The Relationship Between Survival in Bile Duct Cancer Patients and Small Area-Level Deprivation

Aims Health equity, shaped by socioeconomic factors, influences disparities in cancer risk, survival, and screening. Although studied in Korea, research on the link between small-area deprivation and bile duct cancer survival is limited. This study examines bile duct cancer survival rates and risk factors in Busan (2003-2020), focusing on how age, gender, cancer stage, and the Deprivation Index (DI) affect survival using multilevel analysis.

Methods Data from the Busan Regional Cancer Registry included 12,950 bile duct cancer patients diagnosed between 2003 and 2020. The outcome was time from diagnosis to death or end of follow-up (December 31, 2022). Explanatory variables included age, gender, cancer stage, year of diagnosis, and regional DI. Kaplan-Meier survival analysis and multilevel models were applied, with significance set at P<0.05.

Results Among the 12,950 patients, most were aged 65-74 (35.3%), male (52.8%), and diagnosed at a distant stage (48.0%). Bile duct cancer diagnoses significantly increased from 2003 to 2020 (p<0.001), with a median survival time of 42 weeks. Younger age and local-stage cancer showed higher survival rates, while gender had no significant effect. The multilevel model indicated that a one-unit increase in the deprivation index reduced survival by 5.7%. Empirical Bayesian estimation revealed lower survival rates in 2004-2006 and 2008, with improvement after 2013. The graph plotting the deprivation index (x-axis) against survival probability (y-axis) demonstrated that the slope of the regional deprivation index was steeper for 3-year and 5-year survival rates compared to the 1-year rate across all cancer stages.

Conclusions This study shows that individual (age, cancer stage) and regional factors (deprivation) significantly impact bile duct cancer survival in Busan. Despite improvements, disparities persist, particularly among older patients and those in deprived areas. The findings highlight the need for targeted cancer management and policy interventions to reduce regional survival disparities.