Many studies have reported variable, and frequently suboptimal, levels of knowledge of oral cancer, risk factors, and diagnosis among both the public and health-care professionals. Although it is among the ten most common cancers worldwide, OSCC is rarely mentioned in the popular press, and public awareness is dismal (Canto et al., 1998). Significant numbers of the public are unaware of risk factors or even that OSCC exists, sometimes even after high-profile public education campaigns (Papas et al., 2004; Stahl et al., 2004). The reported trend among healthcare professionals is, unsurprisingly, that the knowledge and confidence of appropriate practice is related to education and experience, being greater in specialists than general dental practitioners, who in turn tend to be better informed than general medical practitioners and other health-care professionals (Reed et al., 2005; Sohn et al., 2005; Kujan et al., 2006).
From the perspective of improving the prognosis, there are two major stumbling blocks for a preventive approach. First, although many groups have attempted to educate both public and professionals about the signs and symptoms of OSCC, there is no robust evidence that these campaigns have produced a significant long-term change in the knowledge, attitudes, or behaviors of all the targeted groups or shortened delays in diagnosis (McLeod et al., 2005). Second, the probability of being diagnosed with advanced disease does not relate well to recorded delays, since variations in disease stage at presentation may also reflect underlying differences in the speed of progression of the lesion, and symptomatology does not always correlate with tumor stage (Scott et al., 2005).
Diagnostic Delays
Delays in diagnosis may occur as a result of patient delay in presentation or professional delay in referral to an appropriate specialist center, or both (Onizawa et al., 2003; Llewellyn et al., 2004).
Oral Cancer Screening Programs
Oral cancer fulfills many of the criteria proposed by Wilson and Junger (1968) for a disease to be suitable for screening (Speight et al., 1993), but there are many logistical hurdles and costs to be overcome in order to assess the feasibility of screening and to implement a program. As a consequence, most of the research has reported on process measures such as diagnostic test performance (Moles et al., 2002; Downer et al., 2004) or uptake or compliance with the screening (Speight et al., 2006). Where outcomes have been reported, they have mainly been proxy outcomes such as absolute survival. Survival is an unreliable outcome for this purpose because it is subject to the effects of both lead-time bias and length bias.
A Cochrane systematic review (Kujan et al., 2003) found only one cluster-randomized controlled clinical trial using population-based mortality as the primary outcome measure (Sankaranarayanan et al., 2005). This trial, based in Kerala, India, randomized nearly 200 000 people to 13 clusters to either receive periodic screening (seven clusters) in the form of a visual examination at 3-year intervals or no screening (six clusters). The results indicate no appreciable difference in OSCC mortality between the screened (21.2/100 000 person-years) and nonscreened groups (21.3/100 000 person-years).
In the absence of reliable data on effectiveness, it is difficult to justify the expense of setting up large-scale randomized controlled trials in either developed or developing countries. In an attempt to provide such data, Speight et al. (2006) undertook a computer simulation modeling exercise of the cost-effectiveness of oral cancer screening in primary care in the UK, based on data from primary research, systematic reviews, published health service costs, and – for model parameters where no robust data were available – expert opinion. The model indicated that opportunistic screening of high-risk individuals might be cost-effective in either general dental practice (because dentists performed relatively well in screening) or general medical practice (because of a greater throughput of at-risk patients). However, there was considerable uncertainty in some of the model parameters used.
Opportunities And Barriers To Progress
The randomized controlled trial in Kerala is still in progress. Since it is the only trial to examine the impact of population-based screening for OSCC with mortality as the primary outcome, the long-term results are eagerly awaited. The transferability of the results to other countries or health-care settings will be a source of debate.
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