This review, carried out by authors of the Cochrane Oral Health Group, was conducted to investigate the effectiveness of current screening programmes in detecting oral cancer at an early stage and whether or not they can assist in decreasing deaths due to oral cancer.
Oral cancer is increasing worldwide and it is the sixth most common cancer overall. The highest rates of oral cancer occur in the most disadvantaged sections of the population. Important risk factors in the development of the disease are tobacco, alcohol, age, gender and sunlight although a role for candida (which causes thrush) and the human papillomavirus (which causes warts) has also been documented. People who are heavy drinkers and also smoke have 38 times the risk of developing oral cancer compared with people who do neither. These factors are considered to be especially important in the development of the disease in young people, a group experiencing an increasing incidence of the disease, particularly in countries with a high incidence of it.
Geographic variation in the occurrence of oral cancer around the world is wide. For example 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 is oral cancer whereas only 3% of new cases of cancer in the United Kingdom are oral cancer.
When people first seek medical help, their oral cancer is usually at a late or advanced stage and the effects of the condition as well as the treatment for it can be extremely debilitating. Death rates from oral cancer and the negative effects of the disease are high and increasing rather than declining as for other cancers such as breast and colon.
Prevention screening programmes for other cancers have proven to be effective in early detection. However, whilst there maybe advantages to screening there are disadvantages because screening has the potential to produce either false positive or false negative results. Screening can be targeted at high-risk groups, it can be opportunistic, for example when people attend health services for other reasons, or can be done by looking at statistics across the population as a whole.
The aim of preventive screening for early detection of oral cancer is to screen individuals for pre-cancerous conditions which are lesions such as leukoplakia. The most common screening method is visual inspection by a clinician but other techniques include the use of a special blue dye, the use of imaging techniques and measuring biochemical changes to normal calls.
The evidence on which this review is based is up to date as of 22 July 2013. The only study included was based in rural areas of the city of Trivandrum in Kerala, India. The study included 191,873 apparently healthy adults aged 35 years or older living in 13 clusters with an average of 14,759 participants in each cluster. Screening took place in seven clusters (96,517 participants) and six clusters acted as a control (95,356 participants). Participants were excluded if they were bedridden, if they had open tuberculosis, other debilitating diseases or were already suffering from oral cancer.
Healthcare workers trained in the detection of oral lesions undertook the screening of participants and the social history of participants including use of paan, tobacco, alcohol and dietary supplements was recorded.
The review found that overall there is not enough evidence to decide whether screening by visual inspection reduces the death rate for oral cancer and there is no evidence for other screening methods. However, there is some evidence that it might help reduce death rates in patients who use tobacco and alcohol although the only included study may be affected by bias.
Quality of evidence