Breast cancer-specific survival among immigrants and non-immigrants invited to BreastScreen Norway

Abstract

Introduction: We have previously shown that immigrants have lower attendance in BreastScreen Norway than non-immigrants and that non-Western immigrants have lower incidence of breast cancer, but more advanced disease. Purpose: To compare breast cancer-specific survival for immigrants versus non-immigrants diagnosed with screen-detected or symptomatic breast cancer. Material and methods: We analyzed data from 28,320 women aged 50–69 diagnosed with breast cancer after being invited to BreastScreen Norway. We divided women into three groups; non-immigrants, immigrants from Western countries and immigrants from non-Western countries. We stratified our analyses according to detection mode (screen-detected breast cancer, interval cancer and cancer detected outside screening), and used cox regression to model the association between immigrants/non-immigrants and time to breast cancer death. Results: Among screen-detected breast cancers, 28.7% were histologic grade 3 among immigrants from non-Western countries compared to 21.3% among non-immigrants. Interval cancers and cancers detected outside screening had larger tumor diameter and a higher percentage were histologic grade 3 and lymph node positive among immigrants from non-Western countries compared to non-immigrants. Hazard ratio (95% confidence interval) adjusted for age and year of diagnosis for time to breast cancer death compared to non-immigrants was 0.70 (0.39–1.27) for immigrants from Western countries and 0.52 (0.23–1.17) for immigrants from non-Western countries. Conclusion: Despite more advanced histopathological tumor characteristics among immigrants from non-Western countries compared to non-immigrants, we did not observe statistically significant differences in breast-cancer specific survival between the two groups. Keeping in mind the low number of breast cancer deaths and possible overestimation of survival among immigrants, this might imply that equity in outcome can be achieved through adequate follow-up and treatment despite inequal access.

Keywords

• Migration
• Minority health
• Breast cancer
• Mammographic screening