Risks of papillary and follicular thyroid cancer among immigrants to Sweden

Abstract

Previous studies have indicated that ionizing radiation, particularly during childhood, is the main established risk factor for thyroid cancer. History of benign nodules/adenoma, goiter, iodine deficiency or high‐iodine intake might be other associated factors. We wanted to define the histology‐specific thyroid cancer risk in the first‐generation immigrants to Sweden. We used the 2010 update of the nation‐wide Swedish Family‐Cancer Database (>12 million individuals; 1.8 million immigrants; histology code in force since 1958) to calculate standardized incidence ratios (SIRs) for histology‐specific thyroid cancer among immigrants compared to the native Swedes. The patient series covered 2,604 male and 6,406 female Swedes, and 247 and 863 immigrants. The median age at immigration was 29 years, and the median age at thyroid cancer diagnosis was 46 years. Increased risks for female papillary carcinoma were observed for Finns (SIR = 1.63), former Yugoslavians (2.36), Russians (2.34), other East Europeans (2.14), Turks (3.16), Iranians (2.68), Iraqis (2.77), East and Southeast Asians (2.92), other Asians (1.69) and South Americans (2.23). Male Iranians (2.85), East and Southeast Asians (3.57) and other Asians (2.26) had an increased risk for papillary carcinoma. Only male East and Southeast Asians (2.93) had an increased risk for follicular carcinoma. The data might suggest that immigrant populations in Sweden from areas of low or high‐iodine intake are at risk of papillary carcinoma, implicating iodine imbalance as a contributing factor to our findings. The increased risk of thyroid cancer among Asian immigrants may confirm the role of childhood‐ionizing radiation on thyroid cancer risk.

Trends in Thyroid Cancer Incidence in Korean Children (1999-2012) Based on Palpation and Nonpalpation Detection Methods

“…Regarding genetic susceptibility, it has been suggested that the genetic factors contributing to thyroid cancer development are considerable compared with those of other cancers [20]. Mousavi et al [21] reported that East and Southeast Asians, including South Koreans, were one of the most susceptible populations for developing thyroid cancer according to the Swedish Family-Cancer Database. Familial nonmedullary thyroid cancer (FNMTC), which accounts for approximately 5% of all thyroid cancers, is diagnosed when two or more first-degree relatives have differentiated thyroid cancer without other familial syndromes [22].…”

Growing incidence of thyroid carcinoma in recent years: Factors underlying overdiagnosis

“…49 Other authors have suggested race, ethnicity, and nativity as contributing factors. [50][51][52][53][54][55] In Sweden, immigrants from the middle east, Asia, and South America have an increased incidence of well-differentiated thyroid cancer, 56 and in New Zealand, women from Pacific regions have a higher incidence in comparison with women of European descent. 57 However, other authors did not find differences associated with race in the US population.…”

Telomerase reverse transcriptase promoter mutation and its clinical implication in thyroid cancer

“…The population living in East Asia, including Korea, has been reported to be genetically susceptible to thyroid cancer [9,10]. Extremely high iodine intake, increased exposure to medical radiation, and rising rates of obesity are also potential candidates to explain this phenomenon [11][12][13][14][15][16].…”