Growing social inequality in cancer incidence in Germany

Social inequalities in relation to cancer have been widely documented nationally and internationally. Whether it is the frequency of early detection examinations or cancer incidence, cancer mortality or cancer survival - people's socioeconomic background always has an impact.
Individual income plays a role in this phenomenon, but the regional socioeconomic situation where people live is also significant. For example, during 2010 to 2013, 7.3 percent more men were diagnosed with cancer in the socioeconomically weakest regions in Germany than in affluent areas.
Since 2007, the age-standardized rate of new cancer cases has been falling in Germany for almost all cancer types (lung cancer in women is an important exception). "So far, however, little research has been done on how this trend affects social inequalities," says Lina Jansen of the Epidemiological Cancer Registry Baden-Württemberg at the German Cancer Research Center.

In their current study, the epidemiologists led by Jansen and Volker Arndt examined this question at the regional level using data from cancer registries covering a total of 48 million inhabitants from eight German states. Cancer diagnoses between 2007 and 2018 were taken into account.

The researchers first classified all regions included in the study into one of five groups based on a socioeconomic index. Across the five classifications, cancer incidence rates declined for nearly all cancers during the observation period. But for cancer in total, for colorectal cancer, and lung cancer in men, this decline was much less pronounced in the most deprived regions than in the more affluent areas.

Furthermore, a widening of inequality was observed over the observation period: In 2007, men in the most socioeconomically deprived regions had a 7 percent higher rate of new cancer cases than men in the least deprived areas. This difference increased over the years, reaching 23 percent in 2018. For women, the difference increased from 7 percent in 2007 to 20 percent in 2018.

To address this inequality, it is first important to know what characterizes the most socioeconomically disadvantaged regions. Interestingly, they did not differ significantly from the least disadvantaged regions in terms of access to the health care system, distance to the nearest medical center, physician density, or number of hospital beds. However, there were large differences in individual factors such as unemployment, proportion of welfare recipients or school dropout rates. "So social factors seem to play a much bigger role than general infrastructure," emphasizes Lina Jansen.

The different prevalence of lifestyle-related cancer risk factors also contributes significantly to social inequality in cancer incidence, according to the researchers. Typically, there is a socioeconomic gradient in the prevalence of tobacco use, physical inactivity or severe obesity. "Our results show once again that we need to make special efforts in the future to ensure that all people benefit equally from healthy lifestyle recommendations and cancer screening examinations - regardless of their zip code" sums up Lina Jansen.

Lina Jansen, Lars Schwettmann, Christian Behr, Andrea Eberle, Bernd Holleczek, Christina Justenhoven, Hiltraud Kajüter, Kirsi Manz, Frederik Peters, Ron Pritzkuleit, Andrea Schmidt-Pokrzywniak, Eunice Sirri, Fabian Tetzlaff, Sven Voigtländer, Volker Arndt: Trends in cancer incidence by socioeconomic deprivation in Germany in 2007-2018: An ecological registry-based study. Int J Cancer 2023, DOI: https://doi.org/10.1002/ijc.34662