Annika Idahl

Oral contraceptive use and reproductive factors and risk of ovarian cancer in the European Prospective Investigation into Cancer and Nutrition

Background:It is well established that parity and use of oral contraceptives reduce the risk of ovarian cancer, but the associations with other reproductive variables are less clear.Methods:We examined the associations of oral contraceptive use and reproductive factors with ovarian cancer risk in the European Prospective Investigation into Cancer and Nutrition. Among 327 396 eligible women, 878 developed ovarian cancer over an average of 9 years. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using Cox proportional hazard models stratified by centre and age, and adjusted for smoking status, body mass index, unilateral ovariectomy, simple hysterectomy, menopausal hormone therapy, and mutually adjusted for age at menarche, age at menopause, number of full-term pregnancies and duration of oral contraceptive use.Results:Women who used oral contraceptives for 10 or more years had a significant 45% (HR, 0.55; 95% CI, 0.41–0.75) lower risk compared with users of 1 year or less (P-trend, <0.01). Compared with nulliparous women, parous women had a 29% (HR, 0.71; 95% CI, 0.59–0.87) lower risk, with an 8% reduction in risk for each additional pregnancy. A high age at menopause was associated with a higher risk of ovarian cancer (>52 vs ⩽45 years: HR, 1.46; 95% CI, 1.06–1.99; P-trend, 0.02). Age at menarche, age at first full-term pregnancy, incomplete pregnancies and breastfeeding were not associated with risk.Conclusion:This study shows a strong protective association of oral contraceptives and parity with ovarian cancer risk, a higher risk with a late age at menopause, and no association with other reproductive factors.

Oocyte-Specific Deletion of Pten in Mice Reveals a Stage-Specific Function of PTEN/PI3K Signaling in Oocytes in Controlling Follicular Activation

Immature ovarian primordial follicles are essential for maintenance of the reproductive lifespan of female mammals. Recently, it was found that overactivation of the phosphatidylinositol 3-kinase (PI3K) signaling in oocytes of primordial follicles by an oocyte-specific deletion of Pten (phosphatase and tensin homolog deleted on chromosome ten), the gene encoding PI3K negative regulator PTEN, results in premature activation of the entire pool of primordial follicles, indicating that activation of the PI3K pathway in oocytes is important for control of follicular activation. To investigate whether PI3K signaling in oocytes of primary and further developed follicles also plays a role at later stages in follicular development and ovulation, we conditionally deleted the Pten gene from oocytes of primary and further developed follicles by using transgenic mice expressing zona pellucida 3 (Zp3) promoter-mediated Cre recombinase. Our results show that Pten was efficiently deleted from oocytes of primary and further developed follicles, as indicated by the elevated phosphorylation of the major PI3K downstream component Akt. However, follicular development was not altered and oocyte maturation was also normal, which led to normal fertility with unaltered litter size in the mutant mice. Our data indicate that properly controlled PTEN/PI3K-Akt signaling in oocytes is essential for control of the development of primordial follicles whereas overactivation of PI3K signaling in oocytes does not appear to affect the development of growing follicles. This suggests that there is a stage-specific function of PTEN/PI3K signaling in mouse oocytes that controls follicular activation.

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.

Circulating Inflammation Markers and Risk of Epithelial Ovarian Cancer

Background: Factors contributing to chronic inflammation appear to be associated with increased risk of ovarian cancer. The purpose of this study was to assess the association between circulating levels of inflammation mediators and subsequent risk of ovarian cancer. Methods: We conducted a case-control study of 230 cases and 432 individually matched controls nested within three prospective cohorts to evaluate the association of prediagnostic circulating levels of inflammation-related biomarkers (IL-1β, IL-2, IL-4, IL-5, IL-6, IL-10, IL-12p40, IL-12p70, IL-13, TNFα, IL-1Ra, sIL-1RII, sIL-2Ra, sIL-4R, sIL-6R, sTNF-R1, and sTNF-R2) measured using Luminex xMap technology with risk of ovarian cancer. Results: We observed a trend across quartiles for IL-2 (ORQ4 vs. Q1: 1.57, 95% CI: 0.98–2.52, P = 0.07), IL-4 (ORQ4 vs. Q1: 1.50, 95% CI: 0.95–2.38, P = 0.06), IL-6 (ORQ4 vs. Q1: 1.63, 95% CI: 1.03–2.58, P = 0.03), IL-12p40 (ORQ4 vs. Q1: 1.60, 95% CI: 1.02–2.51, P = 0.06), and IL-13 (ORQ4 vs. Q1: 1.42, 95% CI: 0.90–2.26, P = 0.11). Trends were also observed when cytokines were modeled on the continuous scale for IL-4 (P trend = 0.01), IL-6 (P trend = 0.01), IL-12p40 (P trend = 0.01), and IL-13 (P trend = 0.04). ORs were not materially different after excluding cases diagnosed less than 5 years after blood donation or when limited to serous tumors. Conclusions and Impact: This study provides the first direct evidence that multiple inflammation markers, specifically IL-2, IL-4, IL-6, IL-12, and IL-13, may be associated with risk of epithelial ovarian cancer, and adds to the evidence that inflammation is involved in the development of this disease. Cancer Epidemiol Biomarkers Prev; 20(5); 799–810. ©2011 AACR.

Coffee and tea consumption and the risk of ovarian cancer : a prospective cohort study and updated meta-analysis

BACKGROUND In 2007 the World Cancer Research Fund Report concluded that there was limited and inconsistent evidence for an effect of coffee and tea consumption on the risk of epithelial ovarian cancer (EOC). OBJECTIVE In the European Prospective Investigation into Cancer and Nutrition (EPIC), we aimed to investigate whether coffee intakes, tea intakes, or both are associated with the risk of EOC. DESIGN All women participating in the EPIC (n = 330,849) were included in this study. Data on coffee and tea consumption were collected through validated food-frequency questionnaires at baseline. HRs and 95% CIs were estimated by using Cox proportional hazards models. Furthermore, we performed an updated meta-analysis of all previous prospective studies until April 2011 by comparing the highest and lowest coffee- and tea-consumption categories as well as by using dose-response random-effects meta-regression analyses. RESULTS During a median follow-up of 11.7 y, 1244 women developed EOC. No association was observed between the risk of EOC and coffee consumption [HR: 1.05 (95% CI: 0.75, 1.46) for the top quintile compared with no intake] or tea consumption [HR: 1.07 (95% CI: 0.78, 1.45) for the top quintile compared with no intake]. This lack of association between coffee and tea intake and EOC risk was confirmed by the results of our meta-analysis. CONCLUSION Epidemiologic studies do not provide sufficient evidence to support an association between coffee and tea consumption and risk of ovarian cancer.

Chlamydia antibody testing and diagnosing tubal pathology in subfertile women: an individual patient data meta-analysis

BACKGROUND The Chlamydia IgG antibody test (CAT) shows considerable variations in reported estimates of test accuracy, partly because of the use of different assays and cut-off values. The aim of this study was to reassess the accuracy of CAT in diagnosing tubal pathology by individual patient data (IPD) meta-analysis for three different CAT assays. METHODS We approached authors of primary studies that used micro-immunofluorescence tests (MIF), immunofluorescence tests (IF) or enzyme-linked immunosorbent assay tests (ELISA). Using the obtained IPD, we performed pooled receiver operator characteristics analysis and logistic regression analysis with a random effects model to compare the three assays. Tubal pathology was defined as either any tubal obstruction or bilateral tubal obstruction. RESULTS We acquired data of 14 primary studies containing data of 6191 women, of which data of 3453 women were available for analysis. The areas under the curve for ELISA, IF and MIF were 0.64, 0.65 and 0.75, respectively (P-value < 0.001) for any tubal pathology and 0.66, 0.66 and 0.77, respectively (P-value = 0.01) for bilateral tubal pathology. CONCLUSIONS In Chlamydia antibody testing, MIF is superior in the assessment of tubal pathology. In the initial screen for tubal pathology MIF should therefore be the test of first choice.

Cigarette smoking and risk of histological subtypes of epithelial ovarian cancer in the EPIC cohort study

New data regarding a positive association between smoking and risk of epithelial ovarian cancer (EOC), especially the mucinous tumor type, has started to emerge. The purpose of this study was to examine the association between different measures of smoking exposures and subtypes of EOC in a large cohort of women from 10 European countries. The European Prospective Investigation into Cancer and Nutrition (EPIC) cohort is a multicenter prospective study initiated in 1992. The questionnaires included data about dietary, lifestyle, and health factors. Information about cigarette smoking was collected from individuals in all participating countries. We used Cox proportional hazard regression models to estimate hazard ratio (HR) of EOC overall and serous, mucinous, and endometroid histological subtypes, with 95% confidence intervals (CIs) associated with different measures of smoking exposures adjusting for confounding variables. Altogether 836 incident EOC cases were identified among 326,831 women. The tumors were classified as 400 serous, 83 mucinous, 80 endometroid, 35 clear cell, and 238 unspecified. Compared with never smokers, current smokers had a significantly increased risk for mucinous tumors [HR = 1.85 (95% CI 1.08–3.16)] and those smoking more than 10 cigarettes per day had a doubling in risk [HR = 2.25(95% CI 1.26–4.03)] as did those who had smoked less than 15 pack‐years of cigarettes [HR = 2.18 (95% CI 1.07–4.43)]. The results from the EPIC study add further evidence that smoking increases risk of mucinous ovarian cancer and support the notion that the effect of smoking varies according to histological subtype.

Tumor necrosis factor (TNF)‐α, soluble TNF receptors and endometrial cancer risk: The EPIC study

Chronic inflammation has been hypothesized to play a role in endometrial cancer development. Tumor necrosis factor‐α (TNF‐α), one of the major pro‐inflammatory cytokines, has also been implicated in endometrial physiology. We conducted a case‐control study nested within the European prospective investigation into cancer and nutrition (EPIC) to examine the association of TNF‐α and its two soluble receptors (sTNFR1 and sTNFR2) with endometrial cancer risk. Two‐hundred‐seventy cases and 518 matched controls were analyzed using conditional logistic regression. All statistical tests were two‐sided. We observed an increased risk of endometrial cancer among women in the highest versus lowest quartile of TNF‐α (odds ratio [OR]: 1.73, 95% CI: 1.09‐2.73, Ptrend = 0.01), sTNFR1 (OR: 1.68, 95% CI: 0.99‐2.86, Ptrend = 0.07) and sTNFR2 (OR: 1.53, 95%CI: 0.92‐2.55, Ptrend = 0.03) after adjustment for body‐mass‐index, parity, age at menopause and previous postmenopausal hormone therapy use. Further adjustments for estrogens and C‐peptide had minor effect on risk estimates. Our data show that elevated prediagnostic concentrations of TNF‐α and its soluble receptors are related to a higher risk of endometrial cancer, particularly strong in women diagnosed within 2 years of blood donation. This is the first study of its kind and therefore deserves replication in further prospective studies.

Factors Associated with Inflammation Markers, a Cross-Sectional Analysis

Epidemiological studies have reported associations between circulating inflammation markers and risk of chronic diseases. It is of interest to examine whether risk factors for these diseases are associated with inflammation. We conducted a cross-sectional analysis to evaluate whether reproductive and lifestyle factors and circulating vitamin D were associated with inflammation markers, including C-reactive protein, cytokines (IL-1β, IL-2, IL-4, IL-5, IL-6, IL-10, IL-12p40, IL-12p70, IL-13, TNFα), and cytokine modulators (IL-1RA, sIL-1RII, sIL-2Ra, sIL-4R, sIL-6R, sTNF-R1/R2), among 616 healthy women. We confirmed associations of several inflammation markers with age and BMI. We also observed significantly higher levels of certain inflammation markers in postmenopausal vs. premenopausal women (TNFα, sIL-1RII, sIL-2Ra), with increasing parity (IL-12p40), and with higher circulating 25(OH) vitamin D (IL-13) and lower levels among current users of non-steroidal anti-inflammatory drugs (NSAIDs) (IL-1β, IL-2, IL-10, IL-12p70, and IL-12p40), current smokers (IL-4, IL-13, IL-12p40), and women with a family history of breast or ovarian cancer (IL-4, IL-10, IL-13). Our findings suggest that risk factors for chronic diseases (age, BMI, menopausal status, parity, NSAID use, family history of breast and ovarian cancer, and smoking) are associated with inflammation markers in healthy women.

Reproductive and hormone-related risk factors for epithelial ovarian cancer by histologic pathways, invasiveness and histologic subtypes: Results from the EPIC cohort

Whether risk factors for epithelial ovarian cancer (EOC) differ by subtype (i.e., dualistic pathway of carcinogenesis, histologic subtype) is not well understood; however, data to date suggest risk factor differences. We examined associations between reproductive and hormone‐related risk factors for EOC by subtype in the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort. Among 334,126 women with data on reproductive and hormone‐related risk factors (follow‐up: 1992–2010), 1,245 incident cases of EOC with known histology and invasiveness were identified. Data on tumor histology, grade, and invasiveness, were available from cancer registries and pathology record review. We observed significant heterogeneity by the dualistic model (i.e., type I [low grade serous or endometrioid, mucinous, clear cell, malignant Brenner] vs. type II [high grade serous or endometrioid]) for full‐term pregnancy (phet = 0.02). Full‐term pregnancy was more strongly inversely associated with type I than type II tumors (ever vs. never: type I: relative risk (RR) 0.47 [95% confidence interval (CI): 0.33–0.69]; type II, RR: 0.81 [0.61–1.06]). We observed no significant differences in risk in analyses by major histologic subtypes of invasive EOC (serous, mucinous, endometrioid, clear cell). None of the investigated factors were associated with borderline tumors. Established protective factors, including duration of oral contraceptive use and full term pregnancy, were consistently inversely associated with risk across histologic subtypes (e.g., ever full‐term pregnancy: serous, RR: 0.73 [0.58–0.92]; mucinous, RR: 0.53 [0.30–0.95]; endometrioid, RR: 0.65 [0.40–1.06]; clear cell, RR: 0.34 [0.18–0.64]; phet = 0.16). These results suggest limited heterogeneity between reproductive and hormone‐related risk factors and EOC subtypes.