This guideline covers detecting, diagnosing and treating women (18 years and older) who have, or are suspected of having, epithelial ovarian cancer, fallopian tube cancer, primary peritoneal cancer or borderline ovarian cancer. It aims to enable earlier detection of ovarian cancer and improve initial treatment. A table of NHS England interim treatment regimens gives possible alternative treatment options for use during the COVID-19 pandemic to reduce infection risk. This may affect decisions for patients with ovarian cancer. See the COVID-19 rapid guideline: delivery of systemic anticancer treatments for more details.