The microsomal epoxide hydrolase Tyr113His polymorphism: Association with risk of ovarian cancer

Functional significance has been demonstrated in vitro for the exon 3 T-->C Tyr113His amino acid substitution polymorphism of the microsomal epoxide hydrolase (EPHX) gene. The higher activity or fast TT genotype was previously reported to be associated with an increased risk of ovarian cancer, and this association may reflect enhanced activation of endogenous or exogenous substrates to more reactive and mutagenic derivatives. Components of cigarette smoke are examples of exogenous substrates subject to such bioactivation, and smoking exposure may thus modify the risk associated with the EPHX polymorphism. We examined 545 cases of epithelial ovarian cancer and 287 unaffected controls for this EPHXT-C genetic variant to investigate whether, in the Australian population, the TT genotype was associated with (i) specific ovarian tumor characteristics; (ii) risk of ovarian cancer, overall or for specific subgroups; and (iii) risk of ovarian cancer in smokers specifically. Genotyping was carried out using the Perkin-Elmer ABI Prism 7700 Sequence Detection System for fluorogenic polymerase chain reaction allelic discrimination. Stratification of the ovarian cancer cases according to tumor behavior (low malignant potential or invasive), grade, stage, and p53 immunohistochemical status failed to show any heterogeneity with respect to the genotype defined by the EPHX polymorphism. There was a suggestion of heterogeneity with respect to histologic subtype (P= 0.03), largely due to a decreased frequency of the TT genotype in endometrioid tumors. EPHX genotype distribution did not differ significantly between unaffected controls and ovarian cancer cases (overall, low malignant potential, or invasive) either overall or after stratification by smoking status. However, the TT genotype was associated with a decreased risk of invasive ovarian cancer of the endometrioid subtype specifically (age-adjusted odds ratio = 0.38, 95% confidence interval=0.17-0.87). The results suggest that the proposed EPHX-mediated bioactivation of components of cigarette smoke to mutagenic forms is unlikely to be involved in the etiology of ovarian cancer in general but that a greater rate of EPHX-mediated detoxification may decrease the risk of endometrioid ovarian cancer. (C) 2001 Wiley-Liss, Inc.

Polymorphisms at the glutathione S-transferase GSTM1, GSTT1 and GSTP1 loci: risk of ovarian cancer by histological subtype

The phase II glutathione S-transferases (GSTs) GSTT1, GSTM1 and GSTP1 catalyse glutathione-mediated reduction of exogenous and endogenous electrophiles. These GSTs have broad and overlapping substrate specificities and it has been hypothesized that allelic variants associated with less effective detoxification of potential carcinogens may confer an increased susceptibility to cancer. To assess the role of GST gene variants in ovarian cancer development, we screened 285 epithelial ovarian cancer cases and 299 unaffected controls for the GSTT1 deletion (null) variant, the GSTM1 deletion (null) variant and the GSTP1 codon 104 A-->G Ile-->Val amino acid substitution variant, The frequencies of the GSTT1, GSTM1 and GSTP1 polymorphic variants did not vary with tumour behaviour (low malignant potential or invasive) or p53 immunohistochemical status. There was a suggestion that ovarian cancers of the endometrioid or clear cell histological subtype had a higher frequency of the GSTT1 and GSTM1 deletion genotype than other histological subgroups. The GSTT1, GSTM1 and GSTP1 genotype distributions did not differ significantly between unaffected controls and ovarian cancer cases (overall or invasive cancers only). However, the GSTM1 null genotype was associated with increased risk of endometrioid/clear cell invasive cancer [age-adjusted OR (95% CI) = 2.04 (1.01-4.09), P = 0.05], suggesting that deletion of GSTM1 may increase the risk of ovarian cancer of these histological subtypes specifically. This marginally significant finding will require verification by independent studies.

No significant association between progesterone receptor exon 4 Val660Leu G/T polymorphism and risk of ovarian cancer

Epidemiological studies suggest that ovarian cancer is an endocrine-related tumour, and progesterone exposure specifically may decrease the risk of ovarian cancer. To assess whether the progesterone receptor (PR) exon 4 valine to leucine amino acid variant is associated with specific tumour characteristics or with overall risk of ovarian cancer, we examined 551 cases of epithelial ovarian cancer and 298 unaffected controls for the underlying G-->T nucleotide substitution polymorphism. Stratification of the ovarian cancer cases according to tumour behaviour (low malignant potential or invasive), histology, grade or stage failed to reveal any heterogeneity with respect to the genotype defined by the PR exon 4 polymorphism. Furthermore, the genotype distribution did not differ significantly between ovarian cancer cases and unaffected controls. Compared with the GG genotype, the age-adjusted odds ratio (95% confidence interval) for risk of ovarian cancer was 0.78 (0.57-1.08) for the GT genotype, and 1.39 (0.47-4.14) for the TT genotype. In conclusion, the PR exon 4 codon 660 leucine variant encoded by the T allele does not appear to be associated with ovarian tumour behaviour, histology, stage or grade. This variant is also not associated with an increased risk of ovarian cancer, and is unlikely to be associated with a large decrease in ovarian cancer risk, although we cannot rule out a moderate inverse association between the GT genotype and ovarian cancer.

Safety and efficacy of low anterior en bloc resection as part of cytoreductive surgery for patients with ovarian cancer

Objective. To examine the feasibility and safety of a low anterior resection of the rectosigmoid plus adjacent pelvic tumour as part of primary cytoreduction for ovarian cancer. Methods. This study included 65 consecutive patients with primary ovarian cancer who had debulking surgery from 1996 through 2000. All patients underwent an en bloc resection of ovarian cancer and a rectosigmoid resection followed by an end-to-end anastomosis. Parameters for safety and efficacy were considered as primary statistical endpoints for the aim of this analysis. Results. Postoperative residual tumour was nil, 1 cm in 14, 34, and 14 patients, respectively. The median postoperative hospital stay was 11 days (range, 6 to 50 days). Intraoperative complications included an injury to the urinary bladder in one patient. Postoperative complications included wound complications (n=14, 21.5%), septicemia (n=9, 13.8%), cardiac complications (n=7, 10.8%), thromboembolic complications (n=5, 7.7%) ileus (n=2, 3.1%) anastomotic leak (n=2, 3.1%) and fistula (n=1, 1.5%). Reasons for a reoperation during the same admission included repair of an anastomotic leak (n=1), postoperative hemorrhage (n=1), and wound debridement (n=1). Wound complications, septicemia, and anastomotic leak formation were more frequent in patients who had a serum albumin level of less than or equal to 30 g/L preoperatively. There was one surgically related mortality in a patient who died from a cerebral vascular accident 2 days postoperatively. Conclusions. An en bloc resection as part of primary cytoreductive surgery for ovarian cancer is effective and its morbidity is acceptably low. (C) 2001 Academic Press.

Relationship of XIST expression and responses of ovarian cancer to chemotherapy

Expression profiling to characterize cancer pharmacology has become a new approach to discover novel molecular targets for prognostic markers and cancer therapy. In a study to compare the global RNA expression profiles between primary and recurrent ovarian tumors from the same patient, we have identified XIST (inactive X chromosome-specific transcripts) as the most differentially expressed gene that was down-regulated in the recurrent tumor. XIST encodes a spliced noncoding polyadenylated transcript that is unique in being expressed exclusively from the inactive X chromosome and is involved in the X-inactivation process. Subsequent characterization of XIST expression in a panel of female cancer cell lines showed that the expression level of XIST correlates significantly with Taxol sensitivity. The clinical relevance of this observation is demonstrated by the strong association between XIST RNA levels and disease-free periods of ovarian cancer patients in a group of 21 ovarian cancer cases with Taxol in the therapeutic regiments. Cytogenetic studies on ovarian cancer cell lines indicated that loss of inactive X chromosome is one mechanism for the loss of XIST transcripts in the cell lines. Our data suggest that XIST expression may be a potential marker for chemotherapeutic responses in ovarian cancer.

Dietary influences on survival after ovarian cancer

We evaluated the effects of various food groups and micronutrients in the diet on survival among women who originally participated in a population-based case-control study of ovarian cancer conducted across 3 Australian states between 1990 and 1993. This analysis included 609 women with invasive epithelial ovarian cancer, primarily because there was negligible mortality in women with borderline tumors. The women's usual diet was assessed using a validated food frequency questionnaire. Deaths in the cohort were identified using state-based cancer registries and the Australian National Death Index (NDI). Crude 5-year survival probabilities were estimated using the Kaplan-Meier technique, and adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) were obtained from Cox regression models. After adjusting for important confounding factors, a survival advantage was observed for those who reported higher intake of vegetables in general (HR = 0.75, 95% CI = 0.57-0.99, p-value trend 0.01 for the highest third, compared to the lowest third), and cruciferous vegetables in particular (HR = 0.75, 95% CI = 0.57-0.98, p-value trend 0.03), and among women in the upper third of intake of vitamin E (HR = 0.76, 95% CI = 0.58-1.01, p-value trend 0.04). Inverse associations were also seen with protein (p-value trend 0.09), red meat (p-value trend 0.06) and white meat (p-value trend 0.07), and modest positive trends (maximum 30% excess) with lactose (p-value trend 0.04), calcium and dairy products. Although much remains to be learned about the influence of nutritional factors after a diagnosis of ovarian cancer, our study suggests the possibility that a diet high in vegetable intake may help improve survival. (C) 2003 Wiley-Liss, Inc.

Ovulation and risk of epithelial ovarian cancer

Incessant ovulation is thought to be one of the primary causes of epithelial ovarian cancer. However, the effects of ovulation at different ages and of the various exposures or events that suppress ovulation have not been established. We used data from an Australian case-control study of 791 ovarian cancer cases and 853 controls to examine the effect of ovulation on ovarian cancer risk. The total number of lifetime ovulations was calculated using information provided in a monthly contraceptive/reproductive calendar, as well as incorporating other information such as average menstrual cycle length. An increase of I year's worth of ovulation was associated with a 6% increase in risk of ovarian cancer (95% confidence interval [CI] = 4-8%). Ovulations in the 20-29-year age group were associated with the greatest risk, with a 20% increase in risk associated with each year of ovulation during this age period (95% Cl = 13-26%). When the effects of different exposures that suppress ovulation were compared, there was an indication that some factors may have a greater effect than others. These findings support the theory that incessant ovulation is a major contributor to the occurrence of ovarian cancer and suggest that ovulations during the 20s may be those most associated with disease risk. (C) 2003 Wiley-Liss, Inc.

Characterisation of human kallikrein 6 protease M expression in ovarian cancer

Kallikrein 6 (hK6, also known as protease M/zyme/neurosin) is a member of the human kallikrein gene family. We have previously cloned the cDNA for this gene by differential display and shown the overexpression of the mRNA in breast and ovarian primary tumour tissues and cell lines. To thoroughly characterise the expression of this kallikrein in ovarian cancer, we have developed a novel monoclonal antibody specific to hK6 and employed it in immunohistochemistry with a wide range of ovarian tumour samples. The expression was found elevated in 67 of 80 cases of ovarian tumour samples and there was a significant difference in the expression levels between normal and benign ovarian tissues and the borderline and invasive tumours (P<0.001). There was no difference of expression level between different subtypes of tumours. More significantly, high level of kallikrein 6 expression was found in many early-stage and low-grade tumours, and elevated hK6 proteins were found in benign epithelia coexisting with borderline and invasive tissues, suggesting that overexpression of hK6 is an early phenomenon in the development of ovarian cancer. Quantitative real-time reverse transcription-polymerase chain reactions also showed elevated kallikrein 6 mRNA expression in ovarian tumours. Genomic Southern analysis of 19 ovarian tumour samples suggested that gene amplification is one mechanism for the overexpression of hK6 in ovarian cancer.

Alcohol, wine, and risk of epithelial ovarian cancer

Moderate alcohol intake can influence sex hormone levels and affect ovarian function as well as increasing breast cancer risk. This suggests that alcohol might also influence ovarian cancer risk. We have evaluated this among 696 Australian women with histologically confirmed epithelial ovarian cancer and 786 cancer-free control women, selected at random from the electoral roll. Sociodemographic information and a detailed reproductive history were collected in a face-to-face interview, and information about diet and alcohol consumption was obtained from a food frequency questionnaire. Logistic regression was used to calculate adjusted odds ratios (OR) and 95% confidence intervals (95% CI). Overall, 59% of women drank

Symptoms and diagnosis of borderline, early and advanced epithelial ovarian cancer

Objective. To document symptoms associated with borderline, early and advanced ovarian cancer and identify personal characteristics associated with early versus late diagnosis. Methods. Information concerning symptoms and diagnosis history was available from 811 women with ovarian cancer who took part in an Australian case–control study in the early 1990s. Women were classified into three groups for comparison based on their diagnosis: borderline, early (stage I–II) and advanced (stage III–IV) invasive cancer. Results. Sixteen percent of women with borderline tumors, 7% with early cancer and 4% with advanced cancer experienced no symptoms before diagnosis (P < 0.0001). Among women with symptoms, abdominal pain (44%) or swelling (39%) were most frequently reported; an abdominal mass (12%) and gynecological symptoms (12%) were less common. Compared to advanced stage cancer, women with early stage cancer were more likely to report an abdominal mass or urinary symptoms but less likely to report gastrointestinal problems or general malaise. General malaise and ‘other’ symptoms were least common in borderline disease. Older women, and those with higher parity or a family history of breast or ovarian cancer, were more likely to be diagnosed at an advanced stage of disease. Conclusions. Women who experience persistent or recurrent abdominal symptoms, particularly swelling and/or pain should be encouraged to seek medical attention and physicians should be alert to the possibility of ovarian cancer even in the absence of an abdominal mass. Further information about the prevalence of these symptoms in the general population is essential to assist physicians in patient management.

Height, age at menarche, and risk of epithelial ovarian cancer

Objective: We hypothesized that the hormonal changes of adolescence influence ovarian cancer risk particularly in younger women. We investigated this possibility by examining the relationship between ovarian cancer and adult height and age at menarche as both factors reflect pubertal hormonal levels. Methods: Participants were a population-based sample of women with incident ovarian cancer (n = 794) and control women randomly selected from the Australian Electoral Roll (n = 855). The women provided comprehensive reproductive and lifestyle data during a standard interview. Results: Although neither height nor age at menarche was significantly related to the risk of ovarian cancer overall, increasing height was associated with increasing risk of the subgroup of mucinous borderline ovarian cancer (odds ratio, 5.3; 95% confidence interval, 1.5-19.1 for women 175 cm compared with women < 160 cm, P-trend = 0.02). Similarly, later age at menarche was associated with increasing risk of mucinous borderline cancers (odds ratio, 3.8; 95% confidence interval, 1.3-11.4 for those with age at menarche >= 44 years compared with those < 12 years, P-trend = 0.003). Women with mucinous borderline cancers were significantly younger than the women diagnosed with invasive cancers (mean 44 versus 57 years; P < 0.0001). Conclusions: Development of mucinous borderline ovarian cancers, predominantly diagnosed in women ages under 50 years, seems to be associated with age at menarche and attained adult height. These results are consistent with our original hypothesis that pubertal levels of reproductive hormones and insulin-like growth factor-I influence ovarian cancer risk in younger women.

Double-strand break repair gene polymorphisms and risk of breast or ovarian cancer

Deficiencies in DNA repair have been hypothesized to increase cancer risk and excess cancer incidence is a feature of inherited diseases caused by defects in DNA damage recognition and repair. We investigated, using a case-control design, whether the double-strand break repair gene polymorphisms RAD51 5' untranslated region -135 G > C, XRCC2 R188H G > A, and XRCC3 T241M C > T were associated with risk of breast or ovarian cancer in Australian women. Sample sets included 1,456 breast cancer cases and 793 age-matched controls ages under 60 years of age, 549 incident ovarian cancer cases, and 335 controls of similar age distribution. For the total sample and the subsample of Caucasian women, there were no significant differences in genotype distribution between breast cancer cases and controls or between ovarian cancer cases and combined control groups. The crude odds ratios (OR) and 95% confidence intervals (95% CI) associated with the RAD51 GC/CC genotype frequency was OR, 1.10; 95% CI, 0.80-1.41 for breast cancer and OR, 1.22; 95% CI, 0.92-1.62 for ovarian cancer. Similarly, there were no increased risks associated with the XRCC2 GA/AA genotype (OR, 0.98; 95% CI, 0.76-1.26 for breast cancer and OR, 0.93; 95% CI, 0.69-1.25 for ovarian cancer) or the XRCC3 CT/TT genotype (OR, 0.92; 95% Cl, 0.77-1.10 for breast cancer and OR, 0.87; 95% CI, 0.71-1.08 for ovarian cancer). Results were little changed after adjustment for age and other measured risk factors. Although there was little statistical power to detect modest increases in risk for the homozygote variant genotypes, particularly for the rare RAD51 and XRCC2 variants, the data suggest that none of these variants play a major role in the etiology of breast or ovarian cancer.

RAD52 Y415X truncation polymorphism and epithelial ovarian cancer risk in Australian women

The RAD52 gene is involved in the homologous recombination repair pathway and is a plausible candidate ovarian cancer predisposition gene. We undertook a case-control comparison of 508 epithelial ovarian cancer cases (91 low malignant potential and 417 invasive) and 298 healthy controls to assess the RAD52 Y415X polymorphism as a risk factor for epithelial ovarian cancer in Australian women. Heterozygote frequencies of 2.6 and 4% were observed among cases and controls, respectively. The risk estimate was 0.55 (95%CI 0.24-1.24), suggesting that the RAD52 Y415X polymorphism is not associated with epithelial ovarian cancer in Australian women. (C) 2004 Elsevier Ireland Ltd. All rights reserved.

Over-expression of Eph and ephrin genes in advanced ovarian cancer: ephrin gene expression correlates with shortened survival

Background: Increased expression of Eph receptor tyrosine kinases and their ephrin ligands has been implicated in tumor progression in a number of malignancies. This report describes aberrant expression of these genes in ovarian cancer, the commonest cause of death amongst gynaecological malignancies. Methods: Eph and ephrin expression was determined using quantitative real time RT-PCR. Correlation of gene expression was measured using Spearman's rho statistic. Survival was analysed using log-rank analysis and ( was visualised by) Kaplan-Meier survival curves. Results: Greater than 10 fold over-expression of EphA1 and a more modest over-expression of EphA2 were observed in partially overlapping subsets of tumors. Over-expression of EphA1 strongly correlated ( r = 0.801; p < 0.01) with the high affinity ligand ephrin A1. A similar trend was observed between EphA2 and ephrin A1 ( r = 0.387; p = 0.06). A striking correlation of both ephrin A1 and ephrin A5 expression with poor survival ( r = - 0.470; p = 0.02 and r = - 0.562; p < 0.01) was observed. Intriguingly, there was no correlation between survival and other clinical parameters or Eph expression. Conclusion: These data imply that increased levels of ephrins A1 and A5 in the presence of high expression of Ephs A1 and A2 lead to a more aggressive tumor phenotype. The known functions of Eph/ephrin signalling in cell de-adhesion and movement may explain the observed correlation of ephrin expression with poor prognosis.