Breast and stomach cancer incidence and survival in migrants in the Netherlands, 1996-2006
Migrant populations experience a health transition that influences their cancer risk, determined by environmental changes and acculturation processes. In this retrospective cohort study, we investigated differences in breast and stomach cancer risk and survival in migrants to the Netherlands. Invasive breast and stomach cancer cases diagnosed between 1996 and 2006 were selected from the Netherlands Cancer Registry. Standardized incidence ratios (SIR) were computed as the ratio of observed and expected cancers. Differences in the survival were expressed as hazard ratio (HR) using Cox regression and relative survival rates (RSR). All migrant women exhibited a significantly lower risk for breast cancer compared with Dutch natives. However, 5-year RSR was lower in all migrants (range 68-73%) compared with Dutch natives (85%). Death rates were increased in Moroccan [HR=1.2 (1.0-1.5)] and reduced in Indonesian [HR=0.8 (0.8-0.9)] patients with breast cancer. The incidence of noncardia stomach cancer was significantly elevated in all migrants, being highest in Turkish males [SIR=1.9 (1.6-2.3)]. Cardia stomach cancer was less frequent in all migrants, being lowest in Surinamese males [SIR=0.3 (0.2-0.6)]. Death rates for stomach cancer were lower in patients from Morocco [HR=0.6 (0.4-0.9)], whereas 1-year RSR for stomach cancer was better in all migrant groups. Both lower breast cancer rates and higher stomach cancer rates point to a strong link between environmental exposures, behavioural patterns and cancer risk during the life course. Favourable risks in migrants should be sustained as long as possible whereas survival disparities require careful monitoring and counteraction with preventive means as well as improved access to healthcare.