Epidemiological profile of oral cavity cancer in South Chinese population

Abstract

Oral cavity cancer (OCC) risk factors in Southeast China have not been fully investigated, despite its higher incidence rate compared to other Chinese regions. In order to fill in this gap, trend analysis on OCC incidence in Hong Kong and parallel case control studies in Hong Kong and Guangzhou were performed.

To find the secure trend of the OCC incidence in Hong Kong for the last 25 years, multidirectional statistical analysis was performed by reference to the database of the Hong Kong Cancer Registry. Joinpoint regression analysis was applied to find the change of trend point of gender-segregated age-specific and age-standardized incidence rates. Additionally, the age, period, and cohort (APC) analysis was employed to investigate the age, period, and cohort effects on the OCC incidence.

While only age effect played a causative role among males in the APC modeling, the age effect with an linear increasing period effect was predominant among females. Joinpoint regression analysis detected a change of trend point of age-standardized incidence rates for females in year 2001, from downward (annual percent change (APC): -1.2, 95% confidence interval (C.I.): -2.6, 0.2) to upward (APC: 3.5, C.I.: 0.5, 6.7), whereas constant downward trend (APC: -1.2, 95% C.I. -1.7, -0.6) was found for males. Analysis on age-specific incidence rates for males also showed long-term downward trend in the middle (APC: -3.1, 95% C.I. -4.1, -2.0) and older age groups (APC: -0.9, 95% C.I. -1.7, -0.1), while the older age group of female showed constant upward trend (APC: 1.6, 95% C.I.: 0.5, 2.7).

Two case control studies were carried out both at the Faculty of Dentistry, The University of Hong Kong and Sun Yat-Sen University Cancer Center, Guangzhou, to see the individual risk figures of the population. Cases were OCC patients pathologically diagnosed as squamous cell carcinoma, whereas controls were the hospital-based controls without any cancer history. A standardized questionnaire was prepared for assessing general health status, socioeconomic environment, smoking and drinking habit, oral hygiene status, and dietary habit of the study samples.

Among each 135 cases and controls, alcohol (odds ratio (OR): 3.17, 95% C.I.: 1.93, 12.62) was identified as the dominative risk for males by the multiple logistic regression analysis, while lower level of education (OR: 4.94, 95% C.I. 1.93, 12.62) and poor oral hygiene status, such as less frequency of dental visit (OR: 3.35, 95% C.I. 1.22, 9.24), and awareness of gingival bleeding (OR: 3.26, 95% C.I.: 1.08, 9.81), were highlighted for females.

Whereas alcohol drinking was appeared as the most possible cumulative risk behavior for males of the Southeastern China, lower level of educational attainment and poor oral hygiene status were revealed as dominant for females because of their lower prevalence of alcohol drinkers and smokers.