1.Tumour Molecular Genetics Group, Institute of Medical Genetics, University of Wales College of Medicine, Heath Park, Cardiff, CF14 4XN, UK
Epithelial ovarian carcinoma develops sporadically in about 90-95% of patients. Environmental and dietary factors are thought to have a role. These include use of talc on the perineum and vulva, asbestos, pelvic irradiation, viruses (particularly mumps), high-fat diet, and lactose consumption. Other factors are associated with an increased number of ovulation cycles: low parity, delayed childbearing, early menarche and late menopause. However, genetic factors are the most important risk factor for ovarian epithelial carcinoma (See Genetics section of this review for further details).
Factors that decrease the risk for ovarian cancer predominantly reduce the number of ovulation cycles a women encounters-such as the use of oral contraceptives, breast-feeding and multiparity. Long-term use of oral contraceptives has reduced the risk of ovarian cancer by more than 50% in unselected women. Decreased risk of ovarian cancer has also been associated with tubal ligation and hysterectomy.
Brenner tumours are virtually always benign, and the exceptional malignant cases resemble transitional cell carcinoma of the bladder. As with the other types of ovarian neoplasm, it is usually asymptomatic until it has grown to a large size.
Borderline/LMPBorderline/LMP tumours are characterised by epithelial multilayering of more than 4 cell layers, and less than 4 mitoses per 10 high-power field, mild nuclear atypia, increased nuclear/cytoplasmic ratio, slight-to-complex branching of epithelial papillae and pseudopapillae, epithelial budding and cell detachment into the lumen and no destructive stromal invasion. Borderline mucinous tumours have similar gross morphology to their benign counterparts, cysts with smooth surfaces. The epithelial layer is characterised by stratification of 2-3 layers, nuclear atypia, enlarged nuclei and mitotic figures. Histological examples of borderline mucinous tumours can be found at: http://pathweb.uchc.edu/eAtlas/GYN/1934.htm http://pathweb.uchc.edu/eAtlas/GYN/1935b.htmApproximately 25% of borderline tumours show cell proliferations on the outer surface only. Of these, 90% develop peritoneal implants, which can be invasive or non-invasive. Both have a similar appearance, glandular or papillary proliferations with cell detachments, sometimes Psammoma bodies, cellular atypia and desmoplastic fibrosis. However, epithelial cells infiltrate the stroma in the invasive implants.
Brenner tumours Brenner tumours are solid or cystic, yellow-tan colour and firm upon gross examination. Histological examination of Brenner tumour reveals epithelial nests or cysts of cells, resembling urothelium, separated by a cellular, fibrous stroma (composed of spindle-like cells). The nuclei are relatively uniform, lacking pleomorphism, hyperchromasia or macronucleoli, and mitoses are not identified. There is a moderate amount of eosinophilic cytoplasm. Examples of Brenner tumours can be viewed at: http://pathweb.uchc.edu/eAtlas/GYN/1941b.htm http://pathweb.uchc.edu/eAtlas/GYN/1942.htm http://pathweb.uchc.edu/eAtlas/GYN/1943.htm http://pathweb.uchc.edu/eAtlas/GYN/1299.htm http://pathweb.uchc.edu/eAtlas/GYN/1300.htm http://pathweb.uchc.edu/eAtlas/GYN/1301.htm http://pathweb.uchc.edu/eAtlas/GYN/1302.htm
Clear Cell CarcinomaClear cell carcinoma accounts for 5-12% of ovarian adenocarcinomas. The gross appearance of clear cell carcinoma shows a smooth, lobulated external surface. These tumours are usually solid and firm, but can be cystic. They have a yellow-tan colour. Microscopic examination reveals cells arranged in tubules, nests or cysts, with clear, glycogen rich cytoplasm, sharply demarcated cell borders, and hyperchromatic, pleomorphic nuclei. Hobnail cells with nucleus standing on a stalk of cytoplasm are visible microscopically. Examples of clear cell carcinoma can be found using the following weblinks: http://pathweb.uchc.edu/eAtlas/GYN/1937.htm http://pathweb.uchc.edu/eAtlas/GYN/1938.htm http://pathweb.uchc.edu/eAtlas/GYN/1939.htm http://pathweb.uchc.edu/eAtlas/GYN/1940.htm http://pathweb.uchc.edu/eAtlas/GYN/1049.htm http://pathweb.uchc.edu/eAtlas/GYN/1050.htm http://pathweb.uchc.edu/eAtlas/GYN/1051.htm http://pathweb.uchc.edu/eAtlas/GYN/1052.htm http://pathweb.uchc.edu/eAtlas/GYN/1053.htm
Endometrioid Carcinoma Endometrioid carcinomas are solid, white, firm tumours with smooth or irregular surfaces. They may contain a cystic component and have areas of necrosis and haemorrhage. Histological analysis reveals glands, or glands mixed with solid areas, round-oval vesicular, clear nuclei with prominent nucleoli. Endometrioid carcinoma is indistinguishable from endometrial carcinoma. An example of endometrioid carcinoma can be found at: http://pathweb.uchc.edu/eAtlas/GYN/437.htm
Mixed Mesodermal The gross appearance of mixed mesodermal ovarian tumours are exemplified in the following weblinks: http://pathweb.uchc.edu/eAtlas/GYN/134.htm http://pathweb.uchc.edu/eAtlas/GYN/135.htm http://pathweb.uchc.edu/eAtlas/GYN/136.htmThey are usually large variegated lesions with necrotic and haemorrhagic regions, and may have adhesions. Microscopic examination reveals serous or endometrioid epithelial component displaying squamous differentiation. Stroma may comprise spindle cell or soft tissue differentiation including cartilage, skeletal muscle or smooth muscle.
Clear cell adenocarcinoma has a worse prognosis that the other histological subtypes as it is resistant to platinum-based chemotherapy. Some data suggests familial ovarian cancers have prolonged survival in comparison to the nonfamilial cases. In one study, patients with familial ovarian cancer exhibited a 67% 5-year survival, in comparison with a 17% 5-year survival in the nonfamilial ovarian cancer cases.
Table 1 Definitions of the FIGO classification scheme for Staging Primary Ovarian Carcinoma (taken from Jones, 2000)
Table 2 Survival Rates of Ovarian Carcinoma according to Disease Stage (adapted table from Jones, 2000)
Invasive serous and undifferentiated ovarian carcinomas have complex cytogenetic rearrangements, including amplification of oncogenes. Complex chromosomal anomalies are rarely found in mucinous and endometrioid carcinomas (mainly in advanced stages), and are never found in serous LMP tumours. Epithelial ovarian tumours are characterised by gains at 3q, 8q and 20q, often with high level amplification. Thus the cytogenetic profiles of ovarian carcinomas differ from that of ovarian granulosa cell tumours, trisomy 14 and monsomy 22 are rarely found in ovarian carcinomas. Chromosome 1 and 3 abnormalities are the commonest aberrations found in ovarian metastatic tumours. Cytogenetic investigation of 11 individuals with bilateral ovarian carcinoma showed identical baseline karyotypes, suggesting both tumours arise from the same transformed cell, rather than the tumours arising independently.
46/52 ovarian carcinomas had complex karyotypes, often with a stemline chromosome number that was approaching near-triploid or hypodiploid. Chromosome losses of X, 22, 17, 13, 14 and 8, (lost in 15 imbalances
Their analyses hypothesised that the temporal order of imbalances were as follows: 1q-, 6q-, +7 and +8q occurred early, -4, -8, +1q, +12 and +20 were intermediate imbalances, and the remaining imbalances were late events. It has been concluded that karyotypic evolution in ovarian carcinomas followed at least 2 cytogenetic pathways. The first pathway involved chromosomal gains of +7/+8q/+12 and was associated with low-stage and low-grade tumours. The second pathway involved chromosomal losses of 6q- and 1q- was found in tumours of moderate stage and grade. The early stages of karyotypic evolution result from the step-wise acquisition of changes resulting in Phase I tumours. Chromosome instability resulted in the transition to Phase II tumours, possibly as a result of extensive telomere crisis and breakage fusion breakage cycles, which is linked to imbalances characteristic of the 6q-/1q- pathway. Consequently, low-grade and borderline tumours cannot progress unless they have mixed-pathway features. The 6q-/1q- pathway was associated with triploidization. The 6q-/1q- pathway is instrumental in the progression of ovarian carcinomas. The proposed pathway of karyotypic evolution in ovarian carcinomas is summarised in Figure 1.
A cohort of 114 ovarian neoplasms was analysed, including benign, borderline and invasive carcinomas by conventional and molecular cytogenetics. The chromosome abnormalities were categorised as follows:
The presence of cytogenetic aberrations common to all subtypes suggests these tumours develop by progression.
The main conclusions from cytogenetic investigations of ovarian epithelial tumours are as follows:
Other studies have identified gain of chromosome 8 in 1/10 ovarian carcinomas.
A study of 31 primary ovarian carcinomas in Chinese women by CGH identified several non-random changes in copy number including gains of 3q (17 cases, 55%) with a minimum region of gain of 3q25-q26, 8q (16 cases, 52%), 19q (12 cases, 39%), Xq (11 cases, 35%), 1q (10 cases, 32%), 12p12-q13 (10 cases, 32%), 17q (10 cases, 32%) with a minimum region of gain at 17q21, and 20q (9 cases, 29%); together with losses of 16q (9 cases, 29%), 1p (7 cases, 23%), 18q (7 cases, 23%) and 22 (7 cases, 23%). High copy number amplifications were observed at 3q25-q26 (4 cases), 8q24 (3 cases) and 12p11.2-q12 (3 cases). The commonest imbalances detected by CGH of epithelial neoplasms were gain of 3q25-26, gain of 8q24, loss of 16q, and loss of 17pter-q21. 12p gains were seen in 8/44 cases, which has been reported previously in both ovarian and testicular germ cell tumours. Another study by Hauptmann et al., 2002 using CGH to analyse ovarian carcinomas identified frequent gains of 3q, 6p, 7, 8q and 20, together with losses of 4q, 6q, 12q, 13q and 16q, which have supported the available cytogenetic data.
CGH was used to screen a mucinous ovarian carcinoma and a Brenner tumour coexisting in different ovaries of the same female. Amplification of 12q14-q21 was identified in both tumours, in the presence of other copy number changes, 4 such changes in the Brenner tumour and 6 in the mucinous carcinoma.
Correlation of CGH data with Clinical data
In a large study of 106 primary ovarian carcinomas, the CGH findings were correlated with clinical parameters such as tumour grade of differentiation. 103 tumours displayed imbalances. Amplifications of 8q, 1q, 20q, 3q and 19p were frequent findings present in 69-53% of the tumours. Underrepresentations of 13q, 4q and 18q were also common, present in 54-50% of cases. Underrepresentation of 11p and 13q and overrepresentation of 8q and 7q correlated with undifferentiated ovarian carcinoma, whereas 12p underrepresentation and 18p overrepresentation were more commonly associated with well-differentiated and moderately differentiated tumours. These findings corroborate other CGH studies including.
A CGH study of a cohort of 12 ovarian clear cell carcinomas revealed similarities to the data of other subtypes of epithelial neoplasms, such as gains of 8q and 17q and losses of 19p. They also correlated their findings with disease status (i.e. disease free, recurrent disease, or death from disease). DNA copy number changes present in over 20% of cases included overrepresentation of 8q11-q13, 8q21-q22, 8q23, 8q24-qter, 17q25-qter, 20q13-qter and 21q22; and underrepresentation of 19p. Overrepresentation of 8q11-q13, 8q21-q22, 8q23, 8q24-qter was more common in disease-free patients than in those with recurrent disease or who had died. Conversely, overrepresentation of 17q25-qter, 20q13-qter was more frequent in patients with recurrent disease or non-survivors, than in disease-free patients. This data suggests ovarian clear cell carcinoma develop along 2 cytogenetic pathways.
In a study correlating CGH genomic imbalances with clinical endpoints in 60 ovarian carcinomas, the following associations were found:
CGH findings of Sporadic and Hereditary Ovarian Carcinoma
CGH profiles were compared from sporadic and hereditary (3 BRCA1 and 1 BRCA2 mutation carriers) ovarian cancers. The commonest imbalance included amplification of 8q22.1-qter (66.6%), 1q22-32.1 (41.1%), 3q (75%) and 10p (33.2 %), and deletion of 9q (41.6%) and 16q21-q24 (33.3%). Deletions of 9q were found in all 3 BRCA1 carriers and 2/8 sporadic tumours, and deletions of 19 were found in 2/3 BRCA1 carriers and none of the sporadic cases. These findings suggest preferential somatic losses of chromosome 9 and 19 in BRCA1 mutation carriers. In contrast, another study identified extensive similarity by CGH between sporadic and hereditary ovarian carcinomas, except for 2q24-q32. CGH analysis of a further 36 hereditary tumours found the majority of imbalances to be similar to that of sporadic tumours (Gains: 8q23-qter, 3q26.3-qter, 11q22, 2q31-32; losses: 8p21-pter, 16q22-qter, 22q13, 12q24, 15q11-15, 17p12-13, Xp21-22, 20q13, 15q24-25, 18q21). However some imbalances were identified that were specific to hereditary tumours, including deletions of 15q11-15, 15q24-25, 8p21-pter, 22q13 and 12q24, and gains of 11q22, 13q22 and 17q23-35. Deletions of 15q11-15 and 15q24-25 were found in 16/36 and 12/36 cases respectively which implicated hRAD51 and other tumour suppressor genes in these loci in the genesis of hereditary ovarian cancer.
As mentioned in the Aetiology section, genetic factors are the most important risk factor for ovarian epithelial carcinoma. Having 1 or 2 first-degree relatives with ovarian cancer increases the lifetime risk to 3-5% and 39% respectively. Three hereditary syndromes in which familial aggregation of ovarian carcinoma occurs have been described:
All 3 patterns of familial ovarian cancer are consistent with autosomal-dominant transmission of one or more genes responsible for the development of >1 cancers, with incomplete penetrance and variable expression. The age of diagnosis of hereditary epithelial ovarian cancer is approximately 10 years earlier than its sporadic counterpart.
Breast-Ovarian SyndromeOf the about 10% of ovarian epithelial cancers thought to have a hereditary component, 90% are associated with breast-ovarian syndrome. This syndrome is associated with two genes, BRCA1 at 17q21, and BRCA2 at 13q12.3 (see below), which are involved in DNA repair and transcription regulation. Mutations are distributed throughout the entire coding regions of BRCA1 and BRCA2, and most result in truncation of the protein. Germline mutations in BRCA1 account for about 80% of hereditary breast-ovarian cancers. Germline mutations of BRCA2 account for about 10-35% of familial ovarian cancers. BRCA1 is associated with a 26% cumulative risk for ovarian cancer for most mutation carriers, and a much higher risk, 85%, in a small subset. Women with a germline BRCA1 mutation have an about 40% risk of developing ovarian cancer by 70 years of age. BRCA2 increases susceptibility to a smaller degree. The lifetime risk for developing ovarian cancer in BRCA2 mutation carriers is 27%. However the risks of developing ovarian cancer associated with germline mutations of BRCA1 and BRCA2 vary according to the population studied. A study by revealed a lifetime risk of ovarian cancer of 40-60% for BRCA1 mutation carriers, whereas another one found a 25-30% risk for BRCA1 mutation carriers. Approximately 1/4000 in the general population has a mutation of BRCA1, although some populations have much higher incidences, for example the Ashkenazi Jews. Patients with breast cancer who had BRCA1 or BRCA2 mutations had a tenfold increased risk of developing ovarian cancer.
The variable penetrance of BRCA1 suggests that other genetic and non-genetic factors contribute to the pathogenesis in these individuals. One such modifier is a VNTR polymorphism, 1-kb downstream of HRAS. BRCA1 carriers with rare alleles of the VNTR had an 2.11 increased risk of developing ovarian cancer compared with the common alleles (p=0.015).
about 50% of familial ovarian cancers are not associated with germline BRCA1 or BRCA2 mutations. Linkage and LOH analysis has suggested a susceptibility gene for familial ovarian cancer at 3p22-p25. LOH of 3p33-p25 is higher (52%) in non-BRCA1/BRCA2 familial ovarian cancers than in the BRCA1 (29.7%) group.
HNPCCMutations of the mismatch repair genes (MMR) including MLH1, MSH2 and MSH6 are present in HNPCC syndrome (Lynch 2 Syndrome). This represents the second most common type of ovarian cancer with a hereditary component.
Site-Specific Ovarian Cancer SyndromeThe least common of the familial ovarian cancers is the site-specific ovarian cancer syndrome, in which ovarian cancer is the dominant cancer. It has been suggested that site-specific ovarian cancer is a variant of breast-ovarian syndrome attributable to mutation in either BRCA1 or BRCA2, and not a distinct clinical entity.
Early onset ovarian carcinoma (
Ovary: Epithelial tumors
Atlas Genet Cytogenet Oncol Haematol. 2003-12-01
Online version: http://atlasgeneticsoncology.org/solid-tumor/5230/ovary-epithelial-tumors