Ovarian cancer aetiology: facts and fiction

Multiparametric MRI Evaluation of Complex Ovarian Masses

OBJECTIVE

To assess the role of diffusion-weighted imaging and dynamic contrast-enhanced magnetic resonance imaging in the categorization of complex ovarian masses into benign and malignant.

MATERIALS AND METHODS

This prospective study was done on 33 complex ovarian masses. T1 and T2-weighted sequences, diffusion-weighted imaging, apparent diffusion coefficient, and dynamic contrast-enhanced magnetic resonance imaging were performed on 1.5 T MRI. Time-intensity curves, tissue signal intensity on unenhanced T1 images (SI₀), maximum absolute contrast enhancement (SI_max), time to reach SI_max (T_max), maximum relative SI (SI_rel = [SI_max - SI₀]/SI₀ ×100), maximum Slope (Slope_max = SI_rel/T_max ×100), and wash in rate (WIR = [SI_max - SI₀]/T_max) were calculated. Histopathological diagnosis was taken as gold standard.

RESULTS

A total of 20/33 masses were benign, 2/33 were borderline tumors, and 11/33 were malignant. Diffusion restriction was seen in all malignant masses and 13/20 benign masses. The mean apparent diffusion coefficient values showed a significant difference between malignant and benign, with 81.8% sensitivity and 63.6% specificity. Type III curve showed 100% specificity for malignant lesions. T_max and Slope_max were useful in differentiating benign and malignant masses; with T_max cut-off at 73.5 seconds having a high specificity (81.8%) and Slope_max cut-off at 0.83%/s having high sensitivity (91%) and negative predictive value (94.4%).

CONCLUSION

Multiparametric MRI confers high diagnostic accuracy in stratifying complex ovarian masses.

Genetic modifiers of cancer risk for BRCA1 and BRCA2 mutation carriers

Germline mutations in BRCA1 and BRCA2 confer high risks of female breast and ovarian cancer. However, there is strong evidence that these risks are modified by other factors, including familial or genetic factors. Genome-wide association studies have identified several breast cancer genetic susceptibility variants in the general population that are also associated with breast cancer risk for mutation carriers. The patterns of association for these variants vary between BRCA1 and BRCA2 mutation carriers and this variation appears to be driven by their differential associations with breast cancer subtypes defined by estrogen receptor status. We review the latest evidence regarding genetic modifiers of cancer risk for female BRCA1 and BRCA2 mutation carriers emerging from candidate gene studies, variants found in genome-wide association studies (GWAS) to be associated with cancer risk in the general population and GWAS specifically in mutation carriers. We also discuss the implications of these findings for cancer risk prediction in these women. BRCA1 and BRCA2 mutation carriers could potentially be among the first groups of individuals for whom clinically applicable risk profiling could be developed using the common breast cancer susceptibility variants identified through GWAS.

Micronucleus frequency in lymphocytes and 8-hydroxydeoxyguanosine level in plasma of women with polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) has recently been linked with genomic instability and DNA damage. The aim of this study was to test genomic damage in women PCOS, using two different methods for assessing damage in both chromosome and base level. The study was performed on 36 newly diagnosed women with PCOS and 29 healthy women as controls. The micronucleus (MN) analysis used as a biomarker of chromosomal/DNA damage was performed in peripheral lymphocytes by cytokinesis-block method. 8-hydroxydeoxyguanosine (8-OHdG) levels used as a reliable marker of oxidative DNA damage were measured in plasma using an ELISA kit. We found that MN frequencies obtained from lymphocytes of the women with PCOS were significantly higher than those of controls (4.1 +/- 1.0 vs. 2.1 +/- 0.6, P = 0.001), whereas, no differences in 8-OHdG level were found between the patients with PCOS and controls (0.5 +/- 0.3 vs. 0.5 +/- 0.2, P = 0.858). These findings indicate that women with PCOS seem to have increased genomic instability, but do not appear to have oxidative DNA damage despite the increased oxidative stress associated with PCOS.

Parity and the risk of breast and ovarian cancer in BRCA1 and BRCA2 mutation carriers

Environmental or lifestyle factors are likely to explain part of the heterogeneity in breast and ovarian cancer risk among BRCA1 and BRCA2 mutation carriers. We assessed parity as a risk modifier in 515 and 503 Spanish female carriers of mutations in BRCA1 and BRCA2, respectively. Hazard ratios (HR) and their corresponding 95% confidence intervals (CI) were estimated using weighted Cox proportional hazards regression, adjusted for year of birth and study centre. The results for ever being parous and number of live-births were very similar for carriers of mutations in both genes. For all mutation carriers combined, the estimated HR associated with ever having had a live-birth was 0.74 (95% confidence interval [CI] = 0.55-1.01, P = 0.06), and that associated with each live-birth was 0.87 (95%CI = 0.77-0.98, P = 0.02). The latter association was observed only in women aged 40 and above (HR = 0.81, 95%CI = 0.70-0.94, P = 0.004 vs. HR = 0.99, 95%CI = 0.83-1.18, P = 0.9 for women under age 40), and this trend was highly consistently observed for carriers of mutations in each gene. There was no evidence of an association between breast cancer risk and age at first birth for parous BRCA1 or BRCA2 mutation carriers (P-trend >or= 0.3). The power to detect associations with ovarian cancer risk was much lower, especially for BRCA2 mutation carriers. Nevertheless, having a live-birth was associated with protection for BRCA1 mutation carriers (HR = 0.41, 95%CI = 0.18-0.94, P = 0.03), and a strong and consistent protective effect of age at first birth was observed for parous carriers of mutations in both genes (HR = 0.65, 95%CI = 0.52-0.83, P < 0.001). This is the third independent study to find that, as in the general population, parity appears to be associated with protection from breast cancer in women with mutations in BRCA1 and BRCA2. Parity appears to be protective for ovarian cancer in BRCA1 mutation carriers, but its role in BRCA2 mutation carriers remains unclear. Whether later age at first birth is also protective for ovarian cancer in mutation carriers requires further confirmation.