Association of cigarette smoking with the risk of ovarian cancer

Nicotine inhibits MAPK signaling and spheroid invasion in ovarian cancer cells

Nicotine is the major addictive component of cigarette smoke and although it is not considered carcinogenic, it can enhance or inhibit cancer cell proliferation depending on the type of cancer. Nicotine mediates its effects through nicotinic acetylcholine receptors (nAChRs), which are expressed in many different neuronal and non-neuronal cell types. We observed that the nAChR α4, α5, α7 subunits were expressed in ovarian cancer (OC) cells. Nicotine inhibited the proliferation of SKOV3 and TOV112D OC cells, which have TP53 mutation and wild-type KRAS, but did not inhibit the proliferation of TOV21G or HEY OC cells, which have KRAS mutation and wild-type TP53. Exposure to nicotine for 96 h led to a significant reduction in the amounts of activated extracellular signal-regulated kinase (ERK) and activated p38 mitogen-activated protein kinases (MAPKs) in SKOV3 cells, and in activated ERK in TOV112D cells. In addition, SKOV3 and TOV112D invasion and spheroid formation were substantially inhibited by siRNA knockdown of mixed lineage kinase 3 (MLK3), or MEK inhibition. Nicotine treatment reduced SKOV3 and TOV112D spheroid invasion and compaction but did not significantly affect spheroid formation. Furthermore, SKOV3 spheroid invasion was blocked by p38 inhibition with SB202190, but not by MEK inhibition with U0126; whereas TOV112D spheroid invasion was reduced by MEK inhibition, but not by p38 inhibition. These results indicate that nicotine can suppress spheroid invasion and compaction as well as proliferation in SKOV3 and TOV112D OC cells; and p38 and ERK MAPK signaling pathways are important mediators of these responses.

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.

Dose-risk relationships between cigarette smoking and ovarian cancer histotypes: a comprehensive meta-analysis

PURPOSE

Although smoking has not been associated with overall ovarian cancer risk, a different impact on various histotypes has been reported. Our aim is to provide an accurate, up-to-date estimate of the dose-risk relationships between cigarette smoking and epithelial ovarian cancer, overall and by histotypes.

METHODS

Using an innovative approach for the identification of original study publications, we conducted a systematic review and meta-analysis of epidemiological studies published on the topic until September 2018. Summary relative risks (RR) for cigarette smoking were estimated using random-effects models; dose-risk relationships were evaluated using one-stage random-effects models with restricted cubic splines.

RESULTS

Thirty-seven studies were considered in the meta-analysis. The summary RRs for current versus never smokers were 1.05 (95% confidence interval CI 0.95-1.16) for overall ovarian cancer, 1.78 (95% CI 1.52-2.07) for mucinous, 0.77 (95% CI 0.65-0.93) for clear cell, 0.81 (95% CI 0.73-0.91) for endometrioid, and 1.05 (95% CI 0.94; 1.17) for serous cancer. The risk of borderline mucinous (RR 2.09) and serous (RR 1.16) tumors was higher than for invasive cancers (RR 1.44 and 0.95, respectively). For mucinous cancer, risk was noticeably higher with smoking intensity and duration (RR 2.35 for 20 cigarettes/day, and 2.11 for 20 years of smoking). A non-significant linear relation was found with smoking intensity, duration, and time since quitting for overall ovarian cancer and other histotypes.

CONCLUSIONS

This uniquely large and comprehensive meta-analysis confirms that although cigarette smoking does not appear to be a risk factor for ovarian cancer, and it is even slightly protective for some rare histotypes, there is a strong dose-risk relationship with mucinous ovarian cancer.

Ovarian cancer in the world: epidemiology and risk factors

Aim: Ovarian cancer is one of the most common gynecologic cancers that has the highest mortality rate. Considering the fact that knowledge on the incidence, mortality of ovarian cancer, as well as its risk factors is necessary for planning and preventing complications, this study was conducted with the aim of examining the epidemiology and risk factors of ovarian cancer in the world.

Materials and methods: In order to access the articles, Medline, Web of Science Core Collection, and Scopus databases were searched from their start to the year 2018. Full-text, English observational studies that referred to various aspects of ovarian cancer were included in the study.

Results: In total, 125 articles that had been published during the years 1925–2018 were entered into the study. Ovarian cancer is the seventh most common cancer among women. Increased risk factors of cancer have led to an upward trend in the incidence of cancer around the world. In 2018, 4.4% of entire cancer-related mortality among women was attributed to ovarian cancer. Although the incidence of cancer is higher among high Human Development Index (HDI) countries, the trend of mortality rate tends to be reversing. Various factors affect the occurrence of ovarian cancer, from which genetic factor are among the most important ones. Pregnancy, lactation, and oral contraceptive pills play a role in reducing the risk of this disease.

Conclusion: This study provides significant evidence about ovarian cancer. Considering the heavy burden of ovarian cancer on women's health, preventive measures as well as health education and early detection in high risk groups of women are highly recommended. Although some risk factors cannot be changed, a focus on preventable risk factors may reduce the risk of ovarian cancer. More studies are needed to explore the role of unclear risk factors in ovarian cancer occurrence.

Changing trends in the incidence of ovarian neoplasia and its relationship with the risk factors: a report of 311 cases from north-eastern anatolia region

OBJECTIVE

Ovarian cancer is one of the most common and lethal gynecologic malignancy. In Turkey, the 8(th) most commonly seen neoplasm is ovarian cancer. The risk factors of ovarian cancer are menstrual reproductive events including gravida, menarche and menopause status, and life style habits such as cigarette smoking and habitat. In this study we aimed to determine the risk factors leading to ovarian cancer in Turkish women population and show the tumor markers in this population.

MATERIALS AND METHODS

This study included 311 ovarian neoplasia cases diagnosed at the Pathology Department of Ataturk University in Erzurum over last seven years extending from 2005 to 2013. This study is a retrospective analysis basing on the pathology reports and accesible patient files. Serum tumor markers of the patients were retrospectively reported from their records. Conventional stained preparations existing in our archive examined by two pathologists as well independent of each other, and histopathologic diagnosis and the distribution of the sub-group was revised.

RESULTS

A total of 311 patients were included in this study in which patients were diagnosed at the Pathology Department of Ataturk University in Erzurum. Serous cystadenoma is the most common ovarian tumor followed by mucinous cystadenoma, germ cell tumors, and dysgerminoma. All of the tumor markers were significantly normal.

CONCLUSION

Upto our knowledge this was the first epidemiological study in Turkey. Analysis of each country's statistical information reflecting its own profile is also important. The relationship between the profiles of patients and types of ovarian neoplasia may give an idea about the risk factors of the disease in its region. Additionally, distribution of tumor markers might be considered for the discriminating of the benign or malign characters of the ovarian neoplasia.

Cigarette smoking and risk of ovarian cancer: a pooled analysis of 21 case-control studies

PURPOSE

The majority of previous studies have observed an increased risk of mucinous ovarian tumors associated with cigarette smoking, but the association with other histological types is unclear. In a large pooled analysis, we examined the risk of epithelial ovarian cancer associated with multiple measures of cigarette smoking with a focus on characterizing risks according to tumor behavior and histology.

METHODS

We used data from 21 case-control studies of ovarian cancer (19,066 controls, 11,972 invasive and 2,752 borderline cases). Study-specific odds ratios (OR) and 95 % confidence intervals (CI) were obtained from logistic regression models and combined into a pooled odds ratio using a random effects model.

RESULTS

Current cigarette smoking increased the risk of invasive mucinous (OR = 1.31; 95 % CI: 1.03-1.65) and borderline mucinous ovarian tumors (OR = 1.83; 95 % CI: 1.39-2.41), while former smoking increased the risk of borderline serous ovarian tumors (OR = 1.30; 95 % CI: 1.12-1.50). For these histological types, consistent dose-response associations were observed. No convincing associations between smoking and risk of invasive serous and endometrioid ovarian cancer were observed, while our results provided some evidence of a decreased risk of invasive clear cell ovarian cancer.

CONCLUSIONS

Our results revealed marked differences in the risk profiles of histological types of ovarian cancer with regard to cigarette smoking, although the magnitude of the observed associations was modest. Our findings, which may reflect different etiologies of the histological types, add to the fact that ovarian cancer is a heterogeneous disease.

Non-steroidal anti-inflammatory drug use and ovarian cancer risk: findings from the NIH-AARP Diet and Health Study and systematic review

BACKGROUND

Chronic inflammation has been proposed as a risk factor for ovarian cancer. Some data suggest that anti-inflammatory medications may be protective against ovarian cancer; however, results have been inconsistent.

METHODS

We evaluated the risk of epithelial ovarian cancer with regular use of NSAIDs prospectively in the NIH-AARP Diet and Health Study, using Cox proportional hazard models. We also examined the risk of common subtypes of epithelial ovarian cancer (serous, mucinous, endometrioid, clear cell, and other epithelial) with regular use of NSAIDs. In addition, we performed meta-analyses summarizing the risk of ovarian cancer with "regular use" of NSAIDs in previously published studies.

RESULTS

We did not observe a significant association between regular use of NSAIDs with ovarian cancer risk in the AARP cohort (aspirin: RR 1.06, 95 % CI 0.87-1.29; non-aspirin NSAIDs: RR 0.93, 95 % CI 0.74-1.15); however, summary estimates from prospective cohort studies demonstrated that use of non-aspirin NSAIDs may reduce the risk of ovarian cancer (RR 0.88, 95 % CI 0.77-1.01). Although not significant, we found that mucinous tumors were inversely associated with non-aspirin NSAID use (RR 0.69, 95 % CI 0.23-2.10) in the AARP cohort, which was supported by the meta-analysis (RR 0.69, CI 0.50-0.94.)

CONCLUSION

Although results from the NIH-AARP cohort study were not statistically significant, our meta-analysis suggests that non-aspirin NSAIDs may be protective against ovarian cancer. Additional analyses, focusing on dose, duration, and frequency of NSAID use and accounting for ovarian cancer heterogeneity are necessary to further elucidate the association between NSAID use and ovarian cancer risk.

Ovarian cancer and smoking: individual participant meta-analysis including 28,114 women with ovarian cancer from 51 epidemiological studies

Background

Smoking has been linked to mucinous ovarian cancer, but its effects on other ovarian cancer subtypes and on overall ovarian cancer risk are unclear, and the findings from most studies with relevant data are unpublished. To assess these associations, we review the published and unpublished evidence.

Methods

Eligible epidemiological studies were identified by electronic searches, review articles, and discussions with colleagues. Individual participant data for 28 114 women with and 94 942 without ovarian cancer from 51 epidemiological studies were analysed centrally, yielding adjusted relative risks (RRs) of ovarian cancer in smokers compared with never smokers.

Findings

After exclusion of studies with hospital controls, in which smoking could have affected recruitment, overall ovarian cancer incidence was only slightly increased in current smokers compared with women who had never smoked (RR 1·06, 95% CI 1·01–1·11, p=0·01). Of 17 641 epithelial cancers with specified histology, 2314 (13%) were mucinous, 2360 (13%) endometrioid, 969 (5%) clear-cell, and 9086 (52%) serous. Smoking-related risks varied substantially across these subtypes (p_{heterogeneity}<0·0001). For mucinous cancers, incidence was increased in current versus never smokers (1·79, 95% CI 1·60–2·00, p<0·0001), but the increase was mainly in borderline malignant rather than in fully malignant tumours (2·25, 95% CI 1·91–2·65 vs 1·49, 1·28–1·73; p_{heterogeneity}=0·01; almost half the mucinous tumours were only borderline malignant). Both endometrioid (0·81, 95% CI 0·72–0·92, p=0·001) and clear-cell ovarian cancer risks (0·80, 95% CI 0·65–0·97, p=0·03) were reduced in current smokers, and there was no significant association for serous ovarian cancers (0·99, 95% CI 0·93–1·06, p=0·8). These associations did not vary significantly by 13 sociodemographic and personal characteristics of women including their body-mass index, parity, and use of alcohol, oral contraceptives, and menopausal hormone therapy.

Interpretation

The excess of mucinous ovarian cancers in smokers, which is mainly of tumours of borderline malignancy, is roughly counterbalanced by the deficit of endometrioid and clear-cell ovarian cancers. The substantial variation in smoking-related risks by tumour subtype is important for understanding ovarian carcinogenesis.

Funding

Cancer Research UK and MRC.

Ovarian cancer risk factors by histologic subtypes in the NIH-AARP Diet and Health Study

Data suggest that risk factors for ovarian carcinoma vary by histologic type, but findings are inconsistent. We prospectively evaluated risk factors by histological subtypes of incident ovarian cancer (n = 849) in a cohort of 169,391 women in the NIH-AARP Diet and Health Study. We constructed Cox models of individual exposures by comparing case subtypes to the entire non-case group and assessed p-heterogeneity in case-case comparisons using serous as the reference category. Substantial risk differences between histologic subtypes were observed for menopausal hormone therapy (MHT) use, oral contraceptive (OC) use, parity and body mass index (p-heterogeneity = 0.01, 0.03, 0.05, 0.03, respectively). MHT users were at increased risk for all histologic subtypes except for mucinous carcinomas, where risk was reduced (relative risk (RR) = 0.37; 95% confidence interval (CI): 0.18, 0.80). OC users were only at significantly decreased risk for serous cancers (RR = 0.69; 95% CI: 0.55, 0.85). Although parity was inversely associated with risk of all subtypes, the RRs ranged from 0.28 (clear cell) to 0.83 (serous). Obesity was a significant risk factor only for endometrioid cancers (RR = 1.64; 95% CI: 1.00, 2.70). Our findings support a link between etiological factors and histological heterogeneity in ovarian carcinoma.

Olive oil intake is inversely related to cancer prevalence: a systematic review and a meta-analysis of 13,800 patients and 23,340 controls in 19 observational studies

Dietary fat, both in terms of quantity and quality, has been implicated to cancer development, either positively or negatively. The aim of this work was to evaluate whether olive oil or monounsaturated fat intake was associated with the development of cancer. A systematic search of relevant studies, published in English, between 1990 and March 1, 2011, was performed through a computer-assisted literature tool (i.e., Pubmed). In total 38 studies were initially allocated; of them 19 case-control studies were finally studied (13800 cancer patients and 23340 controls were included). Random effects meta-analysis was applied in order to evaluate the research hypothesis. It was found that compared with the lowest, the highest category of olive oil consumption was associated with lower odds of having any type of cancer (log odds ratio = -0.41, 95%CI -0.53, -0.29, Cohran's Q = 47.52, p = 0.0002, I-sq = 62%); the latter was irrespective of the country of origin (Mediterranean or non-Mediterranean). Moreover, olive oil consumption was associated with lower odds of developing breast cancer (logOR = -0,45 95%CI -0.78 to -0.12), and a cancer of the digestive system (logOR = -0,36 95%CI -0.50 to -0.21), compared with the lowest intake. The strength and consistency of the findings states a hypothesis about the protective role of olive oil intake on cancer risk. However, it is still unclear whether olive oil's monounsaturated fatty acid content or its antioxidant components are responsible for its beneficial effects.

Molecular pathogenesis of endometrial and ovarian cancer

Pregnancy, breastfeeding, and oral contraceptive pill use interrupt menstrual cycles and reduce endometrial and ovarian cancer risk. This suggests the importance of turnover within Mullerian tissues, where the accumulation of mutations in p53 and PTEN has been correlated with number of cycles. The most common type of endometrial cancer (Type I) is endometrioid and molecular abnormalities include mutations in PTEN, KRAS and β-catenin. The Type I precursor is Endometrial Intraepithelial Neoplasia which displays PTEN defects. Type II endometrial cancer (whose precursors are less clear) includes serous and clear cell tumors and the most common alteration is p53 mutation. For ovarian cancer, histopathologic types parallel endometrial cancer and include serous, mucinous, endometrioid, and clear cell; some molecular features are also shared. The most frequent type of ovarian cancer is high grade serous that often displays p53 mutation and its precursor lesions may originate from normal-appearing fallopian tube epithelium that contains a p53 "signature". Mutations in KRAS, BRAF and PTEN are described in mucinous, endometrioid and low grade serous cancers and these may originate from ovarian cortical inclusion cysts. A consideration of molecular and other pathogenetic features, like epidemiology and histopathology, may provide a better understanding of endometrial and ovarian cancer.

Epidemiological and genetic factors associated with ovarian cancer

The purpose of this article was to provide a comprehensive review of the epidemiological and genetic factors associated with ovarian cancer. A more complete understanding of the determinants of ovarian cancer may lead to the development of better screening and detection methods for this disease. The first section of this article reviews current literature on screening and early detection of ovarian cancer. The second section reviews the epidemiology of ovarian cancer, specifically highlighting the risk factors associated with the development of this disease. The article concludes with a discussion of how oncology nurses can apply this information to improve patient care.

Caffeine, alcohol, smoking, and the risk of incident epithelial ovarian cancer

BACKGROUND

Smoking, caffeine, and alcohol intake are all potentially modifiable factors that have an unclear association with ovarian cancer risk. Therefore, the associations between these exposures and ovarian cancer risk were prospectively examined among 110,454 women in the Nurses' Health Study (NHS) for the smoking analyses and 80,253 women for the dietary analyses.

METHODS

Women completed biennial questionnaires assessing ovarian cancer risk factors beginning in 1976, with food frequency questionnaires administered every 2 to 4 years starting in 1980. For the smoking analyses, 737 confirmed cases of epithelial ovarian cancer were identified and for the dietary aims, 507 cases were identified through June 1, 2004.

RESULTS

Compared with never-smokers, neither current nor past smoking was associated with ovarian cancer risk overall; however, both were associated with mucinous tumors (n = 69; rate ratio [RR], past = 2.02 [95% confidence interval (CI), 1.15-3.55]; RR, current = 2.22 [95% CI, 1.16-4.24]). A modest inverse association between caffeine intake and ovarian cancer risk was observed (RR, top vs bottom quintile = 0.80; 95% CI, 0.60-1.07 [P = .03]), which was strongest for women who had never used either oral contraceptives (RR = 0.65; 95% CI, 0.46-0.92 [P for heterogeneity = .02]) or postmenopausal hormones (RR = 0.57; 95% CI, 0.36-0.91 [P for heterogeneity = .13]). Alcohol was not associated with ovarian cancer risk.

CONCLUSIONS

The results of the current study suggest that cigarette smoking may only increase the risk for mucinous ovarian tumors, and alcohol intake was not associated with risk. However, an inverse association was observed between caffeine intake and ovarian cancer risk, particularly in women not using hormones; this finding merits further study.

Cigarette smoking and risk of epithelial ovarian cancer

BACKGROUND

An increased risk of mucinous ovarian tumors among cigarette smokers has been observed in multiple studies. The association of smoking with other histologic types of ovarian cancer is less clear, but potentially holds greater importance for prevention of disease incidence and mortality.

METHODS

In a population-based study of 812 women with ovarian cancer diagnosed in western Washington State from 2002-2005 and 1,313 controls, we assessed the risk associated with cigarette smoking, with a particular focus on tumor subgroups jointly classified according to the degree of invasiveness and histology. Information was collected through in-person interviews, and logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

The incidence of both borderline and invasive mucinous ovarian tumors was increased among women with a history of cigarette smoking (ORs and 95% CIs = 1.8, 1.2-2.9, and 1.8, 0.8-4.3, respectively). Increases in risk of these tumor types were most evident among women with greater smoking duration and pack-years of exposure, and among those who had smoked within the prior 15 years. We noted no clear patterns of risk of serous tumors with duration or pack-years of smoking; however, risk of these tumor types was somewhat elevated among women who had smoked within the previous 15 years (for borderline serous tumors, OR and 95% CI = 1.5, 0.9-2.3; for invasive serous tumors, OR and 95% CI = 1.4, 1.1-1.9). The risk of endometrioid, clear cell, and the remaining histologic types of invasive ovarian cancer was not increased among smokers.

CONCLUSION

In the aggregate, evidence is insufficient to determine whether smoking is linked with risk of serous or other non-mucinous histologic types of ovarian cancer. Studies that employ additional histopathologic and molecular techniques to more accurately delineate subsets of tumors may improve our understanding of the impact of smoking on ovarian cancer risk.

Dietary Habits and Risk of Ovarian Cancer Death in a Large-Scale Cohort Study (JACC Study) in Japan

The Japan Collaborative Cohort (JACC) Study was established in 1988-1990 and consisted of 46,465 men and 64,327 women observed until the end of 2003. A self-administered food frequency questionnaire was used as a baseline survey, and associations of dietary habits with the risk of ovarian cancer death were evaluated, taking into consideration age, menstrual and reproductive, anthropometric, and lifestyle factors. During the observation period, 77 women died of ovarian cancer. Hazard ratios for dietary factors were calculated by Cox's proportional hazards model. Being adjusted only for age, high intakes of dried or salted fish and Chinese cabbage were positively associated with the risk of ovarian cancer death, and the risk increased dose-dependently. In contrast, intake of soybean curd (tofu) was inversely associated with the risk. After being adjusted for age and potential confounding factors, the results regarding the intakes of dried or salted fish and Chinese cabbage did not change. However, the significance relating to the intake of soybean curd (tofu) was attenuated. From the results of this cohort study, it was suggested that high intakes of dried or salted fish and Chinese cabbage were potential risk factors of ovarian cancer death. In contrast, however, a high intake of soy bean curd (tofu) might have preventive effects against the risk.

The effect of lifestyle factors on gynaecological cancer

Several lifestyle factors affect a woman's risk of gynaecological cancer and-potentially-can be modified to reduce risk. This chapter summarises the evidence for the effect of lifestyle factors on the incidence of gynaecological malignancy. The incidence of obesity is increasing in the developed world such that it now contributes as much as smoking to overall cancer deaths. Women with a body mass index (BMI)>40 have a 60% higher risk of dying from all cancers than women of normal weight. They are also at increased risk from gynaecological cancer. Dietary factors significantly influence the risk of gynaecological cancer: fruit, vegetables and antioxidants reduce risk whereas high animal fat and energy intakes increase risk. Alcohol intake adversely affects breast cancer risk, possibly accounting for 4% of all breast cancers. Physical activity protects against ovarian, endometrial and postmenopausal breast cancer, independently of BMI. The oral contraceptive pill has a substantial and long-lasting effect on the prevention of ovarian and endometrial cancer and is one of the best examples of large-scale chemoprevention in the developed world. Childbearing is protective against ovarian, endometrial and breast cancer but increases the risk of cervical cancer. Smoking acts as a cofactor in cervical carcinogenesis and increases the risk of ovarian cancer, particularly mucinous tumours.

Does smoking increase risk of ovarian cancer? A systematic review

OBJECTIVES

Although early reports suggested that smoking was not associated with ovarian cancer risk, recent studies have reported positive associations for cancers of the mucinous subtype. We sought to clarify the relationship between smoking and ovarian cancer by histological subtype.

METHODS

We conducted a systematic literature review and meta-analysis of studies investigating the association between smoking and risk of the different histological subtypes of epithelial ovarian cancer. Eight population-based case-control studies, one pooled analysis of case-control studies, and one cohort study met the inclusion criteria. Summary relative risks (RR), 95% confidence intervals (CI), and tests for heterogeneity were generated from random effects models.

RESULTS

Combined, these studies included a total of 910 women with mucinous and 5564 with non-mucinous ovarian cancers. There was a significant doubling of risk of mucinous ovarian cancer in current smokers compared to never smokers (summary RR 2.1, 95% CI 1.7-2.7), but no increased risk of serous (1.0, 95% CI 0.8-1.2) or endometrioid (0.8, 95% CI 0.6-1.1) cancers and a significant risk reduction for clear cell cancers (0.6, 95% CI 0.3-0.9). The risk of mucinous cancer increased with increasing amount smoked but returned to that of never smokers within 20-30 years of stopping smoking.

CONCLUSIONS

Meta-analysis suggests that current smoking doubles a woman's risk of developing mucinous ovarian cancer. Stopping smoking returns the risk to normal in the long term. Smoking may thus be one of the few modifiable factors offering potential for primary prevention of mucinous ovarian cancer.

In vitro exposure to environmental tobacco smoke induces CYP1B1 expression in human luteinized granulosa cells

Women smokers and women exposed to environmental tobacco smoke (ETS) have reduced ovarian function as evidenced by an earlier menopause, reduced follicular numbers, decreased levels of circulating estradiol, and decreased conception rates; however, the mechanism of action of altered ovarian function by ETS is poorly understood. The direct effects of ETS were evaluated using human luteinized granulosa cells (HLGCs) exposed to ETS in primary cell culture. Exposure to ETS caused a decrease in both estradiol and progesterone production. There was a concentration dependent increase in CYP1B1 gene and protein expression without a change in catechol-O-methyltransferase (COMT) expression. This is the first report of CYP1B1 induction secondary to ETS exposure in cells from the human ovary. CYP1B1 metabolizes both endogenous estrogens and polyaromatic hydrocarbons in ETS to a variety of reactive species and may contribute to the complex effects of ETS on ovarian function.

Active and passive smoking and risk of ovarian cancer

It is unclear whether smoking is a risk factor for epithelial ovarian cancer, although some studies have suggested that it may be associated with an increased risk of mucinous tumors. This study investigated the effect of smoking and environmental tobacco smoke (ETS) on ovarian cancer risk among 434 women with primary epithelial ovarian, peritoneal, or fallopian cancers and 868 age- and region-matched hospital controls with nonneoplastic conditions. All participants completed a comprehensive epidemiologic questionnaire. Results indicate that decreased risk of ovarian cancer was associated with being a nonsmoker exposed to ETS (adjusted odds ratio [aOR] 0.68, 95% confidence interval [CI] 0.46-0.99), a former smoker (aOR 0.76, 95% CI 0.53-1.10), or a current smoker (aOR 0.53, 95% CI 0.32-0.88). A similar protective effect was noted for smokers with moderate or high exposure based on smoking intensity, duration, and cumulative exposure, as well as for never smokers exposed to ETS. Results did not differ substantially by histologic subtype. Although prevailing theories of ovarian cancer etiology implicate incessant ovulation, characteristics of the study population suggest that anovulation was not the protective mechanism in this study. Immunosuppression by nicotine or upregulation of enzymes that metabolize carcinogens may be responsible for the effects observed.

Conditions associated with antibodies against the tumor-associated antigen MUC1 and their relationship to risk for ovarian cancer

Many cancers, including ovarian, overexpress epithelial mucin (MUC1) and promote anti-MUC1 antibodies that may correlate with more favorable prognosis. By extension, risk for ovarian cancer might be reduced by preexisting MUC1-specific immunity. We measured anti-MUC1 antibodies in 705 control women, identified events predicting antibodies, and estimated ovarian cancer risk by comparing profiles of events generating antibodies in controls with those in 668 ovarian cancer cases. Factors predicting antibodies included oral contraceptive use, breast mastitis, bone fracture or osteoporosis, pelvic surgeries, nonuse of talc in genital hygiene, and to a lesser extent intrauterine device use and current smoking. There was a significant increase in the likelihood of having anti-MUC1 antibodies from 24.2% in women with 0 or 1 condition, to 51.4% in those with five or more conditions. By the same index of events, the risk for ovarian cancer was inversely associated with number of conditions predisposing to anti-MUC1 antibodies. Compared with having experienced 0 or 1 event, the adjusted risk for ovarian cancer decreased progressively with relative risks (and 95% confidence limits) of 0.69 (0.52-0.92), 0.64 (0.47-0.88), 0.49 (0.34-0.72), and 0.31 (0.16-0.61), respectively for women with two, three, four, and five or more events related to the presence of antibodies (P(trend) < 0.0001.) We conclude that several traditional and new risk factors for ovarian cancer may be explained by their ability to induce MUC1 immunity through exposure of MUC1 to immune recognition in the context of inflammatory or hormonal processes in various MUC1-positive tissues.

Patterns of gene expression in different histotypes of epithelial ovarian cancer correlate with those in normal fallopian tube, endometrium, and colon

PURPOSE

Epithelial ovarian cancers are thought to arise from flattened epithelial cells that cover the ovarian surface or that line inclusion cysts. During malignant transformation, different histotypes arise that resemble epithelial cells from normal fallopian tube, endometrium, and intestine. This study compares gene expression in serous, endometrioid, clear cell, and mucinous ovarian cancers with that in the normal tissues that they resemble.

EXPERIMENTAL DESIGN

Expression of 63,000 probe sets was measured in 50 ovarian cancers, in 5 pools of normal ovarian epithelial brushings, and in mucosal scrapings from 4 normal fallopian tube, 5 endometrium, and 4 colon specimens. Using rank-sum analysis, genes whose expressions best differentiated the ovarian cancer histotypes and normal ovarian epithelium were used to determine whether a correlation based on gene expression existed between ovarian cancer histotypes and the normal tissues they resemble.

RESULTS

When compared with normal ovarian epithelial brushings, alterations in serous tumors correlated with those in normal fallopian tube (P = 0.0042) but not in other normal tissues. Similarly, mucinous cancers correlated with those in normal colonic mucosa (P = 0.0003), and both endometrioid and clear cell histotypes correlated with changes in normal endometrium (P = 0.0172 and 0.0002, respectively). Mucinous cancers displayed the greatest number of alterations in gene expression when compared with normal ovarian epithelial cells.

CONCLUSION

Studies at a molecular level show distinct expression profiles of different histologies of ovarian cancer and support the long-held belief that histotypes of ovarian cancers come to resemble normal fallopian tube, endometrial, and colonic epithelium. Several potential molecular markers for mucinous ovarian cancers have been identified.

Some life-style factors and the risk of invasive epithelial ovarian cancer in Swedish women

The objective of this nationwide case-control study was to examine body mass index (BMI), alcohol use, coffee consumption, cigarette smoking, and leisure-time physical activity in relation to epithelial ovarian cancer (EOC) risk. Subjects were 655 newly diagnosed EOC cases and 3899 population controls, all 50-74 years of age at recruitment between 1993 and 1995. Data were collected through mailed questionnaires. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using unconditional logistic regression. Women with a BMI > or = 30 kg/m2 compared with those with a BMI < 22 kg/m2 appeared to have an elevated EOC risk (OR = 1.37, 95% CI: 1.01-1.85), particularly of mucinous (OR = 2.76, 95% CI: 1.15-6.61) and clear-cell histologies (OR = 2.68, 95% CI: 0.96-7.48). The OR for EOC among coffee users reporting > or = 6 daily cups compared with non-users was 0.68 (95% CI: 0.42-1.10). Alcohol consumption was unrelated to EOC risk. Compared to non-smokers the ORs of EOC among current smokers were 0.70 (95% CI: 0.52-0.94) for those who smoked 1-10 cigarettes/day and 0.74 (95% CI: 0.53-1.02) for heavier smokers, while former smokers were at an unaltered risk (OR = 0.83, 95% CI: 0.66-1.04). Reduced EOC risks were observed among women in the highest compared with the lowest physical activity levels both at age 18-30 years (OR = 0.67, 95% CI: 0.52-0.87) and during the last years preceding study enrollment (OR = 0.68, 95% CI: 0.53-0.87). We conclude that women may avoid an excess risk of EOC through maintaining a normal BMI and reduce their risk by participation in leisure-time physical activity. The use of coffee, alcohol, or cigarette smoking does not appear to increase the risk of EOC.