Although the oral cancer (OC) burden is not the highest compared with other common cancers, such as colorectal cancer and breast cancer, the disease pattern is characterized by great regional heterogeneity. The highest estimated number of OC cases worldwide in 2018 occurred in Asia [
Regarding the time trends of the OC incidence in both sexes, previous studies in Taiwan revealed that there was a dramatically increasing trend in OC from 2002 to 2012 in males (a significant estimated average annual percent change (EAAPC) of 6.7%) but not in females (EAAPC of 2.0%) [
Three risk factors including betel quid (BQ), smoking, and alcohol consumption have been established as etiologies of OC. The demographic and geographical heterogeneity in the time trends of the OC incidence is thought to be explained by different consumption levels of the three risk factors according to sex and age, with different exposure levels to these risk factors in different calendar years. This can also account for the heterogeneous time trends in Thailand [
As exposure to the three risk factors in each region which is subject to the exposure opportunity, the three time-related dimensions of age, period, and birth cohort (APC) [
Although the time trends of the OC incidence considering APC effects have been studied in a variety of cancers, these effects have rarely been applied to exploring the time trends of OC. In addition, no published study applies APC curves to OC in Taiwan and Khon Kaen, Thailand. It is of interest to compare the trends of the OC incidence between Taiwan and Khon Kaen, Thailand, where the epidemiological disease profiles differ greatly with respect to sex and time. This study aims at using APC curves to explore and compare the time trends of the OC incidence relevant to APCs between Taiwan and Thailand.
Information regarding all new OC cases in Taiwan, namely, the OC incidence data from 1979 to 2016, were obtained from the Cancer Registry of the Health Promotion Administration, Ministry of Health and Welfare. In Thailand, data were retrieved from the population-based cancer registry of Khon Kaen Province for all cases diagnosed between 1985 and 2016. OC cases were determined according to the International Classification of Diseases for Oncology, 3rd edition, codes C00, C01-C02, C03, C04, C05, C06, C9-C10, C12-C13, and C14.
We first examined the sex-specific ASIRs over time in both regions. The ASIRs, considering the world standard population in 2000, were directly calculated, with thirteen age-specified groups; the youngest was 20 to 24 years, and the oldest was 80 to 84 years. We excluded those diagnosed at
We categorized patient age into thirteen 5-year groups (20 to 24, …, 75 to 79, and 80 to 84 years) in both regions, we categorized period into seven 5-year intervals for Taiwan (1982 to 1986, …, 2007 to 20011, and 2012 to 2016) and Khon Kaen (1987 to 1991, …, 2007 to 2011, and 2012 to 2016), and we categorized birth cohorts into 5-year intervals in Taiwan (starting with 1898 to 1902 until 1988 to 1992) and Khon Kaen (starting with 1903 to 1907 until 1988 to 1992). To explore the effects of APCs on OC incidence trends, we plotted APC curves. Data for the APC curves were managed and analyzed using Stata (StataCorp. 2007. Stata Statistical Software: Release 10. College Station, TX: StataCorp LP).
The use of Thailand’s data for this study was approved by the Khon Kaen University Ethics Committee for Human Research (reference number: HE611129). There was no requirement for the use of Taiwan’s data, as they are open access.
Tables
Incidence rates (per 100,000) by age, sex, and period in Taiwan and Thailand.
Age group | Taiwan | ||||||
---|---|---|---|---|---|---|---|
1982-1986 | 1987-1991 | 1992-1996 | 1997-2001 | 2002-2006 | 2007-2011 | 2012-2016 | |
Male | |||||||
20-24 | 0.20 | 0.33 | 0.58 | 0.62 | 0.39 | 0.45 | 0.48 |
25-29 | 0.69 | 1.13 | 1.73 | 3.27 | 3.40 | 2.32 | 1.87 |
30-34 | 1.86 | 3.09 | 6.51 | 10.99 | 15.60 | 13.97 | 9.17 |
35-39 | 5.04 | 7.71 | 14.71 | 25.14 | 34.28 | 41.67 | 31.39 |
40-44 | 10.48 | 16.57 | 27.63 | 45.19 | 60.53 | 76.64 | 74.20 |
45-49 | 13.43 | 25.29 | 41.87 | 63.30 | 86.34 | 103.40 | 109.76 |
50-54 | 18.29 | 28.65 | 49.74 | 79.42 | 100.00 | 126.67 | 139.03 |
55-59 | 16.93 | 31.62 | 53.43 | 84.87 | 101.15 | 126.31 | 144.27 |
60-64 | 20.04 | 26.18 | 48.49 | 78.44 | 104.38 | 125.97 | 139.72 |
65-69 | 27.26 | 26.94 | 38.17 | 61.29 | 90.25 | 117.88 | 123.56 |
70-74 | 24.91 | 35.26 | 35.73 | 49.28 | 70.26 | 95.55 | 115.07 |
75-79 | 21.25 | 27.56 | 40.34 | 40.65 | 52.14 | 72.70 | 93.01 |
80-84 | 20.04 | 19.89 | 31.93 | 40.03 | 47.80 | 57.25 | 67.79 |
Female | |||||||
20-24 | 0.13 | 0.27 | 0.25 | 0.18 | 0.35 | 0.41 | 0.46 |
25-29 | 0.40 | 0.35 | 0.39 | 0.59 | 0.67 | 0.73 | 0.58 |
30-34 | 0.45 | 0.89 | 0.75 | 1.03 | 1.38 | 1.12 | 1.13 |
35-39 | 0.49 | 1.16 | 1.52 | 1.61 | 1.66 | 1.90 | 2.13 |
40-44 | 1.44 | 1.54 | 1.78 | 2.27 | 3.44 | 3.73 | 3.65 |
45-49 | 1.87 | 2.39 | 2.73 | 3.87 | 4.85 | 5.58 | 6.12 |
50-54 | 3.09 | 3.39 | 3.90 | 5.16 | 6.31 | 7.70 | 9.19 |
55-59 | 4.06 | 4.58 | 5.26 | 7.09 | 7.71 | 8.89 | 10.16 |
60-64 | 4.34 | 5.59 | 7.35 | 9.00 | 10.41 | 10.09 | 11.20 |
65-69 | 8.22 | 6.45 | 8.81 | 10.49 | 11.62 | 14.00 | 13.06 |
70-74 | 6.58 | 8.02 | 9.86 | 12.19 | 14.24 | 15.89 | 17.83 |
75-79 | 4.12 | 10.01 | 11.74 | 12.97 | 12.98 | 19.01 | 17.50 |
80-84 | 4.88 | 5.81 | 8.63 | 15.98 | 18.27 | 17.81 | 19.34 |
Incidence rates (per 100,000) by age, sex, and period in Thailand.
Age group | Thailand | |||||
---|---|---|---|---|---|---|
1987-1991 | 1992-1996 | 1997-2001 | 2002-2006 | 2007-2011 | 2012-2016 | |
Male | ||||||
20-24 | 1.24 | 1.30 | NA | 2.84 | NA | 1.34 |
25-29 | 2.19 | 2.15 | NA | 1.73 | 4.17 | NA |
30-34 | 1.57 | 4.43 | 2.67 | 1.52 | 3.74 | 4.01 |
35-39 | 2.41 | 4.63 | 2.45 | 2.94 | 3.09 | 3.15 |
40-44 | 4.09 | 3.65 | 4.16 | 3.82 | 3.89 | 7.15 |
45-49 | 3.92 | 3.58 | 7.83 | 5.16 | 10.50 | 8.64 |
50-54 | 7.66 | 6.52 | 6.48 | 5.60 | 9.76 | 12.78 |
55-59 | 12.71 | 11.92 | 10.17 | 8.90 | 13.74 | 10.68 |
60-64 | 21.34 | 12.91 | 12.72 | 11.07 | 15.25 | 11.66 |
65-69 | 14.82 | 20.56 | 20.50 | 19.12 | 10.06 | 14.01 |
70-74 | 33.51 | 24.26 | 24.39 | 19.28 | 19.59 | 33.51 |
75-79 | 40.36 | 48.49 | 50.84 | 35.30 | 33.93 | 24.67 |
80-84 | 69.25 | 77.46 | 51.00 | 64.76 | 44.05 | 30.99 |
Female | ||||||
20-24 | NA | NA | NA | NA | 1.57 | 1.49 |
25-29 | 1.87 | NA | 1.34 | NA | NA | 2.21 |
30-34 | NA | 2.37 | 2.52 | 2.68 | 1.58 | NA |
35-39 | 2.58 | 3.28 | 1.40 | 1.40 | 2.13 | 3.68 |
40-44 | 2.11 | 3.46 | 1.56 | 2.79 | 2.03 | 2.68 |
45-49 | 4.93 | 3.82 | 4.52 | 4.91 | 2.85 | 4.87 |
50-54 | 8.51 | 7.23 | 5.36 | 4.34 | 3.65 | 2.91 |
55-59 | 13.67 | 15.88 | 17.88 | 8.81 | 5.67 | 4.93 |
60-64 | 23.97 | 29.52 | 24.17 | 15.10 | 14.12 | 5.43 |
65-69 | 38.83 | 41.57 | 46.32 | 28.15 | 20.88 | 14.76 |
70-74 | 68.59 | 64.35 | 44.78 | 56.82 | 33.02 | 16.36 |
75-79 | 50.75 | 56.87 | 71.11 | 47.51 | 49.90 | 32.60 |
80-84 | 50.00 | 58.83 | 61.97 | 41.79 | 68.70 | 52.96 |
The incidence in Taiwan increased with both age and period in females. However, in males, the incidence increased with period but not with age; in fact, the incidence started to decrease after the age of 64. Nevertheless, an increasing trend with age existed in all male birth cohorts. In Thailand, the incidences in both sexes varied with age and period. However, decreasing trends were observed in elderly males and females.
Between 1979 and 2016, the incidence of OC in Taiwanese males dramatically increased with time and predominated over females (Figure
Age-standardized incidence rates (per 100,000) of oral cancer by sex in Taiwan, 1979-2016.
In contrast to Taiwan, the OC trends showed no significant change points in either males or females in Khon Kaen. Gradually, decreasing trends were observed in females (
Age-standardized incidence rates (per 100,000) of oral cancer by sex in Thailand, 1985-2016.
As shown in Figure
APC curves for males in Taiwan (1982-2016) and Thailand (1987-2016).
In males in Khon Kaen, the high incidence rates were found among those over 60 years of age, with the highest incidence rates occurring in those 80 to 84 years of age in 1992 and 1996 (77.46 per 100,000). A decreasing trend was observed in the older age (over 60) group, while age groups younger than 55 years showed a modestly increasing trend. In the past, tremendous gaps between age groups older and younger than 75 years have been observed. Nevertheless, the gap narrowed in the most recent period, as shown in Figure
The time trends of the OC incidence in females in Taiwan and Thailand according to APC are shown in Figure
APC curves for females in Taiwan (1982-2016) and Thailand (1987-2016).
The highest incidence of OC in Thai females was 68.7 per 100,000 (age 80-84) in the period of 2007-2011 (Table
This study was the first to compare the OC incidence rates in Taiwan and Khon Kaen, Thailand; there were some distinct characteristics between the two regions, including the dominant sex (male in Taiwan and female in Khon Kaen), opposing trends (increasing in Taiwan and decreasing in Khon Kaen), and cross-sectional age-specific incidence patterns (concave in Taiwanese male since 1997).
The differences and changes in the OC incidence patterns could be explained by the three established risk factors of chewing BQ, smoking cigarettes, and drinking alcohol [
The increased tendency in BQ chewing, as described above, supports the increased OC incidence over time, as well as the notable EAPC from 1986 to 1999 in males. Remarkably, we observed that the increase in the trend started to decelerate between 2009 and 2016 (Figure
The BQ chewing prevalence in Thailand was notably different from that in Taiwan. Thai females had a higher prevalence than Thai males. A recent study showed that the prevalence of BQ chewing was approximately 1.8% in the total population and 0.3% and 3.3% in males and females [
Age is one of the most common risk factors in epidemiological studies. Cancers are known to be age-related, and the risk of cancer increases with age [
The smoking rates in males in both countries were similar and showed a continuously decreasing trend. The prevalence of smoking in males in Taiwan and Thailand was 40.5% between 2001 and 2013 and 42.1% between 2001 and 2011, respectively [
In Thailand, an almost BQ-free country, people still have a unique type of roll-your-own (RYO) cigarette called Yamuan. This kind of cigarette is possibly more dangerous than factory-made cigarettes [
In Taiwan, alcohol consumption was concluded to play a minor role in the development of OPMDs and thus OC in previous studies [
We found that the incidence in Taiwan increased in the recent cohort in all age groups. One reason for this may be that the period effect was probably occurred by the birth cohort effect because the same pattern appeared in the different age groups. Unlike the pattern that is shown in Figure
In this study, we explored the differences in oral cancer (OC) incidence trends by sex, period, and birth cohort, between two populations in Taiwan and Thailand, and therefore, we cannot look into detailed information by the anatomic site due to sparse cases in Thailand. Moreover, we cannot clearly elucidate specific etiologies, especially for OC cases at the base of the tongue and in the anterior two-thirds of the tongue, which are considered to have distinct etiologies. A further study with different methodology which can tackle the issue of sparse sample size is needed.
In conclusion, an increasing trend in the OC incidence was observed in Taiwan, but the increase began to decelerate in 2009. APC effects were different in males and females in both regions, which may have significant implications for different intervention policies and the use or consumption of high-risk substances over with time in the two regions.
No additional data are available, and the data from the cancer registry in Khon Kaen, Thailand, require ethical proof to access.
The funding source had no role in the study design, data collection, analysis, interpretation, report writing, or the decision to submit this paper for publication.
The authors declare no conflicts of interest.
P Siewchaisakul had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. P Siewchaisakul conducted and is responsible for the data analysis. AMY initiated, planned, and designed the conduct of the study; P Sarakarn and PV conducted the data acquisition, management, and analysis; SLC interpreted the study results; P Siewchaisakul drafted the manuscript; all authors wrote and approved the final manuscript and approved the decision to submit the manuscript.
We would like to thank the Taiwan Cancer Registry and Khon Kaen Cancer Registry, Thailand, for the information on their OC data. This study was supported by the Ministry of Education (MOE) in Taiwan (grant number 106-3805-005-400).