The Secular Trend of Oral Cavity and Pharyngeal Cancer in Taiwan- Classification According to the Primary Site of Cancer and Age-Period-Cohort Analysis
Date Issued
2011
Date
2011
Author(s)
Chiu, Tsan-Jen
Abstract
Background and Objectives
Cancers of the oral cavity and pharynx are common malignancy in the head and neck. According to location, they can be divided into cancers of the oral cavity, nasopharynx, oropharynx and hypopharynx. Each of them has different clinical feature, treatment and prognosis. And different sites of these cancers were usually combined in past epidemiological studies because of special purposes or limited case number in each group. Studies focused on individual cancer were less common before. Therefore, we conducted a population-based study here using the database from Taiwan Cancer Registry. The main objective of this study is to compare the incidence trend and the age, period, cohort effects for each of the four cancers.
Materials and Methods
Between 1979 and 2008, patients with cancers of the oral cavity and pharynx were enrolled from Taiwan Cancer Registry and classified according to the primary site of cancer by four digits of ICD-9. Only squamous cell carcinoma or undifferentiated carcinoma was included in this study. Gender-specific age-standardized incidence rate, percentage difference of incidence and cumulative risk were calculated for each cancer. The incidence trend of cancer was compared by the Joinpoint regression program. Then the individual cancer incidence of men between 1979 and 2008 was analyzed with autoregressive age-period-cohort model.
Results
In Taiwan, cancers of the oral cavity and pharynx had high incidence in men. As for the incidence in different gender, cancer of the oral cavity was highest in men and cancer of nasopharynx in women. Incidences of cancers of the oral cavity, oropharynx and hypopharynx in men continued to increase in recent three decades. And the incidence of cancer of the oropharynx or hypopharynx was close to that of the nasopharynx in men recently. Different incidence trend pattern happened in nasopharyngeal carcinoma between men and women. The incidence trend of nasopharyngeal carcinoma increased slowly in men but decreased slowly in women. Besides, the incidence of cancer of the oral cavity was rather close with that of the nasopharynx in women.
The incidence of cancer of the oral cavity will be overestimated and that of cancer of the oropharynx will be underestimated, if cancer is classified by three digits of ICD-9 rather than by four digits of ICD-9. Besides, if the pathological restriction is not included in the study, the incidence trend of nasopharyngeal carcinoma in men will be changed completely which will decrease slowly.
In age-period-cohort model, the relative risk of age effect for cancers of the oral cavity, nasopharynx, oropharynx and hypopharynx in men is 7.96, 3.35, 17.09 and 60.45 respectively. The relative risk of period effect for four cancers in men is 6.67, 1.27, 8.27 and 7.32 respectively. The relative risk of cohort effect for four cancers in men is 2.08, 1.19, 1.63 and 1.99 respectively.
The result shows similar pattern of age-period-cohort model in cancers of the oral cavity, oropharynx and hypopharynx . Nevertheless, nasopharyngeal carcinoma has different pattern from those of other three cancers.
Conclusions
Though oropharynx is adjacent to nasopharynx and hypopharynx, the incidence trend is quite different among these three cancers. The reason is possibly that cancers of the oropharynx, hypopharynx and oral cavity have similar carcinogens including betel quid, tobacco and alcohol, whereas cancer of the nasopharynx is associated with inheritance, ethnicity, Epstein-Barr virus and environmental factors.
Accurate estimation of the incidence and trend of cancers of the oral cavity and pharynx can be achieved by classification according to the primary site of cancer by four digits of ICD-9 and the pathological inclusion criteria only for squamous cell carcinoma or undifferentiated carcinoma. The methods and criteria of this study are good standards for the future study about this topic.
In Taiwan, male has higher incidence of cancers of the oral cavity and pharynx than in the world. Besides, the incidence of cancer of the oropharynx or hypopharynx is getting close to that of the nasopharynx in men. From the viewpoint of public health, medical research and clinical medicine, it is important to study each of the four cancers individually to set up appropriate cancer prevention programs in Taiwan.
Subjects
age-period-cohort model
incidence
oral cavity and pharynx
squamous cell carcinoma
SDGs
Type
thesis
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