Trends in incidence and survival outcome of epithelial ovarian cancer: 30-year national population-based registry in Taiwan

Abstract

Objective: To investigate the changes of incidence and prognosis of epithelial ovarian cancer in thirty years in Taiwan.

Methods: The databases of women with epithelial ovarian cancer during the period from 1979 to 2008 were retrieved from the National Cancer Registration System of Taiwan. The incidence and prognosis of these patients were analyzed.

Results: Totally 9,491 patients were included in the study. The age-adjusted incidences of epithelial ovarian cancer were 1.01, 1.37, 2.37, 3.24, 4.18, and 6.33 per 100,000 person-years, respectively, in every 5-year period from 1979 to 2008. The age-specific incidence rates increased especially in serous, endometrioid and clear cell carcinoma, and the age of diagnosis decreased from sixty to fifty years old in the three decades. Patients with mucinous, endometrioid, or clear cell carcinoma had better long-term survival than patients with serous carcinoma (log rank test, p<0.001). Patients with undifferentiated carcinoma or carcinosarcoma had poorer survival than those with serous carcinoma (log rank test, p<0.001). The mortality risk of age at diagnosis of 30-39 was significantly higher than that of age of 70 years or more (test for trend, p<0.001). The mortality risk decreased from the period of 1996-1999 (hazard ratio [HR], 0.90; p=0.054) to the period after 2000 (HR, 0.74; p<0.001) as compared with that from the period of 1991-1995.

Conclusion: An increasing incidence and decreasing age of diagnosis in epithelial ovarian cancer patients were noted. Histological type, age of diagnosis, and treatment period were important prognostic factors for epithelial ovarian carcinoma.

Keywords: Epithelial ovarian carcinoma; Histological type; Population-based study; Prognosis.

Fig. 1

(A) Secular trend of age-adjusted incidence rates of ovarian cancer and female gastric carcinoma, 1979-2008. (B) Secular trend of age-adjusted incidence of epithelial ovarian cancer in Taiwan, 1979-2008. Especially the incidence of serous and clear cell carcinoma increased over the period. (C) The percentage of histological types of epithelial ovarian cancer in Taiwan, 1979-2008. The percentages decreased in mucinous carcinoma but increased in clear cell carcinoma over these decades. Others include malignant Brenner tumor, undifferentiated carcinoma, and carcinosarcoma.

Fig. 2

Age-specific incidence of epithelial ovarian cancers in Taiwan, 1979-2008. (A) All epithelial ovarian cancers. The incidence of all age groups increased gradually over the period, and the peak age of diagnosis shifted gradually to 50 years old. (B) Serous carcinomas. The incidence of all age groups increased gradually over the period, and the peak age of diagnosis was around 60 years old. (C) Mucinous carcinoma. The incidence remained steady in all age groups, and the peak age of diagnosis was around 70 years old. (D) Endometrioid carcinomas. The incidence of all age groups increased gradually over the period, and the peak age of diagnosis was around 50 years old. (E) Clear cell carcinomas. The incidence increased especially over latest decade, and the peak age of diagnosis was around 50 years old.

Fig. 3

(A) The survival rates of epithelial ovarian cancer by histological types in Taiwan, 1991-2008. The 2-year survival rate of undifferentiated carcinoma and carcinosarcoma were less than 50. The survival rate of serous carcinoma gradually dropped to 50 in 5-year. In 10-year survival rate, mucinous carcinoma, endometrioid carcinoma and clear cell carcinoma were more than 50. (B) Hazard ratios of death for patients with epithelial ovarian cancer in Taiwan, 1991-2008. The risk of death increased with the age of diagnosis in all the period, but the risk decreased when patients diagnosed after 2000 in almost all ages of diagnosis.

Fig. 4

Percentages of different histological types from 1979 to 2008.