Oral squamous cell carcinoma is a lethal and deforming disease and, as we have seen, there is a serious and realistic threat that a global epidemic of mouth cancer may occur during the 21st century. The last few decades have seen real advances in diagnostic techniques, refinements in ablative tumour surgery and improvements in complex surgical reconstruction of the mouth and face. All of these developments, together with modern chemoradiotherapy regimes, have undoubtedly improved the loco-regional control and quality of life for oral cancer patients.
Unfortunately, however, 5-year mortality rates remain at near 50% levels with patients still dying from local recurrence and now increasingly from widespread blood-borne metastases as well. It has also been recognised more recently that second or even third primary tumours may affect patients as a result of field change cancerisation in the upper aerodigestive tract, and that such recalcitrant disease is highly likely to ultimately prove fatal.
Any further improvements in the mortality rates for mouth cancer will thus require much earlier intervention during the process of carcinogenesis. The oral cavity, unlike many other high-risk upper aerodigestive tract sites, is readily inspected. We are also fortunate to recognise that many, if not all, oral cancers are preceded by pre-invasive potentially malignant disorders that can be detected as either localised or sometimes more widespread mucosal abnormalities.
Potentially malignant disorders may thus present as localised intra-oral leukoplakias, erythroplakias and mixed erythroleukoplakic lesions, and sometimes as more widespread mucosal conditions or as manifestations of systemic conditions. All of these share a common but unpredictable propensity for cancer development.
Whilst the clinical recognition of a mucosal abnormality is relatively straightforward, the precise diagnosis ascribed to an individual patient presenting with a potentially malignant disorder is in reality a more demanding process, which requires detailed coordination of specific clinical and pathological data. More recently, we have recognised the importance and desirability of being able to distinguish ‘high-risk’ from ‘low-risk’ cases, in terms of the overall likelihood of transformation to malignancy.
Historically, there has been confusion and disagreement over both the appropriateness and the effectiveness of treatment for oral potentially malignant disorders. In this book we have presented a case for a proactive and interventional management strategy based upon laser surgical excision of individual potentially malignant lesions and a careful and detailed post-surgical follow up and oral surveillance.
Interventional surgical treatment, as illustrated in practice in the operating theatre in Figure 12.1, is effective in removing active precancer disease, and thus preventing same-site malignant transformation in nearly two-thirds of patients. It also facilitates definitive diagnosis of lesions, and in clinical practice has been shown to be able to identify and excise pre-existing, clinically undetectable squamous carcinoma in approximately 10% of all treated oral precancer patients. It seems very difficult, therefore, to support alternative management strategies based upon observational or medical treatments that do not offer such comprehensive opportunities for definitive histopathological diagnosis and efficacious treatment. These comments apply not only to identifiable potentially malignant lesions, but also to those cases of early invasive cancer of the oral mucosa that would have otherwise remained hidden until a much later stage of clinical presentation.