Declining Incidence of Nasopharyngeal Carcinoma in Brunei Darussalam: a Three Decade Study (1986-2014)

Background: Nasopharyngeal carcinoma (NPC) is linked to Epstein Barr virus infection and is particularly common in the Far East, particularly among some Chinese groups. Certain ethnicities have been reported to have low incidence of NPC. This study looked at NPC in Brunei Darussalam over a three decade period. Materials and Methods: The cancer registry from 1986 to 2014 maintained by the State Laboratory was retrospectively reviewed. The age standardized rates (ASR) and the age specific incidence rates (ASIR) were calculated. Non NPC tumors were excluded from the study. Results: Altogether, there were a total of 450 NPC cases diagnosed accounting for 4.4% of all total cancer cases over the study period, declining from 10.3% in 1986-1990 to 2.3% in 2011-2014. The most common tumor type was the undifferentiated carcinoma (96.4%). The case characteristics were mean age $50.4{\pm}14.4$ years old, male 69%, and predominately Malays 74.4%, followed by Chinese 16.7%. The mean age of diagnosis increased over the study period from $45.6{\pm}17.1$ years (1986-1989) to $54.1{\pm}12.5$ years (ANOVA, p<0.01 for trend). There were no differences in the mean age of diagnosis between the ethnic groups or genders. The ASR showed a declining trend from 11.1 per 100,000 in 1986-1990 to 5.95 per 100,000 in 2011-2014, similar trends been observedfor both genders. Among the age groups, declining trends were seen in all the other age groups apart from the >70 years group. The overall ASRs for the Malays and Chinese were 7.92/100,000 and 8.83/100,000 respectively, both showing declining trends. Conclusions: The incidence of NPC in Brunei Darussalam is comparable to rates reported from Singapore and Malaysia, but higher than rates reported from the other Southeast Asian nations. Unlike higher rates reported for Chinese compared to the Malays in other countries, the rates between the Malays and Chinese in our study was comparable. Importantly, the ASR is declining overall and for both genders and ethnic groups.