Survival of colorectal cancer: the role of contextual, individual and tumour-specific characteristics

Abstract Background Colorectal cancer (CRC) is the second most common cancer in women and the third most common cancer in men in Germany. One in two people suffering from CRC dies within five years after diagnosis. The aim of our ongoing research project is to investigate the interaction of contextual, individual and tumour-specific characteristics and their effect on CRC survival in Bavaria. Methods A total of 124,958 incident cases of CRC (ICD-10 C18-C20) from the Bavarian Cancer Registry are linked with data on area deprivation based on the Bavarian Index of Multiple Deprivation (BIMD). We include all years with a CRC-specific case completeness of 90% or more, i.e. 2004 to 2018. We calculate Kaplan-Meier curves as well as mixed proportional hazards models including non-linear effects. Our modelling strategy starts from a baseline model with random effects at district, municipality, and individual level, which we continuously extend to include regional (deprivation), individual (age at diagnosis, sex) as well as tumour-specific variables (tumour site, grading, cancer stage, histological subtype, diagnosis of multiple primary tumours). Results Preliminary results show significant random effects at district and municipality level as well as a negative impact of deprivation on CRC survival for all sites. Individual as well as tumour-specific characteristics, such as age, grading, and cancer stage, demonstrate the strongest effects on CRC survival and partly explain survival differences according to area level (districts, municipalities), and level of deprivation. The effects of individual as well as tumour-specific characteristics vary between districts and municipalities in Bavaria depending on their level of area deprivation. Conclusions Contextual, individual and tumour-specific characteristics have an impact on CRC survival. Future studies may also include health services characteristics in CRC survival analysis. Key messages CRC survival is inversely associated with area deprivation in Bavaria. The effects of individual and tumour-specific characteristics, e.g. age and cancer stage, increase with the level of deprivation.