Serous tubal intraepithelial neoplasia: the concept and its application

In recent years it has become clear that many extra-uterine (pelvic) high-grade serous carcinomas (serous carcinomas) are preceded by a precursor lesion in the distal fallopian tube. Precursors range from small self-limited 'p53 signatures' to expansile serous tubal intraepithelial neoplasms that include both serous tubal epithelial proliferations (or lesions) of uncertain significance and serous tubal intraepithelial carcinomas. These precursors can be considered from three perspectives. The first is biologic underpinnings, which are multifactorial, and include the intersection of DNA damage with Tp53 mutations and disturbances in transcriptional regulation that increase with age. The second perspective is the morphologic discovery and classification of intraepithelial neoplasms that are intercepted early in their natural history, either incidentally or in risk-reduction surgeries for germline mutations. For the practicing pathologist, as well as the investigators, a distinction between a primary intraepithelial neoplasm and an intramucosal carcinoma must be made to avoid misinterpreting (or underestimating) the significance of these proliferations. The third perspective is the application of this information to intervention, devising strategies that will actually lower the ovarian cancer death rate by opportunistic salpingectomy, widespread comprehensive genetic screening and early detection. Central to this issue are the questions of (1) whether some STICs are metastatic, (2) whether lower-grade epithelial proliferations can invade prior to evolving into intraepithelial carcinoma, or (3) metastasize and become malignant elsewhere ('precursor escape'). An important caveat is the persistent and unsettling reality that many high-grade serous carcinomas are not associated with an obvious point of initiation in the fallopian tube. The pathologist sits squarely in the midst of all of these issues, and has a pivotal role in managing expectations for stemming the death rate from this lethal disease.