Abstract
Introduction:
Oral and oropharyngeal cancer is the sixth most common cancer in the world. The most common type of cancer occurring in the oral and oropharyngeal area is oral squamous cell carcinoma (OSCC). For the purposes of this thesis oral squamous cell carcinoma has been defined as a malignant epithelial neoplasm of the tongue, floor of mouth, gingiva, hard and soft palate and the vermilion and labial mucosa of the lips. Areas of the oral pharynx, tonsils and salivary glands were excluded. Despite numerous studies on the prevalence of OSCC in geographically diverse populations, there are no detailed data analyses on their incidence in the Fiji Islands. The most recent analysis for New Zealand was reported in 1995.
Aim:
Firstly, to determine the prevalence of OSCC in New Zealand and the Fiji Islands and to compare variables such as prevalence rate, gender distribution, age groups affected, ethnic distribution, sites and tumour grade. Secondly, to investigate the known risk factors for oral squamous cell carcinoma in both countries.
Materials and Methods:
This was a retrospective study using data on OSCC in New Zealand and the Fiji Islands that were recorded between 1st January 2000 and 31st December 2010. Data were obtained from the Cancer Registry of New Zealand, the Cancer Registry of the Fiji Islands, Medlab Dental Oral Pathology Diagnostic Service (University of Otago) and Histology Departments at the three main referral hospitals in Fiji. Patient demographic characteristics and other epidemiological parameters were analysed and described.
Results:
In the 11-year duration, a total of 1916 cases of OSCC in New Zealand and 124 in the Fiji Islands were retrieved and eligible for the study. The annual age standardized incidence rate (ASR) for OSCC in New Zealand was 42 per 1,000,000 persons and in comparison to the Fiji Islands; an ASR of 13 per 1,000,000 persons was recorded. The male to female ratio for New Zealand was 1.85:1 and 1:1 for the Fiji Islands. The overall mean age at diagnosis for New Zealand was 63 years and 57 years was for the Fijian population. The tongue was the most commonly affected site for the Fijian population (73.4%) but only accounted for 43% amongst the New Zealand population. The second most common OSCC amongst the Fijian population was the buccal mucosa (11%) whilst the vermilion and labial mucosa of the lips (24%) was the second most common site for New Zealand. A relatively poor response to questionnaires regarding potential aetiological factors made it impossible to carry out a detailed statistical analysis of associated risk factors.
Conclusion:
There was a low prevalence of OSCC in the Fiji Islands compared to New Zealand. The New Zealand male population had a high incidence of OSCC particularly those in the 5th and 6th decades. The tongue was reported as the most common site for both countries. Early detection and diagnosis is paramount in order to improve survival rates for OSCC. It is recommended that practicing clinicians should document full patient history and also record additional information on putative aetiological agents linked to OSCC. Health information agencies collecting cancer data should also place more emphasis on recording full patient details and this information is stored safely in a manner that is easily retrievable. This additional information would be valuable for the management of oral squamous cell carcinoma and also for future health research purposes.