The differences between gonadal and extra-gonadal malignant teratomas in both genders and the effects of chemotherapy

BACKGROUND: A tumor comprising of different types of tissues (such as hair, muscle, bone, etc.) is known as a teratoma. It is a type of germ cell (cells that make sperm or eggs) tumor. When these germ cells have rapid cancerous growth, then such a teratoma is called a malignant teratoma. We have studied the differences between gonadal and extra-gonadal malignant teratomas and the effects of chemotherapy in both genders. METHODS: The samples of 3799 male and 1832 female patients with malignant teratoma samples, between the ages of 1 and 85+ years, were selected from the years 1973 to 2014. Trends in incidence, estimated prevalence, incidence rates, and frequency were calculated in gonadal and extra-gonadal tumors with age adjustment. The five-year observed, expected, and relative survival rates were analyzed to study the prognosis. RESULTS: The gonadal took over a majority percentage of malignant teratomas compared with the extra-gonadal (90% vs. 10% in male; 83% vs. 17% in female). For the male, the total of the gonadal and the extra-gonadal were all significantly decreased from 1973 to 2014 (p < 0.05). For the female, there were no significant trends. As for prevalence, incidence, and frequency, there were two separate peaks of malignant teratomas. One peak was at under 1 year old, which was composed of the extra-gonadal tumor; the other peak was at 20–24 for male and 10–34 for female, which was composed of the gonadal tumor. This separation of the gonadal and extra-gonadal showed a significant difference (p < 0.05). As for the prognosis, the extra-gonadal tumor showed significantly lower survival rates than the gonadal (p < 0.05). In the short term, the survival rate of the chemotherapy group was higher than the supportive care group. However, in the long term, the survival rate of the chemotherapy group was lower than the supportive care group. CONCLUSION: The gonadal and extra-gonadal malignant teratomas show lots of differences. Chemotherapy might not help improve survival rates. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s12885-019-5598-0) contains supplementary material, which is available to authorized users.