Cigarette smoking and risk of epithelial ovarian cancer (Australia)

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.

Delineating Potential Transcriptomic Association with Organochlorine Pesticides in the Etiology of Epithelial Ovarian Cancer

Background

Recent studies have shown that there is an increased risk of Epithelial Ovarian Cancer (EOC) with Organochlorine Pesticides (OCPs). However, the alteration in the gene expression profile has not been explored so far. The goal of the present study is to understand the probable molecular mechanism of OCPs toxicity towards discovery of dysregulation of signaling pathway associated with differential gene expression and candidate transcriptomic set of markers in the pathophysiology of EOC in OCPs exposed population.

Methods

The OCP levels were estimated by gas chromatography and whole genome differential expression study was carried out using expression microarray and candidate genes were validated using Real time RT-PCR.

Results

Significant level of OCP residues such as β-hexachlorocyclohexane (β-HCH), Heptachlor, Heptachlor epoxide B (HTEB), dichlorodiphenyldichloroethylene (p'p'-DDE) and endosulfan-I was found between healthy and EOC patients. The transcriptome profile of several genes revealed regulation of various important cellular processes such as metabolism, inflammation, cytoskeleton dysregulation of TGF and WNT pathway in EOC cases with high OCPs.

Conclusion

This study provides the first evidence showing that differentially expressed genes and dysregulation of signaling pathways might be associated with significant level of OCPs exposure in ovary tissue of epithelial ovarian cancer patients. Moreover, significant correlation of these genes with OCPs revealed that OCPs exposure played vital role in dysregulation of related pathways in the etiology of EOC.

Cigarette smoking and the association with serous ovarian cancer in African American women: African American Cancer Epidemiology Study (AACES)

BACKGROUND

Smoking is a risk factor for mucinous ovarian cancer (OvCa) in Caucasians. Whether a similar association exists in African Americans (AA) is unknown.

METHODS

We conducted a population-based case-control study of incident OvCa in AA women across 11 geographic locations in the US. A structured telephone interview asked about smoking, demographic, health, and lifestyle factors. Odds ratios and 95% confidence intervals (OR, 95% CI) were estimated from 613 cases and 752 controls using unconditional logistic regression in multivariable adjusted models.

RESULTS

Associations were greater in magnitude for serous OvCa than for all OvCa combined. Compared to never smokers, increased risk for serous OvCa was observed for lifetime ever smokers (1.46, 1.11-1.92), former smokers who quit within 0-2 years of diagnosis (5.48, 3.04-9.86), and for total pack-years smoked among lifetime ever smokers (0-5 pack-years: 1.79, 1.23-2.59; >5-20 pack-years: 1.52, 1.05-2.18; >20 pack-years: 0.98, 0.61-1.56); however, we observed no dose-response relationship with increasing duration or consumption and no significant associations among current smokers. Smoking was not significantly associated with mucinous OvCa. Associations for all OvCa combined were consistently elevated among former smokers. The proportion of ever smokers who quit within 0-2 years was greater among cases (23%) than controls (7%).

CONCLUSIONS

Cigarette smoking may be associated with serous OvCa among AA, which differs from associations reported among Caucasians. Exposure misclassification or reverse causality may partially explain the absence of increased risk among current smokers and lack of dose-response associations. Better characterization of smoking patterns is needed in this understudied population.

Progesterone protects ovarian cancer cells from cisplatin-induced inhibitory effects through progesterone receptor membrane component 1/2 as well as AKT signaling

Progesterone, also known as P4 (pregn-4-ene-3, 20-dione), is a C-21 steroid hormone involved in the female menstrual cycle, pregnancy (supports gestation) and embryogenesis of humans and other species. Despite the physiological effects, P4 is also effective for the treatment of numerous pathological states, such as multiple sclerosis, rheumatoid arthritis and systemic lupus erythematosus as well as cancer. Considering the hormone microenvironment of gynecological cancers, P4 should be particularly noted in ovarian cancer. The present study demonstrated that P4 protected the ovarian cancer cell line HO-8910 from cisplatin (CDDP)-induced cell cycle arrest and restored the cell migratory capability following treatment of CDDP. Mechanistically, both progesterone receptor membrane component 1 (PGRMC1) and the progesterone receptor (PGR) were decreased in the cells treated with CDDP plus P4, while the level of progesterone receptor membrane component 2 (PGRMC2) was significantly elevated. Reversely, in the HO-8910 cells treated with CDDP alone, levels of both PGRMC1 and PGR were increased while the level of PGRMC2 was decreased. In addition to the receptor expression profile, the PI3K/AKT signaling pathway was also involved in the action of P4 in the CDDP-resistant HO-8910 cells, and a chemical inhibitor for PI3K, LY294002, significantly abolished the anti-apoptotic effect of P4. Consequently, the addition of a PI3K inhibitor to CDDP-based chemotherapy may have a more beneficial application for ovarian cancer therapy.

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.

Recent alcohol consumption and risk of incident ovarian carcinoma: a pooled analysis of 5,342 cases and 10,358 controls from the Ovarian Cancer Association Consortium

BACKGROUND

Studies evaluating the association between alcohol intake and ovarian carcinoma (OC) are inconsistent. Because OC and ovarian borderline tumor histologic types differ genetically, molecularly and clinically, large numbers are needed to estimate risk associations.

METHODS

We pooled data from 12 case-control studies in the Ovarian Cancer Association Consortium comprising 5,342 OC cases, 1,455 borderline tumors and 10,358 controls with quantitative information on recent alcohol intake to estimate odds ratios (OR) and 95% confidence intervals (CI) according to frequencies of average daily intakes of beer, wine, liquor and total alcohol.

RESULTS

Total alcohol intake was not associated with all OC: consumption of >3 drinks per day compared to none, OR=0.92, 95% CI=0.76-1.10, P trend=0.27. Among beverage types, a statistically non-significant decreased risk was observed among women who consumed >8 oz/d of wine compared to none (OR=0.83, 95% CI=0.68-1.01, P trend=0.08). This association was more apparent among women with clear cell OC (OR, 0.43; 95% CI, 0.22-0.83; P trend=0.02), although based on only 10 cases and not statistically different from the other histologic types (P value for statistical heterogeneity between histologic types = 0.09). Statistical heterogeneity of the alcohol- and wine-OC associations was seen among three European studies, but not among eight North American studies. No statistically significant associations were observed in separate analyses evaluating risk with borderline tumors of serous or mucinous histology. Smoking status did not significantly modify any of the associations.

CONCLUSIONS

We found no evidence that recent moderate alcohol drinking is associated with increased risk for overall OC, or that variation in risk is associated strongly with specific histologic types. Understanding modifiable causes of these elusive and deadly cancers remains a priority for the research community.

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.

Mucinous carcinomas of the ovary and colorectum: different organ, same dilemma

Mucinous carcinomas are uncommon histological types that affect several organ sites. Primary mucinous carcinomas of the ovary are distinct from other ovarian carcinoma types, but they can pose a particular challenge for correct diagnosis from metastases, which most usually originate from the colorectum. Correct diagnosis is the mainstay of treatment, because standard practice states that protocols are tailored to the primary organ site. Little is known of mutational alterations in primary and metastatic mucinous carcinomas of the ovary, and few markers exist that can discriminate between them. We reviewed commonalities between ovarian and colorectal mucinous carcinomas with respect to aetiology, molecular alterations, differential diagnosis, and implications for treatment. Although primary mucinous carcinomas of the ovary and colorectum share similar mutational patterns and unfavourable outcomes at advanced stage, compared with their non-mucinous counterparts, important differences exist with respect to mucin localisation and specific molecular alterations. Technologies--eg, next-generation sequencing--could aid identification of additional driver molecular changes that will help clarify the relation between mucinous carcinomas from different organ sites. Perhaps, then, we can consider moving towards testing and adoption of therapeutic approaches tailored to molecular characteristics of mucinous carcinomas, irrespective of organ site, so patients' survival can be optimised.

Substance use and women's health

Scientific findings show that substance abuse in women yields a higher risk of a variety of health problems than substance abuse in men. Research suggests that women experience addiction telescoping when they abuse alcohol, tobacco, specific stimulants, and possibly opioids. Medical side effects also develop more rapidly in women than men when they abuse many substances. Cancer and cardiac complications, specifically, pose a significant threat for women who abuse almost all types of substances. However, the physical consequences are not the only ones women suffer when they engage in substance abuse. Research on substance abuse in women ties opioids to mood and anxiety disorders, heroin to neurological deficiencies, cocaine to immune system suppression, and alcohol to intimate partner abuse. Additionally, female substance abusers, on average, have a lower level of education and lower rates of employment. In light of these gender-specific concerns, physicians should give particular consideration to detecting substance abuse in women.

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.

Socio-economic status and the risk of liver cancer mortality: a prospective study in Korean men

OBJECTIVE

To examine the association between socio-economic status (SES) and liver cancer mortality among Korean men.

STUDY DESIGN

Prospective cohort study

METHODS

Data were acquired from a large, prospective cohort study that included 548,530 civil service workers aged 30-59 years who had undergone health examination in 1998 provided by the Korean National Health Insurance System. Information on lifestyle and demographic characteristics was acquired through self-administered questionnaires. The main outcome event was mortality from liver cancer. Cox proportional hazards model was used to estimate relative risks (RRs) and 95% confidence intervals (95% CIs) after adjusting for age, body mass index, fasting serum glucose, alcohol consumption, smoking and hepatitis B surface antigen (HBsAg) status.

RESULTS

Liver cancer mortality differentials relating to SES were statistically significant and consistent in the fully adjusted model. Compared with the highest SES category, excess risk associated with liver cancer mortality was observed with decreasing SES levels: the RRs in the upper middle, lower middle and low SES categories were 1.35 (95% CI 1.13-1.61), 1.54 (95% CI 1.28-1.86) and 1.72 (95% CI 1.45-2.04), respectively. There was no effect modification by HBsAg status on the association between SES and liver cancer mortality.

CONCLUSIONS

This study demonstrated an inverse association between SES and liver cancer mortality, suggesting that SES is an independent predictor of liver cancer mortality. The policies and interventions regarding prevention of liver cancer need to focus on disadvantaged groups in order to reduce health disparities related to liver cancer.

Smoking and smoking cessation in relation to mortality in women

CONTEXT

Smoking is associated with an increased risk of total and cause-specific death, but the rate of mortality risk reduction after quitting compared with continuing to smoke is uncertain. There is inadequate or insufficient evidence to infer the presence or absence of a causal relationship between smoking and ovarian cancer and colorectal cancer.

OBJECTIVE

To assess the relationship between cigarette smoking and smoking cessation on total and cause-specific mortality in women.

DESIGN, SETTING, AND PARTICIPANTS

Prospective observational study of 104,519 female participants in the Nurses' Health Study with follow-up from 1980 to 2004.

MAIN OUTCOME MEASURE

Hazard ratios (HRs) for total mortality, further categorized into vascular and respiratory diseases, lung cancer, other cancers, and other causes.

RESULTS

A total of 12,483 deaths occurred in this cohort, 4485 (35.9%) among never smokers, 3602 (28.9%) among current smokers, and 4396 (35.2%) among past smokers. Compared with never smokers, current smokers had an increased risk of total mortality (HR, 2.81; 95% confidence interval [CI], 2.68-2.95) and all major cause-specific mortality. The HR for cancers classified by the 2004 surgeon general's report to be smoking-related was 7.25 (95% CI, 6.43-8.18) and 1.58 (95% CI, 1.45-1.73) for other cancers. Compared with never smokers, the HR for colorectal cancer was 1.63 (95% CI, 1.29-2.05) for current smokers and 1.23 (95% CI, 1.02-1.49) for former smokers. A significant association was not observed for ovarian cancer. Significant trends were observed for earlier age at initiation of smoking for total mortality (P = .003), respiratory disease mortality (P = .001), and all smoking-related cancer mortality (P = .001). The excess risk for all-cause mortality decreases to the level of a never smoker 20 years after quitting, with different time frames for risk reduction observed across outcomes. Approximately 64% of deaths among current smokers and 28% of deaths among former smokers were attributable to cigarette smoking.

CONCLUSIONS

Most of the excess risk of vascular mortality due to smoking in women may be eliminated rapidly upon cessation and within 20 years for lung diseases. Postponing the age of smoking initiation reduces the risk of respiratory disease, lung cancer, and other smoking-related cancer deaths but has little effect on other cause-specific mortality. These data suggest that smoking is associated with an increased risk of colorectal cancer mortality but not ovarian cancer mortality.

Risk factors for ovarian cancer: an overview with emphasis on hormonal factors

Ovarian cancer is the fifth most frequently occurring cancer among women and leading cause of gynecological cancer deaths in North America. Although the etiology of ovarian cancer is not clear, certain factors are implicated in the etiology of this disease, such as ovulation, gonadotropic and steroid hormones, germ cell depletion, oncogenes and tumor suppressor genes, growth factors, cytokines, and environmental agents. Family history of breast or ovarian cancer is a prominent risk factor for ovarian cancer, with 5-10% of ovarian cancers due to heritable risk. Reproductive factors such as age at menopause and infertility contribute to greater risk of ovarian cancer, whereas pregnancy, tubal ligation, and hysterectomy reduce risk. Oral contraceptive (OC) use has clearly been shown to be protective against ovarian cancer. In contrast, large epidemiologic studies found hormone replacement therapy (HRT) to be a greater risk factor for ovarian cancer. The marked influence of hormones and reproductive factors on ovarian cancer suggests that endocrine disrupters may impact risk; however, there is a notable lack of research in this area. Lifestyle factors such as cigarette smoking, obesity, and diet may affect ovarian cancer risk. Exposure to certain environmental agents such as talc, pesticides, and herbicides may increase risk of ovarian cancer; however, these studies are limited. Further research is needed to strengthen the database of information from which an assessment of environmental and toxicological risk factors for ovarian cancer can be made.

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.

Different Risk Factor Profiles for Mucinous and Nonmucinous Ovarian Cancer: Results from the Danish MALOVA Study

OBJECTIVES

The aim of the study was to examine the overall risk factors for epithelial ovarian cancer and according to histologic subtypes.

MATERIALS AND METHODS

Ovarian cancer cases and controls were recruited from 1995 to 1999, and personal interviews were conducted. A total of 554 cases and 1,564 randomly selected controls were included. The analyses were done using multiple logistic regression models.

RESULTS

The overall risk of ovarian cancer decreased with ever being pregnant [odds ratios (OR), 0.40; 95% confidence intervals (CI), 0.30-0.55], with increasing pregnancies (OR, 0.63; 95% CI, 0.45-0.87 and OR, 0.51; 95% CI, 0.37-0.69 for two and three pregnancies as compared with one), and with older age at first and last pregnancy, respectively. Increasing years of ovulation was a very strong risk factor with a 7% to 8% increase in risk for each year of ovulation. Use of oral contraceptives (OR, 0.67, 95% CI, 0.53-0.85) and longer duration of use were associated with a decreased risk of ovarian cancer. Ever use of hormone replacement therapy increased the overall risk (OR, 1.30; 95% CI, 1.05-1.61). For all those variables, the effect was present for serous tumors, endometrioid tumors, and tumors of other histologies, but not for mucinous tumors. In contrast, current smoking was a risk factor only for mucinous tumors (OR, 1.78; 95% CI, 1.01-3.15) and increasing body mass index tended to increase the risk especially for mucinous and endometrioid tumors.

CONCLUSIONS

We confirmed already known risk factors for ovarian cancer, and we observed significant differences in the risk profiles between mucinous and nonmucinous tumors indicating different etiologies.

Gonadotropins and ovarian cancer

Ovarian epithelial cancer (OEC) accounts for 90% of all ovarian cancers and is the leading cause of death from gynecological cancers in North America and Europe. Despite its clinical significance, the factors that regulate the development and progression of ovarian cancer are among the least understood of all major human malignancies. The two gonadotropins, FSH and LH, are key regulators of ovarian cell functions, and the potential role of gonadotropins in the pathogenesis of ovarian cancer is suggested. Ovarian carcinomas have been found to express specific receptors for gonadotropins. The presence of gonadotropins in ovarian tumor fluid suggests the importance of these factors in the transformation and progression of ovarian cancers as well as being prognostic indicators. Functionally, there is evidence showing a direct action of gonadotropins on ovarian tumor cell growth. This review summarizes the key findings and recent advances in our understanding of these peptide hormones in ovarian cancer development and progression and their role in potential future cancer therapy. We will first discuss the supporting evidence and controversies in the "gonadotropin theory" and the use of animal models for exploring the involvement of gonadotropins in the etiology of ovarian cancer. The role of gonadotropins in regulating the proliferation, survival, and metastasis of OEC is next summarized. Relevant data from ovarian surface epithelium, which is widely believed to be the precursor of OEC, are also described. Finally, we will discuss the clinical applications of gonadotropins in ovarian cancer and the recent progress in drug development.

Cigarette smoking and survival after ovarian cancer diagnosis

We have examined the association between cigarette smoking and ovarian cancer survival in 676 women with invasive epithelial ovarian cancer, recruited into a case-control study in the early 1990s. Information about cigarette smoking and other personal and reproductive factors was obtained from a personal interview at the time of diagnosis. Cox proportional hazards models were used to evaluate the association between cigarette smoking and time to ovarian cancer death. Current smokers at diagnosis were more likely to die early than women who had never smoked [adjusted hazard ratio (HR), 1.36; 95% confidence interval (95% CI), 1.01-1.84]. Increased risks of dying were greater among those who had accumulated more pack-years of smoking (HR for 30+ pack-years compared with never smokers, 1.94; 95% CI, 1.41-2.66) and smoked more cigarettes per day (HR, 1.93; 95% CI, 1.37-2.73). All these associations were stronger among women with late-stage disease (HR for current versus never smokers, 1.58; 95% CI, 1.15-2.18). Time since quitting had little effect on survival after adjusting for lifetime smoking exposure. These results validate and extend recent findings and suggest that premorbid cigarette smoking is related to worse outcome in ovarian cancer patients.

Risk Factors for Benign Serous and Mucinous Epithelial Ovarian Tumors

OBJECTIVE

To investigate the risk factors for benign serous and mucinous epithelial ovarian tumors.

METHODS

Cases were women newly diagnosed with benign serous ovarian tumors (n=230) or benign mucinous tumors (n=133) between 2002 and 2005. Control women were selected at random from the general population (n=752). All participants completed a comprehensive reproductive and lifestyle questionnaire. Multivariable logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs) and to simultaneously adjust for potential confounding factors.

RESULTS

Current smoking was associated with a three-fold increase in risk of benign mucinous tumors (OR 3.25, 95% CI 1.97-5.34), and there was a trend of increasing risk with increasing amount smoked (P<.001). Both recent obesity (OR 1.93, 95% CI 1.30-2.88) and obesity at age 20 (OR 4.38, 95% CI 1.88-10.20) were associated with increased risk of benign serous ovarian tumors, and having had a hysterectomy was also related to increased risk of serous (OR 2.75, 95% CI 1.90-3.96), but not mucinous tumors. Ever having had a term pregnancy was inversely associated with both tumor types (combined OR 0.65, 95% CI 0.43-0.97), although greater numbers of pregnancies did not decrease risk further. Use of hormonal contraceptives was unrelated to risk.

CONCLUSION

Our results suggest some differences in risk factors between benign serous and mucinous epithelial ovarian tumors and that risk factors for benign serous tumors differ from those well established for ovarian cancer. The results also suggest that there is potential for prevention of these common conditions through avoidance of smoking and obesity.

LEVEL OF EVIDENCE

II.

Endocrine signaling in ovarian surface epithelium and cancer

Ovarian cancer is the sixth most common cancer and the fifth leading cause of cancer-related death among women in developed countries. Greater than 85% of human ovarian cancer arises within the ovarian surface epithelium (OSE), with the remainder derived from granulosa cells or, rarely, stroma or germ cells. The pathophysiology of ovarian cancer is the least understood among all major human malignancies because of a poor understanding of the aetiological factors and mechanisms of ovarian cancer progression. There is increasing evidence suggesting that several key reproductive hormones, such as GnRH, gonadotrophins and sex steroids, regulate the growth of normal OSE and ovarian cancer cells. The objective of this review was to highlight the effects of these endocrine factors on ovarian cancer cell growth and to summarize the signalling mechanisms involved in normal human OSE and its neoplastic counterparts.

Ovarian cancer

Ovarian cancer accounts for 4% of all cancers in women and is the leading cause of death from gynaecologic malignancies. Because early-stage ovarian cancer is generally asymptomatic, approximately 75% of women present with advanced disease at diagnosis. Survival is highly dependent on stage of disease: 5-year survival in patients with early-stage is 80-90% compared to 25% for patients with advanced-stage disease. For all patients, a comprehensive surgical staging should be performed to obtain the histological confirmation of diagnosis and to evaluate the extent of disease. Patients with early-stage should both be optimally staged and be treated with adjuvant platinum-based chemotherapy if they have a medium or high-risk tumour. For advanced disease the currently recommended management is primary cytoreductive surgery followed by platinum-paclitaxel combination chemotherapy. Appropriate salvage therapy is based on the timing and nature of recurrence and the extent of prior chemotherapy. Surgical resection should be considered in patients with long-term remission, especially in those with isolated recurrences and good performance status. Platinum-based combination represents the standard second-line chemotherapy in patients with platinum-sensitive relapsed ovarian cancer. Salvage chemotherapy in platinum-refractory patients usually results in low response rates and short survival.

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.

Association of Reproductive Factors, Oral Contraceptive Use and Selected Lifestyle Factors with the Risk of Ovarian Borderline Tumors: A Danish Case-control Study

OBJECTIVE

The aim was to examine risk factors for ovarian borderline tumors overall, and according to histological subtype (serous vs. mucinous), in a large Danish population-based case-control study.

METHODS

Ovarian borderline cases and controls were recruited from 1995 to 1999, and personal interviews were conducted. In all, 202 cases and 1,564 randomly selected controls were included. The analysis was performed using multiple logistic regression models.

RESULTS

The risk of ovarian borderline disease decreased with increasing parity (OR=0.79 per birth, 95% CI: 0.63-0.98) and older age at first birth (OR=0.67 per 5 years, 95% CI: 0.53-0.84). Both a history of breastfeeding and use of oral contraceptives reduced the risk of borderline tumor, the effect being most pronounced for serous tumors. Increasing body mass index (BMI) was associated with elevated risk of serous borderline tumor (OR=1.05 per BMI unit; 95% CI: 1.00-1.10), whereas current smoking was a strong risk factor only for mucinous tumors (OR=2.10; 95% CI: 1.22-3.60). Finally, increasing consumption of milk (all types) was found to increase the risk of borderline disease (OR=1.04 per glass milk per week; 95% CI: 1.02-1.06), and increasing intake of total lactose also increased the risk significantly (OR=1.16 per 50 gram lactose per week; 95% CI: 1.06-1.26).

CONCLUSION

The risk profile of ovarian borderline tumors is similar to that of ovarian carcinomas, and we observed significant etiological differences between serous and mucinous borderline tumors.

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.

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.

Cigarette smoking and the risk of ovarian cancer in the Japanese population: Findings from the Japanese Collaborate Cohort study

AIM

The many studies into the relation between cigarette smoking and the risk of ovarian cancer have produced inconsistent results. Here we investigated this relation using data from the Japan Collaborative Cohort Study for Evaluation of Cancer Risk, initiated in 1988.

METHODS

A self-administered questionnaire on smoking habits and other risk factors for cancer was completed by 34 639 Japanese women. After 7.6 years of follow up, 39 cases of ovarian cancer were available for analyses. Cox proportional-hazards models were used to compute relative risks (RR) and to adjust for confounders.

RESULTS

Relative to those who had never smoked, the RR of ovarian cancer were 1.63 (95% confidence interval [CI] = 0.21-12.50) for former smokers and 2.27 (95% CI = 0.85-6.08) for current smokers. Among current smokers, the RR were 1.48 (95% CI = 0.20-10.92), 5.56 (95% CI = 1.68-19.06), and 1.86 (95% CI = 0.25-14.30) among women who smoked <10, 10-19, and at least 20 pack-years ([number of cigarettes smoked per day/20] x number of years subject has smoked), respectively, relative to those who had never smoked. A test for trend was statistically significant (P = 0.044).

CONCLUSIONS

These data indicate that cigarette smoking increases the risk of developing ovarian cancer in the Japanese population.

Endogenous Hormones and Ovarian Cancer: Epidemiology and Current Hypotheses

The effect of major epidemiologic risk factors for ovarian cancer has been reviewed in the light of several hormonal hypotheses, including the gonadotropin, androgens, progesterone, estrogens, insulin-like growth factor-I, and insulin hypotheses. The role of inclusion cyst formation and Mullerian epithelium differentiation in the pathology of the disease are also briefly outlined. Although based on limited data, the observed tendency in current evidence suggests possible etiologic roles for elevated androgens and estrogens and decreased progesterone in the pathogenesis of ovarian cancer. A direct effect of gonadotropins cannot be entirely ruled out, but it is plausible that their effect on ovarian cancer risk is mediated by stimulation of ovarian steroidogenesis. Insulin-like growth factor-I also emerges as a hormone that may be directly involved in the pathogenesis of the disease, but thus far only one prospective study has examined this association. Hyperinsulinemia is an unlikely risk factor for ovarian cancer. The observed tendency for an increased risk with androgens from ovarian origin (in premenopausal women), the lack of association with adrenal androgens, and the relatively weak associations observed with obesity, hormonal replacement therapy use, and endogenous hormones after menopause suggest that ovarian synthesis of sex steroids rather than their circulating levels may be etiologically important. More data from prospective studies will be crucial to improve our understanding of the etiologic role of endogenous hormones in the pathogenesis of ovarian cancer. Such data will ultimately provide opportunities for research targeted; at early detection and preventive interventions.

Common risk factors of breast and ovarian cancer: recent view

Clinicians, epidemiologists, and public health specialists tend to examine breast and ovarian cancer separately. Although this seems fairly rational and expected, both malignancies are estrogen related and thus share many risk factors. In this review, we investigate the common familial, reproductive, anthropometric, nutritional, and lifestyle risk factors of breast and ovarian cancer. We believe that the parallel examination of the two cancer types could significantly contribute to an improved prevention of "gynecological cancer" as a whole.

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.

Epithelial ovarian cancer risk by invasiveness and cell type in the Central Valley of California

OBJECTIVE

To evaluate epithelial ovarian cancer (EOC) risk factors by level of invasiveness and histology.

METHODS

A population-based epidemiologic case-control study of EOC was conducted over a 2-year period (January 2000 to December 2001) in 22 counties of Central California that comprise the reporting area for two regional cancer registries. Telephone interviews were conducted with 256 cases and 1122 control frequencies matched on age and ethnicity. The interview obtained information on demographic factors as well as information pertinent to the respondent's menstrual and reproductive experience, use of exogenous hormones, surgical history, and family history of cancer. Adjusted odds ratios were calculated using stratification as well as Logistic regression methods. Analyses were completed by level of invasiveness and cell type.

RESULTS

Strong protective associations were observed for use of oral contraceptives and parity. Risk increased with a family history of ovarian, but not breast cancer and age at first birth was positively associated with increased risk. Hormone replacement therapy was associated with increased risk only in long-term users. Many of the relationships were observed only in specific histologic subtypes of EOC.

CONCLUSION

Risk of EOC is associated with several lifestyle and environmental exposures but the impact of these effects appears to be dependent upon level of invasiveness and histologic subtypes of EOC. However, the sample size available for analysis limits our statistical power and our ability to analyze data by histologic subtype, thus limiting interpretation of our results.

Association of cigarette smoking with the risk of ovarian cancer

Cigarette smoking may be associated with ovarian cancer risk. This association may differ by histological type. The authors conducted a population-based case-control study in Canada of 442 incident cases of ovarian cancer and 2,135 controls 20-76 years of age during 1994-1997 to examine this association, overall and by histological type. Compared to women who never smoked, those who smoked had higher odds (odds ratio [OR] = 1.22; 95% confidence interval [CI] = 0.98-1.53) of having ovarian cancer, and the OR was larger for ex-smokers (1.30; 95% CI = 1.01-1.67) than for current smokers (1.10; 95% CI = 0.81-1.49). The association with cigarette smoking was stronger for mucinous tumors (OR = 1.77; 95% CI = 1.06-2.96) than for nonmucinous tumors (OR = 1.13; 95% CI = 0.89-1.44). In addition, the odds of smokers having mucinous tumors increased with years of smoking (OR = 1.36, 1.88, 1.19, 4.89 for <20, 21-30, 31-40 and >40 years, respectively; p for trend = 0.002), number of cigarettes smoked per day (OR = 1.55, 1.89, 2.28 for <10, 11-20 and >20 cigarettes/day, respectively; p for trend = 0.014) and smoking pack-years (OR = 1.13, 2.65, 1.77 and 2.39 for <10, 11-20, 21-30 and >30 pack-years, respectively; p for trend = 0.004). Our data suggest that cigarette smoking is associated with an increased risk of ovarian cancer, especially for mucinous types.

Alcohol, Wine, and Risk of Epithelial Ovarian Cancer

Moderate alcohol intake can influence sex hormone levels and affect ovarian function as well as increasing breast cancer risk. This suggests that alcohol might also influence ovarian cancer risk. We have evaluated this among 696 Australian women with histologically confirmed epithelial ovarian cancer and 786 cancer-free control women, selected at random from the electoral roll. Sociodemographic information and a detailed reproductive history were collected in a face-to-face interview, and information about diet and alcohol consumption was obtained from a food frequency questionnaire. Logistic regression was used to calculate adjusted odds ratios (OR) and 95% confidence intervals (95% CI). Overall, 59% of women drank &lt;1 standard drink/week and only 5% of cases and 8% of controls drank an average of ≥2 standard drinks/day. Compared with nondrinkers, the OR for women who drank an average of ≥2 standard drinks/day was 0.49 (95% CI = 0.30–0.81). This effect did not vary for the different subtypes but was restricted to wine (OR = 0.56, 95% CI = 0.33–0.93 for ≥1 glass/day versus nondrinkers) with no effect for beer (OR = 1.26, 95% CI = 0.65–2.46) or sherry/spirits (OR = 1.07, 95% CI = 0.59–1.95). Combining our results with the six previous population-based studies gave a pooled OR of 0.72 (95% CI = 0.54–0.97) for the highest alcohol intake group versus nondrinkers. These data suggest that alcohol does not increase risk of ovarian cancer. In this Australian population, the inverse association with alcohol was due solely to wine consumption and so may be a consequence of antioxidants and/or phytoestrogens in wine rather than the alcohol itself.

Survival among women with borderline ovarian tumors and ovarian carcinoma: a population-based analysis

BACKGROUND

Serous and mucinous ovarian tumors of low malignant potential (LMP-S and LMP-M, respectively) are noninvasive tumors that portend excellent survival when confined to the ovary. Comparison of the survival for women with LMP tumors staged as distant with women who have carcinoma may have important implications for diagnostic terminology and clinical management.

METHODS

The authors compared relative survival rates among patients diagnosed with ovarian tumors during the period 1988-1999 (with follow-up through 2000) by histologic type, disease stage, tumor grade (for carcinomas), and patient age, using data from the Surveillance, Epidemiology, and End Results Program.

RESULTS

The overall relative survival rate at 10 years (+/- 1.96 standard errors) was 96.9% +/- 2.3% for women with LMP-S tumors, 30.4% +/- 1.7% for women with serous carcinoma (CA-S); 94.0% +/- 3.1% for women with LMP-M tumors, and 64.7% +/- 3.4% for women with mucinous carcinoma (CA-M). The survival rate at 10 years for women with distant-stage LMP-S tumors was 89.9% +/- 5.3%, compared with 96.1% +/- 8.6% for women with well differentiated, localized CA-S. The survival rate for women with distant-stage LMP-M tumors at 5 years was 85.5% +/- 9.0%, compared with 95.5% +/- 3.4% for women with well differentiated, localized CA-M (data for 10 years were limited). Mucinous ovarian neoplasms were associated with an excess of second malignancies of the digestive tract.

CONCLUSIONS

Relative survival among women with distant-stage LMP tumors was not 100% and resembled the survival of women who had carcinoma exhibiting favorable prognostic features (localized stage). Future studies of women with high-stage LMP tumors are required to clarify the pathogenesis of extraovarian lesions and their implications for management and prognosis.

Cigarette smoking and the risk of invasive epithelial ovarian cancer in a prospective cohort study

Few cohort studies have examined the association between cigarette smoking and ovarian cancer risk, either overall, or by histological subtype. In relation to the latter, it has been suggested that mucinous ovarian tumours may be aetiologically unrelated to the other types of epithelial tumours and that their respective associations with cigarette smoking may differ. We examined the association between smoking and ovarian cancer risk using data from participants in a randomised controlled trial of screening for breast cancer involving 89,835 women aged 40-59 years at recruitment. Cox proportional hazards models were used to estimate rate ratios (RR) and 95% confidence intervals (CI). During an average of 16.5 years of follow-up, we observed 454 incident cases of ovarian cancer (184 serous, 67 endometrioid, 32 mucinous, 171 other or unknown). We found that women who had smoked for several decades had an approximately two-fold increased risk of epithelial ovarian cancer. Relative to never-smokers, women who had smoked for 40 years or more were at the highest risk (RR=2.50, 95% CI=1.37-4.56). The association with non-mucinous tumours was similar to that observed overall. For mucinous tumours, a two-fold increased risk was observed with smoking of shorter duration, although the number of mucinous tumours in our data-set was small. Long-term cigarette smoking may be associated with an increased risk of epithelial ovarian tumours.

Incidence patterns of invasive and borderline ovarian tumors among white women and black women in the United States. Results from the SEER Program, 1978-1998

BACKGROUND

Malignant tumors of the ovary are the leading cause of death from gynecologic malignancies in the United States. Population-based incidence data for these neoplasms by histopathologic type and race are limited. Variation in rates may provide clues for future etiologic studies.

METHODS

The authors performed a detailed, population-based analysis of U.S. incidence rates by histologic type, race, and age for invasive ovarian tumors that were diagnosed during 1978-1998 and for borderline ovarian tumors that were diagnosed during 1992-1998 using data from the U.S. Surveillance, Epidemiology, and End Results (SEER) Program.

RESULTS

White women had significantly higher rates compared with black women of all types of epithelial tumors, with the white:black rate ratios ranging from 1.23 to 2.56. Black women had higher rates of gonadal stromal tumors. Among both white women and black women, total carcinoma rates did not change greatly from 1978-1982 to 1995-1998. Among white women, the reported incidence rates for invasive serous, endometrioid, and clear cell tumors increased during 1978-1998, whereas the rates of mucinous; papillary, not otherwise specified (NOS); and other epithelial tumors declined. Among black women, the reported rates of papillary, NOS tumors decreased significantly, whereas the rates of other tumor types fluctuated. Incidence rates of borderline ovarian tumors were higher among white women compared with black women and did not change significantly during 1992-1998. Serous and mucinous tumors were the predominant tumors reported for women age < 45 years, whereas serous; papillary, NOS; and other epithelial tumors predominated among older women.

CONCLUSIONS

Incidence rates for malignant ovarian tumors have remained relatively stable, with higher rates for white women compared with black women. The reported rates for some specific histopathologic tumor types have changed over time, in part reflecting more specific pathologic classification. The possible effect of shifting exposure prevalence on incidence patterns warrants further study.

Tobacco use and cancer causation: association by tumour type

In the second part of our review we describe the association between tobacco use and risk of specific cancer types. There is evidence for an established association of tobacco use with cancer of the lung and larynx, head and neck, bladder, oesophagus, pancreas, stomach and kidney. In contrast, endometrial cancer is less common in women who smoke cigarettes. There are some data suggesting that tobacco use increases the risk for myeloid leukaemia, squamous cell sinonasal cancer, liver cancer, cervical cancer, colorectal cancer after an extended latency, childhood cancers and cancer of the gall bladder, adrenal gland and small intestine. Other forms of cancer, including breast, ovarian and prostate cancer, are unlikely to be linked to tobacco use.

Diet and environmental carcinogenesis in breast/gynaecological cancers

This paper reports on recent advances on the relation between diet, other environmental factors and breast and gynaecological cancers. Despite considerable research the issue remains still unsettled. The protective effect of a diet rich in vegetables and fruit, and thus selected (antioxidant) micronutrients, is not consistently reported in various studies. The possible relationship between fats and breast and female genital tract neoplasms also remains unconfirmed, while the potential benefits of physical activity remains unquantified. Alcohol appears to be related to the risk of breast cancer and overweight is associated with post-menopausal breast cancer and is strongly related to the risk of endometrial cancer.