Risk factors for epithelial ovarian cancer by histologic subtype

Appraising the role of previously reported risk factors in epithelial ovarian cancer risk: A Mendelian randomization analysis

BACKGROUND

Various risk factors have been associated with epithelial ovarian cancer risk in observational epidemiological studies. However, the causal nature of the risk factors reported, and thus their suitability as effective intervention targets, is unclear given the susceptibility of conventional observational designs to residual confounding and reverse causation. Mendelian randomization (MR) uses genetic variants as proxies for risk factors to strengthen causal inference in observational studies. We used MR to evaluate the association of 12 previously reported risk factors (reproductive, anthropometric, clinical, lifestyle, and molecular factors) with risk of invasive epithelial ovarian cancer, invasive epithelial ovarian cancer histotypes, and low malignant potential tumours.

METHODS AND FINDINGS

Genetic instruments to proxy 12 risk factors were constructed by identifying single nucleotide polymorphisms (SNPs) that were robustly (P < 5 × 10-8) and independently associated with each respective risk factor in previously reported genome-wide association studies. These risk factors included genetic liability to 3 factors (endometriosis, polycystic ovary syndrome, type 2 diabetes) scaled to reflect a 50% higher odds liability to disease. We obtained summary statistics for the association of these SNPs with risk of overall and histotype-specific invasive epithelial ovarian cancer (22,406 cases; 40,941 controls) and low malignant potential tumours (3,103 cases; 40,941 controls) from the Ovarian Cancer Association Consortium (OCAC). The OCAC dataset comprises 63 genotyping project/case-control sets with participants of European ancestry recruited from 14 countries (US, Australia, Belarus, Germany, Belgium, Denmark, Finland, Norway, Canada, Poland, UK, Spain, Netherlands, and Sweden). SNPs were combined into multi-allelic inverse-variance-weighted fixed or random effects models to generate effect estimates and 95% confidence intervals (CIs). Three complementary sensitivity analyses were performed to examine violations of MR assumptions: MR-Egger regression and weighted median and mode estimators. A Bonferroni-corrected P value threshold was used to establish strong evidence (P < 0.0042) and suggestive evidence (0.0042 < P < 0.05) for associations. In MR analyses, there was strong or suggestive evidence that 2 of the 12 risk factors were associated with invasive epithelial ovarian cancer and 8 of the 12 were associated with 1 or more invasive epithelial ovarian cancer histotypes. There was strong evidence that genetic liability to endometriosis was associated with an increased risk of invasive epithelial ovarian cancer (odds ratio [OR] per 50% higher odds liability: 1.10, 95% CI 1.06-1.15; P = 6.94 × 10-7) and suggestive evidence that lifetime smoking exposure was associated with an increased risk of invasive epithelial ovarian cancer (OR per unit increase in smoking score: 1.36, 95% CI 1.04-1.78; P = 0.02). In analyses examining histotypes and low malignant potential tumours, the strongest associations found were between height and clear cell carcinoma (OR per SD increase: 1.36, 95% CI 1.15-1.61; P = 0.0003); age at natural menopause and endometrioid carcinoma (OR per year later onset: 1.09, 95% CI 1.02-1.16; P = 0.007); and genetic liability to polycystic ovary syndrome and endometrioid carcinoma (OR per 50% higher odds liability: 0.89, 95% CI 0.82-0.96; P = 0.002). There was little evidence for an association of genetic liability to type 2 diabetes, parity, or circulating levels of 25-hydroxyvitamin D and sex hormone binding globulin with ovarian cancer or its subtypes. The primary limitations of this analysis include the modest statistical power for analyses of risk factors in relation to some less common ovarian cancer histotypes (low grade serous, mucinous, and clear cell carcinomas), the inability to directly examine the association of some ovarian cancer risk factors that did not have robust genetic variants available to serve as proxies (e.g., oral contraceptive use, hormone replacement therapy), and the assumption of linear relationships between risk factors and ovarian cancer risk.

CONCLUSIONS

Our comprehensive examination of possible aetiological drivers of ovarian carcinogenesis using germline genetic variants to proxy risk factors supports a role for few of these factors in invasive epithelial ovarian cancer overall and suggests distinct aetiologies across histotypes. The identification of novel risk factors remains an important priority for the prevention of epithelial ovarian cancer.

Association between Cigarette Smoking and Histotype-Specific Epithelial Ovarian Cancer: A Review of Epidemiologic Studies

Many studies have demonstrated that smoking can influence ovarian cancer risk and survival; however, the number of studies investigating this relationship according to histologic subtypes is limited. We conducted a review of epidemiologic research that assessed the role of smoking on ovarian cancer risk and survival after diagnosis, specifically capturing studies that discerned between various histologic subtypes of this disease. In the majority of studies, current smoking was associated with increased risk of mucinous cancer. There was also evidence of a decreased risk of clear cell and endometrioid histotypes. No significant association was observed between cigarette smoking and serous cancer. In the studies investigating the relationship between smoking and survival, all the studies reported an increased risk of mortality associated with smoking. Smoking appeared to be a risk factor for both ovarian cancer risk and mortality. Future studies need to investigate further a potential link between smoking and ovarian cancer by having a better assessment of exposure to smoking and having a larger number of participants with the ability to detect associations within rare histotypes.

Risk of ovarian cancer in women treated with ovarian stimulating drugs for infertility

BACKGROUND

This is an updated version of the original Cochrane Review published in the Cochrane Library in 2013 (Issue 8) on the risk of ovarian cancer in women using infertility drugs when compared to the general population or to infertile women not treated. The link between fertility drugs and ovarian cancer remains controversial.

OBJECTIVES

To evaluate the risk of invasive ovarian cancer and borderline ovarian tumours in women treated with ovarian stimulating drugs for subfertility.

SEARCH METHODS

The original review included published and unpublished observational studies from 1990 to February 2013. For this update, we extended the searches from February 2013 to November 2018; we evaluated the quality of the included studies and judged the certainty of evidence by using the GRADE approach. We have reported the results in a Summary of findings table to present effect sizes across all outcome types.

SELECTION CRITERIA

In the original review and in this update, we searched for randomised controlled trials (RCTs) and non-randomised studies and case series including more than 30 participants.

DATA COLLECTION AND ANALYSIS

At least two review authors independently conducted eligibility and 'Risk of bias' assessments and extracted data. We grouped studies based on the fertility drug used for two outcomes: borderline ovarian tumours and invasive ovarian cancer. We conducted no meta-analyses due to expected methodological and clinical heterogeneity.

MAIN RESULTS

We included 13 case-control and 24 cohort studies (an additional nine new cohort and two case-control studies), which included a total of 4,684,724 women.Two cohort studies reported an increased incidence of invasive ovarian cancer in exposed subfertile women compared with unexposed women. One reported a standardised incidence ratio (SIR) of 1.19 (95% confidence interval (CI) 0.54 to 2.25) based on 17 cancer cases. The other cohort study reported a hazard ratio (HR) of 1.93 (95% CI 1.18 to 3.18), and this risk was increased in women remaining nulligravid after using clomiphene citrate (HR 2.49, 95% CI 1.30 to 4.78) versus multiparous women (HR 1.52, 95% CI 0.67 to 3.42) (very low-certainty evidence). The slight increase in ovarian cancer risk among women having between one and three cycles of in vitro fertilisation (IVF) was reported, but this was not clinically significant (P = 0.18). There was no increase in risk of invasive ovarian cancer after use of infertility drugs in women with the BRCA mutation according to one cohort and one case-control study. The certainty of evidence as assessed using GRADE was very low.For borderline ovarian tumours, one cohort study reported increased risk in exposed women with an SIR of 3.61 (95% CI 1.45 to 7.44), and this risk was greater after treatment with clomiphene citrate (SIR 7.47, 95% CI 1.54 to 21.83) based on 12 cases. In another cohort study, the risk of a borderline ovarian tumour was increased, with an HR of 4.23 (95% CI 1.25 to 14.33), for subfertile women treated with IVF compared with a non-IVF-treated group with more than one year of follow-up. A large cohort reported increased risk of borderline ovarian tumours, with HR of 2.46 (95% CI 1.20 to 5.04), and this was based on 17 cases. A significant increase in serous borderline ovarian tumours was reported in one cohort study after the use of progesterone for more than four cycles (risk ratio (RR) 2.63, 95% CI 1.04 to 6.64). A case-control study reported increased risk after clomiphene citrate was taken, with an SIR of 2.5 (95% CI 1.3 to 4.5) based on 11 cases, and another reported an increase especially after human menopausal gonadotrophin was taken (odds ratio (OR) 9.38, 95% CI 1.66 to 52.08). Another study estimated an increased risk of borderline ovarian tumour, but this estimation was based on four cases with no control reporting use of fertility drugs. The certainty of evidence as assessed using GRADE was very low.However, although some studies suggested a slight increase in risks of ovarian cancer and borderline ovarian tumour, none provided moderate- or high-certainty evidence, as summarised in the GRADE tables.

AUTHORS' CONCLUSIONS

Since the last version of this review, only a few new relevant studies have provided additional findings with supporting evidence to suggest that infertility drugs may increase the risk of ovarian cancer slightly in subfertile women treated with infertility drugs when compared to the general population or to subfertile women not treated. The risk is slightly higher in nulliparous than in multiparous women treated with infertility drugs, and for borderline ovarian tumours. However, few studies have been conducted, the number of cancers is very small, and information on the dose or type of fertility drugs used is insufficient.

Incidence of intraepithelial fallopian tube neoplasias in mexican women over 40 years of age that underwent elective hysterectomy

AIMS

The incidence of intraepithelial neoplasia in the fallopian tubes of women over 40 years of age who had undergone elective hysterectomy was assessed at the Aguascalientes Women's Hospital.

METHODS

An observational, prospective, descriptive study was carried out at the Aguascalientes Women's Hospital on female patients over 40 years of age who underwent elective hysterectomy between July and October 2017. In these 4 months, 85 patients underwent elective hysterectomy.

RESULTS

In this study, 85 patients who received a hysterectomy for non-oncological reasons were analyzed. Salpinx alterations compatible with intraepithelial neoplasia in the Fallopian tubes were found in 2.4% of the patients studied.

CONCLUSIONS

The incidence of intraepithelial neoplasia in the fallopian tubes of high-risk patients at the Aguascalientes Women's Hospital is 2.4%. Prophylactic salpingectomy is a simple procedure and has the potential to decrease the risk of high-grade ovarian cancer. In premenopausal patients, total abdominal hysterectomy with bilateral salpingectomy should be the procedure most often performed.

In Utero Exposure to Benzo[a]pyrene Induces Ovarian Mutations at Doses That Deplete Ovarian Follicles in Mice

Polycyclic aromatic hydrocarbons like benzo[a]pyrene (BaP) are ubiquitous environmental contaminants formed during incomplete combustion of organic materials. Our prior work showed that transplacental exposure to BaP depletes ovarian follicles and increases prevalence of epithelial ovarian tumors later in life. We used the MutaMouse transgenic rodent model to address the hypothesis that ovarian mutations play a role in tumorigenesis caused by prenatal exposure to BaP. Pregnant MutaMouse females were treated with 0, 10, 20, or 40 mg/(kg day) BaP orally on gestational days 7-16, covering critical windows of ovarian development. Female offspring were euthanized at 10 weeks of age; some ovaries with oviducts were processed for follicle counting; other ovaries/oviducts and bone marrow were processed for determination of lacZ mutant frequency (MF). Mutant plaques were pooled within dose groups and sequenced to determine the mutation spectrum. BaP exposure caused highly significant dose-related decreases in ovarian follicles and increases in ovarian/oviductal and bone marrow mutant frequencies at all doses. Absence of follicles, cell packets, and epithelial tubular structures were observed with 20 and 40 mg/(kg day) BaP. Depletion of ovarian germ cells was inversely associated with ovarian MF. BaP induced primarily G > T and G > C transversions and deletions in ovaries/oviducts and bone marrow cells and produced a mutation signature highly consistent with that of tobacco smoking in human cancers. Overall, our results show that prenatal BaP exposure significantly depletes ovarian germ cells, causes histopathological abnormalities, and increases the burden of ovarian/oviductal mutations, which may be involved in pathogenesis of epithelial ovarian tumors. Environ. Mol. Mutagen. 60:410-420, 2019. © 2018 Her Majesty the Queen in Right of Canada.

Endometriosis and ovarian cancer: Their association and relationship

Objectives

To study endometriosis-associated borderline or malignant ovarian epithelial tumors by analyzing their differential clinical features, as well as the histological pattern, survival and immunohistochemical data compared with those without associated endometriosis.

Study design

Setting: Hospital Marina Baixa and San Juan University Hospital, Alicante, Spain. This retrospective study included clinical and pathological data from 36 operated cases with endometriosis-associated ovarian epithelial tumors and 305 cases of ovarian epithelial tumors without endometriosis, including borderline and invasive tumors. We also studied hormonal receptors and p53 protein expression in 13 cases with endometriosis-associated endometrioid and clear cell tumors, and report two cases with histologically-confirmed previous endometriosis.

Results

Associated endometriosis was observed in 10.5% of patients with borderline or invasive ovarian epithelial tumor, 53% of those with endometrioid, and 22% with clear cell tumors. Patients with endometriosis-associated ovarian epithelial tumors were younger, had lower parity, were more frequently premenopausal, had a lower tumor stage or were borderline, and in general had better prognosis and longer survival, although they also more frequently had an associated endometrial carcinoma. Associated endometriosis and endometrioid tumors were generally estrogen-receptor positive, whereas they were negative in the clear cell tumor component. p53 protein positivity was generally observed in clear cell tumors and in associated endometriosis. Two reported cases with previous, known endometriosis were followed in their evolution to borderline endometrioid carcinoma and clear cell carcinoma, respectively.

Conclusions

Our results and review of the literature suggest that the association of ovarian epithelial tumors and endometriosis is a factor for good prognosis for ovarian cancer and that this association might correspond in many cases to an intermediate stage in the development of endometriosis to endometrioid, clear cell, or other invasive carcinomas.

Trends and characteristics of epithelial ovarian cancer in Japan between 2002 and 2015: A JSGO-JSOG joint study

OBJECTIVE

To examine the trends of epithelial ovarian cancer histologic subtypes in Japan.

METHODS

A nationwide retrospective registry study was performed between 2002 and 2015 (Japan cohort, n = 48,640). Trends were also examined in The Surveillance, Epidemiology, and End Results Program (US cohort, n = 49,936). Time-specific proportional changes of four major histological subtypes (serous, clear cell, endometrioid, and mucinous) were examined.

RESULTS

The Japan cohort had more stage I disease (44.1% versus 24.9%) and less stage IV disease (10.0% versus 23.1%) than the US cohort (P < 0.001). The Japan cohort had more non-serous histology, particularly clear cell carcinoma (26.9% versus 8.4%), than the US cohort (P < 0.001). In the Japan cohort, proportion of clear cell carcinoma increased significantly from 23.4% to 29.1% between 2002 and 2010 (P < 0.001). Among stage I disease, clear cell carcinoma increased significantly in the Japan cohort from 32.9% to 40.3% between 2002 and 2015 (P < 0.001), whereas mucinous carcinoma increased significantly in the US cohort from 15.0% to 24.8% (P = 0.01). In 2015, clear cell carcinoma was most common among women aged <50 years from the Japan cohort (30.2%) versus serous carcinoma in the US cohort (50.8%). In the Japan cohort, the peak age was 75 years for serous, 57 for clear cell, and 45 for endometrioid carcinoma (P < 0.001). Mucinous carcinoma decreased until 43 years and increased again after age 73 years (P < 0.001).

CONCLUSION

Characteristics of epithelial ovarian cancer in Japan are largely different compared to the US. In Japan, clear cell carcinoma has increased significantly in recent years to account for nearly 30% of epithelial ovarian cancer.

Analgesic Use and Ovarian Cancer Risk: An Analysis in the Ovarian Cancer Cohort Consortium

BACKGROUND

Aspirin use is associated with reduced risk of several cancers. A pooled analysis of 12 case-control studies showed a 10% decrease in ovarian cancer risk with regular aspirin use, which was stronger for daily and low-dose users. To prospectively investigate associations of analgesic use with ovarian cancer, we analyzed data from 13 studies in the Ovarian Cancer Cohort Consortium (OC3).

METHODS

The current study included 758 829 women who at study enrollment self-reported analgesic use, among whom 3514 developed ovarian cancer. Using Cox regression, we assessed associations between frequent medication use and risk of ovarian cancer. Dose and duration were also evaluated. All statistical tests were two-sided.

RESULTS

Women who used aspirin almost daily (≥6 days/wk) vs infrequent/nonuse experienced a 10% reduction in ovarian cancer risk (rate ratio [RR] = 0.90, 95% confidence interval [CI] = 0.82 to 1.00, P = .05). Frequent use (≥4 days/wk) of aspirin (RR = 0.95, 95% CI = 0.88 to 1.03), nonaspirin nonsteroidal anti-inflammatory drugs (NSAIDs; RR = 1.00, 95% CI = 0.90 to 1.11), or acetaminophen (RR = 1.05, 95% CI = 0.88 to 1.24) was not associated with risk. Daily acetaminophen use (RR = 1.28, 95% CI = 1.00 to 1.65, P = .05) was associated with elevated ovarian cancer risk. Risk estimates for frequent, long-term (10+ years) use of aspirin (RR = 1.15, 95% CI = 0.98 to 1.34) or nonaspirin NSAIDs (RR = 1.19, 95% CI = 0.84 to 1.68) were modestly elevated, although not statistically significantly so.

CONCLUSIONS

This large, prospective analysis suggests that women who use aspirin daily have a slightly lower risk of developing ovarian cancer (∼10% lower than infrequent/nonuse)-similar to the risk reduction observed in case-control analyses. The observed potential elevated risks for 10+ years of frequent aspirin and NSAID use require further study but could be due to confounding by medical indications for use or variation in drug dosing.

Childhood Overweight, Tallness, and Growth Increase Risks of Ovarian Cancer

BACKGROUND

Adult body size is related to ovarian cancer risks, but size in childhood may also influence risks. We investigated if childhood body mass index (kg/m2), height, and growth patterns were associated with ovarian cancer overall and by histologic subtypes, including effects of birthweight.

METHODS

A cohort of 155,958 girls from the Copenhagen School Health Records Register, born 1930 to 1989 with measured weights and heights from 7 to 13 years, were included. During follow-up, 1,041 ovarian cancers were recorded. Overweight was defined using International Obesity Task Force criteria. Cox regressions were performed.

RESULTS

Compared with non-overweight girls, at most ages girls with overweight had increased risks of ovarian cancer overall (HR range: 1.24-1.34), mucinous, endometrioid, and clear cell ovarian cancers, but not serous and other ovarian cancers. Childhood height had positive and significant associations with ovarian cancer overall (HR range: 1.07-1.10 per z-score) and the endometrioid subtype but not with the other subtypes. Adjusting for birthweight minimally altered the associations with childhood body size. In growth analyses, girls with overweight or who were tall at 7 and 13 years had increased risks of ovarian cancer overall compared with average-sized girls at both ages.

CONCLUSIONS

Ovarian carcinogenesis is linked to childhood overweight, tallness, and growth, with variations across histological subtypes, suggesting that early life plays a role in the origins of this disease.

IMPACT

These findings emphasize that healthy body size and growth during childhood are important as they may contribute to reducing ovarian cancer risks.

Social Integration, Marital Status, and Ovarian Cancer Risk: A 20-Year Prospective Cohort Study

OBJECTIVE

Low social integration and divorce/widowhood are chronic psychosocial stressors that may affect health. When assessed after cancer diagnosis, they have been associated with poorer survival, but their role in cancer development, particularly ovarian cancer (OvCA), is less understood. We investigated whether social integration and marital status were related to OvCA risk in a large population-based study.

METHODS

Women from the Nurses' Health Study completed the Berkman-Syme Social Network Index and reported their marital status every 4 years starting in 1992 (N = 72,206), and were followed up until 2012 (20-year follow-up period). Multivariate Cox regression models estimated hazard ratios (HRs) and 95% confidence intervals (CIs) of OvCA risk, considering relevant potential confounders, in lagged analyses whereby psychosocial indicators were assessed 4 to 8 years (n = 436 cases) and 8 to 12 years (n = 306 cases) before diagnosis to account for the effects of prediagnostic symptoms on social measures. Secondary analyses evaluated the stability of and cumulative exposure to these social factors on OvCA risk.

RESULTS

Being socially isolated versus integrated was related to an increased OvCA risk 8 to 12 years later (HR = 1.51, 95% CI = 1.07-2.13), but not 4 to 8 years later. Compared with married women, OvCA risk was significantly higher in widowed but not in separated/divorced individuals, with both time periods (e.g., 8-12 years later: HRwidowed = 1.57 [95% CI = 1.15-2.14] versus HRseparated/divorced = 1.13 [95% CI = 0.74-1.72]). Estimates were comparable or stronger when investigating stability in and cumulative effects of social indicators.

CONCLUSIONS

Results suggest higher OvCA risk among socially isolated and widowed women, particularly when such psychosocial stressors were experienced a decade before diagnosis or were sustained over time.

When Is "Type I" Ovarian Cancer Not "Type I"? Indications of an Out-Dated Dichotomy

The dualistic classification of epithelial ovarian cancer (EOC) into “type I” and “type II” is widely applied in the research setting; it is used as a convenient way of conceptualizing different mechanisms of tumorigenesis. However, this classification conflicts with recent molecular insights of the etiology of EOC. Molecular and cell of origin studies indicate that while type II tumors could be classed together, type I tumors are not homogenous, even within the histological types, and can have poor clinical outcomes. Type II high grade serous carcinoma and type I low grade serous carcinomas best fit the description of the dualistic model, with different precursors, and distinct molecular profiles. However, endometriosis-associated cancers should be considered a separate group, without assuming an indolent course or type I genetic profiles. Furthermore, the very clear differences between mucinous ovarian carcinomas and other type I tumors, including an uncertain origin, and heterogeneous mutational spectrum and clinical behavior, indicate a non-type I classification for this entity. The impression that only type II carcinomas are aggressive, have poor prognosis, and carry TP53 mutations is an unhelpful misinterpretation of the dualistic classification. In this review, we revisit the history of EOC classification, and discuss the misunderstanding of the dualistic model by comparing the clinical and molecular heterogeneity of EOC types. We also emphasize that all EOC research, both basic and clinical, should consider the subtypes as different diseases beyond the type I/type II model, and base novel therapies on the molecular characteristics of each tumor.

The role of menopausal hormone therapy in women with or at risk of ovarian and breast cancers: Misconceptions and current directions

For women who are candidates for menopausal hormone therapy (MHT), estrogen can provide relief from symptomatic menopause, decrease rates of chronic illnesses, and improve health-related quality of life. However, confusion surrounds the evidence regarding the impact of exogenous estrogen and progesterone on the breast and ovary. Available data regarding the risks of MHT (estrogen and/or progestin) related to the development of breast and ovarian cancer are often inconsistent or incomplete. Modern molecular and genetic techniques have improved our understanding of the heterogeneity of breast and ovarian cancer. This enhanced understanding of the disease has impacted our understanding of carcinogenesis. Treatment options have evolved to be more targeted toward hormonal therapy for certain subtypes of disease, whereas cytotoxic chemotherapy remains the standard for other histological and molecular subtypes. The role of MHT in the breast and ovarian cancer survivor, as well as women who are at high risk for the development of hereditary breast and ovarian cancer, remains controversial despite evidence that this treatment can improve quality of life and survival outcomes. Through this article, we examine the evidence for and against the use of MHT with a focus on women who have or are at high risk for breast and ovarian cancer.

Familial risks of ovarian cancer by age at diagnosis, proband type and histology

Ovarian cancer is a heterogeneous disease. Data regarding familial risks for specific proband, age at diagnosis and histology are limited. Such data can assist genetic counseling and help elucidate etiologic differences among various histologic types of ovarian malignancies. By using the Swedish Family-Cancer Database, we calculated relative risks (RRs) for detailed family histories using a two-way comparison, which implied e.g. estimation of RRs for overall ovarian cancer when family history was histology-specific ovarian cancer, and conversely, RRs for histology-specific ovarian cancer when family history was overall ovarian cancer. In families of only mother, only sisters or both mother and sisters diagnosed with ovarian cancer, cancer risks for ovary were 2.40, 2.59 and 10.40, respectively; and were higher for cases diagnosed before the age of 50 years. All histological types showed a familial risk in two-way analyses, except mucinous and sex cord-stromal tumors. RRs for concordant histology were found for serous (2.47), endometrioid (3.59) and mucinous ovarian cancers (6.91). Concordant familial risks were highest for mucinous cancer; for others, some discordant associations, such as endometrioid-undifferentiated (9.27) and serous-undifferentiated (4.80), showed the highest RRs. Familial risks are high for early-onset patients and for those with multiple affected relatives. Sharing of different histological types of ovarian cancer is likely an indication of the complexity of the underlying mechanisms.

Case for a role of the microbiome in gynecologic cancers: Clinician's perspective

In this review, we aimed to provide insight into the microbiome and its association with endometrial and ovarian cancer and their risk factors. We reviewed the literature focusing on the relationship between the microbiome and cancer, as well as the relationship between gynecologic diseases and cancers. The human body contains different kinds of microorganisms in various body parts, which is termed the microbiome. The number of microorganisms that live in and on the human body is greater than that of the human germ and somatic cells by 10-fold. The relationship between a human and their microbiome is complex; it is also one of the most important components of homeostasis. Impairment of microbiome-host homeostasis has been associated with obesity, several cancers, preterm labor, inflammatory and allergic conditions and neurodevelopmental disorders. Direct and strong causal relationships have been established for several cancers and microorganisms, such as gastric lymphoma and Helicobacter pylori infection. Interestingly, eradication of the infectious agents has also been shown to be therapeutic. The association between cancer and the microbiome, however, is more complicated than a 1 bacteria-1 cancer model, and a shift in a healthy microbiome can result in various cancers via inflammation, change in microenvironment or DNA-damaging toxins. The human microbiome is an integral part of homeostasis. Understanding the mechanisms that cause dysbiosis will enable us to elucidate the pathways that result in malignancy and investigate new treatment modalities.

Preterm delivery is associated with an increased risk of epithelial ovarian cancer among parous women

Epithelial ovarian cancer is a fatal disease of largely unknown etiology. Higher parity is associated with reduced risk of ovarian cancer. However, among parous women, the impact of pregnancy-related factors on risk is not well understood. This population-based case-control study included all parous women with epithelial ovarian cancer in Denmark, Finland, Norway and Sweden during 1967-2013 (n = 10,957) and up to 10 matched controls (n = 107,864). We used conditional logistic regression to estimate odds ratios (ORs) with 95% confidence intervals (CIs) for pregnancy-related factors and ovarian cancer risk by histological subtype. Preterm delivery was associated with an increased risk [pregnancy length (last pregnancy) ≤30 vs. 39-41 weeks, OR 1.33 (95% CI 1.06-1.67), adjusted for number of births]; the OR increased as pregnancy length decreased (p for trend < 0.001). Older age at first and last birth was associated with a decreased risk [first birth: 30-39 vs. <25 years: adjusted OR 0.76 (95% CI 0.70-0.83); last birth 30-39 vs. <25 years: adjusted OR 0.76 (95% CI 0.71-0.82)]. Increasing number of births was protective [≥4 births vs. 1; OR 0.63 (95% CI 0.59-0.68)] for all subtypes, most pronounced for clear-cell tumors [OR 0.30, (95% CI 0.21-0.44), p_{heterogeneity}  < 0.001]. No associations were observed for multiple pregnancies, preeclampsia or offspring size. In conclusion, in addition to high parity, full-term pregnancies and pregnancies at older ages were associated with decreased risk of ovarian cancer. Our findings favor the cell clearance hypothesis, i.e. a recent pregnancy provides protection by clearing of precancerous cells from the epithelium of the ovary/fallopian tubes, mediated by placental or ovarian hormones.

Risk of high-grade serous ovarian cancer associated with pelvic inflammatory disease, parity and breast cancer

BACKGROUND

Ovarian carcinoma is not a single disease, but rather a collection of subtypes with differing molecular properties and risk profiles. The most common of these, and the subject of this work, is high-grade serous ovarian carcinoma (HGSC).

METHODS

In this population-based study we identified a cohort of 441,382 women resident in Western Australia who had ever been admitted to hospital in the State. Of these, 454 were diagnosed with HGSC. We used Cox regression to derive hazard ratios (HRs) comparing the risk of disease in women who had each of a range of medical diagnoses and surgical procedures with women who did not.

RESULTS

We found an increased risk of HGSC associated with a diagnosis of pelvic inflammatory disease (PID) (HR 1.47, 95% CI 1.04-2.07) but not with a diagnosis of infertility or endometriosis with HRs of 1.12 (95% CI 0.73-1.71) and 0.82 (95% CI 0.55-1.22) respectively. A personal history of breast cancer was associated with a three-fold increase in the rate of HGSC. Increased parity was associated with a reduced risk of HGSC in women without a personal history of breast cancer (HR 0.57; 95% CI 0.44-0.73), but not in women with a personal history of breast cancer (HR 1.48; 95% CI 0.74-2.95).

CONCLUSIONS

Our finding of an increased risk of HGSC associated with PID lends support to the hypothesis that inflammatory processes may be involved in the etiology of HGSC.

Metastatic gynecologic malignancies: advances in treatment and management

Gynecologic cancers comprise of mostly uterine, ovarian, and cervical malignancies and are responsible for 95,000 new cases annually in the United States. Uterine cancer is the most common and the number of new cases and mortality has been increasing. Cervical cancer has decreased due to screening, early detection, and treatment of pre-invasive cancers. However, ovarian cancer remains the most lethal because of advanced stage at diagnosis and drug resistance. The metastatic spread pattern differs amongst these cancers, with uterine and cervical cancer found mostly in the primary organ and ovarian cancer disseminating throughout the peritoneum and upper abdomen at presentation. The primary treatment of ovarian cancer typically involves surgery followed by systemic therapy for more advanced disease. Previously, systemic chemotherapy with platinums, taxanes, doxorubicin, topotecan, and gemcitabine has been the standard in either upfront or recurrent setting. With molecular and genetic breakthroughs, we now have over eight new indications and five novel biologic therapies including antiangiogenics, poly ADP ribose polymerase inhibitors, and immunotherapies approved over the last 3 years. In this review, we will examine the biology of gynecologic cancer metastasis and focus on new treatment options for these cancers with a focus on ovarian cancer.

Charged-Iron-Particles Found in Galactic Cosmic Rays are Potent Inducers of Epithelial Ovarian Tumors

Astronauts traveling in deep space are exposed to high-charge and energy (HZE) particles from galactic cosmic rays. We have previously determined that irradiation of adult female mice with iron HZE particles induces DNA double-strand breaks, oxidative damage and apoptosis in ovarian follicles, causing premature ovarian failure. These effects occur at lower doses than with conventional photon irradiation. Ovarian failure with resultant loss of negative feedback and elevated levels of gonadotropin hormones is thought to play a role in the pathophysiology of ovarian cancer. Therefore, we hypothesized that charged-iron-particle irradiation induces ovarian tumorigenesis in mice. In this study, three-month-old female mice were exposed to 0 cGy (sham) or 50 cGy iron ions and aged to 18 months. The 50 cGy irradiated mice had increased weight gain with age and lack of estrous cycling, consistent with ovarian failure. A total of 47% and 7% of mice irradiated with 50 cGy had unilateral and bilateral ovarian tumors, respectively, whereas 14% of mice in the 0 cGy group had unilateral tumors. The tumors contained multiple tubular structures, which were lined with cells positive for the epithelial marker cytokeratin, and had few proliferating cells. In some tumors, packets of cells between the tubular structures were immunopositive for the granulosa cell marker FOXL2. Based on these findings, tumors were diagnosed as tubular adenomas or mixed tubular adenoma/granulosa cell tumors. In conclusion, charged-iron-particle-radiation induces ovarian tumors in mice, raising concerns about ovarian tumors as late sequelae of deep space travel in female astronauts.

An Evaluation of Frozen Section and Lymph Node Dissection Results for Mucinous Ovarian Tumors

OBJECTIVES

Intraoperative frozen section has greater than 90% accuracy for ovarian tumors; however, mucinous histology has been shown to be associated with increased frozen section inaccuracy. Recent data demonstrate that primary ovarian mucinous carcinomas have no lymph node involvement, even when extraovarian disease is present, and therefore may not require lymph node dissection. Our primary objective is to evaluate the accuracy of identifying mucinous histology on frozen section.

METHODS/MATERIALS

A cross-sectional review of mucinous ovarian tumors in surgical patients at one institution from 2006 to 2016 was performed. Cases reporting a mucinous ovarian tumor on frozen section or final pathology were identified. Frozen section results were compared with final diagnosis to calculate concordance rates. Analyses with χ and t tests were performed to identify variables associated with pathology discordance.

RESULTS

A total of 126 mucinous ovarian tumors were identified. Of these, 106 were reported as mucinous on frozen section and 103 (97.2%) were concordant on final pathology. Discordant cases included 2 serous and 1 clear cell tumor. Among the 103 mucinous tumors, classification as malignant, borderline, or benign was concordant in 74 (71.8%) of 103 cases, whereas 22 (21.4%) of 103 were discordant and 7 (6.8%) were deferred to final pathology. Lymph node dissection was performed in 33 cases; the only case with lymph node metastasis was a gastrointestinal mucinous adenocarcinoma. Discordance between frozen section and final pathology was associated with larger tumor size and diagnosis other than benign: discordant cases had a mean tumor size of 21.7 cm compared with 14.4 cm for concordant cases (P < 0.001), and 93.5% of discordant cases were borderline or malignant, compared with 30.5% of concordant cases (P < 0.001).

CONCLUSIONS

Intraoperative identification of mucinous histology by frozen section is reliable with a concordance rate to final pathology of 97.2%. No lymph node metastases were present in any malignant or borderline primary ovarian cases.

Migraine and invasive epithelial ovarian cancer risk in the Nurses' Health Study II and the Women's Health Study

Migraine is a common primary headache disorder, which predominantly impacts women. Recently, migraine has been hypothesized to be associated with hormonally related cancers; however, the potential association between migraine and ovarian cancer has not been studied. Therefore, we evaluated the association between migraine and invasive epithelial ovarian cancer risk in two prospective cohorts, the Nurses' Health Study II (NHSII) and the Women's Health Study (WHS). Our prospective analysis included 113,124 NHSII participants aged 25-42 at study baseline as well as 33,490 participants in the WHS who were 45 years or older at study entry. We used Cox proportional hazards models to estimate the hazard ratios (HR) and 95% confidence intervals (CIs) for the association between migraine and ovarian cancer risk in each cohort. In secondary analyses, we stratified by age and menopausal status. After adjusting for potential covariates, there was no statistically significant association between migraine and ovarian cancer risk in either the NHSII (HR = 1.29, 95%CI: 0.96, 1.74) or the WHS (HR = 0.60, 95%CI: 0.34, 1.06). In stratified analysis in the NHSII, there was a statistically significant positive association between migraine and ovarian cancer risk among women <45 years of age (HR = 1.76, 95%CI: 1.01, 3.07). We did not observe a clear association between migraine and ovarian cancer risk in two large prospective cohort studies.

Histological subtypes of ovarian cancer associated with parity and breastfeeding in the prospective Million Women Study

Ovarian cancer risk is known to be reduced amongst women who have had children, but reported associations with breastfeeding are varied. Few studies have had sufficient power to explore reliably these associations by tumour histotype. In a prospective study of 1.1 million UK women, 8719 developed ovarian cancer during follow-up. Cox regression yielded adjusted relative risks (RRs) overall and by tumour histotype amongst women with different childbearing patterns. Nulliparous women had a 24% greater ovarian cancer risk than women with one child, with significant heterogeneity by histotype (p = 0.01). There was no significant increase in serous tumours, a modest increase in mucinous tumours, but a substantial increase in endometrioid (RR = 1.49, 95% CI: 1.18-1.89) and clear-cell tumours (RR = 1.68, 1.29-2.20). Among parous women, each additional birth was associated with an overall 6% reduction in ovarian cancer risk; this association also varied by histotype (p = 0.0006), with the largest reduction in risk for clear-cell tumours (RR per birth = 0.75, 0.65-0.85, p < 0.001) and weak, if any, effect for endometrioid, high-grade serous, or mucinous tumours. We found little association with age at first or last birth. There was about a 10% risk reduction per 12-months breastfeeding (RR = 0.89, 0.84-0.94, p < 0.001), with no significant heterogeneity by histotype, but statistical power was limited. In this large prospective study, ovarian cancer risk associated with parity varied substantially by tumour histotype. Nulliparity was associated with a substantially greater overall risk than expected from the effect of a single birth, especially for clear cell and endometrioid tumours, perhaps suggesting that infertility is associated with these histotypes.

The impact of histological subtype in developing both ovarian and endometrial cancer: A longstanding nationwide incidence study

OBJECTIVES

To estimate the incidence of ovarian cancer (OC) and endometrial cancer (EC) separately, as well as double cancers diagnosed in the same calendar year, and to relate the occurrences to histological subtype.

STUDY DESIGN

All cases of epithelial OC and EC diagnosed in the Netherlands in 1989-2009 were related to population data. Histologically specific associations were made using the ratio of observed and expected incidence numbers, calculated with age-specific incidence rates.

RESULTS

25,489 OC and 32,729 EC were analyzed, and 649 OC/EC. Life-time risks for OC and EC were 1.8% and 2.4%. Among OC, adenocarcinoma (18%) and serous cancers (33%) were the most prevalent subtypes. In EC, adenocarcinoma (39%) and endometrioid cancer (37%) were highest, with hardly any serous cancers. The observed incidence of OC/EC was 50-fold higher than expected (95% CI, 46-54). For patients aged <55years, the O/E ratio was 274, for the elderly 32, both findings are significant. Of the 2345 OC endometrioid subtype, 294 had EC (12.5%), whereas 1.1 was expected. In EC patients, no particular histological subtype was distinguished with a highly elevated occurrence of OC. The 680 serous EC patients had 11 double cancers (1.6%), of which 8 with the ovarian serous subtype.

CONCLUSION

Strong relationships exist between malignancies in the ovary and a second primary malignancy in the endometrium, especially for the endometrioid subtype of ovarian cancer. Viewed from the endometrial site, no special subtype was noted, and the influence of endometrial serous adenocarcinoma in developing serous OC is not plausible.

Ovarian Cancer Prevention in High-risk Women

Ovarian carcinoma is the most lethal malignancy of the female genital tract. Population-based trials in the general population have not demonstrated that screening improves early detection or survival. Therefore, application of prevention strategies is vital to improving outcomes from this disease. Surgical prevention reduces risk and prophylactic risk-reducing salpingo-oophorectomy is the most effective means to prevent ovarian carcinoma in the high-risk patient although the risks do not outweigh the benefits in average risk patients. Other surgical and medical options have unknown or limited efficacy in the high-risk patient. In this review, we define the patient at high risk for ovarian cancer, discuss how to identify these women and weigh their available ovarian cancer prevention strategies.

Missed therapeutic and prevention opportunities in women with BRCA-mutated epithelial ovarian cancer and their families due to low referral rates for genetic counseling and BRCA testing: A review of the literature

Answer questions and earn CME/CNE Fifteen percent of women with epithelial ovarian cancer have inherited mutations in the BRCA breast cancer susceptibility genes. Knowledge of her BRCA status has value both for the woman and for her family. A therapeutic benefit exists for the woman with cancer, because a new family of oral drugs, the poly ADP-ribose polymerase (PARP) inhibitors, has recently been approved, and these drugs have the greatest efficacy in women who carry the mutation. For her family, there is the potential to prevent ovarian cancer in those carrying the mutation by using risk-reducing surgery. Such surgery significantly reduces the chance of developing this, for the most part, incurable cancer. Despite these potential benefits, referral rates for genetic counseling and subsequent BRCA testing are low, ranging from 10% to 30%, indicating that these therapeutic and prevention opportunities are being missed. The authors have reviewed the relevant available literature. Topics discussed are BRCA and its relation to ovarian cancer, the rates of referral for genetic counseling/BRCA testing, reasons for these low rates, potential strategies to improve on those rates, lack of effectiveness of current screening strategies, the pros and cons of risk-reducing surgery, other prevention options, and the role and value of PARP inhibitors. CA Cancer J Clin 2017;67:493-506. © 2017 American Cancer Society.

Tubal ligation and ovarian cancer risk in African American women

PURPOSE

Tubal ligation has been associated with reduced risk of epithelial ovarian cancer (EOC) in studies of primarily white women, but less is known about the association in African American (AA) women. We sought to evaluate the associations among 597 invasive ovarian cancer cases and 742 controls of AA descent recruited from the African American Cancer Epidemiology Study, a population-based case-control study in 11 geographical areas in the US.

METHODS

Multivariable logistic regression models were used to estimate odds ratios (OR) and 95% confidence intervals (CI) adjusted for potentially confounding factors.

RESULTS

An inverse association between tubal ligation and EOC was observed that was not statistically significant (OR 0.88, 95% CI 0.68-1.14). However, an inverse association with EOC risk was observed among women who had a tubal ligation at age 35 years or older (OR 0.64; 95% CI 0.41-0.98), but not among those who had a tubal ligation before age 35 (OR 0.98; 95% CI 0.74-1.29) (p for interaction = 0.08). The association also varied considerably by tumor subtype. A strong inverse association was observed for endometrioid tumors (OR 0.31, 95% CI 0.14-0.70), whereas associations with mucinous (OR 0.87, 95% CI 0.36-2.12) and serous (OR 0.94, 95% CI 0.71-1.24) tumors were weaker and not statistically significant. A statistically non-significant positive association for clear cell tumors (OR 1.84, 95% CI 0.58-5.82) was based on a low number of cases.

CONCLUSIONS

Our findings show that tubal ligation may confer a reduced risk for EOC among AA women that is comparable to the associations that have been previously observed in primarily white populations.

Epidemiology of ovarian cancer: a review

Ovarian cancer (OC) is the seventh most commonly diagnosed cancer among women in the world and the tenth most common in China. Epithelial OC is the most predominant pathologic subtype, with five major histotypes that differ in origination, pathogenesis, molecular alterations, risk factors, and prognosis. Genetic susceptibility is manifested by rare inherited mutations with high to moderate penetrance. Genome-wide association studies have additionally identified 29 common susceptibility alleles for OC, including 14 subtype-specific alleles. Several reproductive and hormonal factors may lower risk, including parity, oral contraceptive use, and lactation, while others such as older age at menopause and hormone replacement therapy confer increased risks. These associations differ by histotype, especially for mucinous OC, likely reflecting differences in etiology. Endometrioid and clear cell OC share a similar, unique pattern of associations with increased risks among women with endometriosis and decreased risks associated with tubal ligation. OC risks associated with other gynecological conditions and procedures, such as hysterectomy, pelvic inflammatory disease, and polycystic ovarian syndrome, are less clear. Other possible risk factors include environmental and lifestyle factors such as asbestos and talc powder exposures, and cigarette smoking. The epidemiology provides clues on etiology, primary prevention, early detection, and possibly even therapeutic strategies.

Epidemiology of ovarian cancer: a review

Ovarian cancer (OC) is the seventh most commonly diagnosed cancer among women in the world and the tenth most common in China. Epithelial OC is the most predominant pathologic subtype, with five major histotypes that differ in origination, pathogenesis, molecular alterations, risk factors, and prognosis. Genetic susceptibility is manifested by rare inherited mutations with high to moderate penetrance. Genome-wide association studies have additionally identified 29 common susceptibility alleles for OC, including 14 subtype-specific alleles. Several reproductive and hormonal factors may lower risk, including parity, oral contraceptive use, and lactation, while others such as older age at menopause and hormone replacement therapy confer increased risks. These associations differ by histotype, especially for mucinous OC, likely reflecting differences in etiology. Endometrioid and clear cell OC share a similar, unique pattern of associations with increased risks among women with endometriosis and decreased risks associated with tubal ligation. OC risks associated with other gynecological conditions and procedures, such as hysterectomy, pelvic inflammatory disease, and polycystic ovarian syndrome, are less clear. Other possible risk factors include environmental and lifestyle factors such as asbestos and talc powder exposures, and cigarette smoking. The epidemiology provides clues on etiology, primary prevention, early detection, and possibly even therapeutic strategies.

Awareness and Knowledge of Ovarian Cancer Symptoms and Risk Factors: A Survey of Jordanian Women

Ovarian cancer accounts for 3% of all female cancers and has a high mortality rate among gynecological malignancies. Early diagnosis carries a high survival rate of 93%. So, this study was carried out to assess the knowledge and awareness of Jordanian women about ovarian cancer symptoms and risk factors. A cross-sectional survey design was used; 896 women completed the survey. The mean of total symptoms recognized was low at level of 3.2 ( SD = 2.7) out of 10. The three highest known symptoms among women were as follows: extreme fatigue (43.2%), back pain (42.4%), and persistent pain in pelvic area (40.7%). The most commonly known risk factor was smoking (68.4%), followed by having ovarian cyst(s) (59.7%). Hence, with the absence of an effective screening program, a national awareness campaign is urgently needed to improve the public's understanding of symptoms and risk factors and increasing women's confidence in symptom recognition.

Ovarian effects of prenatal exposure to benzo[a]pyrene: Roles of embryonic and maternal glutathione status

Females deficient in the glutamate cysteine ligase modifier subunit (Gclm) of the rate-limiting enzyme in glutathione synthesis are more sensitive to ovarian follicle depletion and tumorigenesisby prenatal benzo[a]pyrene (BaP) exposure than Gclm+/+ mice. We investigated effects of prenatal exposure to BaP on reproductive development and ovarian mutations in Kras, a commonly mutated gene in epithelial ovarian tumors. Pregnantmice were dosed from gestational day 6.5 through 15.5 with 2mg/kg/day BaP or vehicle. Puberty onset occurred 5 days earlier in F1 daughters of all Gclm genotypes exposed to BaP compared to controls. Gclm+/- F1 daughters of Gclm+/- mothers and wildtype F1 daughters of wildtype mothers had similar depletion of ovarian follicles following prenatal exposure to BaP, suggesting that maternal Gclm genotype does not modify ovarian effects of prenatal BaP. We observed no BaP treatment or Gclm genotype related differences in ovarian Kras codon 12 mutations in F1 offspring.

Hormonal and reproductive factors and the risk of ovarian cancer

PURPOSE

Hormone-related factors have been associated with ovarian cancer, the strongest being parity and oral contraceptive use. Given reductions in birth rates and increases in oral contraceptive use over time, associations in more recent birth cohorts may differ. Furthermore, consideration of ovarian cancer heterogeneity (i.e., Type I/II invasive cancers) may contribute to a better understanding of etiology. We examined hormone-related factors in relation to ovarian cancer risk overall, for Type I and Type II cancers, as well as borderline tumors.

METHODS

A population-based case-control study was carried out in Montreal, Canada from 2011 to 2016, including 496 cases and 908 controls. For each hormone-related variable, adjusted odds ratios (OR) and 95% confidence intervals (CI) were estimated using logistic regression for ovarian cancer overall, and using polytomous logistic regression for associations by tumor behavior and ovarian cancer type.

RESULTS

Parity was inversely associated with risk overall and by tumor behavior and type, with a stronger OR (95% CI) for Type I [0.09 (0.04-0.24) for ≥3 full-term births vs. nulliparity] vs. Type II [0.66 (0.43-1.02)] invasive cancers; the OR (95% CI) for borderline tumors was 0.41 (0.22-0.77). Oral contraceptive ever use was not associated with risk overall, but ≥10 years of use vs. never use reduced risk, particularly for invasive cancers. A history of endometriosis was most strongly associated with Type I cancers. Associations with other factors were less clear.

CONCLUSIONS

These results suggest that associations with some hormone-related factors may differ between borderline and invasive Type I and II ovarian cancers.

Pelvic Inflammatory Disease and the Risk of Ovarian Cancer and Borderline Ovarian Tumors: A Pooled Analysis of 13 Case-Control Studies

Inflammation has been implicated in ovarian carcinogenesis. However, studies investigating the association between pelvic inflammatory disease (PID) and ovarian cancer risk are few and inconsistent. We investigated the association between PID and the risk of epithelial ovarian cancer according to tumor behavior and histotype. We pooled data from 13 case-control studies, conducted between 1989 and 2009, from the Ovarian Cancer Association Consortium (OCAC), including 9,162 women with ovarian cancers, 2,354 women with borderline tumors, and 14,736 control participants. Study-specific odds ratios were estimated and subsequently combined into a pooled odds ratio using a random-effects model. A history of PID was associated with an increased risk of borderline tumors (pooled odds ratio (pOR) = 1.32, 95% confidence interval (CI): 1.10, 1.58). Women with at least 2 episodes of PID had a 2-fold increased risk of borderline tumors (pOR = 2.14, 95% CI: 1.08, 4.24). No association was observed between PID and ovarian cancer risk overall (pOR = 0.99, 95% CI: 0.83, 1.19); however, a statistically nonsignificantly increased risk of low-grade serous tumors (pOR = 1.48, 95% CI: 0.92, 2.38) was noted. In conclusion, PID was associated with an increased risk of borderline ovarian tumors, particularly among women who had had multiple episodes of PID. Although our results indicated a histotype-specific association with PID, the association of PID with ovarian cancer risk is still somewhat uncertain and requires further investigation.

Epidemiology of ovarian cancer: a review

Ovarian cancer (OC) is the seventh most commonly diagnosed cancer among women in the world and the tenth most common in China. Epithelial OC is the most predominant pathologic subtype, with five major histotypes that differ in origination, pathogenesis, molecular alterations, risk factors, and prognosis. Genetic susceptibility is manifested by rare inherited mutations with high to moderate penetrance. Genome-wide association studies have additionally identified 29 common susceptibility alleles for OC, including 14 subtype-specific alleles. Several reproductive and hormonal factors may lower risk, including parity, oral contraceptive use, and lactation, while others such as older age at menopause and hormone replacement therapy confer increased risks. These associations differ by histotype, especially for mucinous OC, likely reflecting differences in etiology. Endometrioid and clear cell OC share a similar, unique pattern of associations with increased risks among women with endometriosis and decreased risks associated with tubal ligation. OC risks associated with other gynecological conditions and procedures, such as hysterectomy, pelvic inflammatory disease, and polycystic ovarian syndrome, are less clear. Other possible risk factors include environmental and lifestyle factors such as asbestos and talc powder exposures, and cigarette smoking. The epidemiology provides clues on etiology, primary prevention, early detection, and possibly even therapeutic strategies.

Metabolic risk factors and mechanisms of disease in epithelial ovarian cancer: A review

OBJECTIVE

Epithelial ovarian cancer continues to be the deadliest gynecologic malignancy. Patients with both diabetes mellitus and obesity have poorer outcomes, yet research correlating metabolic abnormalities, such as metabolic syndrome, to ovarian cancer risk and outcomes is lacking. This article reviews the literature regarding metabolic derangements and their relationship to epithelial ovarian cancer, with a focus on potential mechanisms behind these associations.

METHODS

PubMed and Google Scholar were searched for articles in the English language regarding epithelial ovarian cancer, obesity, diabetes mellitus, and metabolic syndrome, with a focus on studies conducted since 1990.

RESULTS

Obesity, type II diabetes mellitus, and metabolic syndrome have been associated with poor outcomes in epithelial ovarian cancer. More studies investigating the relationship between metabolic syndrome and epithelial ovarian cancer are needed. A variety of pathologic factors may contribute to cancer risk in patients with metabolic derangements, including altered adipokine and cytokine expression, altered immune responses to tumor cells, and changes in pro-tumorigenic signaling pathways.

CONCLUSION

More research is needed to examine the effects of metabolic syndrome on epithelial ovarian cancer risk and mortality, as well as the underlying pathophysiologies in patients with obesity, diabetes mellitus, and metabolic syndrome that may be targeted for therapeutic intervention.

The association between reproductive and hormonal factors and ovarian cancer by estrogen-α and progesterone receptor status

OBJECTIVE

We assessed the association between reproductive and hormonal factors and ovarian cancer incidence characterized by estrogen receptor-α (ERα) and progesterone receptor (PR) status.

METHODS

Tissue microarrays were used to assess ERα and PR expression among 197 Nurses' Health Study (NHS), 42 NHSII and 76 New England Case-Control Study (NECC) ovarian cancer cases. NHS/NHSII cases were matched to up to 4 controls (n=954) on diagnosis date and birth year. NECC controls (n=725) were frequency matched on age. Cases were considered receptor positive if ≥1% of tumor cells stained positive. Associations by ERα and PR status were assessed using polytomous logistic regression. p-Value for heterogeneity was calculated using a likelihood ratio test.

RESULTS

45% of ovarian tumors were PR(+), 78% were ERα(+) and 45% were ERα(+)/PR(+), while 22% were ERα(-)/PR(-). Postmenopausal status was associated with an increased risk of PR(-) tumors (OR: 2.07; 95%CI: 1.15-3.75; p-heterogeneity=0.01) and age at natural menopause was inversely associated with PR(-) tumors (OR, per 5years: 0.77; 95%CI: 0.61-0.96; p-het=0.01). Increasing duration of postmenopause was differentially associated by PR status (p-het=0.0009). Number of children and tubal ligation were more strongly associated with ERα(-) versus ERα(+) tumors (p-het=0.002 and 0.05, respectively). No differential associations were observed for oral contraceptive or hormone therapy use.

CONCLUSIONS

Postmenopausal women have an increased risk of developing PR(-) ovarian tumors compared to premenopausal women. The associations observed for ovarian cancer differ from those seen for breast cancer suggesting that the biology for tumor development through ERα and PR pathways may differ.

Nurses' Health Study Contributions on the Epidemiology of Less Common Cancers: Endometrial, Ovarian, Pancreatic, and Hematologic

OBJECTIVES

To review the contributions of the Nurses' Health Study (NHS) to epidemiologic knowledge of endometrial, ovarian, pancreatic, and hematologic cancers.

METHODS

We reviewed selected NHS publications from 1976 to 2016, including publications from consortia and other pooled studies.

RESULTS

NHS studies on less common cancers have identified novel risk factors, such as a reduced risk of endometrial cancer in women of advanced age at last birth, and have clarified or prospectively confirmed previously reported associations, including an inverse association between tubal ligation and ovarian cancer. Through biomarker research, the NHS has furthered understanding of the pathogenesis of rare cancers, such as the role of altered metabolism in pancreatic cancer risk and survival. NHS investigations have also demonstrated the importance of the timing of exposure, such as the finding of a positive association of early life body fatness, but not of usual adult body mass index, with non-Hodgkin lymphoma risk.

CONCLUSIONS

Evidence from the NHS has informed prevention strategies and contributed to improved survival from less common but often lethal malignancies, including endometrial, ovarian, pancreatic, and hematologic cancers.

Ovarian Cancer Risk Factors by Histologic Subtype: An Analysis From the Ovarian Cancer Cohort Consortium

PURPOSE

An understanding of the etiologic heterogeneity of ovarian cancer is important for improving prevention, early detection, and therapeutic approaches. We evaluated 14 hormonal, reproductive, and lifestyle factors by histologic subtype in the Ovarian Cancer Cohort Consortium (OC3).

PATIENTS AND METHODS

Among 1.3 million women from 21 studies, 5,584 invasive epithelial ovarian cancers were identified (3,378 serous, 606 endometrioid, 331 mucinous, 269 clear cell, 1,000 other). By using competing-risks Cox proportional hazards regression stratified by study and birth year and adjusted for age, parity, and oral contraceptive use, we assessed associations for all invasive cancers by histology. Heterogeneity was evaluated by likelihood ratio test.

RESULTS

Most risk factors exhibited significant heterogeneity by histology. Higher parity was most strongly associated with endometrioid (relative risk [RR] per birth, 0.78; 95% CI, 0.74 to 0.83) and clear cell (RR, 0.68; 95% CI, 0.61 to 0.76) carcinomas (P value for heterogeneity [P-het] < .001). Similarly, age at menopause, endometriosis, and tubal ligation were only associated with endometrioid and clear cell tumors (P-het ≤ .01). Family history of breast cancer (P-het = .008) had modest heterogeneity. Smoking was associated with an increased risk of mucinous (RR per 20 pack-years, 1.26; 95% CI, 1.08 to 1.46) but a decreased risk of clear cell (RR, 0.72; 95% CI, 0.55 to 0.94) tumors (P-het = .004). Unsupervised clustering by risk factors separated endometrioid, clear cell, and low-grade serous carcinomas from high-grade serous and mucinous carcinomas.

CONCLUSION

The heterogeneous associations of risk factors with ovarian cancer subtypes emphasize the importance of conducting etiologic studies by ovarian cancer subtypes. Most established risk factors were more strongly associated with nonserous carcinomas, which demonstrate challenges for risk prediction of serous cancers, the most fatal subtype.

High-risk HPV is not associated with epithelial ovarian cancer in a Caucasian population

Background

High-risk human papillomavirus (HPV) has been suspected to play a role in the carcinogenesis of epithelial ovarian cancer (EOC). However, results from previous studies are conflicting. In most of these studies, the number of tissue samples was small. The current study was therefore undertaken to examine the prevalence of high-risk HPV DNA in EOC in a large series of patients.

Method

Formalin-fixed, paraffin-imbedded tumor tissue samples from 198 cases consecutively included in the Danish Pelvic Mass Study were analyzed. The material included 163 serous adenocarcinomas, 15 endometrioid adenocarcinomas, 11 mucinous adenocarcinomas and nine clear-cell carcinomas. Genotyping for high-risk HPV DNA was performed by real-time Polymerase chain reaction (PCR) using an in-house TaqMan singleplex assay targeting the E6/E7 region of the HPV 16 and 18 genomes. Additionally, 20 random samples without HPV 16 and/or 18 infections were reanalyzed for HPV subtypes 31, 33, 35, 39, 45, 51 and 52.

Results

The quality criteria were fulfilled in 191 samples. HPV 18 DNA was detected in one sample only, while the rest tested negative. The subgroup analysis for seven additional high-risk HPV subtypes was also negative.

Conclusions

Only one in 191 samples was positive for HPV DNA. We therefore conclude that high risk HPV is unlikely to be associated with EOC in a Caucasian population. Future studies should focus on other microorganisms as possible etiological factors in EOC carcinogenesis.

Electronic supplementary material

The online version of this article (doi:10.1186/s13027-016-0087-4) contains supplementary material, which is available to authorized users.

Lifetime Number of Ovulatory Cycles and Risks of Ovarian and Endometrial Cancer Among Postmenopausal Women

Previous studies have shown that a greater number of ovulatory cycles, cumulatively summed as lifetime number of ovulatory cycles (LOC), increases ovarian cancer risk, but there is no uniform algorithm with which to compute LOC. The association between LOC and endometrial cancer is less certain. Accordingly, we identified 14 different LOC algorithms in a literature review and calculated LOCs in the Polish Cancer Study (2001-2003). We evaluated the associations of LOC with ovarian and endometrial cancer risks using unconditional logistic regression, with and without adjustment for individual risk factors used in the LOC computations. Our analysis included 302 ovarian cancer cases with 1,356 controls and 532 endometrial cancer cases with 1,286 controls. We found a high correlation between LOC values among the combined controls (r ≥ 0.88) and identified 5 groups of similar LOC algorithms. A LOC value in the highest quartile was associated with ovarian cancer risk as computed by 2 algorithms (odds ratio (OR) = 2.22 (95% confidence interval (CI): 1.07, 4.62) and OR = 2.44 (95% CI: 1.22, 4.87)) and with endometrial cancer risk as computed by 1 algorithm (OR = 1.95, 95% CI: 1.11, 3.44). LOC algorithms using a core set of variables widely available in epidemiologic studies may be independently associated with risk of gynecological cancers beyond the contribution of the individual risk factors, such as ages at menopause and menarche.

Circulating Estrogens and Postmenopausal Ovarian Cancer Risk in the Women's Health Initiative Observational Study

BACKGROUND

Hormonal and reproductive factors contribute to the development of ovarian cancer, but few studies have examined associations between circulating estrogens and estrogen metabolites and ovarian cancer risk. We evaluated whether serum estrogens and estrogen metabolite levels are associated with ovarian cancer risk among postmenopausal women in a nested case-control study in the Women's Health Initiative (WHI) Observational Study (OS).

METHODS

We selected all 169 eligible epithelial ovarian cancer cases and 412 matched controls from women enrolled in WHI-OS who were not using menopausal hormones at baseline. Baseline levels of 15 estrogens and estrogen metabolites were measured via liquid chromatography/tandem mass spectrometry. Associations with ovarian cancer risk overall and stratified by histologic subtype (serous/nonserous) were analyzed using logistic regression. The mean time from serum collection to cancer diagnosis was 6.9 years.

RESULTS

Overall, we observed modest ovarian cancer risk associations among women with higher levels of estrone [OR (95% confidence interval) quintile (Q)5 vs. Q1: 1.54 (0.82-2.90), Ptrend = 0.05], as well as 2- and 4-methoxyestrone metabolites [2.03 (1.06-3.88), Ptrend = 0.02; 1.86 (0.98-3.56), Ptrend = 0.01, respectively]. Associations of estrogens and estrogen metabolites varied substantially by histologic subtype. Associations with serous tumors were universally null, while estrone [2.65 (1.09-6.45), Ptrend = 0.01, Pheterogeneity = 0.04], unconjugated estradiol [2.72 (1.04-7.14), Ptrend = 0.03, Pheterogeneity = 0.02] and many of the 2-, 4-, and 16-pathway metabolites were positively associated with nonserous tumors.

CONCLUSIONS

Our study provides novel molecular data showing an association of the parent estrogens and several estrogen metabolites with nonserous ovarian cancers.

IMPACT

These findings further support the heterogeneous etiology of ovarian cancer. Cancer Epidemiol Biomarkers Prev; 25(4); 648-56. ©2016 AACR.

Mucinous ovarian cancer: A therapeutic review

Mucinous ovarian cancer represents approximately 3% of epithelial ovarian cancers (EOC). Despite this seemingly low prevalence, it remains a diagnostic and therapeutic conundrum that has resulted in numerous attempts to adopt novel strategies in managing this disease. Anecdotally, there has been a prevailing notion that established gold standard systemic regimens should be substituted for those utilised in cancers such as gastrointestinal (GI) malignancies; tumours that share more biological similarities than other EOC subtypes. This review summarises the plethora of small studies which have adopted this philosophy and influenced the design of the multinational GOG142 study, which was ultimately terminated due to poor accrual. To date, there is a paucity of evidence to support delivering 'GI style' chemotherapy for mucinous ovarian cancer over and above carboplatin-paclitaxel doublet therapy. Hence there is an urge to develop studies focused on targeted therapeutic agents driven by refined mutational analysis and conducted within the context of harmonised international collaborations.

Does VEGF facilitate local tumor growth and spread into the abdominal cavity by suppressing endothelial cell adhesion, thus increasing vascular peritoneal permeability followed by ascites production in ovarian cancer?

BACKGROUND

Ovarian cancer is mostly associated with pathologically regulated permeability of peritoneal vessels, leading to ascites. Here, we investigated the molecular regulation of endothelial permeability by the vascular endothelial growth factor (VEGF) and both tight and adherens junction proteins (VE-cadherin and claudin 5) with regards to the tumor biology of different ovarian cancer types.

METHODS

Serum and ascites samples before and after surgery, as well as peritoneal biopsies of 68 ovarian cancer patients and 20 healthy controls were collected. In serum and ascites VEGF protein was measured by ELISA. In peritoneal biopsies co-localization of VE-cadherin and claudin 5 was investigated using immunohistochemical dual staining. In addition, the gene expression of VE-cadherin and claudin 5 was quantified by Real-time PCR. Differences in VEGF levels, VE-cadherin and claudin 5 gene expression were analyzed in relation to various tumor characteristics (tumor stage, grading, histological subtypes, resection status after surgery) and then compared to controls. Furthermore, human primary ovarian cancer cells were co-cultured with human umbilical vein endothelial cells (HUVEC) and changes in VE-cadherin and claudin 5 were investigated after VEGF inhibition.

RESULTS

VEGF was significantly increased in tumor patients in comparison to controls and accumulates in ascites. The highest VEGF levels were found in patients diagnosed with advanced tumor stages, with tumors of poor differentiation, or in the group of solid / cystic-solid tumors. Patients with residual tumor after operation showed significantly higher levels of VEGF both before and after surgery as compared to tumor-free resected patients. Results of an immunohistochemical double-staining experiment indicated co-localization of VE-cadherin and claudin 5 in the peritoneal vasculature. Compared to controls, expression of VE-cadherin and claudin 5 was significantly suppressed in peritoneal vessels of tumor patients, but there were no significant differences regarding VE-cadherin and claudin 5 expression in relation to different tumor characteristics. A significant positive correlation was found between VE-cadherin and claudin 5 expression. VEGF inhibition in vitro was associated with significant increase in VE-cadherin and claudin 5.

CONCLUSIONS

Our results indicate that increased peritoneal permeability in ovarian cancer is due to down-regulation of adhesion proteins via tumor derived VEGF. Advanced ovarian cancer with aggressive tumor biology may be associated with early dysregulation of vascular permeability leading to ascites. These patients may benefit from therapeutic VEGF inhibition.

"The impact of debulking surgery in patients with node-positive epithelial ovarian cancer: Analysis of prognostic factors related to overall survival and progression-free survival after an extended long-term follow-up period"

OBJECTIVE

to estimate the prognostic factors associated with survival and progression free survival (PFS) in patients with node-positive epithelial ovarian cancer (EOC) after an extended long-term follow-up period.

METHODS

Data was provided by the Tumor Registry of the Mayo Clinic, Scottsdale, Arizona on 116 node-positive EOC patients who underwent primary cytoreductive surgery observed over the period 1996-2014.

RESULTS

At censoring date, 21 patients were alive (18%), 95 dead (82%), 18 without evidence of disease (NED) (15 alive, 3 dead) and 76 with evidence of disease (ED) (2 alive, 74 dead). Twenty-nine ED patients (38.2%) experienced a recurrence within 2 years, 53 patients (69.7%) before 5 years. No recurrences were recorded after 10 years. The median follow-up in alive patients was 169.8 months (1.20-207.9 months), 34.9 months (0.30-196.2 months) in dead patients, 128.4 months for NED patients (72.8-202.5 months) and 34.6 months (0.1-106.9 months) in ED patients. Multivariate analysis showed an increased risk of dead in patients with age ≥ 60 years (HR: 3.20; p < 0.002), stage IVA/B (compared with stage IIIA1/2, HR: 4.31; p < 0.001 and stage IIIB/C, HR: 5.31; p < 0.010) and incomplete surgery (compared with complete surgery, HR: 3.10; 95% CI, 1.41-6.77; p < 0.003) and a decreased PFS in stage IVA/B (compared with stages IIIB/C; p = 0.003 and stage IIIA; p = 0.000) and residual volume after surgery >0.6 cm (compared with residual disease <0.5 cm; p < 0.023).

CONCLUSIONS

prognostic factors for an extended long-term PFS are similar as those for survival, because after 17-year follow-up period, the majority of alive patients are NED patients.

Epithelial ovarian cancer subtypes attributable to smoking in the Norwegian Women and Cancer Study, 2012

Among European women, ovarian cancer is the fifth most common cancer. Smoking is an established risk factor for mucinous tumors. We estimated the impact of smoking in Norwegian women using population attributable fractions (PAFs) of epithelial ovarian cancer (EOC), by invasiveness and by histological subtypes in the Norwegian Women and Cancer Study with an average of 13.2 years of follow‐up. During >2 million person‐years, a total of 915 incident EOC cases, of which 667 (73%) invasive and 248 (27%) borderline, were identified among 154,234 women aged 34–70 years at enrolment. Compared with never smokers, current smokers had a nonstatistically significant increased risk of mucinous tumors (hazard ratio [HR] = 1.67 [95% confidence interval, (CI), 0.96–2.96]) and more than twice statistically significant risk of borderline mucinous tumors (HR = 2.17 [95% CI, 1.06–4.45]). The corresponding PAF estimates were 16.5% for mucinous and 25% for borderline mucinous. We found that among middle‐aged women, one in six mucinous tumors and one in four borderline mucinous tumors could have been prevented if women did not smoke.

Statistical methods for studying disease subtype heterogeneity

A fundamental goal of epidemiologic research is to investigate the relationship between exposures and disease risk. Cases of the disease are often considered a single outcome and assumed to share a common etiology. However, evidence indicates that many human diseases arise and evolve through a range of heterogeneous molecular pathologic processes, influenced by diverse exposures. Pathogenic heterogeneity has been considered in various neoplasms such as colorectal, lung, prostate, and breast cancers, leukemia and lymphoma, and non-neoplastic diseases, including obesity, type II diabetes, glaucoma, stroke, cardiovascular disease, autism, and autoimmune disease. In this article, we discuss analytic options for studying disease subtype heterogeneity, emphasizing methods for evaluating whether the association of a potential risk factor with disease varies by disease subtype. Methods are described for scenarios where disease subtypes are categorical and ordinal and for cohort studies, matched and unmatched case-control studies, and case-case study designs. For illustration, we apply the methods to a molecular pathological epidemiology study of alcohol intake and colon cancer risk by tumor LINE-1 methylation subtypes. User-friendly software to implement the methods is publicly available.