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Microscopic and early-stage ovarian cancers in BRCA1/2 mutation carriers: building a model for early BRCA-associated tumorigenesis.

ABSTRACT: Risk-reducing salpingo-oophorectomy (RRSO) is the cornerstone of ovarian cancer prevention in BRCA1/2 mutation carriers. Occult fallopian tube and ovarian cancers have been reported in a small percentage of BRCA1/2 mutation carriers undergoing RRSO. Here, we review our single-institution experience with RRSO in BRCA1/2 mutation carriers to characterize cases of microscopic cancers in these patients. At the time of RRSO, 7.9% of BRCA1 mutation carriers were diagnosed with microscopic fallopian tube or ovarian cancers and no cases were diagnosed in BRCA2 mutation carriers. The majority of the microscopic cancers include cases that were confined to the fallopian tubes, although there were also cases involving ovaries only or peritoneal washings only. This suggests that the site of origin may be in the ovary, fallopian tube, or peritoneum for BRCA-associated serous cancers. However, an analysis of early-stage (stages I and II) ovarian and fallopian tube cancers diagnosed in BRCA1/2 mutation carriers confirms that the ovary is a preferred site for tumor growth with 11 of 14 early-stage cancers having a dominant ovarian mass. Overall, these data suggest that cancer initiation may occur in the ovary, fallopian tube, or peritoneum, but tumor growth and progression are favored in the ovary. We present an updated model for BRCA1/2 mutation-associated ovarian and fallopian tube carcinogenesis, which may aid in identifying improved prevention strategies for high-risk women who delay or decline RRSO.

SUBMITTER: Yates MS

PROVIDER: S-EPMC3048908 | biostudies-literature | 2011 Mar

REPOSITORIES: biostudies-literature

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Publications

Microscopic and early-stage ovarian cancers in BRCA1/2 mutation carriers: building a model for early BRCA-associated tumorigenesis.

Yates Melinda S MS Meyer Larissa A LA Deavers Michael T MT Daniels Molly S MS Keeler Elizabeth R ER Mok Samuel C SC Gershenson David M DM Lu Karen H KH

Cancer prevention research (Philadelphia, Pa.) 20110128 3

Risk-reducing salpingo-oophorectomy (RRSO) is the cornerstone of ovarian cancer prevention in BRCA1/2 mutation carriers. Occult fallopian tube and ovarian cancers have been reported in a small percentage of BRCA1/2 mutation carriers undergoing RRSO. Here, we review our single-institution experience with RRSO in BRCA1/2 mutation carriers to characterize cases of microscopic cancers in these patients. At the time of RRSO, 7.9% of BRCA1 mutation carriers were diagnosed with microscopic fallopian tu ...[more]

PMID: 21278312

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Project description:The development of non-invasive primary cancer preventive measures in humans require a thorough understanding of the initial cancer-driving molecular mechanisms. High grade serous extra-uterine M llerian cancers (HGSEMC; formerly classified as ovarian/tubal/peritoneal cancer) present at a very late stage and less than 40% of women survive 5 years. Although the recent TCGA initiatives revealed key molecular changes in established cancers, very little is known about the initial molecular alterations in cancer development. Analysis of normal tissue at extensively high risk prior to the development of any microscopic alterations is critical. BRCA1/2 mutation carriers have an up to 30 40 fold increased risk to develop ovarian cancer, preferentially HGSEMC. Despite a plethora of evidence linking mutations in BRCA1 or BRCA2 to cancer development the core components such as organ specificity (i.e. to breast and Fallopian Tube) are still missing. The Fallopian Tube of BRCA mutation carriers offers a unique opportunity to study carcinogenesis because these cancers originate only from the distal (i.e. fimbrial) end of the Fallopian Tube (which is in close proximity to the ovary), and not from the proximal end (which is close to the uterus). The ovary which is in extreme close proximity to the fimbriae provides an excellent soil for cancer cells which are likely shed from the fimbriae and once the cancer has been discovered the big bulk of tumour is usually present on the ovary and hence the majority of HGSEMC are also referred to as ovarian cancer . To study the earliest steps of human carcinogenesis we performed epigenome-wide DNA methylation (DNAme) analyses (using the Illumina 450k DNA methylation bead-array assay assessing DNAme at ~480 000 CpG sites) in 215 microscopic normal Fallopian Tube samples of BRCA1/2 mutation carriers (n=56) and controls (n=59) who had their tubes/ovaries removed for prophylactic or other reasons, respectively (for 52 and 49 individuals respectively we analysed both fimbrial and proximal Fallopian Tubes). In order to adjust for any epigenetic effects which are not of immediate importance to the carcinogenic process, for each volunteer we analysed both the fimbrial (at risk) and the proximal (non at risk) portion of the tubes separately. Formalin fixed paraffin embedded (FFPE) tissue blocks were retrieved from UCL Biobank (NC09.13). Histopathological features of fimbrial and proximal section of Fallopian Tube from BRCA carriers and control cases were carefully examined. Cases negative for serous tubal intraepithelial carcinoma (STIC) lesions were chosen for DNA isolation to characterize pre-cancer epigenetic changes. For DNA isolation, a core of 3 x 0.6 mm was taken from each block representing fimbrial and proximal end of fallopian tubes from both BRCA carriers and matched control cases. The DNA was isolated using QIAamp(r) DNA FFPE Tissue Kit as per manufacturer's protocol with minor modifications (Dewaxing for 4 hours in xylene and proteinase digestion performed overnight, other procedures were as per the instructions). DNA was quantified using Nandrop and restored using the Infinium FFPE DNA Restore Kit and then 200 nanogram of DNA was bisulfite converted using the EZ DNA Methylation-Gold(tm) and subjected to methylation analysis on the Illumina Infinium Human Methylation450 BeadChip.

Dataset Information

Microscopic and early-stage ovarian cancers in BRCA1/2 mutation carriers: building a model for early BRCA-associated tumorigenesis.

Publications

Microscopic and early-stage ovarian cancers in BRCA1/2 mutation carriers: building a model for early BRCA-associated tumorigenesis.

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