The results of the InEMa study showed higher odds of MSP participation among resettlers compared to women of the general German population. Results from the AMIN study supported this finding, as a large increase in breast cancer diagnoses during the implementation phase of the MSP was observed among resettlers and the proportion of advanced breast cancer diagnoses has decreased between the two periods “1994 to 2006” and “2007 to 2013”. High participation in MSP leads to more diagnoses with earlier stages at diagnosis [27].
The findings from both studies suggest that resettler women have a surprisingly high MSP participation. The facts that these women have lived for about two decades in Germany and are able to communicate well in German might be possible reasons for the high participation of resettler women in the MSP. An ongoing process of acculturation can also increase participation in early detection measures, as studies from the US have previously observed [3, 8].
Another reason could be that resettlers are participating less in opportunistic screening, which could explain the difference in incidence rates before the MSP was implemented. This was also observed in a previous analysis of the InEMa data [28], however, in this analysis, ethnic German migrants who immigrated from Poland, Romania and countries of the FSU were considered as one homogenous group, which is different in our current analysis. Unfortunately, gynaecologists are not reporting opportunistic screening uptake to the cancer registries in Germany, so no data are available to answer this question.
In contrast, Aparicio and colleagues found that resettlers were less likely to participate in cancer screenings than the German population [29]. However, their analysis defined resettlers as ethnic Germans coming from Poland, Romania and countries of the FSU, whereas we excluded resettlers from Poland and Romania from our analyses, since we think these two groups should be investigated separately. Furthermore, the analysis looked at participation in general cancer screenings without considering the population-based MSP, which is structurally different from other early detection measures. It seems that the MSP has fewer barriers for resettlers than other early detection measures. A possible explanation might be that the structured invitation procedure of the MSP leads to an increased willingness to participate among resettlers. However, the exact reasons remain unclear and cannot be determined from the data sources we have used.
Strengths and limitations
When comparing the immigration periods and the countries of origin of the InEMa and AMIN study, the two study populations mostly immigrated after 1990 and came primarily from the Russian Federation and Kazakhstan. Therefore, both studies reflect the expected immigration pattern of resettlers coming to Germany since the early 1990s. As shown in Table 1, both study populations are residing in the north-western part of the federal state NRW. While the results of the AMIN study cover the time period 1994–2013, the results of the InEMa study reflect the participation behaviour of 50-year-old women in 2013 and 2014. The AMIN cohort is a representative sample of resettlers from the FSU, as resettlers were quasi-randomly assigned to their first place of residence (using the Königsteiner Schlüssel), where they had to live for at least 2 or 3 years [16]. Possible name changes of the cohort were considered by using a name thesaurus.
In this study, we used data from two independent studies, which means that we investigated two different study populations and the comparison of the results should be treated with caution. It is to be noted that the InEMa questionnaires were distributed in the German and Turkish language. Hence, it is possible that a small proportion of women were not able to read the material as some resettlers speak only Russian at home (see Table 2). As it seems reasonable that people with poor language skills are less likely to participate in the MSP [8], it is possible that we have overestimated the association between MSP participation and resettler status. Additionally, it is possible that women with a positive attitude towards the MSP were more likely to have participated in the InEMa study. This is suggested by the high proportion of study participants who have participated in the MSP (about 80% InEMa study vs. 55% Germany-wide). Therefore, the results from the InEMa study could also be explained by selection bias, which we cannot rule out.
It should also be noted that the number of resettlers participating in the study was low, resulting in inaccurate estimates with wide confidence intervals. Previous surveys among resettlers in Germany showed a relatively low response as for example 36% [30]. An analysis of response among individuals with foreign background in Germany by Winkler and colleagues showed that study participation among resettlers is only slightly lower compared to Germans [31]. Unfortunately, it is not possible to calculate the response rate of resettlers in the InEMa study. But given the small proportion of resettlers among the overall study population, the interpretation of the results is limited.
When comparing the cancer stages between the two time periods (“1994 to 2006” vs. “2007 to 2013”), it needs to be considered that improved diagnostics may also have led to a decrease of advanced cancer stages. Furthermore, the number of 50 to 69-year old resettler women with a breast cancer diagnosis was very low in the AMIN cohort, thus, the results from the analysis of the cancer stages should be treated with caution. In the AMIN cohort, it was not possible to perform a mortality follow-up, therefore, person-years of the cohort were estimated [22]. However, sensitivity analyses showed negligible differences in the results. A detailed discussion of the strengths and weaknesses of the AMIN study has been published elsewhere [19].
It needs to be emphasised that resettlers are a specific migrant group in Germany. They are ethnic German migrants who were invited by the German government, they received German citizenship at immigration and therefore, full access to the German social and health systems [16]. In contrast to resettlers in Germany, other non-western migrants in Denmark were found to have a considerably lower willingness to participate in the MSP [6]. Therefore, further research is needed to identify the specific factors explaining the good MSP participation among resettlers which may help to examine whether we could derive our findings to other migrant groups. Furthermore, it should be investigated how resettlers are participating in other screening programmes (such as colorectal cancer screening, skin cancer screening, etc.). Results from the NAKO study, a large prospective cohort study in Germany investigating about 200,000 representative study participants, could be useful for this investigation [32].
