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Thyroid. 2001 May;11(5):483-6.
Iodine and cancer.
Feldt-Rasmussen U.
Author information
Abstract
Thyroid carcinomas are the most frequent endocrine malignancies. Among thyroid carcinomas the most frequent types are the differentiated forms (follicular, papillary or mixed papillary-follicular), whereas anaplastic thyroid carcinoma and medullary thyroid carcinomas are rare. Animal experiments have demonstrated a clear increase in incidence of thyroid epithelial cell carcinomas after prolonged iodine deficiency leading to a situation of the thyroid gland by thyrotropin and possibly other growth factors. However, the overall incidence of differentiated thyroid carcinoma is generally not considered to be influenced by the iodine intake of a population, whereas the distribution of the types of thyroid carcinoma seems to be related to the intake of iodine, with fewer of the more aggressive follicular and anaplastic carcinomas and more papillary carcinomas in iodine rich areas. Populations starting iodine prophylaxis demonstrate an increase in the ratio of papillary to follicular carcinoma. Because a population with higher iodine intake usually has fewer benign nodules in the thyroid gland and the incidence of thyroid carcinomas is similar to an iodine-deficient region, the diagnostic work-up of nodules in the thyroid gland may become affected. The incidence of other cancers, such as breast cancer, may be influenced by the iodine intake, but too few studies are available at present. The present article summarizes available data from both epidemiological studies, animal experiments, and basic gene transfection studies. The overall incidence for a relationship between iodine and cancer is poor and future studies are warranted.
Acta Endocrinol (Copenh). 1985 Jan;108(1):55-60.
Thyroid carcinoma and thyroiditis in an endemic goitre region before and after iodine prophylaxis.
Harach HR, Escalante DA, Onativia A, Lederer Outes J, Saravia Day E, Williams ED.
Abstract
Iodine prophylaxis was introduced to the moderately severe goitre endemic area in Salta, Argentina, in 1963. All thyroidectomies from a 20 year period were reviewed, and 148 thyroid malignancies carefully studied. The period from 5 to 15 years after iodization was associated with a lower frequency of follicular carcinomas and a higher frequency of papillary carcinomas than the period before and up to 5 years after prophylaxis. Lymphoid infiltration in the non-tumorous thyroid was relatively infrequent before iodine prophylaxis: it was much higher in each of the post-prophylaxis periods. These results, in agreement with other studies, support the view that an increased iodine intake is associated with an increased incidence of papillary carcinoma of the thyroid and thyroiditis.
Endocr Pathol. 2002 Fall;13(3):175-81.
Thyroid cancer and thyroiditis in Salta, Argentina: a 40-yr study in relation to iodine prophylaxis.
Harach HR1, Escalante DA, Day ES.
Author information
Abstract
The natural history of thyroid cancer and thyroiditis in relation to iodine prophylaxis in the region of Salta, Argentina, where goiter is common was investigated over a time span of 40 yr. For analysis of thyroid cancer, the specimens were divided into two periods. The first 15 yr (59 cases), including 5 yr before prophylaxis, was compared with the second 25 yr (182 cases), a period well after salt iodination. Papillary carcinomas formed the largest group of tumors in both periods, with a significant increase in their proportion in the second period (44 vs 60%, chi(2): p < 0.05), while the percentage of follicular and undifferentiated carcinomas decreased and medullary carcinoma remained about the same. The ratio of papillary to follicular carcinoma rose from 1.7:1 in the first period to 3.1:1 in the second. Four thyroid lymphomas of non-Hodgkin's B-cell type occurred in the second period in females over age 50. A severe lymphoid thyroiditis was present in the two cases with assessable background thyroid tissue. The frequency of moderate to severe lymphoid infiltrate in females rose from 2 of 12 (16.6%) in the preprophylaxis period to 34 of 114 (28.0%) in the last 25 yr after prophylaxis. After salt prophylaxis, thyroiditis was more frequent in patients with papillary carcinoma (36.2%) than in those with nonpapillary tumors (14.7%) (chi(2), p < 0.02). These observations indicate that a high dietary intake of iodine may be associated with a high frequency of papillary carcinoma and thyroiditis, and that thyroiditis is more commonly associated with papillary carcinoma than with other thyroid tumors. The occurrence of non-Hodgkin's lymphomas only in the postprophylaxis period may be linked to an increase in thyroiditis.
Saudi Med J. 2007 Jul;28(7):1034-8.
The effect of iodine prophylaxis on the frequency of thyroiditis and thyroid tumors in Southwest, Iran.
Soveid M1, Monabbati A, Sooratchi L, Dahti S.
Author information
Abstract
OBJECTIVE:
To investigate the effect of the salt iodization program, which was initiated in 1989 on frequencies of thyroiditis and papillary carcinoma in Fars province of Iran, which was previously an iodine deficient area.
METHODS:
Four hundred and eighty-two thyroidectomy specimens belonging to the pre-iodization period from 1983 to 1988, and 466 post iodization specimens from 1998 to 2003 were re-examined for presence of lymphocytic infiltration and types of thyroid tumors. This study was carried out in Shiraz University of Medical Sciences, Iran.
RESULTS:
The frequency of lymphocytic infiltration in non-neoplastic specimens increased from 30-60.5% after salt iodization (p<0.001). Background of lymphocytic infiltration in neoplastic specimens also increased from 18.5-61% after iodine prophylaxis (p<0.001). The frequency of papillary carcinoma in neoplastic specimens increased from 15-43% (p=0.01) and that of follicular adenoma decreased from 69-32.5% (p<0.0001).
CONCLUSION:
Salt iodization is associated with an increased occurrence of histologic thyroiditis and papillary carcinoma.
Cancer. 1977 Jan;39(1):215-22.
Thyroid cancer in an iodide rich area: a histopathological study.
Williams ED, Doniach I, Bjarnason O, Michie W.
Abstract
A comparison of the incidence of the different histological types of thyroid carcinoma in an area of high dietary iodide and an area of normal iodide intake has been made. The areas chosen were Iceland and the region of Northeast Scotland centred on Aberdeen; both areas have clearly defined populations served by a single pathology laboratory. All definite and dubious thyroid carcinomas from both regions were examined and classified by the same two pathologists. The age-specific incidence rates for papillary carcinoma in surgical specimens in both areas rose with age; they were five times higher in Iceland (high iodide area) than in Northeast Scotland. The numbers of follicular carcinomas were small, and this tumor was relatively less frequent in Iceland than Aberdeen. These findings, together with the known high relative frequency of follicular carcinoma and low frequency of papillary carcinoma in areas of endemic goitre, lead to the suggestion that the incidence of papillary carcinoma and follicular carcinoma are separately influenced by dietary iodide, papillary carcinoma being high in areas of high iodide intake and low in areas with low dietary iodide. No evidence to implicate lymphocytic thyroiditis, radiation or genetic factors in the genesis of thyroid carcinoma in Iceland or Northeast Scotland was found in this study. Undifferentiated carcinoma was about three times as common in Iceland as in Northeast Scotland. Malignant lymphoma of the thyroid was suprisingly common in Northeast Scotland, possibly related to the high frequency of thyroiditis found in this region. These studies suggest that the incidence of different histological types of thyroid malignancy is influenced by different etiological factors. They also provide support for the subdivision of thyroid malignancy into these different types, and for the general importance of accurate histological typing in cancer epidemiology.
Iodine and cancer.
Feldt-Rasmussen U.
Author information
Abstract
Thyroid carcinomas are the most frequent endocrine malignancies. Among thyroid carcinomas the most frequent types are the differentiated forms (follicular, papillary or mixed papillary-follicular), whereas anaplastic thyroid carcinoma and medullary thyroid carcinomas are rare. Animal experiments have demonstrated a clear increase in incidence of thyroid epithelial cell carcinomas after prolonged iodine deficiency leading to a situation of the thyroid gland by thyrotropin and possibly other growth factors. However, the overall incidence of differentiated thyroid carcinoma is generally not considered to be influenced by the iodine intake of a population, whereas the distribution of the types of thyroid carcinoma seems to be related to the intake of iodine, with fewer of the more aggressive follicular and anaplastic carcinomas and more papillary carcinomas in iodine rich areas. Populations starting iodine prophylaxis demonstrate an increase in the ratio of papillary to follicular carcinoma. Because a population with higher iodine intake usually has fewer benign nodules in the thyroid gland and the incidence of thyroid carcinomas is similar to an iodine-deficient region, the diagnostic work-up of nodules in the thyroid gland may become affected. The incidence of other cancers, such as breast cancer, may be influenced by the iodine intake, but too few studies are available at present. The present article summarizes available data from both epidemiological studies, animal experiments, and basic gene transfection studies. The overall incidence for a relationship between iodine and cancer is poor and future studies are warranted.
Acta Endocrinol (Copenh). 1985 Jan;108(1):55-60.
Thyroid carcinoma and thyroiditis in an endemic goitre region before and after iodine prophylaxis.
Harach HR, Escalante DA, Onativia A, Lederer Outes J, Saravia Day E, Williams ED.
Abstract
Iodine prophylaxis was introduced to the moderately severe goitre endemic area in Salta, Argentina, in 1963. All thyroidectomies from a 20 year period were reviewed, and 148 thyroid malignancies carefully studied. The period from 5 to 15 years after iodization was associated with a lower frequency of follicular carcinomas and a higher frequency of papillary carcinomas than the period before and up to 5 years after prophylaxis. Lymphoid infiltration in the non-tumorous thyroid was relatively infrequent before iodine prophylaxis: it was much higher in each of the post-prophylaxis periods. These results, in agreement with other studies, support the view that an increased iodine intake is associated with an increased incidence of papillary carcinoma of the thyroid and thyroiditis.
Endocr Pathol. 2002 Fall;13(3):175-81.
Thyroid cancer and thyroiditis in Salta, Argentina: a 40-yr study in relation to iodine prophylaxis.
Harach HR1, Escalante DA, Day ES.
Author information
Abstract
The natural history of thyroid cancer and thyroiditis in relation to iodine prophylaxis in the region of Salta, Argentina, where goiter is common was investigated over a time span of 40 yr. For analysis of thyroid cancer, the specimens were divided into two periods. The first 15 yr (59 cases), including 5 yr before prophylaxis, was compared with the second 25 yr (182 cases), a period well after salt iodination. Papillary carcinomas formed the largest group of tumors in both periods, with a significant increase in their proportion in the second period (44 vs 60%, chi(2): p < 0.05), while the percentage of follicular and undifferentiated carcinomas decreased and medullary carcinoma remained about the same. The ratio of papillary to follicular carcinoma rose from 1.7:1 in the first period to 3.1:1 in the second. Four thyroid lymphomas of non-Hodgkin's B-cell type occurred in the second period in females over age 50. A severe lymphoid thyroiditis was present in the two cases with assessable background thyroid tissue. The frequency of moderate to severe lymphoid infiltrate in females rose from 2 of 12 (16.6%) in the preprophylaxis period to 34 of 114 (28.0%) in the last 25 yr after prophylaxis. After salt prophylaxis, thyroiditis was more frequent in patients with papillary carcinoma (36.2%) than in those with nonpapillary tumors (14.7%) (chi(2), p < 0.02). These observations indicate that a high dietary intake of iodine may be associated with a high frequency of papillary carcinoma and thyroiditis, and that thyroiditis is more commonly associated with papillary carcinoma than with other thyroid tumors. The occurrence of non-Hodgkin's lymphomas only in the postprophylaxis period may be linked to an increase in thyroiditis.
Saudi Med J. 2007 Jul;28(7):1034-8.
The effect of iodine prophylaxis on the frequency of thyroiditis and thyroid tumors in Southwest, Iran.
Soveid M1, Monabbati A, Sooratchi L, Dahti S.
Author information
Abstract
OBJECTIVE:
To investigate the effect of the salt iodization program, which was initiated in 1989 on frequencies of thyroiditis and papillary carcinoma in Fars province of Iran, which was previously an iodine deficient area.
METHODS:
Four hundred and eighty-two thyroidectomy specimens belonging to the pre-iodization period from 1983 to 1988, and 466 post iodization specimens from 1998 to 2003 were re-examined for presence of lymphocytic infiltration and types of thyroid tumors. This study was carried out in Shiraz University of Medical Sciences, Iran.
RESULTS:
The frequency of lymphocytic infiltration in non-neoplastic specimens increased from 30-60.5% after salt iodization (p<0.001). Background of lymphocytic infiltration in neoplastic specimens also increased from 18.5-61% after iodine prophylaxis (p<0.001). The frequency of papillary carcinoma in neoplastic specimens increased from 15-43% (p=0.01) and that of follicular adenoma decreased from 69-32.5% (p<0.0001).
CONCLUSION:
Salt iodization is associated with an increased occurrence of histologic thyroiditis and papillary carcinoma.
Cancer. 1977 Jan;39(1):215-22.
Thyroid cancer in an iodide rich area: a histopathological study.
Williams ED, Doniach I, Bjarnason O, Michie W.
Abstract
A comparison of the incidence of the different histological types of thyroid carcinoma in an area of high dietary iodide and an area of normal iodide intake has been made. The areas chosen were Iceland and the region of Northeast Scotland centred on Aberdeen; both areas have clearly defined populations served by a single pathology laboratory. All definite and dubious thyroid carcinomas from both regions were examined and classified by the same two pathologists. The age-specific incidence rates for papillary carcinoma in surgical specimens in both areas rose with age; they were five times higher in Iceland (high iodide area) than in Northeast Scotland. The numbers of follicular carcinomas were small, and this tumor was relatively less frequent in Iceland than Aberdeen. These findings, together with the known high relative frequency of follicular carcinoma and low frequency of papillary carcinoma in areas of endemic goitre, lead to the suggestion that the incidence of papillary carcinoma and follicular carcinoma are separately influenced by dietary iodide, papillary carcinoma being high in areas of high iodide intake and low in areas with low dietary iodide. No evidence to implicate lymphocytic thyroiditis, radiation or genetic factors in the genesis of thyroid carcinoma in Iceland or Northeast Scotland was found in this study. Undifferentiated carcinoma was about three times as common in Iceland as in Northeast Scotland. Malignant lymphoma of the thyroid was suprisingly common in Northeast Scotland, possibly related to the high frequency of thyroiditis found in this region. These studies suggest that the incidence of different histological types of thyroid malignancy is influenced by different etiological factors. They also provide support for the subdivision of thyroid malignancy into these different types, and for the general importance of accurate histological typing in cancer epidemiology.