Alcohol consumption and the risk of mucinous and nonmucinous epithelial ovarian cancer

Epidemiology of ovarian cancer: a review

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

Epidemiology of ovarian cancer: a review

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

Epidemiology of ovarian cancer: a review

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

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.

Alcohol drinking and epithelial ovarian cancer risk. a systematic review and meta-analysis

OBJECTIVE

In order to provide an updated quantification of the association between alcohol drinking and epithelial ovarian cancer risk, we conducted a meta-analysis of published observational studies.

METHODS

Using PubMed, we performed a literature search of all case-control and cohort studies published as original articles in English up to September 2011. We included 27 observational studies, of which 23 were case-control studies, 3 cohort studies and one pooled analysis of prospective cohort studies, including a total of 16,554 epithelial ovarian cancer cases. We derived pooled meta-analytic estimates using random-effects models.

RESULTS

The pooled relative risk (RR) for any alcohol drinking compared with non/occasional drinking was 1.00 [95% confidence interval (CI), 0.95-1.05]. The RRs were 0.97 (95% CI, 0.92-1.02), 1.03 (95% CI, 0.96-1.11) and 1.09 (95% CI, 0.80-1.50) for light (≤ 1 drink/day), moderate (>1 to <3 drinks) and heavy drinking (≥ 3 drinks/day), respectively. In particular, the pooled RR for invasive epithelial ovarian cancers was 1.00 (95% CI, 0.95-1.06), while for borderline cancers was 0.96 (95% CI, 0.74-1.26). Stratified analyses across cancer histotypes revealed a modest protective effect of alcohol on endometrioid epithelial ovarian tumors (RR=0.82, 95% CI, 0.70-0.96), while no association was found for serous (RR=1.00, 95% CI, 0.84-1.19), mucinous (RR=0.91, 95% CI, 0.78-1.08) and clear cell (RR=0.93, 95% CI, 0.76-1.14) cancers. There was no evidence of publication bias.

CONCLUSIONS

This comprehensive meta-analysis provided no evidence of a material association between alcohol drinking and epithelial ovarian cancer risk.

Induction of ovarian cancer and DNA adducts by Dibenzo[a,l]pyrene in the mouse

Tobacco smoking is an etiological factor of ovarian cacner; however, the mechanisms remain largely undefined. Therefore, as an initial investigation, we examined the carcinogenicity and DNA adducts formation in the ovary of mice treated with DB[a,l]P, a tobacco smoke constituent and environmental pollutant. Ovarian tumors in B6C3F1 mice were induced by direct application of DB[a,l]P (24, 12, 6, and 3 nmol/mouse, three times a week for 38 weeks) into the oral cavity of mice. At 6 nmol, DB[a,l]P induced the highest total ovarian tumor incidence (79%), but the incidence of malignancy was only 15%. However, at the dose of 12 nmol, the total ovarian tumor incidence was 75%, and the incidence of malignancy was 65%. In addition to ovarian tumors, at the dose of 24 nmol, DB[a,l]P induced lesions in sites distal from the ovaries including the skin, mammary, lung, and oral tissues, which were rare at doses lower than 24 nmol. Another bioassay was conducted to detect and quantify DNA adducts induced by DB[a,l]P (24 nmol, three times a week for 5 weeks) in the ovary at 48 h and 1, 2, and 4 weeks after the last administration of DB[a,l]P. DNA was isolated, and the dibenzo[a,l]pyrene-11,12-dihydrodiol-13,14-epoxide (DB[a,l]PDE)-DNA adducts were analyzed by a LC-MS/MS method. DB[a,l]P resulted in the formation of (-)-anti-cis-DB[a,l]PDE-dA and (-)-anti-trans-DB[a,l]PDE-dA adducts, which were 0.8 and 1.6 fmol/10(6) dA, respectively, in ovaries of mice within 48 h, and the level of adducts decreased over a week. Our results indicated that DB[a,l]P can be metabolized to form (-)-anti-DB[a,l]PDE; the latter may, in part, account for DB[a,l]P-induced ovarian cancer. This animal model should assist to better understand the mechanisms, account for the induction of ovarian cancer by tobacco carcinogens, and facilitate the development of chemopreventive agents against ovarian cancer.

Folate, vitamin B(6) , vitamin B(12) , methionine and alcohol intake in relation to ovarian cancer risk

Folate, methionine, vitamin B(6) and vitamin B(12) may influence carcinogenesis due to their roles in the one-carbon metabolism pathway, which is critical for DNA synthesis, methylation and repair. Low intake of these nutrients has been associated with an increased risk of breast, colon and endometrial cancers. Previous studies that have examined the relation between these nutrients and ovarian cancer risk have been inconsistent and have had limited power to examine the relation by histologic subtype. We investigated the association between folate, methionine, vitamin B(6) , vitamin B(12) and alcohol among 1910 women with ovarian cancer and 1989 controls from a case-control study conducted in eastern Massachusetts and New Hampshire from 1992 to 2008. Diet was assessed via food frequency questionnaire. Participants were asked to recall diet one-year before diagnosis or interview. Logistic regression models were used to calculate odds ratios (OR) and 95% confidence intervals (95% CIs). We also examined whether the associations varied by ovarian cancer histologies using polytomous logistic regression. We observed an inverse association between dietary vitamin B(6) (covariate-adjusted OR = 0.76, 95% CI 0.64-0.92; p(trend) = 0.002) and methionine intake (covariate-adjusted OR = 0.72, 95% CI = 0.60-0.87; p(trend) < 0.001) and ovarian cancer risk comparing the highest to lowest quartile. The association with dietary vitamin B(6) was strongest for serous borderline (covariate-adjusted OR = 0.49, 95% CI = 0.32-0.77; p(trend) = 0.001) and serous invasive (covariate-adjusted OR = 0.74, 95% CI = 0.58-0.94; p(trend) = 0.012) subtypes. Overall, we observed no significant association between folate and ovarian cancer risk. One-carbon metabolism related nutrients, especially vitamin B(6) and methionine, may lower ovarian cancer risk.

Wine drinking and epithelial ovarian cancer risk: a meta-analysis

OBJECTIVE

Wine has been the focus in the prevention of epithelial ovarian cancer (EOC) development because resveratrol abundant in wine has anti-carcinogenic properties. However, epidemiologic results have been heterogenous in the chemopreventive effect of wine on the development of EOC. Thus, we performed a meta-analysis for comparing EOC risk between wine and never drinkers using previous related studies.

METHODS

After extensive search of the literature between January 1986 and December 2008, we analyzed 10 studies (3 cohort and 7 case control studies) with 135,871 women, who included 65,578 of wine and 70,293 of never drinkers.

RESULTS

In all studies, there was no significant difference in EOC risk between wine and never drinkers (odds ratio [OR], 1.13; 95% confidence interval [CI], 0.92 to 1.38; random effects). When we performed re-analysis according to the study design, 3 cohort and 7 case control studies showed that there were also no significant differences in EOC risk between wine and never drinkers, respectively (OR, 1.44 and 1.04; 95% CI, 0.74 and 2.82 and 0.88 to 1.22; random effects). In sub-analyses using 2 case-control studies, EOC risk was not different between former and never drinkers (OR, 1.12; 95% CI, 0.87 to 1.44; fixed effect), and between current and former drinkers (OR, 0.74; 95% CI, 0.41 to 1.34; random effects).

CONCLUSION

Although resveratrol, abundantly found in wine, is a promising naturally occurring compound with chemopreventive properties on EOC in preclinical studies, this meta-analysis suggests the epidemiologic evidence shows no association between wine drinking and EOC risk.

Current understanding of risk factors for ovarian cancer

OPINION STATEMENT

Ovarian cancer is the deadliest gynecologic cancer. Unlike many cancers such as breast, cervical and colon cancers, there is no easily clinically identifiable pre-malignant phase of this malignancy making early identification difficult. Similarly, unlike lung, head and neck, and skin cancers, there is not easily identifiable risk factor making prevention short of oophorectomy difficult. Even so, theories as to the causative factors of ovarian cancer continue to evolve making our understanding of the genesis of ovarian cancer more clear. Genetics, parity, environment, hormonal factors, and inflammation all play an important and pivotal role in the development of ovarian cancer. The most current understanding of these elements and their respective contribution to the development of this cancer are presented in this chapter.

Flavonoid intake and ovarian cancer risk in a population-based case-control study

Several recent studies have evaluated the association between dietary flavonoid intake and ovarian cancer risk, and all reported significant or suggestive inverse associations with certain flavonoids or flavonoid subclasses; however, most of these studies were small to moderate in size. We, therefore, examined this association in a large, population-based case-control study. We calculated intake of 5 common dietary flavonoids (myricetin, kaempferol, quercetin, luteolin, and apigenin), as well as total intake of these flavonoids, for 1,141 cases and 1,183 frequency-matched controls. We used unconditional logistic regression to estimate the relative risk (RR) of ovarian cancer for each quintile of flavonoid intake when compared with the lowest quintile. We did not observe an association between total flavonoid intake and ovarian cancer risk. The multivariable-adjusted RR for the highest versus lowest quintile of total flavonoid intake was 1.06 (95% confidence interval [CI] = 0.78-1.45). In analyses of each individual flavonoid, only intake of apigenin was associated with a borderline significant decrease in risk (RR, highest vs. lowest quintile = 0.79, 95% CI = 0.59-1.06; p-trend = 0.26), and this association was significant after adjustment for intake of the other 4 individual flavonoids (comparable RR = 0.72, 95% CI = 0.53-0.98; p-trend = 0.09). These results provide limited support for an association between flavonoid intake and ovarian cancer risk. However, given the findings of previous studies and the biologic plausibility of this association, additional studies are warranted.

Epidemiology of ovarian cancer

Ovarian cancer represents the sixth most commonly diagnosed cancer among women in the world, and causes more deaths per year than any other cancer of the female reproductive system. Despite the high incidence and mortality rates, the etiology of this disease is poorly understood. Established risk factors for ovarian cancer include age and having a family history of the disease, while protective factors include increasing parity, oral contraceptive use, and oophorectomy. Lactation, incomplete pregnancies, and surgeries such as hysterectomy and tubal ligation may confer a weak protective effect against ovarian cancer. Infertility may contribute to ovarian cancer risk among nulliparous women. Other possible risk factors for ovarian cancer include postmenopausal hormone-replacement therapy and lifestyle factors such as cigarette smoking and alcohol consumption. Many of the causes of ovarian cancer are yet to be identified. Additional research is needed to better understand the etiology of this deadly disease.

Ovarian cancer hormonal and environmental risk effect

To understand the influence of hormonal and environmental factors on the risk of ovarian cancer, it is important to remember the established risk factors and postulated mechanisms that lead to the development of ovarian cancer. Several risk factors have been identified as increasing the risk of epithelial ovarian cancer, including low pariety, infertility, early age of menarche, and late age of menopause. This article discusses the different hypotheses and focuses on hormonal and environmental risk factors, as well the chemoprevention of epithelial ovarian cancer.

A prospective study of dietary flavonoid intake and incidence of epithelial ovarian cancer

Flavonoids are antioxidant compounds found in plants, including fruits, vegetables and tea. No prior prospective studies have examined the association between intake of flavonoids in the flavonol and flavone subclasses and ovarian cancer risk. We analyzed the association between intake of 5 common dietary flavonoids and incidence of epithelial ovarian cancer among 66,940 women in the Nurses' Health Study. We calculated each participant's intake of myricetin, kaempferol, quercetin, luteolin and apigenin from dietary data collected at multiple time points, and used Cox proportional hazards regression to model the incidence rate ratio (RR) of ovarian cancer for each quintile of intake. Our analysis included 347 cases diagnosed between 1984 and 2002, and 950,347 person-years of follow-up. There was no clear association between total intake of the 5 flavonoids examined and incidence of ovarian cancer (RR = 0.75 for the highest versus lowest quintile, 95% confidence interval [CI] = 0.51-1.09). However, there was a significant 40% decrease in ovarian cancer incidence for the highest versus lowest quintile of kaempferol intake (RR = 0.60, 95% CI = 0.42-0.87; p-trend = 0.002), and a significant 34% decrease in incidence for the highest versus lowest quintile of luteolin intake (RR = 0.66, 95% CI = 0.49-0.91; p-trend = 0.01). There was evidence of an inverse association with consumption of tea (nonherbal) and broccoli, the primary contributors to kaempferol intake in our population. These data suggest that dietary intake of certain flavonoids may reduce ovarian cancer risk, although additional prospective studies are needed to further evaluate this association. If confirmed, these results would provide an important target for ovarian cancer prevention.

Wine and other alcohol consumption and risk of ovarian cancer in the California Teachers Study cohort

Objective

Whether alcohol consumption influences ovarian cancer risk is unclear. Therefore, we investigated the association between alcohol intake at various ages and risk of ovarian cancer.

Methods

Among 90,371 eligible members of the California Teachers Study cohort who completed a baseline alcohol assessment in 1995–1996, 253 women were diagnosed with epithelial ovarian cancer by the end of 2003. Multivariate Cox proportional hazards regression analysis was performed to estimate relative risks (RRs) and 95% confidence intervals (CIs).

Results

Consumption of total alcohol, beer, or liquor in the year prior to baseline, at ages 30–35 years, or at ages 18–22 years was not associated with risk of ovarian cancer. Consumption of at least one glass per day of wine, compared to no wine, in the year before baseline was associated with increased risk of developing ovarian cancer: RR = 1.57 (95% CI 1.11–2.22), P_trend = 0.01. The association with wine intake at baseline was particularly strong among peri-/post-menopausal women who used estrogen-only hormone therapy and women of high socioeconomic status.

Conclusions

Alcohol intake does not appear to affect ovarian cancer risk. Constituents of wine other than alcohol or, more likely, unmeasured determinants of wine drinking were associated with increased risk of ovarian cancer.

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.

Alcohol consumption and ovarian cancer risk in a population-based case-control study

Alcohol consumption has been investigated as a possible risk factor for ovarian cancer in several epidemiological studies, with inconsistent findings. Recent studies have suggested that the association between alcohol consumption and ovarian cancer may vary according to histologic subtype of ovarian cancer and type of alcohol consumed (e.g., wine, beer, or liquor). We examined these associations in a population-based case-control study comprised of 762 incident cases of epithelial ovarian cancer and 6,271 population controls from Massachusetts and Wisconsin aged 40-79 years. Women reported their usual alcohol consumption as young adults (20-30 years of age) and in the recent past. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated. There was no significant association of ovarian cancer with increasing alcohol consumption either during ages 20-30 years (p trend 0.42) or in the recent past (p trend 0.83). Regular drinking of beer (1 drink/day or more) during ages 20-30 (OR 1.55, 95% CI 1.07-2.26), though not liquor (OR 1.35, 95% CI 0.86-2.11) or wine (OR 0.99, 95% CI 0.49-2.00), was associated with a statistically significant increase in risk of invasive tumors, whereas no significant relationships were observed for recent drinking, regardless of alcohol type. The elevated risk for early adult regular drinking was confined to serous invasive tumors (OR 1.52, 95% CI 1.01-2.30), though results for other subtypes were based on sparse data and results were imprecise. In this study, neither total alcohol consumption as a young adult nor recently was associated with an increase in the risk of ovarian cancer.

Prevention of ovarian cancer

Ovarian cancer is the leading cause of death from gynaecological malignancy. The incidence is high in the Western world. The incidence of ovarian cancer is reduced by pregnancy, lactation, the oral contraceptive pill and tubal ligation. Lifestyle factors are important in the aetiology of ovarian cancer and current evidence suggests the risk can be reduced by eating a diet rich in fruit and vegetables, taking regular exercise, avoiding smoking, avoiding being overweight and avoiding long-term use of hormonal replacement therapy (HRT). Familial ovarian cancer is responsible for about 10% of ovarian cancer cases. Strategies available to high-risk women include screening (covered elsewhere) and prophylactic salpingo-oophorectomy. The precise role of chemoprevention for high-risk women in the form of the oral contraceptive pill is unclear.

Alcohol intake and ovarian cancer risk: a pooled analysis of 10 cohort studies

Alcohol has been hypothesized to promote ovarian carcinogenesis by its potential to increase circulating levels of estrogen and other hormones; through its oxidation byproduct, acetaldehyde, which may act as a cocarcinogen; and by depletion of folate and other nutrients. Case-control and cohort studies have reported conflicting results relating alcohol intake to ovarian cancer risk. We conducted a pooled analysis of the primary data from ten prospective cohort studies. The analysis included 529 638 women among whom 2001 incident epithelial ovarian cases were documented. After study-specific relative risks (RR) and 95% confidence intervals (CI) were calculated by Cox proportional hazards models, and then were pooled using a random effects model; no associations were observed for intakes of total alcohol (pooled multivariate RR=1.12, 95% CI 0.86-1.44 comparing > or =30 to 0 g day(-1) of alcohol) or alcohol from wine, beer or spirits and ovarian cancer risk. The association with alcohol consumption was not modified by oral contraceptive use, hormone replacement therapy, parity, menopausal status, folate intake, body mass index, or smoking. Associations for endometrioid, mucinous, and serous ovarian cancer were similar to the overall findings. This pooled analysis does not support an association between moderate alcohol intake and ovarian cancer risk.

Relationship between body mass index and the risk of ovarian cancer in the Japanese population: Findings from the Japanese Collaborate Cohort (JACC) study

AIM

The incidence of ovarian cancer in Japan has increased since the 1970s. The many studies that have assessed the relationship between body mass index (BMI) and the risk of ovarian cancer have produced contradictory results. Here we investigated this relation using data from the Japan Collaborative Cohort Study for the Evaluation of Cancer Risk, which was initiated in 1988.

METHODS

A self-administered questionnaire on dietary habits and other risk factors for cancer was completed by 36,456 Japanese women. After 7.6 years of follow up, 38 cases of ovarian cancer were available for analysis. Cox proportional-hazards models were used to compute relative risks and to adjust for confounders.

RESULTS

Compared to women with BMI of 18.5-24.9 kg/m2, the relative risk of ovarian cancer was 2.24 (95% CI = 1.10-4.21) for BMI of 25.0-29.9 and 1.78 (95% CI = 0.24-13.34) for BMI of > or = 30 kg/m2. A test for trend revealed that this finding was statistically significant (P = 0.014).

CONCLUSION

The results of this study suggest that being overweight is independently associated with a higher risk of developing ovarian cancer in the Japanese population.

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.

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.

Oral contraceptive use, reproductive history, and risk of epithelial ovarian cancer in women with and without endometriosis

OBJECTIVE

Women with endometriosis may be at an increased risk of ovarian cancer. It is not known whether reproductive factors that reduce the risk of ovarian cancer in general also reduce risk in women with endometriosis. We investigated whether the odds ratios for ovarian cancer that were associated with oral contraceptive use, childbearing, hysterectomy, and tubal ligation differ among women with and without endometriosis.

STUDY DESIGN

We pooled information on the self-reported history of endometriosis from 4 population-based case-controlled studies of incident epithelial ovarian cancer, comprising 2098 cases and 2953 control subjects. We obtained data on oral contraceptive use, childbearing, breastfeeding, gynecologic surgical procedures, and other reproductive factors on each woman. Multivariable unconditional logistic regression was used to calculate odds ratios and 95% CI for ovarian cancer among women with endometriosis compared with women without endometriosis. Similar methods were used to assess the frequencies of risk factors among women with and without endometriosis. Adjustments were made for age, parity, oral contraceptive use, tubal ligation, family history of ovarian cancer, and study site.

RESULTS

Women with endometriosis were at an increased risk of ovarian cancer (odds ratio, 1.32; 95% CI, 1.06-1.65). Using oral contraceptives, bearing children, and having a tubal ligation or hysterectomy were associated with a similar reduction in the odds ratios for ovarian cancer among women with and without endometriosis. In particular, the use of oral contraceptives for >10 years was associated with a substantial reduction in risk among women with endometriosis (odds ratio, 0.21; 95% CI, 0.08-0.58).

CONCLUSION

Women with endometriosis are at an increased risk of epithelial ovarian cancer. Long-term oral contraceptive use may provide substantial protection against the disease in this high-risk population.