New insights uncover how ovarian cancer incidence varies by subtype and geography, calling for tailored healthcare strategies to address disparities and reduce the global burden.
Study: Worldwide patterns and trends in ovarian cancer incidence by histological subtype: a population-based analysis from 1988 to 2017. Image Credit: simonizt / Shutterstock.com
A recent study published in the journal eClinicalMedicine provides an overview of the global patterns and trends in ovarian cancer incidence by histological subtypes.
The global burden of ovarian cancer
Ovarian cancer is the eighth most frequently diagnosed cancer and the leading cause of mortality in women worldwide. In 2022, over 324,000 new cases of ovarian cancer and 206,839 related deaths were reported.
The global burden of ovarian cancer is associated with significant geographic and ethnic disparities. Whereas European and North American regions are associated with a higher incidence of ovarian cancer, Caribbean and African regions report a lower incidence of ovarian cancer.
This highly heterogeneous malignancy has multiple histological subtypes. Epithelial ovarian cancers account for 90% of all ovarian cancers, whereas 10% are non-epithelial ovarian cancers, including sex cord-stromal and germ cell tumors.
Study design
In the current study, researchers assess global patterns and trends in the incidence and distribution of ovarian cancer and its histological subtypes. To this end, incidence patterns of ovarian cancers were analyzed between 2013 and 2017, and temporal trends from 1988-1992 to 2013-2017 were analyzed across 65 and 40 countries, respectively. Data were extracted from the 2024 Cancer Incidence in Five Continents (CI5) volume XII and CI5plus databases.
Temporal trends in age-standardized rates of ovarian cancer and its subtypes were determined over a period of 30 years by calculating annual percent changes. The proportions of age-standardized rates of each subtype relative to the age-standardized rates of ovarian cancer for individual countries were also determined.
Global incidence patterns and trends of ovarian cancer
Significant variations in the worldwide incidence of ovarian cancer were observed across regions, countries, and socioeconomic groups.
The highest age-standardized rates of ovarian cancer were observed in Eastern and Central Europe and regions with very high Human Development Indices (HDIs). Comparatively, the lowest rates were observed in Africa and Asia and regions with medium HDI between 2013 and 2017.
Regarding incidence trends, the age-standardized rates of ovarian cancer have significantly decreased in Europe, America, and Oceania. Conversely, they have increased in Asian countries, including Japan and South Korea.
Global incidence patterns and trends of ovarian cancer by its histological subtypes
Serous carcinomas were identified as the most prevalent ovarian cancer subtype in most of the analyzed countries.
In particular, higher age-standardized rates of serous carcinomas were reported in Europe. Mucinous carcinomas were associated with relatively higher age-standardized rates in many Asian countries, followed by endometrioid and clear cell carcinomas.
Despite an overall stable trend in the age-standardized rates of ovarian cancer subtypes, an increased prevalence was observed for serous carcinomas and germ cell tumors in most of the analyzed countries. However, a reduction in the age-standardized rates of mucinous carcinomas and adenocarcinomas was observed over time.
Global incidence of ovarian cancer by histological subtypes and age groups
Consistently low incidence rates of all ovarian cancer subtypes were observed until considering individuals 35 to 39 years of age. As age increased, a similar rise in the incidence rate of serous carcinomas was observed, with the peak incidence rate observed among women 70 to 74 years of age, followed by a slight reduction among women 85 years and older.
A similar increase in incidence rates with age was observed for adenocarcinomas, which peaked in women between 80 and 84 years of age.
For mucinous carcinomas, endometrioid carcinomas, and clear cell carcinomas, an initial induction and subsequent reduction in age-specific incidence rates were observed, with a reduced risk observed in 65-69, 50-54, and 55-59 age groups, respectively.
A consistently low incidence rate was observed for sex cord-stromal tumors and germ cell tumors across all age groups.
Study significance
The study provides the most recent estimates of patterns and trends in the incidence of ovarian cancer and its histological subtypes throughout the world. Disparities in global incidence observed across different regions, countries, and socioeconomic groups could be due to a wide range of factors, some of which include genetic predispositions, reproductive behaviors, and accessibility to healthcare resources.
The significant variations in ovarian cancer incidence rates observed in regions with different HDIs could be due to inadequate diagnostic facilities and healthcare infrastructures. The highest incidence rate observed in regions with very high HDIs could be attributed to greater health awareness among women, as increased health awareness can promote earlier cancer diagnosis, which can lead to statistically higher incidence rates.
Overall, the study findings emphasize the importance of continued ovarian cancer surveillance and region-specific prevention strategies to reduce the global burden of ovarian cancer.
Journal reference:
- Wei, Y., Ning, L., Xu, Y., et al. (2024). Worldwide patterns and trends in ovarian cancer incidence by histological subtype: a population-based analysis from 1988 to 2017. eClinicalMedicine. doi:10.1016/j.eclinm.2024.102983