Risk reduction and screening of cancer in hereditary breast-ovarian cancer syndromes: ESMO Clinical Practice Guideline

Hereditary breast and ovarian cancer syndrome (HBOC) is clinically defined by family history criteria, and molecularly defined by identification of germline pathogenic variants (PVs) in clinically validated HBOC genes.1 These genes are broadly classified as high-risk genes, increasing breast and/or tubo-ovarian cancer risk by at least fourfold, and moderate-risk genes, increasing risk by two- to fourfold (Table 1). There is a large overlap between clinical and molecular HBOC, i.e. individuals with both family history and a PV.