Screening programmes for the early detection and prevention of oral cancer
Abstract
Background
Oral cancer is an important global healthcare problem, its incidence is increasing and late‐stage presentation is common. Screening programmes have been introduced for a number of major cancers and have proved effective in their early detection. Given the high morbidity and mortality rates associated with oral cancer, there is a need to determine the effectiveness of a screening programme for this disease, either as a targeted, opportunistic or population based measure. Evidence exists from modelled data that a visual oral examination of high‐risk individuals may be a cost‐effective screening strategy and the development and use of adjunctive aids and biomarkers is becoming increasingly common.
Objectives
To assess the effectiveness of current screening methods in decreasing oral cancer mortality.
Search methods
The following electronic databases were searched: the Cochrane Oral Health Group Trials Register (to 20 May 2010), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2010, Issue 2), MEDLINE via OVID (1950 to 20 May 2010), EMBASE via OVID (1980 to 20 May 2010) and CANCERLIT via PubMed (1950 to 20 May 2010). There were no restrictions regarding language or date of publication.
Selection criteria
Randomised controlled trials (RCTs) of screening for oral cancer or potentially malignant disorders using visual examination, toluidine blue, fluorescence imaging or brush biopsy.
Data collection and analysis
The original review identified 1389 citations and this update identified an additional 330 studies, highlighting 1719 studies for consideration. Only one study met the inclusion criteria and validity assessment, data extraction and statistics evaluation were undertaken by six independent review authors.
Main results
One 9‐year RCT has been included (n = 13 clusters: 191,873 participants). There was no statistically significant difference in the age‐standardised oral cancer mortality rates for the screened group (16.4/100,000 person‐years) and the control group (20.7/100,000 person‐years). A 43% reduction in mortality was reported between the intervention cohort (29.9/100,000 person‐years) and the control arm (45.4/100,000) for high‐risk individuals who used tobacco or alcohol or both, which was statistically significant. However, this study had a number of methodological weaknesses and the associated risk of bias was high.
Authors' conclusions
Although there is evidence that a visual examination as part of a population based screening programme reduced the mortality rate of oral cancer in high‐risk individuals, whilst producing a stage shift and improvement in survival rates across the population as a whole, the evidence is limited to one study and is associated with a high risk of bias. This was compounded by the fact that the effect of cluster randomisation was not accounted for in the analysis. Furthermore, no robust evidence was identified to support the use of other adjunctive technologies like toluidine blue, brush biopsy or fluorescence imaging within a primary care environment. Further randomised controlled trials are recommended to assess the efficacy, effectiveness and cost‐effectiveness of a visual examination as part of a population based screening programme.
PICOs
Plain language summary
Screening programmes for the early detection and prevention of oral cancer
There is a need to understand whether screening programmes could detect oral cancer earlier and so reduce the number of deaths from this disease. Cancer of the mouth is becoming increasingly common and has a low survival rate, as many patients present with advanced disease. Screening the general population for oral cancer might make it possible to detect cases earlier. The most common 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 cells. 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 effected by bias.
