Abstract PR07: Synchronous ovarian and endometrial carcinomas: The case for pseudo-metastasis.

Abstract

Abstract Background: Almost half of ovarian endometrioid histotype carcinomas present with concurrent endometrial carcinoma or pre-cancerous lesions. These “synchronous” ovarian and endometrial (SEO) tumors, when organ-confined and low-grade, consistently behave as two independent primary tumors, rather than a tumor-metastasis pair typical of advanced-stage carcinoma. Our study aims to investigate the ancestral relationship between ovarian and endometrial components of SEOs. Methods: We identified a cohort of SEOs and performed targeted, with the Illumina Truseq Custom Amplicon assay, and exome-level, with Nugen Ovation Library System and Agilent SureSelect XT2 capture, library construction followed by massively parallel sequencing on illumina MiSeq or HiSeq. Results: Despite complexities introduced as a result of sampling formalin fixed and paraffin embedded archival specimens we were able to confirm shared identical mutations, and thus a clonal relationship, between ovarian and endometrial tumors in all but one case. Discussion: In simultaneous presentation of cancer of the endometrium and ovary from our series we observed strong evidence of a primary tumor and metastasis relationship. However, the clinical behavior of this series, and SEOs in general, defies the basic tenant of cancer metastasis as a dire prognosis. Curiously similar anomalies, where there is advanced stage yet favorable outcome, occur in other organ systems. We therefore suggest a generalizable process “pseudo-metastasis” through which cells can spread to microenvironment-compatible and physically accessible sites. This restricted metastatic process can occur in cells that lack the full complement of cancer-associated transformation hallmarks required for tissue invasion and hematogenous or lymphatic metastasis. This phenomenon may be an important early step in dissemination of apparent multi-focal benign lesions, pre-malignant lesions, and low-grade carcinomas. This abstract is also presented as Poster B07. Citation Format: Michael S. Anglesio, Yi Kan Wang, Madlen Maassen, Hugo M. Horlings, Ali Bashashati, Blake Gilks, Stefan Kommoss, David G. Huntsman. Synchronous ovarian and endometrial carcinomas: The case for pseudo-metastasis. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research: Exploiting Vulnerabilities; Oct 17-20, 2015; Orlando, FL. Philadelphia (PA): AACR; Clin Cancer Res 2016;22(2 Suppl):Abstract nr PR07.