Socioeconomic deprivation and cancer survival in a metropolitan area: An analysis of cancer registry data from Hamburg, Germany.

Background: Few studies have investigated socioeconomic inequalities within cities. Yet, such analyses are particularly important given the increasing international trend to urbanization. Here we investigated area-based socioeconomic inequalities in cancer survival in Hamburg, a port city in the North of Germany (population: 1.84 million people).

Methods: Patients with a diagnosis of colorectal, lung, female breast, and prostate cancer in 2004-2018 (follow-up until 31.12.2018) and registered in the Hamburg cancer registry were included. Area-based socioeconomic deprivation on urban district level was assigned to the patients and grouped in five quintiles. Relative survival in 2014-2018 was calculated using the period approach. Trend analyses between 2004 and 2018 were conducted. Relative excess risks adjusted for age and stage were computed with model-based period analyses.

Findings: For the 73,106 included patients, age-standardized 5-year relative survival in 2014-2018 decreased with increasing deprivation with significant differences between the most and least deprived group of 14·7 (prostate), 10·8 (colorectal), 8·0 (breast), and 2·5 (lung) percent units. Standardization by cancer stage decreased the difference for prostate cancer to 8·5 percent units and for breast cancer to 3·6 percent units but had only a minor effect for colorectal and lung cancer. Similar socioeconomic inequalities were already present in 2004-08.

Interpretation: Strong socioeconomic inequalities in cancer survival were observed in Hamburg, which could be partly explained by differences in the stage distribution. Further research including information on screening participation as well as information on cancer care are important to further understand and finally overcome these inequalities.

Funding: German Cancer Aid.