Karnchana Daoprasert

In Thailand, five cancer types-breast, cervical, colorectal, liver and lung cancer-contribute to over half of the cancer burden. The magnitude of these cancers must be quantified over time to assess previous health policies and highlight future trajectories for targeted prevention efforts. We provide a comprehensive assessment of these five cancers nationally and subnationally, with trend analysis, projections, and number of cases expected for the year 2025 using cancer registry data. We found that breast (average annual percent change (AAPC): 3.1%) and colorectal cancer (female AAPC: 3.3%, male AAPC: 4.1%) are increasing while cervical cancer (AAPC: -4.4%) is decreasing nationwide. However, liver and lung cancers exhibit disproportionately higher burdens in the northeast and north regions, respectively. Lung cancer increased significantly in northeastern and southern women, despite low smoking rates. Liver cancers are expected to increase in the northern males and females. Liver cancer increased in the south, despite the absence of the liver fluke, a known factor, in this region. Our findings are presented in the context of health policy, population dynamics and serve to provide evidence for future prevention strategies. Our subnational estimates provide a basis for understanding variations in region-specific risk factor profiles that contribute to incidence trends over time.

BACKGROUND: Southeast Asia is undergoing a transition from infectious to chronic diseases, including a dramatic increase in adult cancers. Childhood cancer research in Thailand has focused predominantly on leukemias and lymphomas or only examined children for a short period of time. This comprehensive multisite study examined childhood cancer incidence and survival rates in Thailand across all International Classification of Childhood Cancer (ICCC) groups over a 20-year period. METHODS: Cancer cases diagnosed in children ages 0-19 years (n = 3574) from 1990 to 2011 were extracted from five provincial population-based Thai registries, covering approximately 10% of the population. Descriptive statistics of the quality of the registries were evaluated. Age-standardized incidence rates (ASRs) were calculated using the Segi world standard population, and relative survival was computed using the Kaplan-Meier method. Changes in incidence and survival were analyzed using Joinpoint Regression and reported as annual percent changes (APC). RESULTS: The ASR of all childhood cancers during the study period was 98.5 per million person-years with 91.0 per million person-years in 1990-2000 and 106.2 per million person-years in 2001-2011. Incidence of all childhood cancers increased significantly (APC = 1.2%, P < 0.01). The top three cancer groups were leukemias, brain tumors, and lymphomas. The 5-year survival for all childhood cancers significantly improved from 39.4% in 1990-2000 to 47.2% in 2001-2011 (P < 0.01). CONCLUSIONS: Both childhood cancer incidence and survival rates have increased, suggesting improvement in the health care system as more cases are identified and treated. Analyzing childhood cancer trends in low- and middle-income countries can improve understanding of cancer etiology and pediatric health care disparities.

BACKGROUND: The ability and behaviour of the capture-recapture method using a virtual three-source model for evaluation of the level of completeness of case ascertainment requires exploration. METHODS: Cancer cases obtained from 9 population-based cancer registries in Thailand during 2003 to 2007 were applied for capture-recapture using a model based on clinical, pathological and mortality data. These three virtual sources were derived from three actual items common to all cancer registries: the basis of diagnosis, ICD-O morphology code, and last known patient status. Poisson regression models were fit to the data to estimate parameters which were then transformed into demographic values. A linear model was used to determine the predictors and estimated percentage of completeness (EPC) in case ascertainment among the cancer registries. RESULTS: The EPC was greater than 97% in 5 and less than 90% in 4 registries. The worst had an EPC of 70%. The percentage death certificate only (%DCO) and the interaction between %DCO and morphological verification (MV) were significantly associated with EPC. Other factors intrinsic to registries also exerted influence on the EPC. CONCLUSIONS: In addition to other standard indicators to monitor completeness of cancer registries, the present virtual three-source capture-recapture model can be routinely used to estimate the level of completeness of case ascertainment in cancer registries.

Rapid changes in social and economic development have led to cancer becoming a major cause of national morbidity and mortality in Thailand. Cancer registries have been critical in documenting subnational cancer patterns and transitions in the country; with the establishment of six registries in northern Thailand, a comprehensive assessment of the scale and profile of cancer is now possible in the region. Cancers of the liver, lung, colorectum, breast and cervix were the major cancers 2008-2012, although variations in the profiles of cancer were observed, with a very high incidence of liver cancer seen among males in Phrae, corresponding to one in 11 men developing the disease in a lifetime. Based on data from Lampang and Chiang Mai 1993-2012, rates of lung and cervical cancer incidence have declined, while liver, colorectal and breast cancer incidence have been increasing up to 2012. A more detailed investigation of the incidence trends for specific cancer sites and subtypes at the local level are crucial to the monitoring and evaluation of the cancer control interventions implemented within the Thai national cancer control programme (NCCP). Priority should be given to extend the capacity of the new registries in northern Thailand, ensuring improvement in quality and utilization of the data to drive epidemiologic research and cancer control.

BACKGROUND: The magnitude of differences in mortality incidence (M:I) ratios derived from the national mortality source and those derived from cancer registry (CR) databases may be used to determine associated factors. METHODS: All information on cancer incidence cases and mortality cases from January 1, 2003 to December 31, 2007 were retrieved from 5 population-based cancer registries in four regions of Thailand. Two sources of mortality were used: death cases within the cancer registries and mortality statistics obtained from the Ministry of Public Health (MOPH). Plots of percentage M:I ratios from cancer registry databases and from national mortality sources against 1 minus 5 years relative survival (1-5yrRS) were used to visualize the correlation between the two mortality sources. A Poisson regression model was used to determine the influence of cancer sites and registries on the M:I ratio/[1-5yrRS]. RESULTS: There was high variability between the standard M:I ratio derived from national mortality compared with 1-5 year RS. The factors affecting M:I ratios are sources of mortality data and misclassification of topographic site as the cause of death. CONCLUSIONS: Use of the M:I ratio is not recommended to evaluate completeness of cancer registry data when the quality of mortality data is poor.