Undernutrition as a risk factor for cervical intraepithelial neoplasia: a case-control analysis

Lower dietary mineral intake is significantly associated with cervical cancer risk in a population-based cross-sectional study

Population-based studies investigating the association between dietary mineral intake and risk of cervical intraepithelial neoplasia (CIN) or cervical cancer in Chinese women are few. We performed a cross-sectional analysis of screening data obtained from 2,304 women in 2014 within an ongoing cohort study comprising 40,000 women in China. Dietary intake was assessed using a semiquantitative food frequency questionnaire. Nutrition intake was calculated using a 26-item list of food sources drawn from a validated, comprehensive database. All participants were surveyed through in-person interviews, physical examinations, and laboratory tests. The Pearson chi-square test was used for categorical variables. Multivariable logistic regression models were used to evaluate the relationship between dietary mineral intake and CIN+ risk. The food frequency questionnaire exhibited acceptable reproducibility and reasonable validity in assessing nutrient intakes among these women. After adjusting for multiple potential confounders, low dietary calcium intake was associated with CIN2+ risk (first versus fourth quartile: odds ratio [OR]=1.52, 95% confidence interval [CI]: 1.01-2.32). Similar for magnesium (OR=1.80, 95% CI: 1.20-2.68), phosphorus (OR=1.69, 95% CI: 1.12-2.55), zinc (OR=1.55, 95% CI: 1.03-2.34), and potassium (OR=1.92, 95% CI: 1.28-2.88). Low dietary intakes of calcium and potassium were significantly associated with CIN1 risk. Increased CIN2+ risk correlated with rates of no oral contraceptives and lower levels of dietary Potassium. These results thus proposed that low dietary mineral intake was an independent risk factor, potential synergy may exist between low dietary mineral levels and oral contraceptives contribute to the development of higher-grade CIN and cervical cancer.

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.

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.