Incidence and outcomes of malignant ovarian germ cell tumors in Korea, 1999-2017

Abstract

Objective: Malignant ovarian germ cell tumor (MOGCT) is a rare ovarian malignancy accounting for less than 5% of all ovarian cancers. We aimed to evaluate the incidence, survival, and subsequent malignancies after the diagnosis of MOGCT.

Methods: Data from the Korea Central Cancer Registry were used to identify MOGCTs between 1999 and 2017. The age-standardized rates (ASRs), 5-year relative survival rates (RSR) and standardized incidence ratio (SIR) for subsequent cancer after diagnosis of MOGCT were estimated.

Results: Of 2125 cases of newly diagnosed MOGCTs, 596 (28.0%) were diagnosed with dysgerminoma and 1529 (72.0%) with non-dysgerminoma. The ASR per 100,000 women-years was 0.539; ASR slightly increased over the study period (annual percent change [APC] = 1.01%; p = 0.02). There was an increase and decrease in the incidence of MOGCTs in the age groups 0-19 years (APC = 1.96%; p < 0.01) and ≥ 50 years (APC = -6.51%; p < 0.01), respectively. Patients with dysgerminoma showed significantly higher RSR than patients with non-dysgerminoma (98.0% vs. 94.9%, p < 0.01). Patients aged ≥50 years showed worst 5-year RSR (68.7%) than patients aged 0-19 years (97.8%) and 20-34 years (96.4%) (p < 0.01). The overall SIR for a subsequent cancer occurrence was 2.07, with the most frequent site of subsequent primary cancer being the thyroid (SIR = 2.78).

Conclusions: Our data demonstrated an excellent prognosis of MOGCTs among Korean women. There was a slight increase in MOGCT prevalence, which was more pronounced among those aged <19 years. After MOGCT diagnosis, the risk of developing a subsequent malignancy was doubled compared with the general population.

Keywords: Incidence; Malignant ovarian germ cell tumors; Subsequent cancer; Survival.