No evidence to support the impact of migration background on treatment response rates and cancer survival: a retrospective matched-pair analysis in Germany
Authors: Rüdiger Roman , Geiser Franziska , Ritter Manuel , Brossart Peter , Keyver-Paik Mignon-Denise , Faridi Andree , Vatter Hartmut , Bootz Friedrich , Landsberg Jennifer , Kalff Jörg C. , Herrlinger Ulrich , Kristiansen Glen , Pietsch Torsten , Aretz Stefan , Thomas Daniel , Radbruch Lukas , Kramer Franz-Josef , Strassburg Christian P. , Gonzalez-Carmona Maria , Skowasch Dirk , Essler Markus , Schmid Matthias , Nadal Jennifer , Ernstmann Nicole , Sharma Amit , Funke Benjamin , Schmidt-Wolf Ingo G. H. 
Published: May 2021

Abstract
Background
Immigration has taken the central stage in world politics, especially in the developed countries like Germany, where the continuous flow of immigrants has been well documented since 1960s. Strikingly, emerging data suggest that migrant patients have a poorer response to the treatment and lower survival rates in their new host country, raising concerns about health disparities. Herein, we present our investigation on the treatment response rate and cancer survival in German patients with and without an immigrant background that were treated at our comprehensive cancer center in Germany.

Methods
Initially, we considered 8162 cancer patients treated at the Center for Integrated Oncology (CIO), University Hospital Bonn, Germany (April 2002–December 2015) for matched-pair analysis. Subsequently, the German patients with a migration background and those from the native German population were manually identified and catalogued using a highly specific name-based algorithm. The clinical parameters such as demographic characteristics, tumor characteristics, defined staging criteria, and primary therapy were further adjusted. Using these stringent criteria, a total of 422 patients (n = 211, Germans with migration background; n = 211, native German population) were screened to compare for the treatment response and survival rates (i.e., 5-year overall survival, progression-free survival, and time to progression).

Results
Compared to the cohort with migration background, the cohort without migration background was slightly older (54.9 vs. 57.9 years) while having the same sex distribution (54.5% vs. 55.0% female) and longer follow-up time (36.9 vs. 42.6 months). We did not find significant differences in cancer survival (5-year overall survival, P = 0.771) and the response rates (Overall Remission Rate; McNemar’s test, P = 0.346) between both collectives.

Conclusion
Contrary to prior reports, we found no significant differences in cancer survival between German patients with immigrant background and native German patients. Nevertheless, the advanced treatment protocols implemented at our comprehensive cancer center may possibly account for the low variance in outcome. To conduct similar studies with a broader perspective, we propose that certain risk factors (country-of-origin-specific infections, dietary habits, epigenetics for chronic diseases etc.) should be considered, specially in the future studies that will recruit new arrivals from the 2015 German refugee crisis.