ORAL HEALTH EVIDENCE-BASED PRACTICE PROGRAM
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Title Antioxidants Play a Preventative Role in Patients At-Risk for Oral Cancer
Clinical Question Does a diet rich in antioxidants reduce the risk of oral cancer in adult patients as compared to patients with inadequate diets?
Clinical Bottom Line The results that are reviewed highly favor the preventative role of antioxidants in patients at-risk for oral cancer, however, no definitive proof has been found according to the studies that have been conducted to date.
Best Evidence (you may view more info by clicking on the PubMed ID link)
PubMed ID Author / Year Patient Group Study type
(level of evidence)
#1) 17684136Rossi/2007805 oral cavity and pharyngeal cancer patients. Case control
Key resultsFor the study, the case group was 805 patients with oral or pharyngeal cancer diagnosed within the year. The control group consisted of 2,081 subjects admitted for a wide variety of nonneoplastic conditions. The patients’ diets were assessed over a 2 year period. Of specific interest was the amount and frequency of consumption of 6 types of flavonoids. There was an inverse relationship between flavonoids and oral and pharyngeal cancer that was consistent across categories of sex, age, education, BMI, tobacco smoking, and alcohol drinking. It is worth noting that this association of flavonols was stronger in never/ex-smokers than in current smokers.
#2) 19892663Tsao/2009Patients with high-risk oral premalignant lesions (OPL).RCT
Key resultsThe patients evaluated in this study were randomly assigned to one of four groups- a placebo group, ones receiving green tea extract (GTE) at 500, 750, or 1,000mg/m(2) 3 times a day for 12 weeks. There was a significant clinical response to the groups receiving the 2 highest doses of GTE- suggesting that the results seen are dose-related. The preventative activity of the GTE is thought to be a result of the inhibition of angiogenesis in OPLs which promote carcinogenesis.
#3) 11706428Schwartz/199380 adult male hamsters.Animal study
Key resultsThe 80 hamsters were divided into 4 groups; Group 1- DMBA treated (tumor control), Group 2- DMBA treated and vitamin E administered systemically, Group 3- untreated control, Group 4- vitamin E control. Levels of protein expression (p53) were assessed after immunohistochemical staining of buccal pouch. Significant inhibition of tumor development was found in animals receiving vitamin E after 8 weeks and particularly at the end of week 14. Vitamin E acts as an inhibitor of free radical formation and increases DNA repair. Mutant p53 had strong expression in carcinomas of controls and was relatively absent in tumors of animals receiving vitamin E. These animals also saw an increase in wild type p53 levels (which is stimulated by vitamin E.)
Evidence Search "Mouth Neoplasms"[Mesh] AND "Antioxidants"[Mesh]
Comments on
The Evidence
Study 1: Validity- This study had adequate compliance, follow-up, equal treatment of case and control groups, and a low level of bias. There was a large sample size and a very reproducible and valid food questionnaire was used to obtain the results. Perspective-The results presented in the study highlighted the variable consumption of the individuals sampled, which increases the validity and strength of the results. It is also important to consider that the study was conducted in Italy, where a Mediterranean diet is common. Also, the specific flavonoid content of the nutrients consumed cannot be regulated or measured, so these might vary depending on the region. Study 2: Validity- Of the 41 eligible patients, 39 were evaluated after 12 weeks of treatment. The groups were equally randomized and given the same treatment during the study. Recall bias is unlikely, but there is a potential conflict of interests in that one of the authors is an employee of the company who funded the trial. Perspective- The evidence that was found in this study is highly suggestive of a dose-related response of the OPLs to the GTE treatment administered. The preventative role of GTE in patients with premalignant lesions is relevant and significant. Studies conducted over a longer period of time would be beneficial in evaluating the long-term effects of GTE administration. Study 3: Validity- The test animals were similar at the start, all completed treatment with adequate follow up, proper treatment, and no recall bias. Perspective- The fact that this is a lab study makes this evidence weak for applicability to human patients. Other studies involving the same genes and treatment have been initiated and will add validity should similar results be found. Many other types of studies are referenced that have shown the same relationship between vitamin E and the p53 suppressor gene.
Applicability This information is highly applicable to patients, especially if they are at higher risk for developing oral cancer (smokers, etc). The introduction of more antioxidants to the diet is relatively convenient and cost effective. Educating the patient on the advantages of such additions/changes is a key element to the success of this therapy.
Specialty/Discipline (Public Health) (Oral Medicine/Pathology/Radiology) (General Dentistry)
Keywords Mouth Neoplasms, Antioxidants
ID# 2621
Date of submission: 03/22/2014spacer
E-mail CearleyA@livemail.uthscsa.edu
Author Allie Cearley
Co-author(s)
Co-author(s) e-mail
Faculty mentor/Co-author Georgiana Gross, MPH
Faculty mentor/Co-author e-mail GrossG@uthscsa.edu
Basic Science Rationale
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