Time trends in incidence and prognosis of primary liver cancer and liver metastases of unknown origin in a Danish region, 1985-2004

Objectives Changes, over the last 20 years, in the diagnostic procedures and treatment of primary liver cancer (PLC) and liver metastases of unknown origin (LMUO) may have affected the clinical course of both cancers. Few longitudinal studies examined this issue. In a population-based setting, we studied changes in the incidence and prognosis of PLC and LMUO over time. Methods Between 1985 and 2004, we identified 2675 patients with PLC and LMUO in three Danish counties, with a population of 1.4 million. We computed the standardized incidence rate (SIR), ratio of PLC to LMUO diagnoses, median survival, and estimated mortality rate ratio adjusted for age, sex, and comorbidity. Results The SIR of PLC increased from 3.2 in 1985 to 5.0 in 2003, and the SIR of LMUO increased from 3.7 to 6.4. No increase was noted in the PLC-to-LMUO ratio over time (P=0.1 for trend). From 1985 to 2004, the median survival of PLC patients increased from 1.6 to 2.9 months whereas that of LMUO patients decreased from 1.7 to 1.3 months. Adjusting for age, sex, and comorbidity did not affect the mortality rate ratio estimates. Conclusions The incidence of both PLC and LMUO increased over time, whereas the PLC-to-LMUO ratio remained unchanged. Median survival of PLC patients has increased whereas that of LMUO patients remained practically unchanged.