Taking action on oral cancer

OLYMPUS DIGITAL CAMERA

Biopsy of a highly differentiated squamous cell carcinoma of the mouth

Cancer of the mouth is a serious condition and only half of those that develop the disease survive after five years. It is the sixth most common cancer across the world. People who are heavy drinkers and also smoke have 38 times more risk of developing oral cancer than those who do neither. Geographic variation in the occurrence of oral cancer around the world is wide. It is the most common cancer for men in India, Sri Lanka and Pakistan and 30% of all new cases of cancer in these countries are oral cancer. Death rates from oral cancer and the negative effects of the disease are high and increasing compared with other forms of cancer, such as breast or colon cancer.

This month is Mouth Cancer Action Month, and the Cochrane Oral Health Group has published a new review and a review update on the diagnosis of oral cancer in The Cochrane Library.

Clinical assessment to screen for the detection of oral cavity cancer and potentially malignant disorders in apparently healthy adults is the Group’s first published review of Diagnostic Test Accuracy Studies.

Oral cancer is often preceded by visible lesions, which can be treated and result in better outcomes for patients if they are identified early in their development. There is a need to understand how good different types of tests are at the early detection of oral cancer and the lesions that precede it (potentially malignant disorders of the lip and oral cavity). The most common method is an oral visual inspection by a dentist or doctor, but other tests can include the use of a blue “dye”, illumination with a special light or self-examination by the individual.

The review included 13 studies of apparently healthy adults which looked at the diagnostic accuracy of the conventional oral examination used on its own or in combination with one of the above tests. 68,362 participants were recruited to these studies. After analysing the results, the review team found that visual examination by a front-line health worker is the best method of detection. Between 59% and 99% of mouth cancers were detected, although sometimes normal tissue was mistaken for oral cancer. The other techniques which were examined were not as good as visual examination, and detected less than a third of cases. General dental practitioners and health professionals should remain vigilant for signs of potentially malignant disorders whilst performing routine oral examinations in practice.

This review is published alongside a review update on Screening programmes for the early detection and prevention of oral cancer. This review considers the effectiveness of current screening programmes in detecting oral cancer at an early stage, and whether they can assist in decreasing deaths due to oral cancer. Prevention screening programmes have proved to be effective in early detection of other cancers, although screening has the potential to produce either false positive or false negative results.

Only one study met the inclusion criteria for this review. It was undertaken in Kerala, India and included 191,873 people. This study provides some evidence that screening might help to reduce death rates in patients who use tobacco and alcohol, as there was a 24% reduction in oral cancer mortality between the intervention and control arms of the trial for these people. However, the review team found that the trial was at risk of bias and one study alone does not provide enough evidence to come to a conclusion on the efficacy of screening programmes. Further randomized controlled trials are recommended. These should be well designed and should ensure that the methodology is clearly reported.

Links

Walsh T, Liu JLY, Brocklehurst P, Glenny A-M, Lingen M, Kerr AR, Ogden G, Warnakulasuriya S, Scully C. Clinical assessment to screen for the detection of oral cavity cancer and potentially malignant disorders in apparently healthy adults. Cochrane Database of Systematic Reviews 2012 , Issue 11 . Art. No.: CD010173. DOI: 10.1002/14651858.CD010173

Brocklehurst P, Kujan O, O’Malley LA, Ogden G, Shepherd S, Glenny A-M. Screening programmes for the early detection and prevention of oral cancer. Cochrane Database of Systematic Reviews 2010 , Issue 11 . Art. No.: CD004150. DOI: 10.1002/14651858.CD004150.pub3