Divergent trends in the incidence of endometrial and ovarian cancer in Scotland, 1971–2020

Background

Endometrial and ovarian cancers are the 4th and 6th most common cancers among women in the UK, with about 10,200 and 7,700 new cases each year, respectively. Although they share major risk factors (i.e. genetic susceptibility, hormonal and reproductive influences, obesity), their incidence patterns differ greatly. We conducted a population‑based cohort study to ascertain trends in incidence of both cancers in Scotland from 1971 to 2020.

Methods

Individual level data for women diagnosed with endometrial or ovarian cancer, and the corresponding national population (denominator) data were obtained from Public Health Scotland. Average annual incidence rates (AAIR) were calculated for two age groups (0-49 and 50+ years) across 10 five-year time periods (1971-75 to 2016-20).

Results

During the 50-year study period, 25,793 endometrial and 27,975 ovarian cancers were registered in Scotland. The majority of cases were diagnosed in women aged 50+ years (92% for endometrial, 83% for ovarian cancer). Overall, the AAIR of endometrial cancer increased steadily from 13.2 per 100,000 in 1971-75 to 30.5 per 100,000 in 2016-20 (+131%); the largest increase was observed among women aged 50+year (+87%), whereas AAIR in women aged 0-49 remained fairly stable. In contrast, ovarian cancer AAIR increased from 14.8 per 100,000 in 1971-75 to a peak of 24.2 per 100,000 in 1996-2000 (+64%), followed by a subsequent decline. This recent decline occurred in both women aged 0-49 years (-18%) and 50+ years (-25%).

Conclusions

In analogy with the trends observed in other high-income countries, the incidence of endometrial cancer – which is strongly associated with hormonal and reproductive factors and obesity – has increased steadily in Scotland. On the other hand, the incidence of ovarian cancer has declined. Considering their distinct aetiological profiles, the reasons for these divergent trends in the incidence of endometrial and ovarian cancers need further investigation.

Key messages

• Endometrial cancer, which is a model for hormonal carcinogenesis, is the most common gynaecological cancer in high-income countries and its incidence is rising globally.

• Ovarian cancer incidence has been stable or declining in several high‑income countries, partly due to changes in reproductive patterns, oral contraceptive use, and evolving diagnostic classification.