There are few epidemiological studies on cancer in pregnancy, as national registries usually do not combine data on both cancer diagnosis and obstetrics. Nationwide linkage studies estimated the incidence of pregnancy-associated cancer, defined as a cancer diagnosis during pregnancy or within 12 months from delivery, to be 1 in 1000–2000 pregnancies [1]. The difference in estimated incidence between studies is explained by the difference in denominator used (live births, births beyond 20 weeks or pregnancies). The distribution of the various cancer types diagnosed in pregnancy is similar to that in the non-pregnant premenopausal population. Gynaecological cancers are one of the most common oncological diagnoses during pregnancy, after breast cancer, melanoma and haematological cancers [2]. Figure 74.1 represents the distribution of patients with a diagnosis during pregnancy in the registry of the international network on Cancer, Infertility and Pregnancy (www.cancerinpregnancy.org). Melanoma is probably underrepresented in this registry, as these patients are mostly diagnosed in the early stage and often not referred to centres that participate in the registration study.

Due to their largely different histology, biology and clinical features, ovarian malignancies in children and adolescents may represent unique problems for clinicians who diagnose and treat mainly adult patients with ovarian neoplasms. In order to provide the highest chance of cure with the lowest risk of late sequelae for these patients, specific knowledge and experience is required for the recognition, diagnosis and optimal management of these tumours.