Whole-genome allelotyping identified distinct loss-of-heterozygosity patterns in mucinous ovarian and appendiceal carcinomas

Purpose: Mucinous adenocarcinoma of the ovary is one of the common histologic types of ovarian cancer. Its pathogenesis is largely unknown. In addition, the differential diagnosis of metastatic mucinous Carcinomas to the ovaries, particularly those originating from the appendix, remains challenging. The purpose of this study is to identify molecular biomarkers for mucinous ovarian adenocarcinoma and compare them with those of appendiceal origin. Experimental Design: Genome-wide loss-of-heterozygosity (LOH) analysis was done on DNA isolated from 28 microdissected primary mucinous ovarian carcinomas and five appendiceal adenocarcinomas. Markers from high-loss regions were selected for further analysis on a total of 32 ovarian and 14 appendiceal cancers. Results: High levels of LOH rates (> 40%) were detected on chromosome arms 9p, 17p, and 21q in mucinous ovarian carcinoma cases. The frequency of allelic loss was similar between high-grade and low-grade mucinous ovarian carcinoma cases but was significantly higher in ovarian versus appendiceal cases. In addition, LOH rates on five chromosomal loci were statistically different between ovarian and appendiceal carcinomas. Conclusion: A high frequency of LOH can be found in mucinous ovarian adenocarcinomas independent of grade. Despite histologic similarities between mucinous ovarian carcinomas and metastatic appendiceal carcinomas, they have distinct LOH profiles, which may be used for distinguishing the two diseases.