Time and deprivation trends in incidence of primary liver cancer subtypes in England

Rationale, aims and objectives Primary liver cancer consists of distinct subtypes with differing aetiology so it is valuable to study the incidence of these subtypes separately. This study aims to investigate time and socio-economic deprivation trends in the incidence of primary liver cancer subtypes in England, identifying the burden in the population. Methods Data were extracted from the population-based National Cancer Data Repository (NCDR) for patients diagnosed with primary liver cancer between 1990 and 2009. Subtypes were defined by the 10th edition of the International Classification of Diseases (ICD-10) codes: liver cell carcinoma (C22.0), intrahepatic bile duct carcinoma (C22.1), other (C22.2-C22.4, C22.7) and unspecified (C22.9). A sensitivity analysis was carried out on the main histological subtypes of liver cell carcinoma and intrahepatic bile duct using the 2nd edition of the International Classification of Diseases for Oncology (ICD-O-2). Male and female age-standardized incidence rates per 100 000 World standard population were calculated for each year and for the period 1999-2009 by socio-economic deprivation quintile. Results A total of 40 945 patients were diagnosed with primary liver cancer between 1990 and 2009. Liver cell carcinoma incidence increased in men from 0.63 in 1990 to 2.48 per 100 000 in 2009. While incidence was low in women, rates increased from 0.18 to 0.59, respectively. Intrahepatic bile duct carcinoma incidence increased between 1990 and 2009 from 0.40 to 1.25 per 100 000 in men, and from 0.28 to 1.08 in women. Incidence of the other liver cancer subtype remained low throughout the study period at less than 0.3 per 100 000 in each year in both men and women. The highest rate of liver cell carcinoma and intrahepatic bile duct carcinoma was generally in men and women resident in the most deprived areas between 1999 and 2009. The largest difference by deprivation quintile was observed for liver cell carcinoma in men, where the incidence was more than double in the most deprived quintile with an average rate of 3.56 per 100 000 compared to the least deprived quintile at 1.43. Conclusions Liver cell carcinoma and intrahepatic bile duct carcinoma incidence increased between 1990 and 2009 in both sexes. This pattern was largely driven by patients living in the most deprived areas. Differences observed may be due to the variation in the prevalence of known risk factors such as chronic hepatitis B and C viral infections and excessive alcohol consumption.