A case-control study of diet and invasive cervical cancer

Dietary Vitamin A Intake and Circulating Vitamin A Concentrations and the Risk of Three Common Cancers in Women: A Meta-Analysis

BACKGROUND

According to relevant clinical research, dietary and circulating antioxidants vitamin A are connected with the risk of breast, cervical, and ovarian cancer in women. However, there was inconsistency between the findings. We completed this meta-analysis at the right moment to address this contradiction of the problem.

METHODS

Web of Science, Embase, and PubMed databases were searched using the proposed search strategy and filtered using the inclusion and exclusion criteria as well as the NOS quality score. As of May 2022, low intake or low concentration was used as a control, and odds ratio (OR) or relative risk (RR) and ninety-five percent confidence intervals (95% CI) were extracted for high intake. Stata 12.0 was used to process the data.

RESULTS

Our meta-analysis included a total of 49 studies, 29 on breast cancer, 10 on ovarian cancer, and 10 on cervical cancer. There were 38 case-control studies included, with 25,363 cases and 42,281 controls; there were 11 cohort studies included, 1,334,176 individuals were followed up, and finally 9496 obtained cancer. The pooled OR value results were as follows: diet or supplements (OR = 0.83, 95% CI 0.76-0.90, I ² = 56.1%) and serum or plasma (OR = 0.96, 95% CI 0.86-1.09, I ² = 29.5%). Subgroup analyses were performed according to cancer type, diet or supplements, serum or plasma, study type, and geographic regions.

CONCLUSIONS

In North American and Asian populations, high dietary consumption of vitamin A or supplements decreases the incidence of three cancers in women, with breast and ovarian cancers being more significant. However, high circulating vitamin A concentrations were not significantly connected with the risk of the three malignancies.

Natural Bioactives: Back to the Future in the Fight against Human Papillomavirus? A Narrative Review

Human papillomavirus (HPV) still represents an important threat to health worldwide. Better therapy in terms of further improvement of outcomes and attenuation of related side-effects is desirable. The pharmaceutical industry has always targeted natural substances-phytochemicals in particular-to identify lead compounds to be clinically validated and industrially produced as antiviral and anticancer drugs. In the field of HPV, numerous naturally occurring bioactives and dietary phytochemicals have been investigated as potentially valuable in vitro and in vivo. Interference with several pathways and improvement of the efficacy of chemotherapeutic agents have been demonstrated. Notably, some clinical trials have been conducted. Despite being endowed with general safety, these natural substances are in urgent need of further assessment to foresee their clinical exploitation. This review summarizes the basic research efforts conducted so far in the study of anti-HPV properties of bio-actives with insights into their mechanisms of action and highlights the variety of their natural origin in order to provide comprehensive mapping throughout the different sources. The clinical studies available are reported, as well, to highlight the need of uniformity and consistency of studies in the future to select those natural compounds that may be suited to clinical application.

Consumption of Sweet Beverages and Cancer Risk. A Systematic Review and Meta-Analysis of Observational Studies

The consumption of sweet beverages, including sugar-sweetened beverages (SSB), artificial-sweetened beverages (ASB) and fruit juices (FJ), is associated with the risk of different cardiometabolic diseases. It may also be linked to the development of certain types of tumors. We carried out a systematic review and meta-analysis of observational studies aimed at examining the association between sweet beverage intake and cancer risk. Suitable articles published up to June 2020 were sourced through PubMed, Web of Science and SCOPUS databases. Overall, 64 studies were identified, of which 27 were selected for the meta-analysis. This was performed by analyzing the multivariable-adjusted OR, RR or HR of the highest sweet beverage intake categories compared to the lowest one. Random effects showed significant positive association between SSB intake and breast (RR: 1.14, 95% CI: 1.01–1.30) and prostate cancer risk (RR: 1.18, 95% CI: 1.10–1.27) and also between FJs and prostate cancer risk (RR: 1.03, 95% CI: 1.01–1.05). Although the statistically significant threshold was not reached, there tended to be positive associations for the following: SSBs and colorectal and pancreatic cancer risk; FJs and breast, colorectal and pancreatic cancer risk; and ASBs and pancreatic cancer risk. This study recommends limiting sweet beverage consumption. Furthermore, we propose to establish a homogeneous classification of beverages and investigate them separately, to better understand their role in carcinogenesis.

Fruits and vegetables and cervical cancer: a systematic review and meta-analysis

We conducted a meta-analysis to examine the association of fruits and vegetables intake with the occurrence of cervical intraepithelial neoplasia (CIN) and invasive cancer. MEDLINE, LILACS, Scopus, Cochrane Library, and Web of Science databases and gray literature on Google Scholar were searched before December 17, 2018. Odds ratio (OR) or relative risk (RR) estimates for the highest vs. the lowest intake of intake and 95% confidence intervals (CI) from the included studies were pooled using fixed and random-effects models. We found 18 studies: 17 case-control studies (n = 9,014 cases, n = 29,088 controls) and one cohort study (n = 299,651). No association was observed for CIN. The pooled adjusted ORs (95% CI) for cervical cancer were 0.61 (95% CI 0.52-0.73) for vegetables and 0.80 (95% CI 0.70-0.93) for fruits. However, no association was observed when the pooled effect was estimated among studies that adjusted for human papillomavirus (HPV). Consumption of vegetables and fruits was not associated with incidence of cervical cancer among studies that controlled for HPV infection. The level of evidence is limited because only one cohort study was included in the analysis.

Interactions between serum folate and human papillomavirus with cervical intraepithelial neoplasia risk in a Chinese population-based study

Background

Although folate deficiency has long been implicated in cancer development, uncertainties remain concerning its role in cervical cancer prevention. In particular, the interaction between human papillomavirus (HPV) and folate in the risk of cervical intraepithelial neoplasia (CIN) has been little studied.

Objective

The goal of this study was to evaluate the dose-response association of serum folate with the risk of CIN, and the potential for HPV to modify the risk of CIN.

Design

We performed a cross-sectional analysis of screening data in 2304 women aged 19-65 y who participated in an ongoing cohort of 40,000 women in China. Both categoric and spline analyses were used to evaluate the dose-response relation between serum folate and CIN risk.

Results

After adjusting for potential confounders, a statistically significant inverse association between serum folate concentration and at least grade 2 CIN (CIN2+) risk was observed (1st quartile compared with 4th quartile: OR = 1.40; 95% CI: 1.09, 1.79; P-trend < 0.01); however, serum folate concentration was not associated with CIN1 risk. The risk patterns are similar when limited to only CIN2 and CIN3. An inverse linear relation between increased serum folate concentration and the risk of higher-grade CIN (CIN2, CIN3, and CIN2+) was also observed (for CIN2+: P-overall < 0.01, P-nonlinearity = 0.96). The highest risk of CIN2+ was observed in women with high-risk HPV types, who also had the lowest serum folate concentrations (P-interaction < 0.01).

Conclusions

Our study indicates that serum folate is inversely associated with the risk of higher-grade CIN in Chinese women either with or without high-risk HPV infection. Thus, maintenance of normal serum folate levels may prove important for reducing the risk of CIN in women.

Association between vitamin C Intake and the risk of cervical neoplasia: A meta-analysis

To assess the association between vitamin C intake and cervical neoplasia (CN) risk. Databases including PubMed, Embase, and Springer link were retrieved up to June 10, 2014 with predefined strategy. The combined odds ratios (ORs) and their 95% confidence intervals (CIs) were calculated for overall and subgroup analyses. The publication bias was assessed using Begg's test and Egger's test. Sensitivity analysis was also conducted. Twelve studies consisting of 1 prospective cohort study and 11 case-control studies were included. In overall analysis, vitamin C intake was significantly associated with the reduced risk of CN (OR = 0.58; 95% CI: 0.44 to 0.75; P < 0.001). Subgroup analysis stratified by vitamin C dose indicated all dose categories achieved a reduced CN risk. Furthermore, increased vitamin C intake by 50 mg/day was related to the reduced risk of CN (OR = 0.92; 95% CI: 0.89 to 0.94; P < 0.05). No publication bias was detected by Begg's test (P = 0.169) and no apparent fluctuation was observed in summary OR by sensitivity analysis. Vitamin C intake was inversely associated with the risk of CN and this association was dose-dependent. However, more randomized controlled trials are required for further validation.

Serum carotenoid, retinol and tocopherol concentrations and risk of cervical cancer among Chinese women

BACKGROUND

Despite many epidemiological studies on the effects of dietary antioxidant micronutrients on risk of cervical cancer, the findings remain uncertain and little evidence is available for serum nutrient markers. The present study aimed to examine the relationship between serum carotenoid, retinol and tocopherol concentrations and risk of cervical cancer among Chinese women.

MATERIALS AND METHODS

We conducted a hospital-based case- control study in which 358 adults (158 incident cases and 200 controls) were recruited from Xinjiang, China. Serum levels of carotenoids (α-carotene, β-carotene, β-cryptoxanthin, lycopene and lutein/zeaxanthin), retinol, and tocopherols (α-tocopherol and γ-tocopherol) were assessed by reverse-phase high-performance liquid chromatography.

RESULTS

We found inverse associations between serum carotenoid (α-carotene, β-carotene, and lutein/zeaxanthin) and tocopherol (α-tocopherol) concentrations and the risk of cervical cancer after adjusting for potential confounders, but a null association for retinol. The ORs for 1-SD increase were 0.71 (95% CI: 0.56- 0.92; p=0.003) for total carotenoids and 0.75 (95% CI: 0.60-0.94; p=0.008) for total tocopherols.

CONCLUSIONS

These results show that higher serum concentrations of some carotenoids and tocopherols are associated with a lower risk of cervical cancer among Chinese women.

Palliative Vitamin C Application in Patients with Radiotherapy-Resistant Bone Metastases: A Retrospective Study

The aim of this study was to observe effects of ascorbic acid application on pain, performance status, and survival time in cancer patients. A retrospective cohort of 39 patients with bone metastases treated with radiotherapy was identified. All patients were radiotherapy-resistant. Fifteen patients who received chemotherapy, and 15 patients who received an infusion of 2.5 g ascorbic acid were included in the study. Nine control patients were treated with neither chemotherapy nor vitamin C. Eastern Cooperative Oncology Group Performance Status Scale and Visual Analog Scale were used to determine performance status and pain assessments. Survival time and rate in patients were defined. Statistical analyses were performed to compare the results of groups. Performance status was increased in 4 patients of vitamin C group and 1 patient of chemotherapy group, whereas performance status in control group was decreased. A median reduction of 50% in pain was observed among the patients in the vitamin C group. Median survival time was 10 mo in patients receiving ascorbic acid, whereas the chemotherapy and control groups had a median survival of 2 mo. Intravenous vitamin C application seems to reduce pain in patients in comparison to other patients who did not receive it. Patient performance status and survival rate were increased using vitamin C.

Involvement of the Nrf2 pathway in the regulation of pterostilbene-induced apoptosis in HeLa cells via ER stress

Among the various cancer cell lines, HeLa cells were found to be sensitive to pterostilbene (Pte), a compound that is enriched in small fruits such as grapes and berries. However, the mechanism involved in the cytotoxicity of Pte has not been fully characterized. Using biochemical and free radical biological experiments in vitro, we identified the pro-apoptotic profiles of Pte and evaluated the level of redox stress-triggered ER stress during HeLa cell apoptosis. The data showed a strong dose-response relationship between Pte exposure and the characteristics of HeLa apoptosis in terms of changes in apoptotic morphology, DNA fragmentation, and activated caspases in the intrinsic apoptotic pathway. During drug exposure, alterations in the intracellular redox homeostasis that favor oxidation were necessary to cause ER stress-related apoptosis, as demonstrated by enzymatic and non-enzymatic redox modulators. A statistically significant and dose-dependent increase (P < 0.05) was found with regard to the unique expression levels of Nrf2/ARE downstream target genes in HeLa cells undergoing late apoptosis, levels that were restored with anti-oxidant application with the Pte treatment. Our research demonstrated that Pte trigged ER stress by redox homeostasis imbalance, which was negatively regulated by a following activation of Nrf2.

Vitamin A and risk of cervical cancer: a meta-analysis

OBJECTIVE

To conduct a systematic review with meta-analysis of studies assessing the association of vitamin A (retinol, carotene and other carotenoids) intake or blood (serum or plasma) levels of vitamin A (retinol and carotene) with risk of cervical cancer.

METHODS

We evaluated the studies published in English and Chinese on diet or blood vitamin A for the risk of cervical cancer. We also reviewed reference lists from retrieved articles. Meta-analysis was applied to calculate the combined effect values and their 95% confidence intervals. The risk of bias was assessed by the Egger regression asymmetry test.

RESULTS

As many as 11 articles on dietary vitamin A and 4 articles on blood vitamin A were selected according to the eligibility criteria and were included in the meta-analysis, for a total of 12,136 participants. The pooled odds ratios (ORs) of cervical cancer were 0.59 (95% CI, 0.49-0.72) for total vitamin A intake and 0.60 (95% CI, 0.41-0.89) for blood vitamin A levels. The combined ORs of cervical cancer were 0.80 (95% CI, 0.64-1.00), 0.51 (95% CI, 0.35-0.73) and 0.60 (95% CI, 0.43-0.84) for retinol, carotene and other carotenoid intake, and 1.14 (95% CI, 0.83-1.56) and 0.48 (95% CI, 0.30-0.77) for blood retinol and carotene.

CONCLUSIONS

Vitamin A intake and blood vitamin A levels were inversely associated with the risk of cervical cancer in this meta-analysis.

Food consumption pattern in cervical carcinoma patients and controls

Background:

The uterine cervix is the second most common site of cancer among Indian women.Though the human papillomavirus has been demonstrated to be a causative agent for this cancer, a variety of other risk factors are in play, such as sexual and reproductive patterns, socioeconomic, hygienic practices, and diet. The accumulated evidence suggests that cervical cancer is preventable and is highly suitable for primary prevention. The dietary intake of antioxidants and vitamins like vitamin A, carotenoids, vitamin C, folacin and tocopherol is found to have protective effects against cancer of the cervix. Dietary data regarding cervical cancer are still scanty.

Objective:

The present study was therefore undertaken to study the dietary pattern among uterine cervical cancer patients and normal controls.

Materials and Methods:

A total of 60 consecutive patients and 60 controls were enrolled from a referral hospital during the year 2004. A schedule inclusive of the food frequency pattern and 24-h dietary recall along with the general information was administered to all the enrolled subjects to describe findings on the food consumption pattern along with other important factors.

Results:

The mean intake of energy, protein, vitamins, etc., between the cases and controls was not significantly different except for the vitamin C level. Serum vitamin E was found to have lower average in patients as compared to controls. The nutrient intake of cervical cancer patients and controls was grossly deficient in the socioeconomic group studied. With regard to the macronutrient intake, calorie and protein intakes showed a deficit of around 50% when compared to RDA.

Conclusion:

The food consumption profile was not significantly different between cervical cancer patients and normal controls.

The association between fruit and vegetable consumption and HPV viral load in high-risk HPV-positive women with cervical intraepithelial neoplasia

We evaluated the relationship between the dietary intake of vegetables and fruits, and the risk of cervical intraepithelial neoplasia (CIN) and determined whether these associations were modified by human papillomavirus (HPV) viral load. We enrolled 1,096 women aged 18-65 to participate in a HPV cohort study from March 2006 up to present. For this analysis, we included 328 HPV-positive women (166 controls, 90 CIN I and 72 CIN II/III). The multivariate odds ratios (ORs) and corresponding 95% confidence intervals (CIs) were estimated by multinomial logistic methods. After controlling for potential confounders, we found that a higher HPV viral load was associated with an increased risk of CIN I (OR = 2.68, 95% CI, 1.19-6.04) and CIN II/III (OR = 2.78, 95% CI, 1.15-6.72). The relationships between HPV infection, dietary intake of vegetables and fruits and risk of CIN were not statistically significant. However, subjects with lower intake of vegetables and fruits, and a higher viral load (> or =15.5) have a higher risk of CIN II/III (OR = 2.84(1.26-6.42), interaction p = 0.06 for vegetables; OR = 2.93(1.25-6.87), interaction p = 0.01 for fruits), compared with subjects with lower intake of vegetables and fruits, and a lower viral load (<15.5). Our findings suggest that the dietary intake of vegetables and fruits is associated with the progression of cervical carcinogenesis.

Fruit and vegetables in cancer prevention

Our aim was to review the epidemiological literature on possible cancer-preventive effects of the consumption of fruits and vegetables in humans, to quantify the effect of high versus low consumption of fruits and vegetables, and to give an overall assessment of the existing evidence. We based our work on an expert meeting conducted by the International Agency for Research on Cancer in 2003. A qualitative reading and evaluation of relevant articles on the cancer-preventive effect of the consumption of fruits and vegetables was made followed by the calculation of the mean relative risk and range for cohort and case-control studies separately. The possible population-preventable fraction for modifying diet in relation to fruit and vegetable consumption was calculated as well as an overall statement about the degree of evidence for the cancer-preventive effect of fruit and vegetable consumption for each cancer site. There is limited evidence for a cancer-preventive effect of the consumption of fruits and vegetables for cancer of the mouth and pharynx, esophagus, stomach, colon-rectum, larynx, lung, ovary (vegetables only), bladder (fruit only), and kidney. There is inadequate evidence for a cancer-preventive effect of the consumption of fruits and vegetables for all other sites. Applying this range of risk difference to the range of prevalence of low intake, the preventable fraction for low fruit and vegetable intake would fall into the range of 5-12%. It is important to recognize that this is only a crude range of estimates and that the proportion of cancers that might be preventable by increasing fruit and vegetable intake may vary beyond this range for specific cancer sites and across different regions of the world.

Effectiveness of cervical cancer screening over cervical cancer mortality among Japanese women

BACKGROUND

Various studies have revealed that cervical cancer (CC) screening significantly reduces both CC incidence and mortality in developed countries. Although Japan introduced a nationwide government funded annual CC screening for the women aged 30+ in 1982, the effectiveness of CC screening on CC mortality has not yet been evaluated by any prospective cohort study. Therefore, the present study evaluated the association of CC mortality with self-reported CC screening and some other factors by a nationwide cohort study.

METHODS

Baseline survey of the Japan Collaborative Cohort Study for the enrollment of subjects was completed during 1988-90 and followed until 2003. This study only analyzed 63,541 women, aged 30-79 years, who were free from any cancer history at enrollment.

RESULTS

During the follow-up period, 38 CC deaths were identified. The mean age at mortality was 67.0 years, with a mortality rate of 4.2 per 100,000 person-years. Participation rate in CC screening was 46.9%. Age-adjusted Cox model indicated significantly lower CC mortality [hazard ratio (HR) = 0.30, 95% confidence interval (CI) = 0.12-0.74] due to CC screening. Protectiveness remained almost the same (HR = 0.30, 95% CI = 0.12-0.76) when adjusted for age, body mass index and number of deliveries. The results also revealed that CC screening could reduce at least 50% of CC deaths even after excluding the effect of possible self-selection bias.

CONCLUSIONS

CC screening in Japan may reduce CC mortality significantly for women aged 30-79 years. However, further studies with more CC deaths and increased statistical power are needed to validate the findings.

Human papillomavirus and disease mechanisms: relevance to oral and cervical cancers*

Oral squamous cell carcinoma (OSCC) is the sixth most common malignancy and is a major cause of cancer morbidity and mortality worldwide. Carcinoma of the uterine cervix is the most common female malignancy in the world. While cervical cancer is a worldwide disease, oral cancer has the highest incidence in developing countries, especially among tobacco and alcohol users and betel quid chewers. A strong association of cervical and oral cancer with high-risk human papillomavirus (HPV) 16 and 18 infections underlines the importance of the virus in the pathogenesis of these squamous cell carcinomas. Functionally high-risk HPV infection contributes to carcinogenesis and tumor progression predominantly through the actions of two viral oncogenes, E6 and E7. The E6 and E7 genes have been studied in different patient populations and a number of variants have been described. More than 40 variants have been classified and may be related to differences in progression of squamous intraepithelial lesions. The transcription factor, NFkappaB and its activation pathways are frequently targeted by viruses and aberrant constitutive activation of NFkappaB is frequently found in human tumors of diverse tissue origin. Diet-gene interactions are also likely to contribute considerably to the observed inter-individual variations in HPV associated cancer risk, in response to exposures to the nutritional factors that have the potential to promote or protect against cancer.

Vitamin E: the evidence for multiple roles in cancer

There is accumulating evidence that vitamin E may have different roles in the prevention and treatment of cancer. The purpose of this review is to summarize and evaluate this evidence and to suggest future avenues of research. A comprehensive literature review of vitamin E and cancer was conducted. Articles were organized into the following categories: 1) cancer prevention, 2) direct antineoplastic activity, 3) augmentation of chemotherapy effects, and 4) attenuation or treatment of chemotherapy toxicity. The evidence was systematically evaluated using guidelines developed by the U.S. Preventative Services Task Force. There is evidence to suggest that those individuals with higher serum vitamin E levels and those receiving vitamin E supplementation have a decreased risk of some cancers, including lung, prostate, stomach, and gastrointestinal carcinoma. However, these results differed depending on the study design and the population studied. There is insufficient evidence to support anticancer activity and attenuation of chemotherapy toxicity by vitamin E. Vitamin E is likely to be important in the prevention of some cancers. The therapeutic role of vitamin E is poorly understood. Further research will be required before routine use of vitamin E in patients with cancer can be advocated in the clinical setting.

Vitamin C in human health and disease is still a mystery? An overview

Ascorbic acid is one of the important water soluble vitamins. It is essential for collagen, carnitine and neurotransmitters biosynthesis. Most plants and animals synthesize ascorbic acid for their own requirement. However, apes and humans can not synthesize ascorbic acid due to lack of an enzyme gulonolactone oxidase. Hence, ascorbic acid has to be supplemented mainly through fruits, vegetables and tablets. The current US recommended daily allowance (RDA) for ascorbic acid ranges between 100-120 mg/per day for adults. Many health benefits have been attributed to ascorbic acid such as antioxidant, anti-atherogenic, anti-carcinogenic, immunomodulator and prevents cold etc. However, lately the health benefits of ascorbic acid has been the subject of debate and controversies viz., Danger of mega doses of ascorbic acid? Does ascorbic acid act as a antioxidant or pro-oxidant? Does ascorbic acid cause cancer or may interfere with cancer therapy? However, the Panel on dietary antioxidants and related compounds stated that the in vivo data do not clearly show a relationship between excess ascorbic acid intake and kidney stone formation, pro-oxidant effects, excess iron absorption. A number of clinical and epidemiological studies on anti-carcinogenic effects of ascorbic acid in humans did not show any conclusive beneficial effects on various types of cancer except gastric cancer. Recently, a few derivatives of ascorbic acid were tested on cancer cells, among them ascorbic acid esters showed promising anticancer activity compared to ascorbic acid. Ascorbyl stearate was found to inhibit proliferation of human cancer cells by interfering with cell cycle progression, induced apoptosis by modulation of signal transduction pathways. However, more mechanistic and human in vivo studies are needed to understand and elucidate the molecular mechanism underlying the anti-carcinogenic property of ascorbic acid. Thus, though ascorbic acid was discovered in 17th century, the exact role of this vitamin/nutraceutical in human biology and health is still a mystery in view of many beneficial claims and controversies.

Meta-analysis of social inequality and the risk of cervical cancer

Previous studies of the relationship between socio-economic status and cervical cancer have been mainly based on record linkage of routine data, such as cancer registry incidence rates and regional measures of social class based on census data. These routine data are liable to substantial misclassification with respect to socio-economic status. Previous reports are also primarily from developed countries, whereas the major burden of cervical cancer is in developing countries. We have therefore pooled the data from previously reported case-control studies of cervical cancer or dysplasia, which contain individual-level information on socio-economic characteristics to investigate the relationship between cervical cancer, social class, stage of disease, geographical region, age and histological type. Based on 57 studies, we found an increased risk of approximately 100% between high and low social class categories for the development of invasive cervical cancer, and an increased risk of approximately 60% for dysplasia, including carcinoma in situ. Although the difference was observed in all countries, it was stronger in low/middle income countries and in North America than in Europe. No clear differences were observed between squamous cell carcinoma and adenocarcinoma, or between younger and older women. These results indicate that both cervical infection with human papillomavirus, which is linked to both female and male sexual behaviour, and access to adequate cervical cancer screening programmes are likely to be important in explaining the large cervical cancer incidence rates observed in different socio-economic groups, and that the importance of these factors may vary between different geographical regions.

Folate, vitamin B12, and homocysteine status. findings of no relation between human papillomavirus persistence and cervical dysplasia

OBJECTIVES

Human papillomavirus (HPV) infections are the cause of most, if not all, cervical cancers. Women consistently positive for oncogenic type HPV infections have a greater risk of developing cervical dysplasia compared with women transiently infected. HPV infection alone appears to be insufficient to produce disease, suggesting that other cofactors may be needed. Folate, vitamin B12, and homocysteine, through their role in DNA methylation, may be involved in cervical neoplasia.

METHODS

This study examined the associations between HPV persistence and circulating folate, vitamin B12, and homocysteine levels among 91 low-income Hispanic women. Further, the relation of these nutrients to cervical pathology was evaluated. HPV status was determined at two visits approximately 3 mo apart.

RESULTS

Adjusted mean circulating concentrations of folate, vitamin B12, and homocysteine were not statistically different between women with two positive HPV tests, one positive test, or two negative HPV tests. No association was observed between tertiles of folate, vitamin B12, or homocysteine and HPV persistence risk. Further, adjusted mean levels of these nutrients were not statistically different between cytologic grades.

CONCLUSIONS

Results from this small study did not support a role for folate, vitamin B12, or homocysteine in HPV persistence or cervical dysplasia.

Flavonoids and steroid hormone-dependent cancers

Steroid-hormone dependent cancers, including those of the breast, prostate and colon, are leading causes of morbidity and mortality in western countries. In rural Asian areas, these diseases are relatively uncommon. Dietary factors, including low consumption of fruit, vegetables and soy in the west have been shown in various epidemiologic studies as reasons for these differences. This review discusses flavonoids, one component of these plant foods that is being investigated for their role in chemoprevention. Epidemiological, in vitro, animal and human studies shall be explored to look at mechanisms involved, including steroid hormone activity, effects on cell growth, antioxidant activities, inhibition of chemical carcinogenesis and influences on modulators of cancer risk. Although the in vitro and animal models point to several pathways by which flavonoids may reduce incidence of these cancers, the clinical data are still relatively lacking. More research is needed to determine how best to use foods containing these compounds to reduce steroid hormone-dependent cancer risk.

Relationship of folate to colorectal and cervical cancer: review and recommendations for practitioners

Evidence suggests that folate may play a role in cancer prevention. A plausible mechanism for prevention lies in the integral role that folate plays in deoxyribonucleic acid (DNA) synthesis and methylation. DNA methylation most likely regulates gene expression. Abnormal methylation, specifically hypomethylation, has been associated with tumorigenesis. The availability of methyl groups needed for adequate DNA methylation may be negatively influenced by low folate status, alcohol intake, or genetic polymorphisms that affect folate metabolism. Observational studies evaluating the association between folate and risk for colorectal and cervical cancers or precancerous conditions have produced conflicting results, and clinical trial data are needed to confirm a cause-and-effect relationship. However, several studies show interesting associations between cancer risk and factors that influence methyl group availability. Although data relating folate to cancer risk remain equivocal, when coupled with the other potential health benefits associated with folate, evidence supports recommending that people consume folate-rich foods such as fruits and vegetables. People consuming alcohol on a daily basis may especially benefit from additional folate in their diets.

Prospects for chemoprevention of cancer

The recent progress in molecular biology and pharmacology has increased the likelihood that cancer prevention will rely increasingly on interventions collectively termed 'chemoprevention'. Cancer chemoprevention is the use of agents to inhibit, delay or reverse carcinogenesis. A number of potential targets for chemoprevention have recently been identified. Many classes of agents including antioestrogens, anti-inflammatories, antioxidants and other diet-derived agents have shown a great deal of promise. In this review, we will begin by describing the general classes of chemopreventive agents and the mechanisms by which these agents act. We will then describe the opportunities that presently exist for chemoprevention of specific cancers.

Serum micronutrients and cervical dysplasia in Southwestern American Indian women

We carried out a clinic-based case-control study to assess serum micronutrients as risk factors for cervical dysplasia among Southwestern American Indian women, a group with high rates of cervical preinvasive lesions. Cases were American Indian women with biopsy-proven cervical intraepithelial neoplasia (CIN I or CIN II/III). Controls were from the same Indian Health Service clinics with normal cervical epithelium. We interviewed women about histories of sexually transmitted diseases, sexual behavior, diet, hygienic practices, cigarette smoking, and reproductive factors. Laboratory assays included serum for retinol (vitamin A), ascorbic acid (vitamin C), alpha-tocopherol (vitamin E), and red blood cell folate levels, DNA for human papillomavirus (HPV) typing, and tests for other sexually transmitted diseases. The strongest risks for cervical dysplasia were associated with cervical HPV infection [odds ratio (OR) = 3.2, 95% confidence interval (CI) = 2.2-4.6 and OR = 7.9, 95% CI = 4.8-13.1 for CIN I and CIN II/III, respectively]. With adjustments made for HPV infection and other relevant confounders, subjects in the lowest serum retinol quartile were at increased risk of CIN I compared with women in the highest quartile (OR = 2.3, 95% CI = 1.3-4.1). The data suggest that low serum alpha-tocopherol was associated with CIN I/III, although the adjusted OR was not statistically significant (OR = 2.0, 95% CI = 0.9-4.8). Low serum ascorbic acid and red blood cell folate were not associated with cervical dysplasia.

Relevance of folate metabolism in the pathogenesis of colorectal cancer

The purpose of this review is to outline the principal mechanisms involved in folate metabolism and how they may relate to the pathogenesis of colorectal cancer (CRC). In recent years, mild folate depletion (low normal level) has been associated with an increased risk of developing certain cancers, in particular colorectal neoplasia. The epidemiologic and mechanistic evidence linking folate deficiency with carcinogenesis is reviewed, with a particular emphasis on colorectal neoplasia. Methylenetetrahydrofolate reductase (MTHFR) is a critical folate metabolizing enzyme, and a functional polymorphic variant of this enzyme, the so-called thermolabile variant, caused by a C677T transition in the MTHFR gene, is common in the general population. This review critically examines the evidence that suggests that carriers of this C677T variant may be at increased risk of developing colorectal neoplasia. Although folate depletion may predispose to the initiation of the neoplastic process, folate supplementation, on the other hand, might potentiate the progression of an already established early neoplastic clone (eg, a colorectal adenoma). This could have potential public health implications, given an increasingly widespread policy of folate supplementation of food staples.

Low serum and red blood cell folate are moderately, but nonsignificantly associated with increased risk of invasive cervical cancer in U.S. women

Previous observational epidemiologic studies of folate and cervical cancer, as well as folate supplementation trials for cervical dysplasia, have produced mixed results. We examined the relationship between serum and RBC folate and incident invasive cervical cancer in a large, multicenter, community-based case-control study. Detailed in-person interviews were conducted, and blood was drawn at least 6 mo after completion of cancer treatment from 51% of cases and 68% of controls who were interviewed. Blood folate was measured with both microbiologic and radiobinding assays. Included in the final analyses were 183 cases and 540 controls. Logistic regression was used to control for all accepted risk factors, including age, sexual behavior, smoking, oral contraceptive use, Papanicolaou smear history and human papillomavirus (HPV)-16 serology. For all four folate measures, the geometric mean in cases was lower than in controls (e.g., 11.6 vs. 13.0 nmol/L, P < 0.01 for the serum radiobinding assay). Folate measures using microbiologic and radiobinding assays were correlated (serum: r = 0.90; RBC: r = 0.77). For serum folate, multivariate-adjusted odds ratios (OR) in the lowest vs. highest quartile were 1.3 [95% confidence interval (CI) = 0.8--2.9] and 1.6 (0.9--2.9), using the microbiologic and radiobinding assays, respectively. For RBC folate, comparable OR were 1.2 (0.6--2.2) and 1.5 (0.8--2.7). Similar risks were obtained when restricting analyses to subjects with a history of HPV infection. Thus, low serum and RBC folate were each moderately, but nonsignificantly, associated with increased invasive cervical cancer risk. These findings support a role for one-carbon metabolism in the etiology of cervical cancer.

Alpha-tocopherol content in 62 edible tropical plants

Vitamin E was determined by the high-performance liquid chromatography (HPLC) method. All the plants tested showed differences in their alpha-tocopherol content and the differences were significant (p < 0.05). The highest alpha-tocopherol content was in Sauropus androgynus leaves (426.8 mg/kg edible portion), followed by Citrus hystrix leaves (398.3 mg/kg), Calamus scipronum (193.8 mg/kg), starfruit leaves Averrhoa belimbi (168.3 mg/kg), red pepper Capsicum annum (155.4 mg/kg), local celery Apium graveolens (136.4 mg/kg), sweet potato shoots Ipomoea batatas (130.1 mg/kg), Pandanus odorus (131.5 mg/kg), Oenanthe javanica (146.8 mg/kg), black tea Camelia chinensis (183.3 mg/kg),papaya Carica papaya shoots (111.3 mg/kg), wolfberry leaves Lycium chinense (94.4 mg/kg), bird chili Capsicum frutescens leaves (95.4 mg/kg), drumstick Moringa oleifera leaves (90.0 mg/kg), green chili Capsicum annum (87 mg/kg), Allium fistulosum leaves (74.6 mg/kg), and bell pepper Capsicum annum (71.0 mg/kg). alpha-Tocopherol was not detected in Brassica oleracea, Phaeomeria speciosa, Pachyrrhizus speciosa, Pleurotus sajor-caju, and Solanum melongena.

Serum carotenoids and vitamins and risk of cervical dysplasia from a case-control study in Japan

The relationships between risk of cervical dysplasia and dietary and serum carotenoids and vitamins were investigated in a case-control study. Cases were 156 women who attended Papanicolaou test screening in nine institutes affiliated with Japan Study Group of Human Papillomavirus (HPV) and Cervical Cancer and had cervical dysplasia newly histologically confirmed. Age-matched controls were selected from women with normal cervical cytology attending the same clinic. Blood sample and cervical exfoliated cells were obtained for measuring serum retinol, alpha-carotene, beta-carotene, zeaxanthin/lutein, cryptoxanthin, lycopene and alpha-tocopherol and for HPV detection. Higher serum level of alpha-carotene was significantly associated with decreased risk of cervical dysplasia after controlling for HPV infection and smoking status (odds ratio (OR) = 0.16, 95% confidence interval (CI) 0.04-0.62 for the highest as compared with the lowest tertile). Decreased risk for the highest tertile of serum lycopene (OR = 0.28) was marginally significant. Decreased risks observed for the highest tertiles of beta-carotene (OR = 0.65) and zeaxanthin/lutein (OR = 0.53), were not statistically significant.

Dietary factors in oral leukoplakia and submucous fibrosis in a population-based case control study in Gujarat, India

OBJECTIVES

To investigate the relationship of specific nutrients and food items with oral precancerous lesions among tobacco users.

DESIGN

A population-based case-control study.

SETTING

Villages in Palitana taluk of Bhavnagar district, Gujarat, India.

SUBJECTS AND METHODS

An interviewer-administered food frequency questionnaire, developed and validated for this population, was used to estimate nutrient intake in blinded, house-to-house interviews. Among 5018 male tobacco users, 318 were diagnosed as cases. An equal number of controls matched on age (+/- 5 years), sex, village, and use of tobacco were selected.

MAIN OUTCOME MEASURES

Odds ratios (OR) from multiple logistic regression analysis controlling for relevant variables (type of tobacco use and economic status).

RESULTS

A protective effect of fibre was observed for both oral submucous fibrosis (OSF) and leukoplakia, with 10% reduction in risk per g day-1 (P < 0.05). Ascorbic acid appeared to be protective against leukoplakia with the halving of risk in the two highest quartiles of intake (versus the lowest quartile: OR = 0.46 and 0.44, respectively; P < 0.10). A protective effect of tomato consumption was observed in leukoplakia and a suggestion of a protective effect of wheat in OSF.

CONCLUSION

In addition to tobacco use, intake of specific nutrients may have a role in the development of oral precancerous lesions.

Content of alpha-tocopherol in blood serum of human Papillomavirus-infected women with cervical dysplasias

The studies were carried out in a group of 228 female patients with normal cytological smear and 324 patients with cervical intraepithelial neoplasia. The applied method of identification, i.e., the human Papillomavirus (HPV) digene hybrid capture system, made it possible to select a control group consisting of 168 HPV-negative patients with normal Pap smear, as well as a group of 228 HPV-positive patients with cervical intraepithelial neoplasia. The high-performance liquid chromatography method was employed to evaluate the level of alpha-tocopherol in the blood serum of the patients who were examined. A statistically significantly lower level of alpha-tocopherol was observed in the blood serum of HPV-positive patients with cervical intraepithelial neoplasia. The risk of dysplasia was four times higher for an alpha-tocopherol level < 7.95 mumol/l.

Effects of beta-carotene and other factors on outcome of cervical dysplasia and human papillomavirus infection

Women with histopathologically confirmed cervical intraepithelial neoplasia (CIN) were followed at 3-month intervals in a randomized double-blinded trial to evaluate the efficacy of beta-carotene to cause regression of CIN. Questionnaire data, plasma levels of micronutrients, and a cervicovaginal lavage for human papillomavirus (HPV) detection were obtained at each visit, and an endpoint biopsy was performed at 9 months. Sixty-nine subjects had a biopsy endpoint evaluation; 9 of 39 (23%) subjects in the beta-carotene group versus 14 of 30 (47%) in the placebo group had regression of CIN (P = 0.039). Independent risk factors for persistent CIN at 9 months included type-specific persistent HPV infection (OR = 11.38, P = 0.006) and continual HPV infection with a high viral load (OR = 14.25, P = 0.007) at baseline and 9 months, an initial diagnosis of > or =CIN II (OR = 6.74, P = 0.016), and older age (OR for > or =25 years = 4.10, P = 0.072). After controlling for these factors, the beta-carotene and placebo groups did not differ in risk for having CIN at 9 months (OR = 1.53, P = 0.550). Resolution of baseline HPV infection was significantly correlated with non-high-risk HPV types (RR = 2.94, P = 0.015), age <25 years (RR = 2.62, P = 0.014), and douching after sexual intercourse (RR = 3.02, P = 0.012), but not with randomization group. Our data indicate that a large proportion of mild CIN lesions regress; age and HPV infection play an important role in the natural course of CIN; and repeated HPV testing may have a value in distinguishing women who need aggressive treatment for CIN versus those who do not. Supplementation of beta-carotene does not appear to have a detectable benefit in treatment of CIN.

Diet and prostate cancer: a case-control study

A case-control study, performed in two towns of Serbia (Yugoslavia) from 1990 to 1994, comprised 101 patients with histologically confirmed prostate cancer and 202 hospital controls individually matched by age (+/-2 years), hospital admittance and place of residence. Dietary information was obtained by using a standard questionnaire. After adjustment for possible confounders, risk factors for prostate cancer appeared to be the highest tertile of protein (odds ratio (OR) = 13.54, 95% confidence interval (CI) = 2.38-77.13), saturated fatty acid (OR = 3.63, 95% CI = 1.03-12.79), fibre (OR = 4.02, 95% CI = 1.38-11.73), and vitamin B12 intake (OR = 2.07, 95% CI = 1.08-3.97); a protective effect was found for the highest tertile of alpha-tocopherol (OR = 0.15, 95% CI = 0.05-0.53), calcium (OR = 0.37, 95% CI = 0.14-0.99) and iron intake (OR = 0.34, 95% CI = 0.12-0.95). There were significant (P < 0.05) linear trends in the odds ratios for alpha-tocopherol, vitamin B12, calcium and iron. According to logistic regression step by step analysis, risk factors for prostate cancer were dietary intake of retinol equivalent (OR = 1.64, 95% CI = 1.01-2.67) and vitamin B12 (OR = 1.87, 95% CI = 1.15-3.05), and a protective effect was found for dietary intake of iron (OR = 0.40, 95% CI = 0.27-0.58).

Vegetables, fruit, and cancer prevention: a review

In this review of the scientific literature on the relationship between vegetable and fruit consumption and risk of cancer, results from 206 human epidemiologic studies and 22 animal studies are summarized. The evidence for a protective effect of greater vegetable and fruit consumption is consistent for cancers of the stomach, esophagus, lung, oral cavity and pharynx, endometrium, pancreas, and colon. The types of vegetables or fruit that most often appear to be protective against cancer are raw vegetables, followed by allium vegetables, carrots, green vegetables, cruciferous vegetables, and tomatoes. Substances present in vegetables and fruit that may help protect against cancer, and their mechanisms, are also briefly reviewed; these include dithiolthiones, isothiocyanates, indole-3-carbinol, allium compounds, isoflavones, protease inhibitors, saponins, phytosterols, inositol hexaphosphate, vitamin C, D-limonene, lutein, folic acid, beta carotene, lycopene, selenium, vitamin E, flavonoids, and dietary fiber. Current US vegetable and fruit intake, which averages about 3.4 servings per day, is discussed, as are possible noncancer-related effects of increased vegetable and fruit consumption, including benefits against cardiovascular disease, diabetes, stroke, obesity, diverticulosis, and cataracts. Suggestions for dietitians to use in counseling persons toward increasing vegetable and fruit intake are presented.

Reproductive variables and risk of uterine cervical cancer in Norwegian registry data

The influence of reproductive variables on cervical cancer incidence, controlling for other sociodemographic factors, was estimated in Norwegian register and census data, using Poisson regression models. Among the 1.3 million women under observation, a total of 2,870 cases of cervical cancer were diagnosed. According to models restricted to parous women, parity level had no independent impact on cervical cancer incidence, but a clear effect of age at first birth was noted. It was most pronounced in the squamous cell carcinomas, where the incidence was reduced by 48 percent from age at first birth < 21 years to age at first birth 27+ years. Women without children had the same cervical cancer incidence as parous women with a first birth after age 24. The sociodemographic variables controlled for exerted a strong net effect on the cervical cancer incidence. Educational level was related inversely to the cancer risk. Moreover, an increased risk was seen for women who had given birth when they were still single (never married) and for those who were divorced/separated at the time of the last previous census. A fairly small excess risk was found to be associated with living in non-rural compared with rural areas.

Risk factors for invasive cervix cancer in young women

The aim of the study was to evaluate risk factors for invasive cervix cancer in young British women and to look for factors which might explain its increased incidence in younger ages. A case-control study involving 121 women with invasive cervix cancer diagnosed before the age of 40 years, and 241 matched controls was undertaken. Questions were asked about demography, sexual behaviour, reproductive and contraceptive history, smoking, diet and hygiene. Age at first intercourse and lifetime number of sexual partners were found to be the most important factors, whereas parity, educational attainment and social class were not related to risk. Smoking was only weakly related to risk (P = 0.01) and this effect disappeared after adjustment for sexual behaviour variables. A weak protective effective of increased fruit consumption was observed (P = 0.03), but again this became non-significant after adjustment for sexual behaviour. Only factors related to sexual behaviour were found to be important in this study and other cofactors often associated with invasive cancer in older women were not found to be involved. It is possible that genetic factors influencing viral persistence, and specific more virulent strains of human papillomavirus may be more important in early onset cases.

Nutrition and cervical neoplasia

Epidemiologic evidence on the relation between nutrition and cervical cancer is reviewed. Cervical cancer is the leading cancer among women in many developing countries, and remains a major public health problem worldwide. This review of nutritional research on cervical neoplasia encompasses the range of epithelial abnormalities from early preneoplastic lesions to invasive cancer. Identified risk factors for cervical neoplasia suggest a multifactorial etiology with several cancer-associated human papillomaviruses (HPV) as the central cause. Studies of nutritional predictors of cervical neoplasia to date, however, have been limited by inadequate HPV measures, which compromise the interpretations of findings. Current research using accurate measures of HPV will be most revealing. Nonetheless, agreement in findings from previous studies suggest a role for nutritional factors in some or all stages of cervical neoplasia. Low vitamin C and carotenoid status are associated fairly consistently with both cervical cancer and precursors, whereas results for vitamin E status are less consistent. The effect of folate status may be restricted to early preneoplastic cervical lesions and not to more advanced disease. Current research is addressing nutritional influences on HPV infection and persistence and on progression of cervical disease. Limitations and recommendations for future research directions are discussed in light of methodologic issues related to nutritional and HPV research.

Chemoprevention trials and surrogate end point biomarkers in the cervix

Cervical cancer is the second most common malignancy in women worldwide and remains a significant health problem for women, especially minority and underserved women. Despite an understanding of the epidemiologic risks, the screening Papanicolaou smear, and morbid and costly treatment, overall survival remains 40%. New strategies, based on the clinical and molecular aspects of cervical carcinogenesis, are desperately needed. Chemoprevention refers to the use of chemical agents to prevent or delay the development of cancer in healthy populations. Chemoprevention studies have several unique features that distinguish them from classic chemotherapeutic trials; these features touch on several disciplines and weave knowledge of the biology of carcinogenesis into the trial design. In the design of chemoprevention trials, four factors are important: high risk cohorts must be identified; suitable medications must be selected; study designs should include Phases I, II, and III; and studies should include the use of surrogate end point biomarkers. Surrogate end point biomarkers are sought because the cancer develops over a long period of time, and studies of chemopreventives would require a huge number of subjects followed for many years. Surrogate end point biomarkers serve as alternative end points for examination of the efficacy of chemopreventives in tissue. High risk cohorts include women with cervical intraepithelial neoplasia (CIN) or squamous intraepithelial lesions (SIL). Nutritional studies have helped define micronutrients of interest (folate, carotenoids, vitamin C, vitamin E). Other medications of interest include retinoids (4-hydroxyphenylretinamide [4-HPR], retinyl acetate gel, topical all-trans-retinoic acid), polyamine synthesis inhibitors (alpha-difluoromethylornithine [DFMO]), and nonsteroidal anti-inflammatory drugs (ibuprofen). Phase I chemoprevention studies of the cervix have tested retinyl acetate gel and all-trans-retinoic acid. Phase II trials of all-trans-retinoic acid, beta-carotene, and folic acid have been and are being carried out, whereas Phase III trials of all-trans-retinoic acid have been completed and have shown significant regression of CIN 2 but not CIN 3. Phase I studies of DFMO and Phase II studies of DFMO and 4-HPR are underway. Surrogate end point biomarkers under study include (1) quantitative cytology and histopathology; (2) human papillomavirus type testing; (3) biologic measures of proliferation, regulation, differentiation, and genomic instability; and 4) fluorescence spectroscopic emission. Clinical trials with biologic end points will contribute to our understanding of the neoplastic process and hence aid us in developing new preventive and therapeutic strategies.

Folic acid fortification of grain: an economic analysis

OBJECTIVES

The purpose of this study was to compare the economic costs and benefits of fortifying grain with folic acid to prevent neural tube defects.

METHODS

A cost-benefit analysis based on the US population, using the human capital approach to estimate the costs associated with preventable neural tube defects, was conducted.

RESULTS

Under a range of assumptions about discount rates, baseline folate intake, the effectiveness of folate in preventing neural tube defects, the threshold dose that minimizes risk, and the cost of surveillance, fortification would likely yield a net economic benefit. The best estimate of this benefit is $94 million with low-level (140 micrograms [mcg] per 100 g grain) fortification and $252 million with high-level (350 mcg/100 g) fortification. The benefit-to-cost ratio is estimated at 4.3:1 for low-level and 6.1:1 for high-level fortification.

CONCLUSIONS

By averting costly birth defects, folic acid fortification of grain in the United States may yield a substantial economic benefit. We may have underestimated net benefits because of unmeasured costs of neural tube defects and unmeasured benefits of higher folate intake. We may have overestimated net benefits if the cost of neurologic sequelae related to delayed diagnosis of vitamin B12 deficiency exceeds our projection.

Epidemiology of cervical intraepithelial neoplasia: the role of human papillomavirus

The evidence implicating specific HPV types in the aetiology of cervical cancer is now strong enough to establish a causative role. HPV infection of the cervix affects the developing immature metaplastic cells of the transformation zone. Cervical neoplasia can be viewed as the interaction of high risk papillomavirus and immature metaplastic epithelium. Once maturity is reached, there is minimal risk of subsequent development of cervical squamous neoplasia. Exposure to HPV is an extremely common event, especially in young sexually active women. Yet, despite frequent HPV exposure at that phase of life in which the cervical transformation zone is at its most vulnerable, established expressed disease is relatively uncommon. Most studies in which the natural history of CIN is not altered by cervical biopsy reveal a progression rate from low to high grade CIN of less than one third. Where viral type is taken into account, however, the progression rate from normal but high risk HPV-infected cervical epithelium to CIN 2 or 3 is higher. Despite this, most cervical abnormalities will not transform into invasive cancer, even if left untreated. The variance between the high rate of HPV infection, the intermediate rate of CIN and the relatively low rate of cervical cancer establishes a stepwise gradient of disease of increasing severity with decreasing prevalence. In an immunocompetent host, HPV infection alone does not appear to be sufficient to induce the step from high grade CIN to invasion. Epidemiological studies indicating that HPV infection with oncogenic viral types is far more common than cervical neoplasia suggest the necessity of cofactors in cervical carcinogenesis. The long time-lag between initial infection and eventual malignant conversion suggests that random events may be necessary for such conversion, and the spontaneous regression of many primary lesions suggests that most patients are not exposed to these random events. Potential cofactors include cigarette smoking, hormonal effects of oral contraceptives and pregnancy, dietary deficiencies, immunosuppression and chronic inflammation. In those women who develop cervical cancer, malignant progression is rarely rapid, more commonly taking many years or decades. Malignant progression has been documented in patients who presented initially with only low grade HPV-induced atypia. On the other hand, progression may be a misnomer, as 'apparent' progression may really represent adjacent 'de novo' development of higher grade CIN. Although most cervical cancers contain high risk HPV types, up to 15% of such cancers test negative for HPV, raising the possibility that a few, usually more aggressive, cervical cancers may arise from from a non-viral source.(ABSTRACT TRUNCATED AT 400 WORDS)

Primary prevention of gynecologic cancers

A shift from treatment to prevention of the three major gynecologic cancers is overdue. The traditional approach to cervical, endometrial, and ovarian cancers has been secondary or tertiary prevention--early detection and treatment or mitigation of damage, respectively. We reviewed the literature on these cancers to identify strategies for primary prevention. Cervical cancer behaves as a sexually transmitted disease. As with other such diseases, barrier and spermicidal contraceptives lower the risk of cervical cancer; the risk reduction approximates 50%. Combination oral contraceptives help prevent both endometrial and epithelial ovarian cancers. The risk of endometrial cancer among former oral contraceptive users is reduced by about 50% and that of ovarian cancer by about 30% to 60%. Weight control confers strong protection against endometrial cancer. Breast-feeding and tubal sterilization also appear to protect against ovarian cancer. Although women have a range of practical, effective measures available to reduce their risk of these cancers, few are aware of them. Without this information, women cannot make fully informed decisions about their health.

The protective but nonsynergistic effect of dietary beta-carotene and vitamin E on skin tumorigenesis in Skh mice

Various epidemiological and experimental studies have indicated that beta-carotene and vitamin E protect against a variety of cancers. This investigation determined whether a synergistic protective effect could be observed against chemically induced skin tumorigenesis in Skh mice by combining these two antioxidants in the diet. Forty-five mice were used in each of four diet groups. Control animals were fed standard mouse chow. Three other groups received the chow supplemented with one of the following: 0.5% beta-carotene, 0.12% vitamin E (added as d-alpha-tocopheryl succinate), or 0.5% beta-carotene + 0.12% vitamin E. Mice were topically treated with a single application of the initiator 7,12-dimethylbenz[a]anthracene and promoted with multiple applications of phorbol 12-myristate 13-acetate. Mice were observed for tumors each week for 27 weeks after initiation. The protective effect of each diet was determined by the decrease in the number of skin tumors in supplemented diet groups compared with that of the control diet group. Decreases in the number of cumulative tumors at Week 27 were 32% for beta-carotene-, 25% for vitamin E-, and 21% for beta-carotene+vitamin E-supplemented diet groups. However, differences in the number of tumors among the three groups supplemented with beta-carotene and/or vitamin E were not statistically significant. Thus, although protection was provided by the individual supplements, there was no synergistic effect for a decrease in the number of chemically induced skin tumors by the simultaneous dietary administration of beta-carotene and vitamin E.

Folate and cancer: A review of the literature

Folate, a water-soluble vitamin, part of the vitamin B complex, plays an important role in methylation reactions and DNA/RNA synthesis. This review examines the experimental and epidemiological evidence for the association between folate status and risk of cancer. Data have accumulated indicating that low folate status may promote carcinogenesis. Low folate levels are associated with cytogenetic abnormalities in vivo and in vitro. Findings from animal studies are conflicting and suggest that the effect of folate on neoplasia depends on factors such as the animal and tumor model, the type, timing, dose, and length of application of carcinogen, the stage of carcinogenesis, and the level and form of folate administered. Epidemiological studies examined the association between folate and cancer of the cervix, colorectum, lung, esophagus, and brain and suggest that low folate status may play an important role early in the neoplastic process. The potential for inhibition of precursor lesions in the cervix and colorectum, namely, cervical intraepithelial neoplasia and adenomatous polyps, respectively, is of particular interest. Additional research designed to clarify the role of folate in carcinogenesis is warranted.

Ascorbic acid (vitamin C) modulates the mutagenic effects produced by an alkylating agent in vivo

Recent reports suggest that ascorbic acid (vitamin C) inhibits tumorigenesis as well as exerts a protective effect against mutagenesis in vitro; however, there is no information on its ability to affect gene mutations induced in vivo. In this study, we have investigated the antimutagenic effects of ascorbic acid on the frequency of 6-thioguanine-resistant (6-TGr) T-lymphocytes produced in Fischer 344 rats dosed with the direct-acting alkylating agent, N-ethyl-N-nitrosourea (ENU). The frequency of 6-TGr T-lymphocytes from the spleen measured five weeks after ENU treatment indicated that ENU produced a substantial mutagenic response. Pretreatment and/or post-treatment of rats with ascorbic acid administered in the drinking water appeared to inhibit the response, but the inhibition was statistically significant only when data from the various dosing schedules were pooled. In addition, there was no clear dose-dependency to the inhibitory effect of ascorbic acid. To further evaluate the time effects of the vitamin supplement on ENU mutagenicity, rats were exposed to the mutagen together with ascorbic acid, which was given continuously for the entire duration of the experiment. At specific times after ENU treatment, the frequency of 6-TGr T-cells was determined in lymphocytes isolated from the spleen and the thymus. Time-dependent increases in the frequency of 6-TGr T-cells were observed with ENU treatment; ascorbic acid significantly reduced the ENU-mediated mutagenic responses, most dramatically in the spleen at weeks 6 and 8 (P < 0.0001), and to a lesser extent in the thymus (P < 0.01 at week 6 and P < 0.006 at week 8). Our data suggest that ascorbic acid intake affects the in vivo mutagenicity of ENU, a direct-acting mutagen/carcinogen, and that the reported inhibitory effects of the antioxidant on carcinogenesis may be partially mediated by its effects on mutagenesis. Although it is difficult to extrapolate from rodent studies to humans, the results presented suggest an explanation for epidemiological data that link vitamin C ingestion with decreased cancer risk.

Lung glutathione reductase induction in aging catalase-depleted frogs correlates with early survival throughout the life span

A comprehensive experimental study on free radical-related parameters was performed in the lung throughout the life span of 220 initially young or old frogs. No age related differences were found transversely or longitudinally for lung superoxide dismutase, catalase, Se-dependent and -independent glutathione peroxidases, glutathione reductase, GSH, GSSG, or GSSG/GSH ratio. Continuous catalase depletion with aminotriazole led to glutathione reductase induction in the lung after 14.5 months of experimentation. This was accompanied by a great increase in survival rate of treated animals in relation to controls (especially in the old group). After 26.5 months of experimentation, glutathione reductase induction was lost and GSSG/GSH values tended to increase. This was followed by a 3-month long period of acute decrease in survival rate of treated animals. It is suggested that a high antioxidant/prooxidant balance is of protective value against causes of early death and can possibly be used in the future (when appropriately controlled) to increase the number of healthy years of the normal life span.