Analysis: because the five year survival rate for oral cancer in Europe is only 50 percent, it is of paramount importance to diagnose the disease early

In 2012, there were an estimated 529,500 cases worldwide of lip, oral cavity and pharyngeal cancers. This has been predicted to rise to 856,000 cases by 2035 due to changing demographics. Worldwide, lip and oral cavity cancer incidence is significantly higher in men than women.

The factors contributing to oral cancer are smoking, alcohol intake, chewing smokeless tobacco, pan, ghutka and quid, exposure to human papilloma virus (HPV) and over exposure to the sun. The five year survival rate for oral cancer in Europe is only 50 percent and patients often present with advanced disease. Multiple primary tumours are common and there is a high risk of developing secondary tumours. Therefore, it is of paramount importance to diagnose the disease early. 

All the new techniques are aiming to diagnose the disease at a pre-malignant stage, so that the patient gets better treatment and the survival rate increases. It takes nearly six to eight years for neoplasia to develop to cancer.

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From RTÉ Six One News, a report on how dentists are concerned about the rise in oral cancers

Self-examination is highly recommended so the general public should examine their mouths regularly before brushing. They should look for persistent red or white patches, lumps or ulcers which are present for more than three weeks. Presence of sore throat or a neck lump for three weeks or more needs medical attention and they should consult a doctor or a dentist within a week.

This simple examination is important even if the person has no teeth as it is the examination of the complete oral cavity. The doctor or dentist would carry the oncological examination of the oral cavity which is simple, relatively inexpensive, non-invasive and can be carried out by all general practitioners and dentists. Screening for oral cancer includes a thorough history and physical examination. This is also known as conventional oral examination (COE). The clinicians visually inspect and palpate the head, neck, oral, and pharyngeal regions.

The next challenge we face today is the treatment of these premalignant conditions. Because most lesions are asymptomatic, the primary management goal is to prevent and/or detect any cancer development early. Currently, there is no reliable method to predict when and whether these lesions will undergo malignant transformation. It is important to weigh the risks and potential morbidity of any therapeutic intervention carefully against the potential benefits.

There is a significant need for new diagnostic techniques to detect pre-malignant lesions

There are three strategies for patients with premalignant lesions: close observation, surgical removal and ablation, and medical therapies. Close observation using frequent clinical examinations is the usual method for the management of premalignant conditions. 

Carcinoma causes structural loss in the stratification of epithelium, subsequent invasion and infiltration of malignant epithelial cells into the connective tissue. Presently, the gold standard for the assessment of oral malignancy is microscopic evaluation of haematoxylin and eosin (H&E) stained tissue sections. It combines architectural, cytological and arrangement of epithelial strata changes for the diagnosis and grading of oral cancers.

However, this method is time consuming and prone to inter/intra observer variations. Moreover, the diagnostic accuracy also depends on the precision of the resected biopsy material that represents the actual suspected lesion. It is known that, in diseased conditions, biochemical modifications precede morphological changes in the process of transformation of tissue from normal to malignant state. A protocol which detects these biochemical changes is potentially a more powerful route towards early and more objective identification of the onset of disease.

Some of the factors contributing to oral cancer are smoking, alcohol intake and over exposure to the sun

As a result, there is a significant need for new diagnostic techniques to detect pre-malignant lesions. Changes in the structure and molecular composition of pathologically altered tissues provide opportunities for the development of tools for guiding diagnostic and therapeutic procedures and molecular level diagnosis is gaining importance for early detection of cancer. Optical spectroscopic techniques have been shown to be promising for the characterisation of tissues.

Of the various optical techniques, Raman spectroscopic techniques are gaining ground. It is known that molecular changes precede morphological changes. Raman scattering is the inelastic scattering of light by chemical bonds and can therefore show molecular specificity. Raman spectroscopy can detect those changes and identifies variations that occur between healthy and diseased specimens. It has many advantages over conventional cytology and histopathology, including objective and reproducible diagnosis, independent of fatigue, experience, inter-observer variability, and imperceptible morphological changes.

A number of previous studies have shown the potential of Raman spectroscopy for oral cancer diagnosis. These studies were carried out on oral tissue ex vivo or in vivo. My PhD research involved Raman mapping of oral tissues ex vivo. Biofluids and exfoliated cells have also been recently investigated as minimally invasive samples for diagnosis of cancer by Raman spectroscopy. Ultimately, Raman spectroscopy could provide more accurate, faster chair-side diagnosis for the patient. And we're aiming for just that. 

The views expressed here are those of the author and do not represent or reflect the views of RTÉ