Abstract
BackgroundThe aim of this paper is to analyze changes in thyroid cancer incidence trends in Lithuania during the period 1978–2003 using joinpoint regression models, with special attention to the period 1993–2003.MethodsThe study was based on all cases of thyroid cancer reported to the Lithuanian Cancer Registry between 1978 and 2003. Age group-specific rates and standardized rates were calculated for each gender, using the direct method (world standard population). The joinpoint regression model was used to provide estimated annual percentage change and to detect points in time where significant changes in the trends occur.ResultsDuring the study period the age-standardized incidence rates increased in males from 0.7 to 2.5 cases per 100 000 and in females from 1.5 to 11.4 per 100 000. Annual percentage changes during this period in the age-standardized rates were 4.6% and 7.1% for males and females, respectively. Joinpoint analysis showed two time periods with joinpoint in the year 2000. A change in the trend occurred in which a significant increase changed to a dramatic increase in thyroid cancer incidence rates. Papillary carcinoma and stage I thyroid cancer increases over this period were mainly responsible for the pattern of changes in trend in recent years.ConclusionA moderate increase in thyroid cancer incidence has been observed in Lithuania between the years 1978 and 2000. An accelerated increase in thyroid cancer incidence rates took place in the period 2000–2003. It seems that the increase in thyroid cancer incidence can be attributed mainly to the changes in the management of non palpable thyroid nodules with growing applications of ultrasound-guided fine needle aspiration biopsy in clinical practice.
Highlights
The aim of this paper is to analyze changes in thyroid cancer incidence trends in Lithuania during the period 1978–2003 using joinpoint regression models, with special attention to the period 1993–2003
The Registry covers the entire population of the Republic of Lithuania (3.48 million at the 2001 census) and is located at the national cancer center recently operating as Vilnius University Institute of Oncology, where more that 50% of cancer patients in Lithuania are admitted for treatment
Thyroid cancer incidence rates in males changed during the study period from 0.7/100 000 in 1978 to 2.5/100 000 in the year 2003, and from 1.5/100 000 to 11.4/100 000 in females (Figure 1)
Summary
The aim of this paper is to analyze changes in thyroid cancer incidence trends in Lithuania during the period 1978–2003 using joinpoint regression models, with special attention to the period 1993–2003. Thyroid cancers constitute 1% of all malignancies worldwide and are heterogenous in terms of histology, clinical presentation, treatment response and prognosis. The annual incidence of thyroid cancer varies considerably in different registries. High incidence rates in Hawaii, Iceland and Israel have been known for some years. BMC Cancer 2006, 6:284 http://www.biomedcentral.com/1471-2407/6/284 relatively low incidence characterizes the UK, Netherlands and Denmark. The only established risk factor for thyroid cancer in humans, besides age and gender, is ionizing radiation [2]. Iodine deficiency and other factors have been proposed as risk factors for thyroid cancer, but the findings are inconsistent [3-7]
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