Serous carcinogenesis in the fallopian tube: a descriptive classification

Serous tubal intraepithelial carcinoma: its potential role in primary peritoneal serous carcinoma and serous cancer prevention

PURPOSE

A diagnosis of primary peritoneal serous carcinoma (PPSC) requires exclusion of a source in other reproductive organs. Serous tubal intraepithelial carcinoma (STIC; stage 0) has been described in asymptomatic women with BRCA mutations and linked to a serous cancer precursor in the fimbria. This study examined the frequency of STIC in PPSC and its clinical outcome in BRCA-positive women.

PATIENTS AND METHODS

Presence or absence of STIC was recorded in consecutive cases meeting the 2001 WHO criteria for PPSC, including 26 patients with nonuniform sampling of the fallopian tubes (group 1) and 19 patients with complete tubal examination (group 2; sectioning and extensively examining the fimbriated end, or SEE-FIM protocol). In selected cases, STIC or its putative precursor and the peritoneal tumor were analyzed for p53 mutations (exons 1 to 11). Outcome of STIC was ascertained by literature review.

RESULT

Thirteen (50%) of 26 PPSCs in group 1 involved the endosalpinx, with nine STICs (35%). Fifteen (79%) of 19 cases in group 2 contained endosalpingeal involvement, with nine STICs (47%). STIC was typically fimbrial and unifocal, with variable invasion of the tubal wall. In five of five cases, the peritoneal and tubal lesion shared an identical p53 mutation. Of 10 reported STICs in BRCA-positive women, all patients were without disease on follow-up.

CONCLUSION

The fimbria is the source of nearly one half of PPSCs, suggesting serous malignancy originates in the tubal mucosa but grows preferentially at a remote peritoneal site. The generally low risk of recurrence in stage 0 (STIC) disease further underscores STIC as a possible target for early serous cancer detection and prevention.

Tubal and ovarian pathways to pelvic epithelial cancer: a pathological perspective

Prolongation of ovarian epithelial cancer survival depends on early detection or improved responses to chemotherapy. Gains in either have been modest at best. Understanding the diverse pathogenesis of this disease is critical to early intervention or prevention. This review addresses six important variables, including (i) cell of origin, (ii) site of origin, (iii) initial genotoxic events, (iv) risks imposed by hereditary and other promoting conditions, (v) subsequent factors that promote different patterns of metastatic spread, and (vi) prospects for intervention. This review proposes two distinct pathways to pelvic epithelial cancer. The first initiates in ovarian surface epithelium (OSE), Mullerian inclusions or endometriosis in the ovary. The second arises from the endosalpinx and encompasses a subset of serous carcinomas. The serous carcinogenic sequence in the distal fallopian tube is described and contrasted with lower grade serous tumors based on tumour location, earliest genetic change and ability (or lack of) to undergo terminal (ciliated) differentiation. Ultimately, a clear understanding of tumour origin and the mechanism(s) leading to the earliest phases of the serous and endometrioid carcinogenic sequences may hold the greatest promise for designing prevention strategies and/or developing new therapies.

Recent advances in the understanding of the pathogenesis of serous carcinoma: the concept of low- and high-grade disease and the role of the fallopian tube

In the past 50 years, the concept of serous ovarian cancer has been progressively refined, with the distinction of the borderline serous tumour, identification of a smaller subset of well-differentiated serous malignancies and, recently, closer attention to the pathogenesis of high-grade serous malignancies. High-grade serous carcinoma, traditionally presumed to arise within Müllerian inclusion cysts of the ovarian surface, cortex and peritoneum, has recently been linked to the distal fallopian tube. This review addresses the disparate forms of serous neoplasia, which reflect both different genetic abnormalities and stages of differentiation of Müllerian epithelium. The significance of these different origins is addressed in the context of ovarian cancer prevention.

Chromosomal instability in fallopian tube precursor lesions of serous carcinoma and frequent monoclonality of synchronous ovarian and fallopian tube mucosal serous carcinoma

OBJECTIVES

Pelvic serous carcinomas are classified according to the location of greatest mass of tumor as ovarian, peritoneal or fallopian tube. Recent studies suggest these cancers may arise in the fallopian tube. This study explores the relationship between ovarian cancers and fallopian tube mucosal involvement.

METHODS

Sixteen consecutive cases of epithelial ovarian malignancy were prospectively identified and the fallopian tubes submitted in toto for histopathological examination for tubal mucosal involvement. Immunohistochemical staining for p53 and Ki-67, and fluorescent in situ hybridization (FISH) analysis for chromosomal copy number changes were performed on 10 cases. Three cases of mucosal epithelial abnormalities identified in risk-reducing salpingectomy specimens were similarly characterized.

RESULTS

Of sixteen cases, twelve were high-grade serous carcinoma, stage III, and four cases were stage I, two borderline mucinous, one borderline serous, and one low-grade mucinous carcinoma. Ten cases of high-grade serous carcinoma showed either unilateral fallopian tube mucosal involvement (n = 7) or tubal obliteration ipsilateral to the dominant ovarian mass (n = 3), compared to none of the other carcinomas. FISH analysis showed similar copy number changes in the ovarian and fallopian tube mucosal carcinoma in 3 cases, suggesting a unifocal origin; one case had differences suggesting multifocal origin of cancer. One case had equivocal FISH results. From risk-reducing salpingectomy cases, the multiple foci of tubal intraepithelial carcinoma and focus of invasive carcinoma showed similar gene copy number changes within each case, suggesting monclonality. Both cases of epithelial atypia/dysplasia showed gene copy number changes.

CONCLUSIONS

Fallopian tube mucosal and ovarian tumors have similar genetic abnormalities in most cases, indicating a monoclonal origin that may originate either from the ovary, peritoneum or fallopian tube. In situ epithelial lesions of the fallopian tube from risk-reducing salpingectomies show gene copy abnormalities consistent with these being early lesions of serous carcinoma and suggest that chromosomal instability is a very early event in serous carcinogenesis.