Performance measures among non-immigrants and immigrants attending BreastScreen Norway: a population-based screening programme.

Objectives: To explore performance measures among non-immigrants and immigrants attending BreastScreen Norway.

Methods: We analysed data from 2,951,375 screening examinations among non-immigrants and 153,026 among immigrants from 1996 to 2015. Immigrants were categorised into high- and low-incidence countries according to the incidence of breast cancer in their birth country. Performance measures, including attendance and recall rates, rates of screen-detected cancer (SDC) and interval breast cancer (IBC), positive predictive value (PPV) and histopathological tumour characteristics, were analysed. We used Fisher's exact model and t tests for descriptive statistics, and Poisson regression, adjusting for age and screening history, comparing results for non-immigrants versus immigrants.

Results: Attendance rates were 78% for non-immigrants and 56% for immigrants (p < 0.001). Rates of prevalent screens were 24% for non-immigrants and 32% for immigrants (p < 0.001). Immigrants from low-incidence countries were younger at diagnosis than non-immigrants (57 years versus 60 years, p < 0.001). Recall rates were 3.1% for non-immigrants and 3.8% for immigrants (p < 0.001), while PPVs were 17% and 14% (p < 0.001), respectively. IBCs in immigrants from low-incidence countries were more often triple negative (RR 1.81, 95% CI 1.11-2.94) than those in non-immigrants. Both SDC and IBC in immigrants from low-incidence countries tended more often to be histological grade 3 than those in non-immigrants.

Conclusion: Immigrants had lower attendance rates, higher recall rates and lower PPV than non-immigrants. The optimal age range and screening interval for immigrant women from low-incidence countries need to be further investigated.

Key Points: • Immigrants from countries with a low incidence of breast cancer had their breast cancer diagnosed at a younger age than non-immigrants. • Interval breast cancers detected in immigrants from countries with a low incidence of breast cancers were more often triple negative than those in non-immigrants. • The optimal age range and screening interval for immigrant women from low-incidence countries and non-immigrants might differ.