Oral malignant neoplasia: A survey of 428 cases in two Zimbabwean hospitals
Introduction
Oral malignant neoplasms are the sixth most common malignancy in the world and when malignancy of the pharynx is included it accounts for the third most common malignancy in the developing world.1 There is, however, a worldwide geographic variation in the prevalence of oral malignant neoplasms ranging from only a few percent in most Western countries to over 40% in South and South-East Asia.2 The vast majority of malignant neoplasms 75% occur in the developing world where the oral cavity is often the first or second most common site for malignancy.1, 3 In the United States of America oral malignancy accounts for 2–4% of all malignant tumours and in South Africa in females and males it accounts for 1.8% and 5% of all malignancies, respectively.4, 5, 6 In Harare, Zimbabwe, lip and oral cavity malignant neoplasms account for 2.1% and 1.8% of all cancers in females and males, respectively.7, 8 This wide variation in frequency should be accepted on the background of varied socio-cultural characteristics and the level of development of health services in the various populations.3 This variation could also be reflective of major geographic differences in risk factors.
The major risk factors for oral malignant neoplasms are the use of tobacco products and excessive alcohol consumption estimated to account for 75% of all oral malignant neoplasms in the United States of America, France and Italy.9, 10, 11, 12, 13 In Africa the use of tobacco products and excessive alcohol consumption are also risk factors for oral malignant neoplasia.14, 15, 16 There are essentially four smokeless tobacco products: loose leaf or chewing tobacco, snuff, plug tobacco and twist or roll tobacco. Chewing tobacco and snuff are by far the most widely distributed type of smokeless tobacco. In Sudan oral snuff called toombak has been implicated as a risk factor for oral malignant neoplasia.15, 17 In South Africa, among females of Indian descent, an important factor in the high incidence of oral squamous cell carcinoma is attributable to betel nut chewing.18 Betel nut chewing is a known carcinogen in the Indian sub continent.
Other risk factors include possible genetic characteristics and oncogenic viruses.19 Human papilloma virus (type 16), has recently been associated with a 2.2-fold increase in the risk of oral squamous cell carcinoma, after adjusting for smoking.20
Non-Hodgkins lymphomas are relatively common complications of HIV/AIDS in Western countries but little is known about the impact of the AIDS epidemic in Africa on the risk of these tumours.21
Minor salivary gland tumours tend to be more common in African studies than in the Western series, 15–20%.21, 22, 23 The most common malignant salivary gland neoplasms are adenoid cystic carcinoma and mucoepidermoid carcinoma.
There has been an increase in cancer incidence among blacks in Zimbabwe due to the HIV/AIDS epidemic.24 This is mainly due to the increased incidence of Kaposi’s sarcoma.
Although oral malignant neoplasms appear to be uncommon in comparison with other malignancies it still is a significant disorder for both the patient and the health care professional. Early detection of the oral malignancy by the dental practitioner affords effective treatment for the patient with minimal morbidity.
These two hospitals in which this study has been done, are the major referral centres in Zimbabwe with established oral and maxillofacial surgical services receiving patients from all over the country. The patients seen here are thus fairly representative of the Zimbabwean population. The purpose of this study is intended to provide information that should be useful to the oral health practitioners for community education, diagnosis, early treatment and research.
Section snippets
Materials and methods
The case definition for this study was any histologically diagnosed malignant neoplasm in any one of the following sites, as defined by the international classification of disease codes for oncology (ICD-O), ICD-O 1990: lip (47), tongue, gingivae, floor of the mouth, buccal mucosa, hard and soft palate (Table 1). Medical records were retrieved of 428 patients seen at Harare Central Hospital and Parirenyatwa Government Hospital, Harare, Zimbabwe, during the period January 1982 to December 1991
Results
During this 10 year period, 1723 biopsies were accessioned by these hospitals; 24.8% (n = 428) were oral malignant neoplasia as previously defined.
Table 1 shows the relative frequency of different types of oral malignancies by gender, age and histologic type: squamous cell carcinoma 73.1% (n = 313) was the most frequent. However, when lip cancer (n = 14) is excluded the frequency figure becomes 69.9%. Other figures are: malignant minor salivary gland tumours 4.9%, Burkitt’s lymphoma 4.7%, Kaposi’s
Discussion
Oral and pharyngeal malignant neoplasia are the sixth most common malignancy in the world.1 In the developing countries the oral cavity and pharynx comprise the third most common malignancy site.2 The comparative frequency of oral malignant neoplasia ranges from only a few percent in most Western countries to over 40% in South and South-East Asia.2 It typically occurs in elderly men during the fifth and through to the eighth decades of life and rarely in young persons.
In the present study oral
Acknowledgement
The author wishes to thank Ms V Deshe for secretarial assistance in the preparation of this manuscript.
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