Incidence and mortality of primary liver cancer in England and Wales: changing patterns and ethnic variations.

AIM

To explore recent trends, modes of diagnosis, ethnic distribution and the mortality to incidence ratio of primary liver cancer by subtypes in England and Wales.

METHODS

We obtained incidence (1979-2008) and mortality (1968-2008) data for primary liver cancer for England and Wales and calculated age-standardised incidence and mortality rates. Trends in age-standardised mortality (ASMR) and incidence (ASIR) rates and basis of diagnosis of primary liver cancer and subcategories: hepatocellular carcinoma, intrahepatic bile duct and unspecified liver tumours, were analysed over the study period. Changes in guidelines for the diagnosis of primary liver cancer (PLC) may impact changing trends in the rates that may be obtained. We thus explored changes in the mode of diagnosis as reported to cancer registries. Furthermore, we examined the distribution of these tumours by ethnicity. Most of the statistical manipulations of these data was carried out in Microsoft excel® (Seattle, Washington, United Sttaes). Additional epidemiological statistics were done in Epi Info software (Atlanta, GA, United Sttaes). To define patterns of change over time, we evaluated trends in ASMR and ASIR of PLC and intrahepatic bile duct carcinoma (IHBD) using a least squares regression line fitted to the natural logarithm of the mortality and incidence rates. We estimated the patterns of survival over subsequent 5 and 10 years using complement of mortality to incidence ratio (1-MIR).

RESULTS

Age-standardised mortality rate of primary liver cancer increased in both sexes: from 2.56 and 1.29/100000 in 1968 to 5.10 and 2.63/100000 in 2008 for men and women respectively. The use of histology for diagnostic confirmation of primary liver cancer increased from 35.7% of registered cases in 1993 to plateau at about 50% during 2005 to 2008. Reliance on cytology as a basis of diagnosis has maintained a downward trend throughout the study period. Although approximately 30% of the PLC registrations had information on ethnicity, there was a relatively higher registration of the major tumour subtypes in patients whose ethnic backgrounds were from high incident regions of the world. Survival from PLC is estimated to get poorer in 10 years (2018) relative to 2008, particularly as a result of IHBD.

CONCLUSION

Incidence and mortality of PLC, and particularly IHBD, have continued to rise in England and Wales. Changes in the modes of diagnosis may be contributing.