Tubal origin of ovarian cancer – the double-edged sword of haemoglobin

Ovarian high-grade serous carcinoma (HGSC) is the most malignant neoplasm of the gynaecological tract. While the origins of many human malignant neoplasms are clear, the origin of HGSC remains poorly understood. This lack of knowledge limits our understanding of its pathogenesis and compromises efforts devoted to developing better early detection tools and effective preventative interventions. The paradigm of the tubal origin of HGSC has been advanced since the initial report of dysplastic lesions (now known as serous tubal intraepithelial carcinomas or STICs) that morphologically resemble HGSC in the Fallopian tube. These were observed in a group of patients with a genetic predisposition to ovarian cancer who were undergoing risk-reducing salpingo-oophorectomy. Since then, a series of clinico-pathological and molecular studies have characterized STICs and their concurrent HGSCs, and the results support the new paradigm of a tubal origin of many ‘ovarian’ HGSCs. Reactive oxygen species-containing ovulatory follicular fluid has been thought to be the major culprit behind DNA damage in tubal epithelial cells, leading to either cell death or, if the cells survive, mutagenesis. A recent report from this journal demonstrates that ferryl haemoglobin (Hb) in peritoneal fluid could prevent cell death from DNA-damaged fimbrial epithelial cells, facilitating ovulation-induced carcinogenesis of tubal epithelium. This timely study provides new insight into the tumour initiation event in HGSC.