Ultrasonographic screening for occult thyroid cancer

Secondary and tertiary preventions of thyroid disease

INTRODUCTION

Secondary and tertiary preventions are concerned with the recognition of the disease process in a very early stage and delay in progression to complete disease and minimization of complications and the impact of illness.

METHODS

All articles related to secondary and tertiary prevention of thyroid diseases were reviewed. Using related key words, articles published between 2001 and 2015 were evaluated, categorized, and analyzed.

RESULTS

In secondary prevention, congenital hypothyroidism and subclinical hypo and hyperthyroidism are equally important. Routine screening of patients with multinodular goiter by either ultrasonography or calcitonin is a controversial issue, while calcitonin assessments in medullary cancer and RET in family members are recommended. Screening of thyroid disease in pregnancy is limited to those with risk factors. Views regarding the importance of thyroid autoimmunity in secondary prevention are also presented. In tertiary prevention, prescribing excessive doses of levothyroxine, in the elderly in particular and appropriate care of all patients to avoid progression and complications are the key issues.

CONCLUSION

Optimization of management of thyroid diseases requires timely screening, prevention of progression to more sever disease, optimal medical care, and avoidance of iatrogenic conditions.

Epidemiology of nodular goitre. Influence of iodine intake

More than one tenth of the world population is to some degree affected by goitre and most of these harbour nodules. The large differences in thyroid disease prevalence between populations may be caused by genetic and environmental factors. Among the latter, iodine deficiency seems by far to be the most important risk factor. Thus, nodular goitre is a condition predominantly seen in iodine deficient areas of the world. In the present review, we evaluated in detail autopsy and ultrasound studies of the thyroid gland. In autopsy studies, large thyroid volumes and high frequencies of goitres have been reported in countries affected by iodine deficiency. Many cross-sectional studies using thyroid ultrasound investigations have been performed world-wide and reported high thyroid volumes and goitre prevalences, and to some extent also high prevalences of thyroid nodules in iodine-deficient countries. Most of these goitres were classified as nodular goitres. On the other hand, few studies have shown that abundant iodine intake may lead to development of diffuse goitres, but world-wide this has been a minor problem compared with development of nodular goitres. In the past century we have observed a trend towards smaller thyroid glands, and hopefully less than 10% of the world population will experience goitre within a few decades.

Ultrasonography survey and thyroid cancer in the Fukushima Prefecture

Thyroid cancer is one of the major health concerns after the accident in the Fukushima Dai-ichi nuclear power station (NPS). Currently, ultrasonography surveys are being performed for persons residing in the Fukushima Prefecture at the time of the accident with an age of up to 18 years. Here, the expected thyroid cancer prevalence in the Fukushima Prefecture is assessed based on an ultrasonography survey of Ukrainians, who were exposed at an age of up to 18 years to (131)I released during the Chernobyl NPS accident, and on differences in equipment and study protocol in the two surveys. Radiation risk of thyroid cancer incidence among survivors of the atomic bombings of Hiroshima and Nagasaki and preliminary estimates of thyroid dose due to the Fukushima accident were used for the prediction of baseline and radiation-related thyroid cancer risks. We estimate a prevalence of thyroid cancer of 0.027 % (95 % CI 0.010 %; 0.050 %) for the first screening campaign in the Fukushima Prefecture. Compared with the incidence rate in Japan in 2007, the ultrasonography survey is predicted to increase baseline thyroid cancer incidence by a factor of 7.4 (95 % CI 0.95; 17.3). Under the condition of continued screening, thyroid cancer during the first fifty years after the accident is predicted to be detected for about 2 % of the screened population. The prediction of radiation-related thyroid cancer in the most exposed fraction (a few ten thousand persons) of the screened population of the Fukushima Prefecture has a large uncertainty with the best estimates of the average risk of 0.1-0.3 %, depending on average dose.

Ultrasonography survey and thyroid cancer in the Fukushima Prefecture

Thyroid cancer is one of the major health concerns after the accident in the Fukushima Dai-ichi nuclear power station (NPS). Currently, ultrasonography surveys are being performed for persons residing in the Fukushima Prefecture at the time of the accident with an age of up to 18 years. Here, the expected thyroid cancer prevalence in the Fukushima Prefecture is assessed based on an ultrasonography survey of Ukrainians, who were exposed at an age of up to 18 years to (131)I released during the Chernobyl NPS accident, and on differences in equipment and study protocol in the two surveys. Radiation risk of thyroid cancer incidence among survivors of the atomic bombings of Hiroshima and Nagasaki and preliminary estimates of thyroid dose due to the Fukushima accident were used for the prediction of baseline and radiation-related thyroid cancer risks. We estimate a prevalence of thyroid cancer of 0.027 % (95 % CI 0.010 %; 0.050 %) for the first screening campaign in the Fukushima Prefecture. Compared with the incidence rate in Japan in 2007, the ultrasonography survey is predicted to increase baseline thyroid cancer incidence by a factor of 7.4 (95 % CI 0.95; 17.3). Under the condition of continued screening, thyroid cancer during the first fifty years after the accident is predicted to be detected for about 2 % of the screened population. The prediction of radiation-related thyroid cancer in the most exposed fraction (a few ten thousand persons) of the screened population of the Fukushima Prefecture has a large uncertainty with the best estimates of the average risk of 0.1-0.3 %, depending on average dose.

Very high prevalence of ultrasound thyroid scan abnormalities in healthy volunteers in Modena, Italy

BACKGROUND

Italy is characterized by high prevalence of goiter. To date, only limited data about the prevalence of goiter in the Italian adult population are available.

AIM

To investigate the prevalence of thyroid ultrasound abnormalities in adults unaware of any thyroid disease and evaluate the rate of differentiated thyroid cancer (DTC) obtained by this intervention.

METHODS

Ultrasound (US) thyroid scan was performed in adult volunteers recruited by advertisement in Modena, Italy. One hundred and thirty-five women and 66 men (no.= 201), unaware of any thyroid disease (mean age of 46 ± 10.7 yr) underwent their first thyroid US scan.

RESULTS

US thyroid abnormalities were found in 101 subjects (50.3%): 91 nodular goiters (45.2%) and 13 US-thyroiditis (6.5%) associated with positive auto-antibodies in 11 of them. Seventeen subjects (18%) with nodules underwent US-fine needle aspiration biopsy with the following cytological class (C) outcome: 14 patients C2 (82%), 1 patient C3 (6%), 2 patients had C4 (12%), the latter received histological confirmation.

CONCLUSIONS

The prevalence of thyroid abnormalities is very high in subjects unaware of any thyroid disease. DTC was found in 1% of subjects and in 2% of those affected by nodular goiter. Compared to the detection rate of the well-established screening programs for breast (0.45%) and colorectal (0.27%) cancer, the prevalence of DTC seems to be much higher. Thyroid US screening could allow the detection of DTC in asymptomatic subjects and this diagnosis often includes DTC at an advanced stage. Thus, US screening not necessarily results in the over-diagnosis of clinically not relevant thyroid diseases.