Exploring the survival rate of colorectal cancer in relation to the individual and geographical variation in Malaysia, 2013-2018

Colorectal cancer (CRC) is the third most common cancer and the second most deadly cancer globally. Despite advancements in CRC management, a marked disparity in CRC survival rates is still documented even in highly developed countries. Poorer CRC survival rates were found mainly in socioeconomically deprived areas and lack of healthcare accessibility. There is a lack of studies concerning geographical disparities in CRC survival in Malaysia. Hence, this study aims to determine the survival rate of CRC patients in relation to individual and geographical variation in Malaysia using the National Cancer Registry (NCR) database. This was a retrospective cohort study utilizing secondary data. All cases captured in the NCR database between 1 January 2013 and 31 December 2018 that fulfilled the inclusion criteria were included in this study. Survival analysis was conducted to determine the 5-year survival rate and factors that contribute to the overall CRC survival. Spatial analysis was carried out to identify the geographical areas with high priority for intervention. A total of 18,513 CRC patients were diagnosed between 2013 and 2018, with 10,819 deaths occurred during follow-up. The national 5-year CRC-specific survival rate was 42% with a median survival time of 36 months (95%CI 34.46-37.54). The East coast region (Kelantan, Terengganu and Pahang) had the lowest survival (38.0%). Among the 143 districts, eighty-one (56.6%) reported survival rates below the national average while sixteen (11.2%) were identified as high-priority districts. After adjusting for confounding variables in multilevel multivariable Cox proportional hazard regression analysis, the study found that older age (adjusted Hazard Ratio (aHR) 1.01, 95%CI 1.01-1.01), male gender (aHR 1.17, 95%CI 1.10-1.23), Malay (aHR 1.20, 95%CI 1.05-1.36) and other ethnicities (aHR 1.33, 95%CI 1.11-1.59), living in Peninsular Malaysia (Northern region [aHR 1.22, 95%CI 1.08-1.37], Central region [aHR 1.21, 95%CI 1.07-1.37], Southern region [aHR 1.37, 95%CI 1.22-1.54], East coast region [aHR 1.28, 95%CI 1.12-1.46]), rectal (aHR 1.11, 95%CI 1.04-1.18), rectosigmoid (aHR 1.10, 95%CI 1.02- 1.19), and anal cancers (aHR 1.28, 95%CI 1.06-1.55), advanced disease stage (Stage III [aHR 2.40, 95%CI 2.05-2.80], Stage IV [aHR 6.70, 95%CI 5.75-7.81]), receiving other (aHR 2.12, 95%CI 1.56-2.87), none or delayed treatments (aHR 1.48, 95%CI 1.18- 1.85), and living in less densely populated areas (Low [aHR 1.10, 95%CI 1.02-1.19] and Moderate [aHR 1.13, 95%CI 1.04-1.23]) were significantly associated with a higher risk of mortality (p<0.05). This study identified several factors associated with CRC survival. Healthcare resource planning and service provision are closely aligned with the characteristics of specific local areas. Thus, we recommended area-based targeted interventions to improve cancer detection, management, and access to healthcare. Identifying the factors that influence the difference in survival rates across the region may help public health authorities to better plan healthcare delivery, and eventually, reduce disparities in CRC survival in Malaysia.