Differential trends in the rising incidence of endometrial cancer by type: data from a UK population-based registry from 1994 to 2006

BACKGROUND: Endometrial cancer is the most common gynaecological cancer in the western world, the incidence increasing in the United Kingdom by over 40% since 1993. Two types of endometrial cancer exist – oestrogen-dependent type 1 with good prognosis and non-oestrogen-dependent type 2 with poor prognosis. The histopathological distribution of the increase in endometrial cancer is unknown. This study investigates the observed incidence trends of the two types, the age, stage, and socioeconomic distribution of this increase and survival outcome. METHODS: Data were analysed from 6867 women with endometrial cancer registered between 1994 and 2006, at a UK population-based cancer registry. RESULTS: Increased endometrial cancer incidence is confined to type 1 cancers with a significant increase in age standardised incidence rate (ASR) from 12.0 per 100 000 (confidence interval (CI) 10.7–13.2) in 1994 to 16.3 per 100 000 (CI 14.9–17.7), P<0.001 in 2006, while ASR of type 2 cancer changed from 2.5 per 100 000 (CI 2.0–3.1) in 1994 to 2.2 per 100 000 (CI 1.7–2.7) in 2006, which was not statistically significant P>0.05. Increase in type 1 cancer is most marked in age groups 60–69 years (P<0.001) and 70–79 years (P<0.001) and distributed equally among socioeconomic quintiles. While outcome for type 1 cancer has improved, 1-year survival in type 2 cancer is unchanged from 73.1% in 1994 to 74.3%, P=0.089 and 5-year survival decreased from 55.1% to 40.9%, P=0.001. CONCLUSION: Increased incidence in endometrial cancer is confined to type 1 cancers, seen most in the 60–79 age groups and across all socioeconomic quintiles. Survival in type 2 cancer has decreased significantly. Urgent research is needed to investigate prevention strategies in type 1 and improve therapy in type 2 cancers.