Only a few studies have been carried out to assess the effect of blood serum levels of antioxidant vitamins and the risk of cervical cancer. The findings from these studies were inconsistent. However, a new study conducted with 1,200 participants from the city of Harbin, in Northern China, has yielded promising results, indicating that alpha carotene, beta carotene, vitamin E and vitamin C could be beneficial in reducing the risk of cervical cancer in Chinese women. The effect was particularly noticeable in women who suffered from the effects of passive smoking.
A new paper (1) has demonstrated an encouraging, dose-dependent negative correlation between the intake of antioxidant vitamins and the incidence of cervical cancer in Chinese women. The new work reinforces a previous meta-analysis carried out in 2011 (2), which documented the beneficial effect of beta carotene, vitamin C and vitamin E on reducing the risk of cervical cancer.
Cervical cancer arises from the abnormal growth of cells in the cervix. It is often asymptomatic in the early stages. It is the fourth most common form of cancer in women worldwide (3).
The new study was conducted in the northern Chinese city of Harbin, the capital city of Heilongjiang Province. The participants were women aged 18 to 70 years, of which 458 had cases of invasive cervical cancer, whilst a further 742 were matched controls. Intake assessments were made using validated food frequency questionnaires, and absolute blood serum levels of antioxidant vitamins were measured. The odds ratios (OR) comparing the highest quartile with the lowest quartile of serum antioxidant vitamin levels gave values of 0.66, 0.63, 0.53 and 0.48 for alpha carotene, beta carotene, vitamin E and vitamin C respectively. There was no correlation with retinol.
It is well known that smoking greatly increases the risk of cancer, including cervical cancer. In China, very few women smoke but some 60% are subject to the effects of passive smoking (1). In the current study, the beneficial effects of antioxidant vitamins were particularly strong in the group of passive smokers. Antioxidant vitamins, such as vitamin E, are thought to be able to reduce the oxidative damage caused by smoking by scavenging free radicals and blocking nitrosamine formation.
It is hoped that this study will encourage similar studies to be set up in other geographical areas around the world.