distributions of histopathological tumour size and lymph node involvement in invasive cases did not differ between the two regions for interval cancers diagnosed during the first year after screening. In contrast, in the second year after screening, tumour characteristics remained stable in Norway but became prognostically more favorable in NC. Conclusion Even when applying a common set of definitions of interval cancer, the ICR was lower in Norway than in NC. Different definitions of interval cancer did not influence the ICR within Norway or NC. Organization of screening and screening performance might be major contributors to the differences in ICR between Norway and NC.

Sensitivity and specificity of mammographic screening as practised in Vermont and Norway

“…The findings were consistent with other international studies [2][3][4]. Different radiological reading procedures have been suggested as a possible reason for the findings [1,2,4].…”

PAM50 and Risk of Recurrence Scores for Interval Breast Cancers

“…Previous studies based on CMR have reported higher proportions of screen detected cases (e.g. Henderson et al reported 80% of cases were screen detected using a 1 year-interval(14); Hofvind et al reported 60% of cases were screen detected given the 24-month definitions used herein(11)). We were unable to retrospectively review mammographic images to confirm which interval cases arose from false negatives, but we minimized misclassification within screen and interval-detected groups by classifying women with missing screening data as ‘unknown’.…”

“…These cancers tend to be higher stage and grade at the time of diagnosis whereas screen-detected cancers have been reported to have more indolent molecular characteristics(7–10). The proportion of interval cancers in screened populations varies from 14% to 38%(11–14), depending on screening interval and underlying population breast cancer incidence rates(15). …”

Bidrar overdiagnostikk til høye melanomtall?

“…Two qualitative studies of the experiences of women diagnosed with interval cancer indicate that some women postponed help-seeking when they developed breast cancer symptoms, due to the negative mammography examination [143] and that despite being diagnosed with interval cancer, the interviewed women remained positive towards the screening program [142]. …”

“…The study is based on the same qualitative methods and interviews as the study by Solbjør et al described above [143].…”