Oral contraceptives and cancer: an update

Strategies to safely target widely expressed soluble adenylyl cyclase for contraception

In humans, the prototypical second messenger cyclic AMP is produced by 10 adenylyl cyclase isoforms, which are divided into two classes. Nine isoforms are G protein coupled transmembrane adenylyl cyclases (tmACs; ADCY1-9) and the 10th is the bicarbonate regulated soluble adenylyl cyclase (sAC; ADCY10). This review details why sAC is uniquely druggable and outlines ways to target sAC for novel forms of male and female contraception.

Mechanism of semen liquefaction and its potential for a novel non-hormonal contraception†

Semen liquefaction is a proteolytic process where a gel-like ejaculated semen becomes watery due to the enzymatic activity of prostate-derived serine proteases in the female reproductive tract. The liquefaction process is crucial for the sperm to gain their motility and successful transport to the fertilization site in Fallopian tubes (or oviducts in animals). Hyperviscous semen or failure in liquefaction is one of the causes of male infertility. Therefore, the biochemical inhibition of serine proteases in the female reproductive tract after ejaculation is a prime target for novel contraceptive development. Herein, we will discuss protein components in the ejaculates responsible for semen liquefaction and any developments of contraceptive methods in the past that involve the liquefaction process.

Ovarian cancer: epidemiology and risk factors

The present overview of ovarian cancer epidemiology summarizes the main results for a network of case-control studies in Italy and from the Collaborative Group on Epidemiological Studies of Ovarian Cancer. There are consistent inverse relations between parity, oral contraceptive use and the risk of ovarian cancer. For other menstrual and hormonal factors (i.e. early age at menarche and late menopause), there are established associations, but of limited impact on ovarian cancer incidence on a population level. Serous and endometrioid ovarian cancers (but not mucinous or clear cell types) are related to current and recent use of hormone replacement therapy in menopause. There are no strong associations with alcohol and tobacco overall, but a direct link for tobacco with (borderline) mucinous cancers, of limited impact, however, on overall ovarian cancer mortality. There are direct associations of ovarian cancer risk with height and BMI, as well as possible relations with selected dietary factors - in the absence, however, of consistent findings - and a possible inverse association with physical activity. There is a strong association with a family history of ovarian cancer (and a few selected other neoplasms, including colorectum and endometrium). Recognized risk factors explain only a limited proportion of ovarian cancer cases on a population level. A key reason for the recent favourable trends of ovarian cancer incidence and mortality in several high-income countries is the widespread use of oral contraceptive in the generations born after 1930.

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.

Relationship between prolactin, breast cancer risk, and antipsychotics in patients with schizophrenia: a critical review

OBJECTIVE

A recent meta-analysis showed that breast cancer probably is more common in female patients with schizophrenia than in the general population (effect size = 1.25, P < 0.05). Increasing experimental and epidemiological data have alerted researchers to the influence of prolactin (PRL) in mammary carcinogenesis. We therefore investigated the possible relationship between antipsychotic-induced hyperprolactinemia (HPRL) and breast cancer risk in female patients with schizophrenia.

METHOD

A literature search (1950 until January 2015), using the MEDLINE database, was conducted for English-language published clinical trials to identify and synthesize data of the current state of knowledge concerning breast cancer risk (factors) in women with schizophrenia and its (their) relationship between HPRL and antipsychotic medication.

RESULTS

Although an increasing body of evidence supports the involvement of PRL in breast carcinogenesis, results of human prospective studies are limited, equivocal, and correlative (with risk ratios ranging from 0.70 to 1.9 for premenopausal women and from 0.76 to 2.03 for postmenopausal women). Moreover, these studies equally do not take into account the local production of PRL in breast epithelium, although amplification or overexpression of the local autocrine/paracrine PRL loop may be a more important mechanism in tumorigenesis. Until now, there is also no conclusive evidence that antipsychotic medication can increase the risk of breast malignancy and mortality.

CONCLUSION

Other breast risk factors than PRL, such as nulliparity, obesity, diabetes mellitus, and unhealthy lifestyle behaviours (alcohol dependence, smoking, low physical activity), probably are of greater relevance in individual breast cancer cases within the population of female patients with schizophrenia.

Is there any association between hormonal contraceptives and cervical neoplasia in a poor Nigerian setting?

Background

The association between hormonal contraception and cervical cancer is controversial. These controversies may hamper the uptake of hormonal contraceptives.

Objective

To determine the association between hormonal contraceptives and cervical neoplasia.

Materials and methods

This was a case-control study in which Pap-smear results of 156 participants on hormonal contraceptives were compared with those of 156 participants on no form of modern contraception. Modern contraception is defined as the use of such contraceptives as condoms, pills, injectables, intrauterine devices, implants, and female or male sterilization. Those found to have abnormal cervical smear cytology results were subjected further to colposcopy. Biopsy specimens for histology were collected from the participants with obvious cervical lesions or those with suspicious lesions on colposcopy. The results were analyzed with descriptive and inferential statistics at a 95% level of confidence.

Results

A total of 71 (45.5%), 60 (38.5%), and 25 (16.0%) of the participants on hormonal contraceptives were using oral contraceptives, injectable contraceptives, and implants, respectively. Cervical neoplasia was significantly more common among participants who were ≥35 years old (6% versus 1%, P<0.0001), rural dwellers (6% versus 3.5%, P<0.0001), unmarried (7.6% versus 3.5%, P<0.0001), unemployed (6.8% versus 3.5%, P<0.0001), less educated (6% versus 3.8%, P<0.0001), and had high parity (6.8% versus 3.6%, P<0.0001). There was no statistical significant difference in cervical neoplasia between the two groups of participants (7 [4.5%] versus 6 [3.8%], P=1.0).

Conclusion

There was no association between hormonal contraceptives and cervical neoplasia in this study.

Association of oral contraceptives use and lung cancer risk among women: an updated meta-analysis based on cohort and case-control studies

BACKGROUND

Previous studies on the association of oral contraceptives (OC) use and lung cancer generated inconsistent findings. The aim of this study was to confirm any definite correlation between OC use and lung cancer risk.

METHODS

Publications were reviewed and obtained through PubMed and EMBASE databases literature search up to November, 2013. Reference lists from retrieved articles were also reviewed. The language of publication was restricted to English. A meta-analysis was performed to evaluate the association by calculating pooled odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

A total of 14 studies consisting of 9 case- control studies and 5 cohort studies were finally included in this meta-analysis. There was no significant association observed between OC use and lung cancer risk in the overall analysis (OR=0.91; 95% CI=0.81-1.03). There was a significant protective effect in Europe (OR=0.74; 95% CI=0.60-0.91) and a borderline significant protective effect with an adenocarcinoma histology (OR=0.90; 95% CI=0.80-1.01) in subgroup analyses. No association was observed for methodological quality of study, study design, smoking status and case number of study.

CONCLUSION

This meta-analysis suggests that OC use is not likely to be associated with the risk of lung cancer at all. While a significant protective effect of OC use on lung cancer was observed in Europe, interpretation should be cautious because of the potential biases of low-quality studies. At the same time, more attention should be paid to the possible association of OC use with adenocarcinoma of lung. Our findings require further research, with well-conducted and large-scale epidemiological studies to confirm effects of OC use on lung cancer.

Oral contraceptive use and risk of breast, cervical, colorectal, and endometrial cancers: a systematic review

Oral contraceptives may influence the risk of certain cancers. As part of the AHRQ Evidence Report, Oral Contraceptive Use for the Primary Prevention of Ovarian Cancer, we conducted a systematic review to estimate associations between oral contraceptive use and breast, cervical, colorectal, and endometrial cancer incidence. We searched PubMed, Embase, and Cochrane Database of Systematic Reviews. Study inclusion criteria were women taking oral contraceptives for contraception or ovarian cancer prevention; includes comparison group with no oral contraceptive use; study reports quantitative associations between oral contraceptive exposure and relevant cancers; controlled study or pooled patient-level meta-analyses; sample size for nonrandomized studies ≥100; peer-reviewed, English-language; published from January 1, 2000 forward. Random-effects meta-analyses were conducted by estimating pooled ORs with 95% confidence intervals (CIs). We included 44 breast, 12 cervical, 11 colorectal, and 9 endometrial cancers studies. Breast cancer incidence was slightly but significantly increased in users (OR, 1.08; CI, 1.00-1.17); results show a higher risk associated with more recent use of oral contraceptives. Risk of cervical cancer was increased with duration of oral contraceptive use in women with human papillomavirus infection; heterogeneity prevented meta-analysis. Colorectal cancer (OR, 0.86; CI, 0.79-0.95) and endometrial cancer incidences (OR, 0.57; CI, 0.43-0.77) were significantly reduced by oral contraceptive use. Compared with never use, ever use of oral contraceptives is significantly associated with decreases in colorectal and endometrial cancers and increases in breast cancers. Although elevated breast cancer risk was small, relatively high incidence of breast cancers means that oral contraceptives may contribute to a substantial number of cases.

Concepts of contraception for adolescent and young adult women with chronic illness and disability

Sexual behavior is common in adolescents and young adults with or without chronic illness or disability, resulting in high levels of unplanned pregnancy and STDs. Individuals with chronic illness or disability should not receive suboptimal preventive health care. These individuals have a need for counseling regarding issues of sexuality and contraception. Sexually active adolescent and young adult women can be offered safe and effective contraception if they wish to avoid pregnancy. Women with chronic illnesses and disabilities who are sexually active should also be offered contraception based on their specific medical issues. Condoms are also recommended to reduce STD risks. Table 36 summarizes basic principles of contraception application for specific illnesses, which have been identified since the release of the combined OC in 1960. Clinicians should also consider the noncontraceptive benefits of this remarkable and life-changing technology that allows all reproductive age women to improve their lives, including those with chronic illnesses and disabilities.

Contraceptive use by obese women 1 year postpartum

BACKGROUND

Obese women have higher rates of pregnancy complications, making the prevention of unintended pregnancies in this group of particular importance.

STUDY DESIGN

We performed a secondary analysis of data from Active Mothers Postpartum (AMP), a randomized controlled trial aimed at postpartum weight reduction. We assessed contraceptive use among 361 overweight/obese women 12 months postpartum. Logistic regression was used to model the effect of body mass index (BMI) categories on effective contraceptive use (intrauterine, hormonal or sterilization methods) while adjusting for potential confounders including age, race, parity, breastfeeding, education and chronic illness.

RESULTS

Effective contraceptive use was reported by 45% of women. In the multivariable model, women with a BMI >or=35 kg/m(2) were less likely to use effective contraception than women with a BMI <30 kg/m(2) (OR 0.5, 95% CI 0.3-0.8). There was a trend towards less use of effective contraception among women with a BMI 30-34.9 kg/m(2) as compared to women with a BMI <30 kg/m(2).

CONCLUSION

At 12 months postpartum, obese women were less likely to use effective contraceptive methods than overweight women. Although certain contraceptive methods may be preferred over others in this population, providers should reinforce the importance of effective contraception to avoid unintended pregnancies in obese women.

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.

Non-contraceptive benefits of oral contraceptives

BACKGROUND

There is increasing awareness of the opportunity that many contraceptive interventions may provide for additional health benefits. However, treatment of medical problems with oral contraceptives (OCs) is often an 'off-label' practice.

OBJECTIVE

The aim of this review is to summarize available data on non-contraceptive benefits of OCs.

METHODS

Review of the literature.

RESULTS

OCs have been shown to reduce the risk of ovarian, endometrial, and colorectal cancer. It has been suggested that OCs may be used in treatment of endometriosis, menorrhagia, and uterine leiomyomas. Pelvic inflammatory disease, dysmenorrhea, premenstrual syndrome, and acne have been shown to improve under OCs.

CONCLUSION

OCs are important for global and female health. Besides contraception, non-contraceptive effects of OCs are evidence based, well established, and commonly used in clinical practice.

Cervical dysplasia and cancer and the use of hormonal contraceptives in Jamaican women

BACKGROUND

This study was conducted to determine whether use of hormonal contraceptives is associated with cervical dysplasia and cancer in a population where there is widespread use of hormonal contraception and the rates of cervical cancer remain high at 27.5/100,000.

METHODS

A case-control study was conducted among women visiting the colposcopy and gynaelogical clinics at a tertiary referral hospital. Two hundred and thirty six cases CIN I (72), II (59), III (54), cancer (51) and 102 controls, consented and were interviewed on use of contraceptives using a structured questionnaire. Logistic regression was used to determine odds ratios (ORs) and 95% confidence intervals (CIs) associated with use of hormonal contraception in cases and controls and in low and high risk cases. Recruitment was carried out from 2001-2002.

RESULTS

Contraceptives used were: oral contraceptives - 35%, injections (depot medroxy progesterone acetate (Depo-provera) - 10%, Intrauterine devices - 2%, combinations of these and tubal ligation - 30%. 23% reported use of 'other' methods, barrier contraceptives or no form of contraception. Barrier contraceptive use was not significantly different between cases and controls. Current and/or past exposure to hormonal contraceptives (HC) by use of the pill or injection, alone or in combination with other methods was significantly higher in the cases. In multivariate analysis with age and number of sexual partners as co-variates, use of hormonal contraception was associated both with disease, [OR, 1.92 (CI 1.11, 3.34; p = 0.02] and severity of the disease [OR, 2.22 (CI 1.05, 4.66) p = 0.036]. When parity and alcohol consumption were added to the model, hormonal contraception was no longer significant. The significant association with high risk disease was retained when the model was controlled for age and number of sexual partners. Depo-provera use (with age and number of sexual partners as covariates) was also associated with disease [OR, 2.43 (CI 1.39, 4.57), p = 0.006] and severity of disease [OR 2.51 (1.11, 5.64) p = 0.027]. With parity and alcohol added to this model, depo-provera use retained significance. Exposure to HC > 4 years conferred more risk for disease and severity of disease.

CONCLUSION

Hormonal contraception did confer some risk of dysplasia and women using HC should therefore be encouraged to do regular Pap smear screening.

New forms of contraception

Women have many options regarding contraception. A patient's desire for a long- or short-term method, for one that is reversible or permanent, and her belief that she can be compliant with the method all factor into the choice of contraceptive method. Practitioners must discuss coexisting conditions, contraindications, and whether the patient desires scheduled monthly bleeding or if she will tolerate unscheduled bleeding. Finally, cost and coverage by insurance tends to be one of the most important factors in choosing the method of contraception.

Cancer risk among users of oral contraceptives: cohort data from the Royal College of General Practitioner's oral contraception study

OBJECTIVE

To examine the absolute risks or benefits on cancer associated with oral contraception, using incident data.

DESIGN

Inception cohort study.

SETTING

Royal College of General Practitioners' oral contraception study.

PARTICIPANTS

Directly standardised data from the Royal College of General Practitioners' oral contraception study.

MAIN OUTCOME MEASURES

Adjusted relative risks between never and ever users of oral contraceptives for different types of cancer, main gynaecological cancers combined, and any cancer. Standardisation variables were age, smoking, parity, social class, and (for the general practitioner observation dataset) hormone replacement therapy. Subgroup analyses examined whether the relative risks changed with user characteristics, duration of oral contraception usage, and time since last use of oral contraception.

RESULTS

The main dataset contained about 339,000 woman years of observation for never users and 744,000 woman years for ever users. Compared with never users ever users had statistically significant lower rates of cancers of the large bowel or rectum, uterine body, and ovaries, tumours of unknown site, and other malignancies; main gynaecological cancers combined; and any cancer. The relative risk for any cancer in the smaller general practitioner observation dataset was not significantly reduced. Statistically significant trends of increasing risk of cervical and central nervous system or pituitary cancer, and decreasing risk of uterine body and ovarian malignancies, were seen with increasing duration of oral contraceptive use. Reduced relative risk estimates were observed for ovarian and uterine body cancer many years after stopping oral contraception, although some were not statistically significant. The estimated absolute rate reduction of any cancer among ever users was 45 or 10 per 100,000 woman years, depending on whether the main or general practitioner observation dataset was used.

CONCLUSION

In this UK cohort, oral contraception was not associated with an overall increased risk of cancer; indeed it may even produce a net public health gain. The balance of cancer risks and benefits, however, may vary internationally, depending on patterns of oral contraception usage and the incidence of different cancers.

Oral contraceptives and ovarian cancer: an update, 1998-2004

Over the last two decades, ovarian cancer incidence and mortality for younger generations have been declining in most developed countries, and the decline has been greatest in countries where oral contraceptive (OC) use had spread earlier. The overall estimated protection from cohort and case-control studies is approximately 30% for ever OC users, and increases with duration of use by approximately 5% per year of use to about 50% for long-term (> or =10 years) users. The favourable effect of OC against ovarian cancer risk persists for at least 20 years after OC use has ceased, and it is not confined to any particular type of OC formulation. The reduced risk among OC users is observed in women without or with family history or genetic predisposition to ovarian cancer, and for most histological types of epithelial ovarian cancer, although the pattern of risk is less consistent for mucinous than for other types. The protection of OC on ovarian cancer risk, also in view of its long-term persistence, corresponds to the avoidance of 3000-5000 ovarian cancers (and 2000-3000 deaths) per year in Europe, and a similar figure in North America.

Hormone replacement therapy is more prevalent among Jewish BRCA1/2 mutation carriers

The aim of this study was to compare reproductive factors, use of oral contraceptives (OC) and hormone replacement therapy (HRT) in consecutive Jewish Ashkenazi breast cancer patients, with and without BRCA1/BRCA2 mutations. Jewish Israeli women with breast cancer (n=385) were genotyped for the three predominant Jewish mutations in BRCA1 and BRCA2, and data on reproductive factors, OC and HRT use, were analyzed using logistic regression analyses. Overall, 28/385 (7.3%) of participants were mutation carriers, the majority of whom were Ashkenazi (n=22; 78.6%) and were diagnosed with breast cancer at or under age 49 years (n=18; 64.3%). Mutation carriers were more likely than non-carriers to ever use OC (39.3% vs. 20.2%; P=0.053), HRT (35.7% vs. 13.7%; P=0.007), and have first menarche at or below 12 years of age (71.4% vs. 40.6%; P=0.03). Multivariate analysis showed that Ashkenazi women diagnosed with breast cancer under 40 years of age, with a family history of breast/ovarian cancer, who ever used HRT were more likely to be mutation carriers. This study has shown that HRT use is more prevalent among Jewish Ashkenazi mutation carriers, but its role in modifying breast cancer risk in mutation carriers remains unknown.

The influence of smoking and other cofactors on the time to onset to cervical cancer in a southern European population

Cervical cancer is a complex and multifactorial disease. Although there are substantial data supporting the causative role of persistent human papillomavirus (HPV) infection in the development of cervical cancer, the complete course of the disease has never been completely understood. Several risk cofactors have been suggested with controversial results. Portugal has the highest incidence of squamous cell carcinoma (SCC) within western Europe and there are no known studies regarding the role of cofactors in SCC. The aim of our study was to evaluate the role of smoking, sexual behaviour, reproductive and contraceptive history, in the time-to-onset (TTO) of severe cervical lesions (HGSIL/SCC) in the Portuguese population. We verified that age of first sexual intercourse under 18 years (odds ratio (OR) 2.8), pregnancy (OR 2.9), first pregnancy under 21 years (2.6), number of pregnancies (OR 2.3-5.4) and parity (OR 1.9-5.7) are risk factors in the development of cervical neoplasia. Smoke exposure index (SEI) was significantly different (P=0.002) between cases and controls. Our results regarding time-to-onset demonstrate that smoking (P<0.001, log rank test), number of sexual partners (P<0.001, log rank test) and use of oral contraceptives (P<0.001, log rank test) are important determinants in the earlier onset of severe cervical lesions. Using this approach, our findings may help to clarify the role of smoking and other cofactors in the persistence and progression of cervical lesions.

Drug bioactivation, covalent binding to target proteins and toxicity relevance

A number of therapeutic drugs with different structures and mechanisms of action have been reported to undergo metabolic activation by Phase I or Phase II drug-metabolizing enzymes. The bioactivation gives rise to reactive metabolites/intermediates, which readily confer covalent binding to various target proteins by nucleophilic substitution and/or Schiff's base mechanism. These drugs include analgesics (e.g., acetaminophen), antibacterial agents (e.g., sulfonamides and macrolide antibiotics), anticancer drugs (e.g., irinotecan), antiepileptic drugs (e.g., carbamazepine), anti-HIV agents (e.g., ritonavir), antipsychotics (e.g., clozapine), cardiovascular drugs (e.g., procainamide and hydralazine), immunosupressants (e.g., cyclosporine A), inhalational anesthetics (e.g., halothane), nonsteroidal anti-inflammatory drugs (NSAIDSs) (e.g., diclofenac), and steroids and their receptor modulators (e.g., estrogens and tamoxifen). Some herbal and dietary constituents are also bioactivated to reactive metabolites capable of binding covalently and inactivating cytochrome P450s (CYPs). A number of important target proteins of drugs have been identified by mass spectrometric techniques and proteomic approaches. The covalent binding and formation of drug-protein adducts are generally considered to be related to drug toxicity, and selective protein covalent binding by drug metabolites may lead to selective organ toxicity. However, the mechanisms involved in the protein adduct-induced toxicity are largely undefined, although it has been suggested that drug-protein adducts may cause toxicity either through impairing physiological functions of the modified proteins or through immune-mediated mechanisms. In addition, mechanism-based inhibition of CYPs may result in toxic drug-drug interactions. The clinical consequences of drug bioactivation and covalent binding to proteins are unpredictable, depending on many factors that are associated with the administered drugs and patients. Further studies using proteomic and genomic approaches with high throughput capacity are needed to identify the protein targets of reactive drug metabolites, and to elucidate the structure-activity relationships of drug's covalent binding to proteins and their clinical outcomes.

Other Gynecologic Cancers: endometrial, ovarian, vulvar and vaginal cancers

HEALTH ISSUE: In Canada, cancers of the endometrium, ovaries, vulva, vagina, placenta and adnexa account for 11% of all malignant neoplasms in women and 81% of all genital cancers. Although the incidence and mortality from vulvar and vaginal cancers are very low, endometrium and ovarian cancer are important public health problems. KEY FINDINGS: In Canada, there has been no appreciable improvement in survival for women with advanced endometrial (EC) or ovarian cancer (OC) over the past 30 years. The prognosis of EC is good for most patients because diagnosis is made at early stages. However, survival of OC is poor; more than 70% of cases are diagnosed at late stages. Up to 10% of OCs is linked to familial aggregation. Cancers of the vulva and of the vagina are very rare. The survival experience for women with the latter is worse than for those with the former. Both share many risk factors with cervical cancer and the recent developments in the study of HPV infection should be applicable to these diseases as well. Of particular interest will be the advent of vaccines for the primary prevention of HPV infection. DATA GAPS AND RECOMMENDATIONS: At present, the best available means to diagnose gynecologic malignancies is a detailed clinical examination, considering the totality of information on potential and proven risk factors, such as age, reproductive health, sexual practices, use unopposed estrogens or of oral contraceptives or tubal ligation, obesity, diet, smoking, and the familial clustering of some of these cancers.

Prevention of mammary carcinogenesis by short-term estrogen and progestin treatments

Introduction

Women who have undergone a full-term pregnancy before the age of 20 have one-half the risk of developing breast cancer compared with women who have never gone through a full-term pregnancy. This protective effect is observed universally among women of all ethnic groups. Parity in rats and mice also protects them against chemically induced mammary carcinogenesis.

Methods

Seven-week-old virgin Lewis rats were given N-methyl-N-nitrosourea. Two weeks later the rats were treated with natural or synthetic estrogens and progestins for 7–21 days by subcutaneous implantation of silastic capsules.

Results

In our current experiment, we demonstrate that short-term sustained exposure to natural or synthetic estrogens along with progestins is effective in preventing mammary carcinogenesis in rats. Treatment with 30 mg estriol plus 30 mg progesterone for 3 weeks significantly reduced the incidence of mammary cancer. Short-term exposure to ethynyl estradiol plus megesterol acetate or norethindrone was effective in decreasing the incidence of mammary cancers. Tamoxifen plus progesterone treatment for 3 weeks was able to confer only a transient protection from mammary carcinogenesis, while 2-methoxy estradiol plus progesterone was effective in conferring protection against mammary cancers.

Conclusions

The data obtained in the present study demonstrate that, in nulliparous rats, long-term protection against mammary carcinogenesis can be achieved by short-term treatments with natural or synthetic estrogen and progesterone combinations.

Epidemiological research on cancer with a focus on Europe

Cancer has been a growing public health problem throughout the last century. Cancer mortality rates in both sexes combined in the European Union (EU) reached a peak in 1988. Thereafter, they declined by 9.4% in 1998. Likewise, lung cancer rates in the EU for both sexes combined increased by 58% between 1960 and 1988, but declined by 14% in 1998. Over a third of the decline was accounted for by lung cancer alone and approximately half by the combination of tobacco-related neoplasms. About half of the decline in total cancer mortality not attributable to tobacco derived from the steady fall in mortality from gastric cancer. The remaining half, including favourable trends in colorectal, breast, testis and lymphoid neoplasms, can be at least in part attributed to advancements in cancer diagnosis and treatment. The major causes of cancer and hence the most important priorities for research will be reviewed, with a specific focus on European priorities for research.

Oral contraceptives and colorectal cancer

BACKGROUND

Only limited information and understanding are available on the potential relation between oral contraceptive use and the risk of colorectal cancer. Further data on the issue are therefore useful and may help informed choice of contraception.

METHODS AND RESULTS

Data were derived from a case-control study of colorectal cancer conducted between 1992 and 2001 in the Swiss Canton of Vaud, including 131 women with colorectal cancer and 373 controls admitted in the same hospital as the cases with diagnosis of acute, non-neoplastic disease, unrelated to long-term modification of diet. Oral contraceptive use was reported by 11% of cases versus 17% of controls, corresponding to multivariate odds ratio of 0.8 (95% CI: 0.4-1.7). The odds ratio was non-significantly below unity across strata of duration, time since first and last oral contraceptive use.

CONCLUSION

These findings add further evidence on a possible inverse relation between oral contraceptive and colorectal cancer risk.

Long-term effects of oral contraceptives on ovarian cancer risk

Several epidemiologic studies have reported a protective effect of oral contraceptives (OCs) on ovarian cancer. However, there remain open issues, including better quantification of time-related factors such as time since last use, age at first use and time since first use. We performed a collaborative reanalysis of 6 case-control studies conducted between 1978 and 1999 in the United Kingdom, Greece and Italy, including a total of 2,768 incident, histologically confirmed cases of epithelial ovarian cancer and 6,274 hospital controls under age 70 years. A reduced risk of ovarian cancer was found for ever- compared to never-users [odds ratio (OR) = 0.66, 95% confidence interval (CI) 0.56-0.79], and a stronger reduction was observed for women who had used OCs for > or =5 years (OR = 0.50, 95% CI 0.33-0.76) compared to those who had used them for <5 years. The protective effect of OCs on ovarian cancer was consistent across strata of age, parity, menopausal status and family history of breast or ovarian cancer. After allowance for duration of use, no other time factor was related to ovarian cancer risk: the reduced risk was similar for women who stopped OC use > or =20 years before compared to <10 years; likewise, no significant modification of risk reduction was observed for age at first OC use and time since first OC use. The present analysis indicates that, after taking into account duration of OC use, the OC protection from ovarian cancer persists for a long time after stopping use.

Human papillomavirus update with a particular focus on cervical disease

Human papillomavirus (HPV) is a common viral infection of squamous epithelial tissues, but its importance has only recently been recognised by the medical community. HPVs are now realised to consist of many genotypes and are associated with a diverse spectrum of clinical manifestations. Within the genital tract, some diseases have been recognised since antiquity; for example, genital warts which are caused by HPV types distinct from those causing genital cancer. However, others (such as cervical cancer), although recognised centuries ago as linked to sexual activity, have only been associated with oncogenic HPVs relatively recently, with the tools of molecular biology. We now understand that genital HPV infections are the most common sexually transmitted viral infections, are largely transient, asymptomatic and of no consequence. This virus manifests as more than just benign warts. Chronic carriage of with oncogenic genotypes (over years and in a minority of patients), together with other cofactors (host and/or exogenous) in complex pathways not totally understood, result in severe dysplasia or, ultimately, carcinogenesis. As it takes time for precursor lesions to develop and there are effective screening programmes for their detection and treatment, HPV-related neoplastic disease of the cervix is largely a preventable reproductive health issue of women. Yet, on a global scale, cervical cancer is the second most common cancer of women, with the majority of cases occurring in developing countries. Although HPV is noncultivatable by traditional diagnostic virological methods, successfully applied molecular biology techniques have underpinned development of vaccines which are now in phase II/III clinical trials. Successful vaccination ultimately has the greatest potential to impact upon the global burden of disease from genital HPV infection. However, the outcome from reduction in incidence of dysplasia and neoplasia will take years to eventuate; consequently, various cervical cancer prevention strategies still need to be endorsed and maintained in the meantime.