Objective: The Norwegian Breast Cancer Screening Programme invites women aged 50-69 to biennial mammographic screening. Although 84% of invited women have attended at least once, attendance rates vary across the country. We investigated attendance rates among various immigrant groups compared with non-immigrants in the programme.Methods: There were 4,053,691 invitations sent to 885,979 women between 1996 and 2015. Using individual level population-based data from the Cancer Registry and Statistics Norway, we examined percent attendance and calculated incidence rate ratios, comparing immigrants with nonimmigrants, using Poisson regression, following women's first invitation to the programme and for ever having attended.Results: Immigrant women had lower attendance rates than the rest of the population, both following the first invitation (53.1% versus 76.1%) and for ever having attended (66.9% versus 2 86.4%). Differences in attendance rates between non-immigrant and immigrant women were less pronounced, but still present, when adjusted for sociodemographic factors. We also identified differences in attendance between immigrant groups. Attendance increased with duration of residency in Norway. A subgroup analysis of migrants' daughters showed that 70.0% attended following the first invitation, while 82.3% had ever attended. Conclusions:Immigrant women had lower breast cancer screening attendance rates. The rationale for immigrant women's non-attendance needs to be explored through further studies targeting women from various birth countries and regions.

Background: Several studies have shown that immigrants attend mammographic screening less frequently than non-immigrants. Studies have also shown that attendance is influenced by socio-demographic factors. We aimed to describe the relationship between socio-demographic factors and first attendance among immigrant and nonimmigrant women invited to BreastScreen Norway. Methods: Our cohort consisted of 885,979 women invited to BreastScreen Norway for their first time between 1996 and 2015. We merged individual level socio-demographic data to attendance data corresponding to women's first invitation to the program. Using Poisson regression, we calculated rate ratios with 95 % confidence intervals (95% CI) for attendance, stratified by region of origin. Covariates of interest included age, income, education level, employment status, marital status, citizenship and years since immigration, among others. Results: 53% of immigrants and 76% of non-immigrants attended mammographic screening after their first invitation; immigrants as a whole had lower attendance rates across all socio-demographic factors. However, the association between socio-demographic factors and attendance varied between immigrant groups. For all immigrants, no recorded education demonstrated the strongest association with non-attendance, compared to ≤ 10 years recorded education (RR adj : 0.69, 95% CI: 0.67-0.71). Other factors associated with non-attendance were low income, living in Oslo, not being employed and being a recent immigrant. Conclusion: The association between socio-demographic factors and mammographic screening attendance differed between immigrant groups. Further studies and preventive health measures should take into account that considering immigrants as a homogenous group may lead to less effective interventions.

Norwegian women attending the screening program are reasonably accurate in self-reporting their breast cancer and mammography histories. On average, women consistently reported weight and height within one kg/cm.

Purpose To describe screening outcomes from BreastScreen Norway stratified by volumetric breast density (VBD). Materials and Methods This retrospective study included data from 107 949 women aged 50-69 years (mean age ± standard deviation, 58.7 years ± 5.6) who underwent 307 015 screening examinations from 2007 to 2015. Automated software classified mammographic density as nondense (VBD <7.5%) or dense (VBD ≥7.5%). Rates and distributions of screening outcomes (recall, biopsy, screen-detected and interval breast cancer, positive predictive values of recall and of needle biopsy, sensitivity, specificity, and histopathologic tumor characteristics) were analyzed and stratified by density. Tests of proportions, including propensity score and t tests, were used. Results In 28% (87 021 of 307 015) of the screening examinations, the breasts were classified as dense. Recall rates for women with nondense versus dense breasts were 2.7% (5882 of 219 994) and 3.6% (3101 of 87 021); biopsy rates were 1.1% (2359 of 219 994) and 1.4% (1209 of 87 021); rates of screen-detected cancer were 5.5 (1210 of 219 994) and 6.7 (581 of 87 021) per 1000 examinations; and rates of interval breast cancer were 1.2 (199 of 165 324) and 2.8 (185 of 66 674) per 1000 examinations, respectively (P < .001 for all). Sensitivity was 82% (884 of 1083) for nondense breasts and 71% (449 of 634) for dense breasts, whereas specificity was 98% (160 973 of 164 440) and 97% (64 250 of 66 225), respectively (P < .001 for both). For screen-detected cancers, mean tumor diameter was 15.1 mm and 16.6 mm (P = .01), and lymph node-positive disease was found in 18% (170 of 936) and 24% (98 of 417) (P = .02) of women with nondense and dense breasts, respectively. Conclusion Screening examinations of women with dense breasts classified by using automated software resulted in higher recall rate, lower sensitivity, larger tumor diameter, and more lymph node-positive disease compared with women with nondense breasts.