Serous cancers, including HG-SCs and LG-SCs, originate mostly from the tubal fimbriated end (TFE). For LG-SCs, benign tubal epithelia (BTE) are able to form OEIs through an unclear pathway, then evolve into benign cystadenomas, borderline tumors and eventually LG-SCs. Some OEIs may derive from OSE. However, those OSE-derived OEIs are thought to have limited proliferative index and rarely develop into LG-SCs. Less than 10% of LG-SCs might develop into HG-SCs upon the acquisition of p53 mutation. HG-SCs also mainly originate from the TFE, starting from serous tubal intraepithelial carcinoma (STIC). This figure is adapted from REF [48].