Source: Evid Based Dent, January 1, 2010; 11(1): 24
Author: I Al-Dakkak

Data sources:
Medline, Embase, ISI Proceedings and the reference lists of relevant articles were used to find relevant studies.

Study selection:
Studies were included if: they presented original data from observational studies; included patients with a confirmed pathological diagnosis of oral or oropharyngeal squamous cell carcinoma; the outcome of interest was clearly defined as disease stage (TNM classification); the exposure of interest was total diagnostic delay, defined as the period between the patient noticing either the first sign or symptom and definitive diagnosis (data were collected from interviews using a standardised questionnaire and medical records); provided relative risks (RR) and 95% confidence intervals (CI) or provided enough data to allow calculation of these figures.

Data extraction and synthesis:
Quality assessment was undertaken independently by two reviewers and followed the recommendations of the Meta-analysis of Observational Studies in Epidemiology (MOOSE). Meta-analysis was conducted using fixed and random-effects models.

Results:
Nine studies carried out in nine different countries met the inclusion criteria and were included in the analysis. The fixed-effects pooled relative risk (RR) of advanced stages of oropharyngeal cancer when diagnostic delay is present was 1.32 (95% CI, 1.07-1.62). This association was stronger when the analysis was restricted to oral cancer (pooled RR, 1.47; 95% CI, 1.09-1.99) and when the delay was longer than 1 month (pooled RR, 1.69; 95% CI, 1.26-2.77).

Conclusions:
The probability for people with delayed diagnosis to present with an advanced-stage tumour at diagnosis was significantly higher than that of individuals with no delay in diagnosis. New prospective studies with strict methodology are needed, however, to shed more light on this association.

Author’s affiliation:
Centre for Evidence-based Dentistry, Oxford, UK.