Search

The reasons for an increasing incidence of oral cancer, particularly amongst younger persons is unclear. It has been hypothesised either to be a result of an increase in exposure to known risk factors amongst certain groups in the community, or to be due to new aetiological agents. Prior to conducting large expensive population-based studies, it seems appropriate to conduct initial smaller-scale surveys to assess evidence for each of these two hypotheses. This survey of young persons with oral cancer suggest that most are exposed to traditional risk factors of tobacco smoking, drinking alcohol and a low consumption of fruit and vegetables.

Data were examined to determine trends in survival from cancers of the oral cavity and pharynx in Scotland between 1968 and 1987, and to analyse survival rates and the previously noted increases in the incidence of such cancers according to the level of social deprivation. Incidence data on oral cavity and pharyngeal cancer and survival rates following diagnosis were obtained from the Information and Statistics Division of the Common Services Agency for the National Health Service in Scotland, covering the period 1968-92. It was found that survival rates for cancers of the tongue, mouth and pharynx diagnosed among persons less than 65 years of age decreased between 1968-72 and 1983-87. Five year relative survival rates fell from 47% to 39% over this period, while the equivalent rates among persons older than 65 years have shown a modest improvement from 34% to 38%. When considered by level of social deprivation, survival is lower among persons from the most deprived areas, and it is among such persons that the recent increases in occurrence of cancers of the oral cavity and pharynx have primarily occurred. The poorer survival among those from more socially deprived areas, and the evidence that the largest increase in incidence has occurred in such areas may to some extent explain the non-favourable trends in mortality. More importantly it emphasises the potential benefits of targeting such a population for oral health information. An educational campaign should include both information on the risk factors for developing oral cancer, and also the importance of seeking an early professional consultation in the case of symptoms.

Data over at least 20 years from three large population-based registries in Europe and Australasia have been used to assess the risk of second primary tumours occurring after a cancer of the mouth or pharynx. These patients have previously been shown in clinical series to be at a particularly high risk of subsequent tumours, while data from cancer registries have shown conflicting results on the magnitude of the risk. In this study, patients were found to have between a 2-fold (Scotland and New South Wales) and 4-fold (Slovenia) increase in risk of a subsequent tumour over that in the population, although the actual risk in each centre was similar (between 2.8 and 3.1 per 100 person years). The risk remained for 10 years after diagnosis of the original tumour and was primarily in the upper aerodigestive tract. The most elevated risks (approximately 10-fold) were for tumours in the oral cavity and oesophagus. These data provide higher estimates of risk than previously reported from European cancer registries for second primary tumours and emphasize the need for close follow-up of patients who may represent an appropriate population in which to assess possible new chemopreventive agents.

This combined analysis of data from three large case-control studies of oral cancer confirms the important effect of tobacco in the aetiology of the disease. The studies have been conducted in the United States, Italy and China and results for risks associated with tobacco smoking were generally consistent across centres, while those for alcohol were not; increased risks amongst alcohol drinkers were evident in two centres but not in the study conducted in Turin, Italy. In addition, the combined analysis had large enough numbers to analyse the risk of tobacco consumption in non-drinkers. In females these showed increased risks while in males the effect of tobacco alone was weaker. Given the popularity of tobacco smoking, and its consequent high attributable risk in terms of oral cancer it is reassuring, in terms of public health, that cessation will result in a substantial reduction in risk; a 30% reduction in risk for those stopping smoking between 1 and 9 years, and a 50% reduction for those stopping more than 9 years. Although encouraging smokers to stop should be the principal aim, decreases in risk for everyone could be achieved by encouraging high fruit and vegetable consumption.

A European School of Oncology Advisory Group has reviewed current knowledge on the epidemiology, treatment and prevention of cancer of the oral cavity. While the major factors in the aetiology of such cancers are thought to be well understood, i.e. tobacco and alcohol consumption, current increases in the occurrence of the disease, especially in young adults throughout Europe, are cause for concern. The reasons for such increases are not clearly evident and the Advisory Group has suggested further work which is required to be carried out to understand the aetiology. In treatment of the disease there have been no major improvements in survival for patients in recent decades and the importance of examining new radiotherapy modalities and defining the role of chemotherapy is emphasized. Primary prevention of oral cancer could be achieved by stopping smoking tobacco, limiting alcohol consumption to a minimum (2-3 drinks per day) and increasing intake of fruits and vegetables. To supplement these actions, while neither population screening programmes nor screening trials could be recommended by the Advisory Group, initial chemoprevention trials have produced some promising results and this represents an interesting area which is the focus of much current research.

Incidence and mortality rates for oral and pharyngeal cancers have been reported to be increasing in Europe and the United States, with particularly large increases in mortality in central and eastern Europe. Such increases have been noted to be birth cohort-based, primarily affecting young and middle-aged men. In this report oral and pharyngeal cancer incidence data from New South Wales, Australia has been analysed for the period 1972-90. Although an increase in the incidence of oral and pharyngeal cancer occurred during the mid-1970s and early 1980s, it did not continue. This pattern is consistent with Australian trends in per capita consumption of tobacco, alcohol, fruit and vegetables. Individual regions within metropolitan Sydney showed substantial geographical variation with age-specific rates of oral and pharyngeal cancers (combined) in middle-aged men being at least three times higher in the city of Sydney than in New South Wales as a whole. Given the preventable nature of the disease, such high rates need not occur.

Oral cancer is considered widely to be a form of cancer whose etiology is well understood and which is becoming relatively rare in developed countries. There have been, however, a series of recent reports indicating that after many years of declining risk, the rates may be rising again in men. To investigate the extent of such changes, national time-series of oral-cancer mortality data available in the World Health Organization's mortality database have been analyzed. Age-period-cohort modeling was used to establish the extent and nature of these changes and to allow comparisons among countries. Nineteen out of 24 national datasets demonstrate a similar pattern of recent increasing cohort-effects for oral cancer in men. The largest increases have occurred in countries of central and eastern Europe where rates have increased by a factor of from three to 10 within a generation. The cohort-based nature of the changes observed in men suggest that there will be a continuing increase in the absolute numbers of cases of oral cancer to be treated in the coming decades.

Oral cancer incidence and/or mortality has been reported to be currently increasing in several countries, particularly those of central and eastern Europe. Most of these reports pertain to men, although increases in incidence among women also have been found. In this report, data from twenty-four countries in the World Health Organization's mortality database are analyzed. The widespread increase observed in oral cancer mortality among men is not occurring in women. Nevertheless, increases have occurred in several countries in Europe, and oral-cancer death rates--especially in central and eastern Europe--are likely to increase further if tobacco smoking, in particular, becomes more popular among younger women.

Slovakia currently has one of the highest incidence rates of oral cancer in Europe. Incidence data from the Slovakian Cancer Registry relating to oropharyngeal cancer are analyzed for the period 1968-1989 to examine trends in the incidence of these malignancies, representing the first such reported time-series from Central Europe. Over this period, rates in males have increased from 4.5 per 100,000 in 1968-1970 to 17.9 per 100,000 in 1987-1989, with more marked increases noted amongst middle-aged males (35 to 64 years), among whom rates have increased from 6.8 to 47.9 per 100,000 over the same period. Rates in women have been relatively low and stable. Changes in rates in men follow a period during the 1950s and 1960s when there was a marked increase in alcohol and tobacco consumption. The magnitude of the increases have resulted in oropharyngeal cancer becoming an important public health problem in Slovakia and emphasizes the importance of measures to prevent further increases in the consumption of tobacco and alcohol.

Objectives: To determine the incidence of oral cancer in Scotland between 1960 and 1989 and oral cancer mortality from 1911 to 1989., Setting: Data were obtained on oral cancer incidence from the information and statistics division of the Common Services Agency of the Scottish Health Service and mortality data from the office of the registrar general for Scotland., Results: Mortality from intraoral cancers in Scotland substantially declined throughout this century until the mid-1970s. This trend, however, was then reversed, and fourfold increases in incidence were observed in younger age groups after 1960. Death rates in these younger age groups increased to levels previously recorded in the 1940s. These increases seemed to be cohort based and may therefore continue into the future., Conclusions: Reasons for increasing rates among younger age groups are speculative and rely on combining knowledge about risk factors and available ecological data. Though increases in incidence at younger ages do not result in a large change in the number of cases diagnosed, possible similar increases continuing into older ages, when oral cancer is more common, will correspond to a much larger increase in the actual number of cases. Given that such a large attributable risk is associated with tobacco and alcohol, however, these increases may be preventable.

Cancer of the oral cavity is an important contributor to the overall international cancer burden, especially in the developing countries. Smoking cessation, moderation of alcohol consumption, and increased consumption of fruits, and probably vegetables, have been identified by epidemiologic studies as three actions that could lead to the prevention of approximately three fourths of cases in Western countries. Similar effects could be brought about in developing countries through cessation of cigarette smoking and, where appropriate, betel quid chewing and increased consumption of fruits and vegetables. Since this disease is increasing in frequency in many countries, it is important to implement these health education messages. A similar situation holds true for larynx cancer. Clearly many head and neck cancers are preventable and it is worth repeating that prevention should become an epidemiologic priority. There are exciting prospects of effective chemoprevention opportunities in head and neck cancer, with a number of compounds having activity. Further developments in this important area are awaited.

The oral cavity and pharynx combined is the sixth commonest site of cancer in both sexes. In many countries the mortality rate is increasing among younger men born since approximately 1910-1920. A causal role in the aetiology of mouth cancer has been established for tobacco use, both smoking and chewing, separately and in conjunction with betel-quid chewing; with alcohol consumption and, less certainly, with other factors such as poor oral hygiene, nutritional factors and certain occupational exposures. In Western countries, there is convincing evidence that a large attributable risk can be ascribed to the joint habits of cigarette smoking and alcohol consumption. In Asian societies, a high attributable risk can be ascribed to cigarette smoking and betel chewing. Mouth cancer is at the same time an important form of cancer, and one for which practical prospects for prevention already exist. Against this background of a continually increasing trend among younger persons, it seems essential to engage upon programmes of prevention, including increasing awareness for early detection, against mouth cancer at the present time.