Nasopharyngeal Carcinoma Incidence in North Tunisia: Negative Trends in Adults but not Adolescents, 1994-2006

Nasopharyngeal carcinoma (NPC) is the second most common neoplasm of head and neck in Tunisia. Thedistribution is bimodal with a first period occurrence between 15 and 20 years old and a second peak at around50 years of age. Undifferentiated carcinoma of nasopharynx type III (UCNT) is the predominant histologicaltype (93.4%). Data of cancer registry of North Tunisia confirmed that it is an intermediate risk area for NPCwith overall ASRs of 3.6 and 1.6/100,000 respectively in males and females. This study aimed to present theevolution of incidence rate of nasopharyngeal carcinoma over a period of 12 years (1994-2006). Data of cancerregistry of North Tunisia (NTCR), covering half of the Tunisian population, were used to determine evolutionof NPC incidence, calculated by 5 year periods. The estimated annual percentage change (EAPC) was used asan estimate of the trend. To best summarize the behavior or the data trend across years, we used a join-pointregression program. Between 1994 and 2006, we observed negative annual average change of standardizedincidence in men and women (-3.3%and -2.7%) also for the standardized incidences which showed a ratherimportant decline (26.4% in males and 22.3% in females). The truncated age standardized incidence rate ofNPC in adults aged of 30 years old and more (N= 1209) decreased by -0.4% per year from 1994 to 2006 overtime in north Tunisia dropping from 6.09 to 4.14 person-years. However, the rate was relatively stable duringthis period among youths aged 0-29 years (N= 233) in both sexes. NPC demonstrated a favorable evolution from1994-2006 probably due to a improvement in socioeconomic conditions.