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

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.