ReviewGlobal epidemiology of oral and oropharyngeal cancer
Introduction
This review on ‘oral and oropharyngeal cancer’ describes the global epidemiology of cancers of the lip, tongue and mouth (oral cavity) [ICD-10: C00-06], and oropharynx [ICD-10: C09-C10], excluding the salivary glands [C07-08] and other pharyngeal sites [C11-13]. In some world reports, cancers of all sites of the oral cavity and pharynx are grouped together [ICD-10: C00-14], and these are cited in the review as they are originally described. More than 90% of oral malignancies in the upper aerodigestive tract are squamous cell carcinomas. The large majority of oral cancers have risk factors similar to those occurring in the rest of the head and neck or the upper aerodigestive tract. Most cancers of lip and oral cavity are preventable.
Section snippets
Global incidence
Oral cancer is a serious and growing problem in many parts of the globe. Oral and pharyngeal cancer, grouped together, is the sixth most common cancer in the world. The annual estimated incidence1 is around 275,000 for oral and 130,300 for pharyngeal cancers excluding nasopharynx, two-thirds of these cases occurring in developing countries. There is a wide geographical variation (approximately 20-fold) in the incidence of this cancer. The areas characterised by high incidence rates for oral
European Union and Eastern European countries
In 2004, there were 67,000 new cases registered in the countries of the European Union (EU). Overall in the EU, oral and pharyngeal cancer occupies the 7th position.3 Within the EU countries the highest male incidence rates are found in France and Hungary, and the lowest rates are found in Greece and Cyprus. In one report the rate for oral cancer in men in France was almost seven times greater than that for men in Greece.4 The lifetime risk of developing oral and pharyngeal cancer in Europeans
United States of America
Approximately 34,360 cases of oral cancer and pharynx cancer are reported in the United States of America.9 Age-adjusted incidence rates are 15.6 per 100,000 for men and 6.1 per 100,000 for women (10.5 for men and women). Higher rates are observed among the black males in USA particularly for oropharynx.
South America and the Caribbean
In South America and the Caribbean, cancers of mouth and pharynx rank fifth in men and sixth in women. The region comprising of Argentina, Southern Brazil and Uruguay has the highest incidence levels, though highest rates are observed in Brazil. Male population in Brazil has the highest risk in the world for cancer of mouth after those in France and India.10 In 2008, 14,160 new cases of oral and pharyngeal cancer (C00-10) are expected to occur in Brazil (10,380 in males: crude rate 11 per
Africa
Data from Africa are limited to few hospital cancer registries. It is therefore difficult extrapolate the true incidence in these countries, but reported rates do not show evidence that oral cancer is a serious problem in the African continent. There are descriptive studies from the Sudan that suggest oral cancer rates in males are high, linking this high incidence to toombak, a product of oral snuff mixed with sodium bicarbonate.13
Asia
Some countries with the highest incidence rates for oral cancer in the world are located in the region of South Asia. India has always been cited as the country with the highest incidence in the world, though in some recent reports Sri Lanka and Pakistan are ranked at the top. In India alone over 100,000 cases are registered every year. According to Cancer Incidence in V Continents – vol. VIII14 one district of India (Bhopal) has the highest AAR for cancers of both the tongue (10.9 per 100,000)
Lip cancer
Highest incidence rates for cancers of the lip are reported in white populations in Canada and Australia (Fig. 2). For example, more than 50% of oral cancers in Australians are located on the lip.18 It is rare in non-white populations.
Migrant studies
Several studies describe patterns of oral cancer incidence among migrant groups, most of which reflect life style influences. Studies on migrants and minority ethnic populations in Britain have reported significantly higher incidence rates in South Asian populations living in Greater London, Birmingham and Yorkshire.19, 20 Risk of cancer mortality from 1973 to 1985 in persons born in the Indian subcontinent who migrated to England and Wales compared with cancer mortality in the native
Trends
The age standardised incidence of oral cancer in Western Europe has steadily increased in the past two decades. For example in the UK since 1989, an average increase of 2.7% each year has been reported. Increased consumption of alcohol across the UK since post-second World War years has been implicated in the rising trends of oral cancer30; the role of binge drinking remains to be explored.
In the USA, rising trends were noted for incidence in black men from 1974 to 1990. For the period
Survival
Many patients who are successfully treated for oral cancer have to cope with the devastating consequences of their treatment.31 These may affect the patient’s appearance and function, e.g. eating, drinking, swallowing and speaking. These residual defects may lead to other problems such as depression and nutritional deficiency. Quality of life issues are therefore especially important for this group of patients.
For most countries, five-year survival rates for cancers of the tongue, oral cavity
Mortality
For most countries age-adjusted death rates from oral cancer have been estimated at 3–4 per 100,000 men and 1.5–2.0 per 100,000 for women. Mortality from oral cancer had been rising appreciably in most European countries between 1950s and 1980s.34 For example, among the Germans about fourfold increase was noted during this period. Within the UK mortality rates are highest for Scottish men reflecting their high incidence rates.7 Oral cancer mortality among French women has risen in the past 20
Second primary tumours
Successful initial treatment with loco-regional control of oral cancer has led to the emergence of second primary tumours (SPT). The relative risk for multiple primary cancer is higher in younger subjects, those who continue to smoke and drink alcohol after therapy, those treated with radiotherapy alone and those treated post-1990 compared with those treated in earlier decades. A study in Southern England has estimated that by 20 years from the time of the first head and neck cancer,
Risk factors
The etiology of oral cancer is multifactorial. These are discussed in more detail in the paper by Stephano Petti in this supplement. Based on available global evidence the risk factors known to us could be grouped as established, strongly suggestive, possible and speculative factors (see Table 1). The most important etiological factors are tobacco, excess consumption of alcohol36 and betel quid usage37, these factors act separately or synergistically.38 Attributable risk of oral cancer due to
Delay in diagnosis
Many oral cancers present at a late stage of the disease. Studies examining delay report that patients usually delay seeking professional advice for periods up to 3 months after having become aware of any oral symptom that could be linked to oral cancer. The proportion of patients presenting with advanced disease had not changed in 40 years despite public education.50 The responsibility for delay when apportioned to the patient or physician, mostly accounts due to patients’ delay. In younger
Primary prevention
At least three-quarters of oral cancers could be prevented by the elimination of tobacco smoking and a reduction in alcohol consumption. The removal of these two risk factors also reduces the risk of second tumours in existing oral cancer patients. Smoking cessation contributes to reducing the risk of oral cancers, with a 50% reduction in risk within 5 years.52 Ten years after smoking cessation, the risk for ex-smokers approaches that for life-long non-smokers. Treatment of tobacco dependence
Screening (secondary prevention)
Patient delay has been cited as the main reason for late attendance and it seems probable that in both the high-risk and the general population, neither the symptoms of oral cancer nor the main risk factors are well understood.61 With rising incidence rates, especially in younger age groups whose expectation of cancer is low, public education is urgently needed.51
It is well established that the treatment of early stage oral cancers achieves higher survival rates with less attendant morbidity
Conclusions
Oral cancer remains a lethal disease for over 50% of cases diagnosed annually. This is largely reflected by the fact that most cases are in advanced stages at the time of detection despite easy accessibility of the oral cavity for regular examination. Studies have reported an alarming lack of awareness about oral cancer, its symptoms and causes and these gaps in knowledge need to be addressed by further public education, possibly targeted at high-risk groups.
In order to address delays in
Conflict of Interest Statement
None declared.
Acknowledgements
I wish to gratefully acknowledge several colleagues for permitting to reproduce Figure 3, Figure 4, Figure 5. Fig. 3 was supplied by Dr. Laurent Remontet of Service de Biostatistique des Hospices Civils de Lyon Laboratoire de Biostatistique-Santé CNRS/Université Lyon, France, Figure 4, Figure 5 were supplied by Marceli de Oliveira Santos, Cancer Information Department Prevention Coordination, National Cancer Institute of Brazil – INCA, Brazilian Health Ministry and Figure 6 was kindly supplied
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