Ovarian cancer risk factors by tumor dominance, a surrogate for cell of origin

Ovarian Cancer Risk Factor Associations by Primary Anatomic Site: The Ovarian Cancer Cohort Consortium

BACKGROUND

Epithelial ovarian, fallopian tube, and primary peritoneal cancers have shared developmental pathways. Few studies have prospectively examined heterogeneity in risk factor associations across these three anatomic sites.

METHODS

We identified 3,738 ovarian, 337 peritoneal, and 176 fallopian tube incident cancer cases in 891,731 women from 15 prospective cohorts in the Ovarian Cancer Cohort Consortium. Associations between 18 putative risk factors and risk of ovarian, peritoneal, and fallopian tube cancer, overall and for serous and high-grade serous tumors, were evaluated using competing risks Cox proportional hazards regression. Heterogeneity was assessed by likelihood ratio tests.

RESULTS

Most associations did not vary by tumor site (P het ≥ 0.05). Associations between first pregnancy (P het = 0.04), tubal ligation (P het = 0.01), and early-adult (age 18-21 years) body mass index (BMI; P het = 0.02) and risk differed between ovarian and peritoneal cancers. The association between early-adult BMI and risk further differed between peritoneal and fallopian tube cancer (P het = 0.03). First pregnancy and tubal ligation were inversely associated with ovarian, but not peritoneal, cancer. Higher early-adult BMI was associated with higher risk of peritoneal, but not ovarian or fallopian tube, cancer. Patterns were generally similar when restricted to serous and high-grade serous cases.

CONCLUSIONS

Ovarian, fallopian tube, and primary peritoneal cancers appear to have both shared and distinct etiologic pathways, although most risk factors appear to have similar associations by anatomic site.

IMPACT

Further studies on the mechanisms underlying the differences in risk profiles may provide insights regarding the developmental origins of tumors arising in the peritoneal cavity and inform prevention efforts.

Intrauterine Device Use and Ovarian Cancer Risk: A Systematic Review and Meta-analysis

OBJECTIVE

To explore the relationship between intrauterine device (IUD) use and risk of ovarian cancer through systematic review of the literature and meta-analysis.

DATA SOURCES

We searched MEDLINE, EMBASE, Cochrane Library, Web of Science Core Collection from inception to June 2018. For the MEDLINE search, we included the MeSH terms "intrauterine devices" AND "ovarian neoplasms," however also searching "intrauter*," "ovar*" and "fallopian tube," as well as "cancer" and "carcinoma" as keywords to include all possible variations. Similar search terms were used in the other databases. We also searched ClinicalTrials.gov.

METHODS OF STUDY SELECTION

Case-control and cohort studies that collected individual level data on IUD use and ovarian cancer diagnosis were critically reviewed and data extracted. Review of abstracts from 399 articles through systematic database review and an additional 200 articles through Google Scholar identified a total of 15 studies with individual level data regarding IUD use and incident ovarian cancer. On critical review, 11 of these studies were used for meta-analysis. All case reports and reviews were excluded.

TABULATION, INTEGRATION, AND RESULTS

The data were harmonized and weighted and summary odds ratios (ORs) were calculated. Covariates were identified evaluated separately. A random-effects meta-analysis was performed to confirm minimal bias. Harmonization and weighting of the data revealed an OR association between ever use of an IUD and incident ovarian cancer to be 0.68 (95% CI 0.62-0.75). There were no significant differences found between covariates. Heterogeneity among all studies was found to be I=68%.

CONCLUSION

Intrauterine device use is associated with a reduced incidence of ovarian cancer based on a review of existing retrospective data. Unfortunately, prospective investigation into the role of IUDs in ovarian cancer prevention is limited.

Reproductive and Hormonal Factors and Risk of Ovarian Cancer by Tumor Dominance: Results from the Ovarian Cancer Cohort Consortium (OC3)

BACKGROUND

Laterality of epithelial ovarian tumors may reflect the underlying carcinogenic pathways and origins of tumor cells.

METHODS

We pooled data from 9 prospective studies participating in the Ovarian Cancer Cohort Consortium. Information on measures of tumor size or tumor dominance was extracted from surgical pathology reports or obtained through cancer registries. We defined dominant tumors as those restricted to one ovary or where the dimension of one ovary was at least twice as large as the other, and nondominant tumors as those with similar dimensions across the two ovaries or peritoneal tumors. Competing risks Cox models were used to examine whether associations with reproductive and hormonal risk factors differed by ovarian tumor dominance.

RESULTS

Of 1,058 ovarian cancer cases with tumor dominance information, 401 were left-dominant, 363 were right-dominant, and 294 were nondominant. Parity was more strongly inversely associated with risk of dominant than nondominant ovarian cancer (P heterogeneity = 0.004). Ever use of oral contraceptives (OC) was associated with lower risk of dominant tumors, but was not associated with nondominant tumors (P heterogeneity = 0.01). Higher body mass index was associated with higher risk of left-dominant tumors, but not significantly associated with risk of right-dominant or nondominant tumors (P heterogeneity = 0.08).

CONCLUSIONS

These data suggest that reproductive and hormonal risk factors appear to have a stronger impact on dominant tumors, which may have an ovarian or endometriosis origin.

IMPACT

Examining the associations of ovarian cancer risk factors by tumor dominance may help elucidate the mechanisms through which these factors influence ovarian cancer risk.

Anti-Inflammatory Drug Use and Ovarian Cancer Risk by COX1/COX2 Expression and Infiltration of Tumor-Associated Macrophages

BACKGROUND

Nonsteroidal anti-inflammatory drug (NSAID) use may affect ovarian cancer risk via prostaglandin synthesis and tumor-associated macrophage (TAM) infiltration. We evaluated if associations between aspirin or non-aspirin NSAID use and ovarian cancer risk differed by tumor expression of prostaglandin-related (COX1, COX2) and TAM-related (CD68, CD163) markers.

METHODS

We evaluated cases and matched controls from the Nurses' Health Study (NHS), NHSII, and New England Case-Control Study (NECC). Cases with IHC data on COX1 and COX2 (n = 532) or CD68 and CD163 (n = 530) were included. We used polytomous logistic regression, adjusted for ovarian cancer risk factors, to estimate OR for NSAID use and ovarian cancer risk by marker level.

RESULTS

Recent aspirin use had a nonsignificant inverse association and recent non-aspirin NSAID use had no association with ovarian cancer risk. NSAID use was not differentially associated with ovarian cancer by COX1 or COX2 expression. However, recent aspirin use was associated with lower ovarian cancer risk for high [OR 0.54; 95% confidence interval (CI), 0.37-0.78], but not low (OR 1.50; 95% CI, 0.97-2.31), CD163 density (P _{heterogeneity} < 0.001). Similar results were observed for aspirin duration and tablets and for recent non-aspirin NSAID use. Results were not clearly different by macrophage density defined by the less specific macrophage marker, CD68.

CONCLUSIONS

NSAID use was inversely associated with risk of ovarian cancer with high density CD163, a marker for M2-type, immunosuppressive macrophages. However, the relationship did not differ by prostaglandin synthesis markers.

IMPACT

Future research should explore prostaglandin-independent mechanisms for the association between NSAID use and ovarian cancer risk, including immune mechanisms.

Cells of origin of ovarian cancer: ovarian surface epithelium or fallopian tube?

OBJECTIVE

Ovarian cancer is the fifth most common cancer in women and one of the leading causes of death from gynecological malignancies. Despite of its clinical importance, ovarian tumorigenesis is poorly understood and prognosis remains poor. This is particularly true for the most common type of ovarian cancer, high-grade serous ovarian cancer.

RESULTS

Two models are considered, whether it arises from the ovarian surface epithelium or from the fallopian tube. The first model is based on (1) the pro-inflammatory environment caused by ovulation events, (2) the expression pattern of ovarian inclusion cysts, and (3) biomarkers that are shared by the ovarian surface epithelium and malignant growth. The model suggesting a non-ovarian origin is based on (1) tubal precursor lesions, (2) genetic evidence of BRCA1/2 mutation carriers, and (3) recent animal studies. Neither model has clearly demonstrated superiority over the other. Therefore, one can speculate that high-grade serous ovarian cancer may arise from two different sites that undergo similar changes. Both tissues are derived from the same embryologic origin, which may explain how progenitor cells from different sites can respond similar to stimuli within the ovaries. However, distinct molecular drivers, such as BRCA deficiency, may still preferentially arise from one site of origin as precancerous mutations are frequently seen in the fallopian tube.

CONCLUSIONS

Confirming the origin of ovarian cancer has important clinical implications when deciding on cancer risk-reducing prophylactic surgery. It will be important to identify key biomarker to uncover the sequence of ovarian tumorigenesis.

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.

Ovarian cancer

Ovarian cancer is not a single disease and can be subdivided into at least five different histological subtypes that have different identifiable risk factors, cells of origin, molecular compositions, clinical features and treatments. Ovarian cancer is a global problem, is typically diagnosed at a late stage and has no effective screening strategy. Standard treatments for newly diagnosed cancer consist of cytoreductive surgery and platinum-based chemotherapy. In recurrent cancer, chemotherapy, anti-angiogenic agents and poly(ADP-ribose) polymerase inhibitors are used, and immunological therapies are currently being tested. High-grade serous carcinoma (HGSC) is the most commonly diagnosed form of ovarian cancer and at diagnosis is typically very responsive to platinum-based chemotherapy. However, in addition to the other histologies, HGSCs frequently relapse and become increasingly resistant to chemotherapy. Consequently, understanding the mechanisms underlying platinum resistance and finding ways to overcome them are active areas of study in ovarian cancer. Substantial progress has been made in identifying genes that are associated with a high risk of ovarian cancer (such as BRCA1 and BRCA2), as well as a precursor lesion of HGSC called serous tubal intraepithelial carcinoma, which holds promise for identifying individuals at high risk of developing the disease and for developing prevention strategies.

Ovarian cancer

Ovarian cancer is not a single disease and can be subdivided into at least five different histological subtypes that have different identifiable risk factors, cells of origin, molecular compositions, clinical features and treatments. Ovarian cancer is a global problem, is typically diagnosed at a late stage and has no effective screening strategy. Standard treatments for newly diagnosed cancer consist of cytoreductive surgery and platinum-based chemotherapy. In recurrent cancer, chemotherapy, anti-angiogenic agents and poly(ADP-ribose) polymerase inhibitors are used, and immunological therapies are currently being tested. High-grade serous carcinoma (HGSC) is the most commonly diagnosed form of ovarian cancer and at diagnosis is typically very responsive to platinum-based chemotherapy. However, in addition to the other histologies, HGSCs frequently relapse and become increasingly resistant to chemotherapy. Consequently, understanding the mechanisms underlying platinum resistance and finding ways to overcome them are active areas of study in ovarian cancer. Substantial progress has been made in identifying genes that are associated with a high risk of ovarian cancer (such as BRCA1 and BRCA2), as well as a precursor lesion of HGSC called serous tubal intraepithelial carcinoma, which holds promise for identifying individuals at high risk of developing the disease and for developing prevention strategies.

Ovarian cancer

Ovarian cancer is not a single disease and can be subdivided into at least five different histological subtypes that have different identifiable risk factors, cells of origin, molecular compositions, clinical features and treatments. Ovarian cancer is a global problem, is typically diagnosed at a late stage and has no effective screening strategy. Standard treatments for newly diagnosed cancer consist of cytoreductive surgery and platinum-based chemotherapy. In recurrent cancer, chemotherapy, anti-angiogenic agents and poly(ADP-ribose) polymerase inhibitors are used, and immunological therapies are currently being tested. High-grade serous carcinoma (HGSC) is the most commonly diagnosed form of ovarian cancer and at diagnosis is typically very responsive to platinum-based chemotherapy. However, in addition to the other histologies, HGSCs frequently relapse and become increasingly resistant to chemotherapy. Consequently, understanding the mechanisms underlying platinum resistance and finding ways to overcome them are active areas of study in ovarian cancer. Substantial progress has been made in identifying genes that are associated with a high risk of ovarian cancer (such as BRCA1 and BRCA2), as well as a precursor lesion of HGSC called serous tubal intraepithelial carcinoma, which holds promise for identifying individuals at high risk of developing the disease and for developing prevention strategies.

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.

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.

Ovarian cancer survival by tumor dominance, a surrogate for site of origin

OBJECTIVES

Recent studies suggest that a proportion of ovarian tumors may actually originate in the distal fallopian tube. The objective of this study was to examine the relationship between dominance (a surrogate for site of origin) and survival, following a diagnosis of epithelial ovarian cancer.

METHODS

We classified 1,386 tumors as dominant (putatively originating in the ovary) and non-dominant (putatively originating in the fallopian tube), using parameters obtained from pathology reports. Dominant tumors were restricted to one ovary or one involved ovary that exceeded the other in dimension by at least twofold, while non-dominant tumors were identified as having a greater likelihood of a tubal origin if the disease was equally distributed across the ovaries. Cox proportional hazards models were used to estimate the hazard ratios (HRs) and 95% confidence intervals (CIs) associated with dominance.

RESULTS

Non-dominant tumors were more likely to be serous, stage III/IV, and be associated with a BRCA1/2 mutation, increasing parity and use of estrogen hormone replacement therapy (p ≤ 0.01). In contrast, 46 and 26% of the dominant tumors were serous and endometrioid, respectively, with a more even distribution of stage (p < 0.0001). Women with a non-dominant tumor had an increased risk of death compared to women with a dominant tumor (multivariate HR 1.28; 95% CI 1.02-1.60). Findings were similar in our analysis restricted to serous only subtypes (HR 1.28; 95% CI 1.01-1.63).

CONCLUSION

These preliminary findings suggest significantly worse survival among women diagnosed with a tumor putatively arising from fallopian tube.

An increased risk of epithelial ovarian cancer in Taiwanese women with a new surgico-pathological diagnosis of endometriosis

Background

Epidemiological evidence of relationships between endometriosis and epithelial ovarian cancer (EOC) has been obtained mainly from Western countries. Our goal was to determine the risk of EOC due to endometriosis in Taiwanese women.

Methods

A retrospective cohort study was performed by linking to the National Health Insurance Research Database (NHIRD) of Taiwan. A total of 5,945 women with a new surgico-pathological diagnosis of endometriosis from 2000 to 2010 and 23,780 multivariable-matched controls (1:4) were selected. The Cox regression model adjusted for potential confounders was used to assess the risk of EOC due to endometriosis.

Results

The EOC incidence rate (IR) of the women with and without endometriosis was 11.64 and 2.66 per 10,000 person-years, contributing to a crude hazard ratio (HR) of 4.48 (95% confidence interval [CI] 2.84-7.06), and HR after adjustment for all confounders (adjusted HR) of 5.62 (95% CI 3.46-9.14); the risk was higher in clear-cell carcinoma subtypes (adjusted HR 7.36, 95% CI 1.91-28.33). The EOC IR of women with endometriosis consistently increased with increasing age, ranging from 4.99 (<30 years) to 35.81 (≥50 years) per 10,000 person-years, contributing to a progressively increased risk of EOC (crude HRs ranging from 2.80 to 6.74 and adjusted HRs ranging from 3.34 to 9.63) compared to age-matched women without endometriosis, whose EOC IR also increased with age. The older women (≥50 years) with endometriosis had a risk of EOC that was higher than both the age-matched women without endometriosis (adjusted HR 9.63, 95% CI 3.27-28.37) and the youngest women (<30 years) with endometriosis (adjusted HR 4.97, 95% CI 1.03-24.09).

Conclusions

These significant findings corroborate the previously reported association between endometriosis and increased risk of EOC. Since the risk of EOC in women with a new surgico-pathological diagnosis of endometriosis constantly increased with age and this increased risk of EOC was more significant in women aged ≥50 years, active and intensive surgical intervention should be taken into consideration for older women with endometriosis.

Menstrual pain and epithelial ovarian cancer risk

PURPOSE

Menstrual pain is associated with increased production of inflammatory molecules, such as prostaglandins. Inflammation is involved in pathogenesis of several cancers, including ovarian cancer. In this study, we examined the association between menstrual pain and risk of ovarian cancer.

METHODS

We conducted a case-control study with 2,028 cases of epithelial ovarian cancer and 2,091 age- and study center-matched controls. Women were asked to report the severity of menstrual pain during their twenties and thirties, when not using oral contraceptives or breastfeeding. We used an unconditional logistic regression to evaluate the association between menstrual pain and epithelial ovarian cancer risk overall, and polytomous logistic regression to evaluate whether the association differed across tumor subtypes.

RESULTS

Risk of ovarian cancer was increased in women with moderate (OR 1.22, 95 % CI 1.05-1.42) and severe pain (OR 1.34, 95 % CI 1.09-1.65) compared to women with no or mild pain during menstrual period. The association differed by histologic subtypes, with significant associations for severe pain with endometrioid (OR 1.64, 95 % CI 1.15-2.34) and clear cell tumors (OR 1.91, 95 % CI 1.11-3.28).

CONCLUSIONS

Our data suggest that moderate and severe pain during menstrual period are associated with increased risk of epithelial ovarian cancer. Due to high prevalence of menstrual pain in women of reproductive age, this observation warrants further studies.

Through the glass darkly: intraepithelial neoplasia, top-down differentiation, and the road to ovarian cancer

It is currently hoped that deaths from extra-uterine high-grade serous cancer (HGSC) will be reduced via opportunistic salpingectomy in healthy women. Accumulated data implicate the fimbria as a site of origin and descriptive molecular pathology and experimental evidence strongly support a serous carcinogenic sequence in the Fallopian tube. Both direct and indirect ('surrogate') precursors suggest that the benign tube undergoes important biological changes after menopause, acquiring abnormalities in gene expression that are often shared with malignancy, including PAX2, ALDH1, LEF1, RCN1, RUNX2, beta-catenin, EZH2, and others. However, the tube can be linked to only some HGSCs, recharging arguments that nearby peritoneum/ovarian surface epithelium (POSE) also hosts progenitors to this malignancy. A major sticking point is the difference in immunophenotype between POSE and Müllerian epithelium, essentially requiring mesothelial to Müllerian differentiation prior to or during malignant transformation to HGSC. However, emerging evidence implicates an embryonic or progenitor phenotype in the adult female genital tract with the capacity to differentiate, normally or during neoplastic transformation. Recently, a putative cell of origin for cervical cancer has been identified in the squamo-columnar (SC) junction, projecting a model whereby Krt7+ embryonic progenitors give rise to immunophenotypically distinct progeny under stromal influences via 'top down' differentiation. Similar differentiation can be seen in the endometrium with a parallel in juxtaposed mesothelial and Müllerian differentiation in the ovary. Abrupt mesothelial-Müllerian transitions remain to be proven, but would explain the rapid evolution, short asymptomatic interval, and absence of a defined epithelial starting point in many HGSCs. Resolving this question will require accurately distinguishing progenitor from progeny tumour cells in HGSC and pinpointing where initial transformation and trans-differentiation occur, whether in the tube or POSE. Both will be critical to expectations from prophylactic salpingectomy and future approaches to pelvic serous cancer prevention.