Key messages
- There is a lack of high-certainty evidence to support the use of screening tests for cancer of the mouth and conditions that may lead to mouth cancer in the general population.
- General dental practitioners and healthcare professionals should be watchful for signs of oral potentially malignant disorders (OPMD) and malignancies whilst performing routine oral examinations in practice for other common oral lesions/conditions.
Detection of oral cancer
Cancer of the mouth (oral cancer) is a serious condition, and only half of those that develop the disease will survive after 5 years. This is because it is often detected late. Early detection when the oral cancer is small or as a 'preceding' condition or lesion (which can become cancer) can result in simpler treatment and much better outcomes. As a result, 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.
What did we want to find out?
The aim of this review was to find out the accuracy of different screening tests for cancer of the mouth and conditions that may lead to mouth cancer.
What did we do?
We searched for studies that reported the test accuracy of different screening tests in detecting cancer of the mouth or OPMDs during a screening procedure. Diagnosis of cancer of the mouth or OPMDs was provided by specialist clinicians or pathologists, or alternatively through follow-up. We compared and summarised the results of the studies and rated our confidence in the evidence, based on factors such as study methods and sizes.
What did we find?
We included 18 studies recruiting 72,202 participants, published between 1986 and 2019. These studies evaluated a conventional oral examination (COE) or visual inspection (10 studies), mouth self-examination (four studies), and remote screening (three studies). One randomised controlled trial of test accuracy directly compared conventional oral examination plus vital rinsing with conventional oral examination alone.
No eligible studies evaluated the accuracy of tests of blood or saliva.
There was substantial variation in the participants that were recruited, the setting, the prevalence of mouth cancer or OPMDs, and how the different tests were carried out, and so we were unable to pool the data.
- Most studies evaluated the accuracy of the different COEs (10 studies, 25,568 participants). The prevalence of mouth cancer or OPMDs in these studies ranged from 1% to 51%. For the seven COE studies with a prevalence of 10% or lower, a prevalence more comparable to the general population, the sensitivity estimates (proportion of true positives) ranged from 0.50 to 0.99 with specificity estimates (proportion of true negatives) from 0.94 to 0.99.
- Evidence for mouth self-examination (4 studies, 35,059 participants) and remote screening (3 studies, 3600 participants) was more limited.
What are the limitations of the evidence?
We judged the overall certainty of the evidence for COE to be low and downgraded for the variation across studies and applicability of the study samples. We judged the overall certainty of the evidence for mouth self-examination and remote screening to be very low, and downgraded for variation across studies, applicability of the study samples, and imprecise accuracy estimates.
How up to date is this evidence?
The evidence is up to date to October 2020.
There is a lack of high-certainty evidence to support the use of screening programmes for oral cavity cancer and OPMD in the general population. Frontline screeners such as general dentists, dental hygienists, other allied professionals, and community healthcare workers should remain vigilant for signs of OPMD and OSCC.
The early detection of oral cavity squamous cell carcinoma (OSCC) and oral potentially malignant disorders (OPMD), followed by appropriate treatment, may improve survival and reduce the risk for malignant transformation respectively. This is an update of a Cochrane Review first published in 2013.
To estimate the diagnostic test accuracy of conventional oral examination, vital rinsing, light-based detection, mouth self-examination, remote screening, and biomarkers, used singly or in combination, for the early detection of OPMD or OSCC in apparently healthy adults.
Cochrane Oral Health's Information Specialist searched the following databases: Cochrane Oral Health's Trials Register (to 20 October 2020), MEDLINE Ovid (1946 to 20 October 2020), and Embase Ovid (1980 to 20 October 2020). The US National Institutes of Health Trials Registry (ClinicalTrials.gov) and the World Health Organization International Clinical Trials Registry Platform were searched for ongoing trials. No restrictions were placed on the language or date of publication when searching the electronic databases. We conducted citation searches, and screened reference lists of included studies for additional references.
We selected studies that reported the test accuracy of any of the aforementioned tests in detecting OPMD or OSCC during a screening procedure. Diagnosis of OPMD or OSCC was provided by specialist clinicians or pathologists, or alternatively through follow-up.
Two review authors independently screened titles and abstracts for relevance. Eligibility, data extraction, and quality assessment were carried out by at least two authors independently and in duplicate. Studies were assessed for methodological quality using the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2). We reported the sensitivity and specificity of the included studies. We provided judgement of the certainty of the evidence using a GRADE assessment.
We included 18 studies, recruiting 72,202 participants, published between 1986 and 2019. These studies evaluated the diagnostic test accuracy of conventional oral examination (10 studies, none new to this update), mouth self-examination (four studies, two new to this update), and remote screening (three studies, all new to this update). One randomised controlled trial of test accuracy directly evaluated conventional oral examination plus vital rinsing versus conventional oral examination alone. There were no eligible studies evaluating light-based detection or blood or salivary sample analysis (which tests for the presence of biomarkers for OPMD and OSCC). Only one study of conventional oral examination was judged as at overall low risk of bias and overall low concern regarding applicability.
Given the clinical heterogeneity of the included studies in terms of the participants recruited, setting, prevalence of the target condition, the application of the index test and reference standard, and the flow and timing of the process, the data could not be pooled within the broader categories of index test. For conventional oral examination (10 studies, 25,568 participants), prevalence in the test accuracy sample ranged from 1% to 51%. For the seven studies with prevalence of 10% or lower, a prevalence more comparable to the general population, the sensitivity estimates were variable, and ranged from 0.50 (95% confidence interval (CI) 0.07 to 0.93) to 0.99 (95% CI 0.97 to 1.00); the specificity estimates were more consistent and ranged from 0.94 (95% CI 0.88 to 0.97) to 0.99 (95% CI 0.98 to 1.00). We judged the overall certainty of the evidence to be low, and downgraded for inconsistency and indirectness.
Evidence for mouth self-examination and remote screening was more limited. We judged the overall certainty of the evidence for these index tests to be very low, and downgraded for imprecision, inconsistency, and indirectness. We judged the evidence for vital rinsing (toluidine blue) as an adjunct to conventional oral examination compared to conventional oral examination to be moderate, and downgraded for indirectness as the trial was undertaken in a high-risk population.