[Reproductive history, contraceptives and cigarette smoke as risk factors for cancer of the thyroid in women. Case-control study]. / Storia riproduttiva, contraccettivi e fumo di sigaretta come fattori di rischio del cancro della tiroide nel sesso femminile.

BACKGROUND: Evaluation of the influence of hormonal and reproductive factors and the role of cigarette smoking in the onset of thyroid carcinoma. METHODS: Comparison between a group of 78 female patients all living in the district of Lazio, operated for thyroid follicular or papillary carcinoma at the Third Clinical Surgery Dept., Policlinico Umberto I, Rome (Italy) from 1990 to 1997, and a group of 150 women free from neoplastic and/or hormonal pathology, recruited by the compilation of a questionnaire. RESULTS: Cigarette smoking can be associated with risk reduction of developing thyroid neoplasia. On the contrary, no risk variation has been associated with the number of normal pregnancies, with pregnancy interruption both spontaneous and voluntary and with anthropometric characteristics of the analysed individuals. The first pregnancy at very young age and the use of contraceptives seem to determine a risk increase of thyroid cancer, at the limit of statistical significance. CONCLUSIONS: The antiestrogenic action of cigarette smoking exerts a protective action for thyroid carcinomas. Spontaneous or volontary interruption of pregnancy did not show a significant effect as risk factor.

Pathogenesis of thyroid nodules: histological classification?

Thyroid nodule genesis may be considered as an amplification of thyroid heterogeneity due to genetic and/or epigenetic mechanisms. We classified the thyroid nodules in five types with distinct histological features: hyperplastic, neoplastic, colloid, cystic and thyroiditic nodules. Hyperplastic: Thyrocyte proliferation is under the control of TSH but several other paracrine and autocrine factors are secreted by follicular cells, the stromal apparatus and the lymphocytes, which are implicated in initiation and perpetuation of thyroid hyperplasia. Growth occurs mainly through TSHR, cAMP and PKA. Constitutive cAMP overproduction has been shown to be due to point mutation of the TSHR or Gs protein, producing overgrowth and hyperfunction. Neoplastic: Several activated oncogenes have been identified in thyroid malignancies. Oncogenes relevant to the thyroid carcinogenesis are: mutated TSHR and gsp (constitutive activation of cAMP); TRK (receptor for NGF); RET/PTC (phosphorylation of tyrosine kinase receptor)--an isoform of this oncogene is induced by radiation: ras (it encodes Gs proteins transducing mitogenic signals); and c-MET (receptor for hepatocyte growth factor). The evolution of a differentiated thyroid cancer towards an undifferentiated cancer is due to a mutation of a family of proteins (i.e., p53), which acts as a brake, preventing the genomic instability of cancer. It is suggested that a tumor initiates by RET or ras and possibly progresses--as a result of additional mutations and by p53 mutation--to anaplastic carcinoma. Colloid: Flattening of the epithelium and dilatation of follicles containing viscous material--made up by a concentrated solution of thyroglobulin (hTg)--is the characteristic of the colloid nodule. A defect of intraluminal reabsorption of hTg has been suggested but not proven. Experimentally, a load of iodine is able to change thyroid hyperplasia to a colloid feature; however, a load of iodine is rarely found in the clinical history of patients. A new clue to the pathogenesis comes from the finding that a relevant part of the colloid (10-20%) is made up of insoluble globules, where hTg is compacted in a polymeric form. It is suggested that stocking hTg into globules is defective in colloid nodules, leading to enormous enlargement of the follicle. Cystic: It is estimated that between 15 and 40% of thyroid nodules are partly or entirely cystic. The 'true cyst' is rare; most of the so-called cystic nodules are 'pseudocysts', which follow necrosis and colliquation. Necrosis issues as an imbalance between growth and the precisely regulated process of angiogenesis. More recently, the VEGF/VPF has been found to be at the origin of recent and recurrent cysts. Immunotoxic and apoptotic mechanisms have also been suggested. Chemical analysis of cystic fluid showed a 'denatured' and 'serum-like' pattern suggesting different mechanisms in the pathogenesis of the pseudocystic thyroid nodules. Thyroiditic: Nodular lymphocytic thyroiditis (NLT) includes two different entities: 1) lymphocyte thyroiditis growing as a nodule in a hyperplastic or normal gland, and 2) lymphocyte thyroiditis associated in the same nodule with other nodular diseases of the thyroid: papillary thyroid carcinoma and lymphoma have been found to be associated to chronic lymphocytic thyroiditis.

Lipoprotein(a) increase associated with thyroid autoimmunity.

Conflicting results have been reported regarding serum lipoprotein(a) (Lp(a)) concentrations in patients with hypothyroidism. We addressed the question whether thyroid autoimmunity could be associated with elevated Lp(a) values independent of the thyroid status. Lp(a) was measured by ELISA in 30 males, 29 premenopausal and 30 postmenopausal females positive for thyroid peroxidase- and/ or thyroglobulin-antibody (T-Abs) and normolipidemic, screened out respectively from 428 male donors, 162 premenopausal donors and 108 postmenopausal females; they were compared with 65 males, 72 premenopausal and 48 postmenopausal females, negative for thyroid antibodies, normolipidemic and matched for age. T-Abs-positive male donors showed serum Lp(a) concentrations significantly increased compared with males without T-Abs (mean 19.7 +/- 15.9 vs 12.7 +/- 17.5 mg/dl; median 17.0 vs 4.0 mg/dl; Mann Whitney U test: P = 0.0000). In premenopausal females no difference could be found between T-Abs-positive and T-Abs-negative subjects (mean 13.2 +/- 16.1 vs 12.3 +/- 13.9 mg/dl; median 5.2 vs 8.7 mg/dl), suggesting an Lp(a) lowering effect of estrogens. The study was, therefore, extended to postmenopausal females. Significantly elevated Lp(a) levels were found in 30 postmenopausal females with T-Abs when compared with 48 postmenopausal females without T-Abs (40.0 +/- 34.2 mg/dl vs 20.7 +/- 19.3 mg/dl; median 32.0 vs 18.0 mg/dl; Mann Whitney U test: P = 0.0002). Finally, 21 postmenopausal, normolipidemic, autoimmune hypothyroid patients on L-thyroxine and euthyroid compared with 48 postmenopausal females without T-Abs also showed increased serum levels of Lp(a) (mean 27.0 +/- 16.8 mg/dl vs 20.7 +/- 19.3 mg/dl, median 25.0 vs 18 mg/dl; Mann Whitney U test: P = 0.0024). Thyrotropin levels in all subjects and patients were within the normal range. In conclusion, our results in males and postmenopausal females with T-Abs and euthyroid show an association between thyroid autoimmunity and increased levels of Lp(a), while the results obtained in premenopausal females suggest that estrogens might interfere with the Lp(a) increase related to thyroid autoimmunity.

[Thyroid carcinoma. Retrospective analysis of case records of the III. Surgery Department at the Umberto I Clinics in Rome in the years 1990-93]. / Il carcinoma tiroideo. Analisi retrospettiva da una casistica della III Clinica Chirurgica (anni 1990-1993) del Policlinico Umberto I di Roma.

BACKGROUND: The aim of this investigation was to ascertain: 1) temporal trends in the incidence of thyroid carcinoma between 1990-1993; 2) regional differences in the incidence and histotype among the five provinces of Latium; 3) identification of risk factors, particularly of a preexisting thyroid tumour (goitre). METHODS: Records of patients submitted to thyroid surgery at the Istitute of III Clinica Chirurgica dell'Università "La Sapienza" di Roma have been reviewed and a questionnaire filled-in. RESULTS: In the period 1990-1993, 144 cases of thyroid carcinomas were operated; 77.7% of those resided in the Latium region. Average age was 43 +/- 16.2, F:M = 3:1. During the four years observation period there was an increase in all surgical interventions and proportionally increased also thyroid surgery (hyperplasia, thyroiditis, hyperthyroidism and thyroid cancer). Thyroid cancer was found in 10% of thyroid patients, this proportion remains constant in the period 1990-1992, in 1993 rising to 14% (p = 0.032). Differences of incidence although not significant were found in the five provinces of Latium. A higher proportion of follicular histotypes was found in the province of Frosinone (FR vs RM, 20 vs 13.5% p = 0.45). A previous goitre, standing for period of three or more years, was reported in the records of 25% of patients. Seven percent of patients have been previously submitted to a partial thyroidectomy for benign thyroid disease, most of those being operated for thyroid adenoma (8 out 10 cases). CONCLUSION: During a four year period of observation an increase of thyroid carcinoma was observed only in 1993. This increase cannot be attributed to an increase in the incidence of thyroid carcinoma. The province of Frosinone, known to be an endemic area, shows a proportion of the follicular histotype higher than that of other provinces. Goiter precedes malignant thyroid neoplasia in a high proportion of patients (25%). Follicular adenoma found frequently at the histology of patients operated for benign thyroid disease suggesting a transformation from benign to a malignant condition.

Thyroglobulin determined in thyroid fine needle aspiration biopsies by radial immunodiffusion and electroimmunodiffusion.

Radial immunodiffusion and electroimmunodiffusion were used to measure thyroglobulin, the main component of thyroid colloid, in thyroid fine needle aspiration biopsies. A linear relationship was established between precipitation ring diameter and thyroglobulin concentration by radial immunodiffusion (0.5-3.0 g/l), and between "rocket" height and thyroglobulin concentration by electroimmunodiffusion (0.1-2.0 g/l). A nearly complete correlation was observed between the two methods (r = 0.97). In radial immunodiffusion the ring diameter is dependent on time of diffusion and on the antiserum concentration in the agar gel. In this study, the observation time was standardised at 48 h, and the rabbit anti-thyroglobulin serum concentration at 26 ml/l. The intrathyroidal concentration of thyroglobulin was determined by radial immunodiffusion and the thyroid find needle aspiration biopsy of 45 thyroid tumours with different cytological-laboratory- and clinical diagnoses. It was found that in colloid nodules or cysts thyroglobulin is markedly higher than in euthyroid nodular goitre (13.7 +/- 11.9 g/l vs. 1.35 +/- 0.8 g/l, p = 0.005). In conclusion radial immunodiffusion and electroimmunodiffusion are precise, easy to perform, low cost, non polluting methods, which do not require high sample dilution (in contrast, high sample dilution is necessary for measurement of thyroglobulin in thyroid fine needle aspiration biopsy by radial immunodiffusion). Measurement of thyroglobulin in thyroid fine needle aspiration biopsy provides a quantitative estimate of colloid, an important marker in the differential diagnosis of thyroid nodules.

Aetiology of thyroid cancer: an epidemiological overview.

Thyroid cancer is a relatively rare cancer (5 new cases/y/10(5) inhabitants). An excess of thyroid carcinoma has been found in some but not in all goiter endemic areas. Follicular and anaplastic carcinomas have been found particularly frequent in regions of goitre endemia. A significant increase of thyroid carcinoma has also been found in iodine sufficient areas (Norway, Iceland, Hawaii). In several surveys a positive correlation has been found between parity and incidence of differentiated thyroid carcinoma. Natural goitrogens and chemotherapeutic agents have been proved to induce hyperplasia but their role in carcinogenesis of exposed populations is not yet definitely ascertained. Exposure to external radiation is carcinogenic for the thyroid both in human and in experimental animals. Patients treated for hyperthyroidism or thyroid cancer or given diagnostic doses of 131-I (0.5 Gy/test) indicate that under these conditions 131-I is not carcinogenic. Findings on population exposed to radioactive fallout showed an increased incidence of thyroid carcinomas compared to unexposed populations. After the Chernobyl accident (1986) particular attention was given to calculate the risk of thyroid cancer caused by the fallout of 131-I. Up to now a considerable increase of thyroid carcinoma has been reported in children of a region near Chernobyl (Belarus).

[Efficacy of L-thyroxine (L-T4) therapy on the volume of the thyroid gland and nodules in patients with euthyroid nodular goiter (ENG)]. / Efficacia della terapia con L-tiroxina (L-T4) sul volume della tiroide e dei noduli in pazienti con gozzo nodulare eutiroideo (GNE).

The efficacy of treatment with TSH suppressive doses of L-thyroxine was evaluated by echography in 35 patients with euthyroid nodular goiter. Patients have been subdivided in two groups comparable for sex age and size of the goiter. Sixteen patients were treated for nine months with suppressive doses of thyroxine and nineteen were followed without therapy as control. Patients in treatment were then followed up for additional 9 months without therapy. The mean decrease of thyroid volume at nine months was 25% (27 +/- 10 ml vs 20 +/- 8 ml; p < 0.01). After discontinuation of treatment thyroid volume increased and had returned to base line values after nine months of follow up. In the control group mean thyroid volume had increased by 17.7% at nine months (28 +/- 17 vs 33 +/- 19 ml; p < 0.001). Thyroid nodules in response to thyroid hormone treatment showed a variable behaviour: 30.7% (4/13) of the nodules responded to the therapy with a reduction > to 25% at the ninth month; the remaining nodules were insensitive to the therapy. In conclusion suppressive thyroxine treatment is effective in reducing the goiter, nodules instead are only in part sensitive to the treatment. Thyroxine therapy of euthyroid nodular goiter must be followed for long term since upon thyroxine discontinuation there is a prompt reappearance of the goiter.

Isoelectric focusing and immunoblotting analysis of thyroglobulin from different thyroid diseases.

Thyroglobulins (Tgs) have been obtained from macro-microfollicular goiter, toxic adenomas, papillary carcinomas and metastatic lympho-node and chromatographed by gel filtration. The 19S Tgs so obtained have been characterized by isoelectric focusing (IEF) and immunoblotting. IEF showed microheterogeneity pattern of Tgs from normal tissue, macro-microfollicular goiter and toxic adenomas to be within pH range from 4.2 to 4.5, while that from papillary carcinomas and metastatic lympho-node showed a wider microheterogeneity. Passive blotting of focused Tgs and immunoreaction with rabbit anti-Tg peroxidase conjugated antibody have been carried out and a positive reaction for all examined samples have been evidenced. Also two bands, focused at more cathodic pH value (pH 4.7), observed in IEF patterns of Tgs from carcinomas and metastatic lympho-node, gave a positive reaction with anti-Tg conjugated antibody. These differences observed in IEF and immunoblotting patterns of Tgs from papillary carcinomas and metastatic lympho-node are discussed in this report.

Population survey of thyroid autoimmunity in Italy. Three year follow up.

Thyroid autoimmunity and primary hypothyroidism have been evaluated in a 3 year interval in 4 samples of general population from Bologna, Napoli, Palermo, Rome and Cagliari. The average prevalence of Mic-Abs was in males 4.1% and in females 10%. A significantly higher prevalence of Mic-Abs was found in the Cagliari sample where it reaches in males 6.1% and in females 20.4% (p less than 0.0005). Likewise Tg-Abs have been found increased in Cagliari (males: 4.6% vs 10.7%; females: 10.0% vs 16.6%; p less than 0.01). In the 3 year follow up Mic-Abs titre increases significantly whereas the Tg-Abs titre remains substantially unchanged. In the initial screening 1.65% of subjects were found to be latent (1.2%) or overt (0.45%) hypothyroids. Hypothyroidism was particularly frequent in the Cagliari sample and was constantly associated with Mic-Abs. In the 3 year follow up only 1 of 8 latent hypothyroids became overt.

Physiopathology of thyroid cysts in euthyroid nodular goiter.

Following the introduction of echography it has became evident that a large proportion of nodules (15-37%) in euthyroid nodular goiter is entirely or partially cystic (20% in the A. experience). It is thought that cystic areas are subsequent to hemorrhagic necrosis occurring during goitrogenesis and therefore the term "pseudocysts" seems to be preferred. The article summarizes some hypothetical mechanisms of pseudocyst formation. In pseudocysts of recent onset a direct or indirect viral or bacterial etiology is suggested; in longstanding pseudocysts a deficient angiogenesis or immunotoxic mechanisms are proposed.

The clonal origin of thyroid nodules in euthyroid nodular goiter.

Prevalence of euthyroid nodular goiter varies widely according to the endemia of the region studied. The goiter hyperplasia under goitrogenic stimuli progresses in the formation of nodules. Presently the pathophysiology of the thyroid nodules' formation in euthyroid nodular goiter is unknown. The A. reviews the two current hypothesis on the clonal origin of thyroid nodules. According to one hypothesis the nodule issues as the result of a coordinated replication of a cluster of follicles with an increased growth potential. According to the second hypothesis the formation of new follicles during goitrogenesis is due to a sprouting of one or a few cells from the follicles shell; nodules formation is the result of post-necrotic fibrosis and uneven growth.

Monoclonal autoantibody to thyroglobulin as a possible vector in immunodiagnosis and immunotherapy of differentiated thyroid cancer.

Differentiated thyroid carcinoma synthetize and secrete thyroglobulin. During its biosynthesis this antigen becomes expressed in the microvilli-bearing surface of carcinoma cells. Attempts have been carried out to target, with specific antithyroglobulin antibodies, the membrane bound absorption thyroglobulin in cancer cells for in vivo diagnosis and therapy. In the serum of patients with autoimmune thyroid diseases a high concentration of antithyroglobulin antibodies is frequently found (1-3 mg/ml). Their purification by immunoabsorption and dissociation is hampered by a low recovery and partial denaturation. It has been recently reported that about 1% of sera from Hashimoto's thyroiditis bear in their electrophoretogram a "myeloma-like protein". In the present report we describe in the serum of a Hashimoto patient a myeloma-like IgG which is an antithyroglobulin autoantibody with restricted functional and structural properties. The serum concentration of this myeloma-like IgG was found to be 40 mg/ml with a capacity of 6.5 nM of human thyroglobulin/mg IgG. The light chain composition was determined to be mostly of the lambda type. The clonal analysis of this myeloma IgG carried out by isoelectrofocusing, immunoblotting and autoradiography resulted in the recognition of several distinct clones, two of which were prominent at pH 8.7 and 7.8. By this technique and in view of the high serum concentration of this myeloma-like IgG, single clones of antithyroglobulin autoantibody can be easily obtained in high yields and without denaturation from human serum. This reagent could offer an ideal immunovector to target membrane-bound thyroglobulin of cancer cells.

Restricted clonality of antithyroglobulin antibodies in an M-component of Hashimoto's serum.

In serum of a 70 y. female with Hashimoto's thyroiditis we have identified an M-component IgG which is predominantly composed by a single class of antihuman thyroglobulin antibody. Our assumption is supported by Scatchard analysis and by the high concentration of lambda chains in serum and IgG fraction which are absorbed by h-thyroglobulin. Attempts to dissociate the monoclonal antibody treating the immunoprecipitate at acidic pH, were unsuccessful; only a few percent (3.7) of the antibodies could be released from immunoprecipitate and those were polyclonal. In order to explain the immunoprecipitating reaction of the monoclonal antibody, it is suggested that the antibody is reacting with a repetitive structure of the h-thyroglobulin molecule.

Identification of serum proteins, thyroglobulin and antithyroid antibodies in the fluid of thyroid cysts.

Fluid from fourteen thyroid cysts has been submitted to electrophoretic and immunochemical procedures in order to describe the biochemical structure of the fluid. Two patterns have been identified: a pattern showing a composition similar to that of normal serum ("serum-like"); thyroglobulin concentration is low, IgG are sometimes above normal and hTg-Abs are frequently detectable. A second pattern shows instead, a picture in which serum protein fractions are largely denatured and not identifiable ("denatured"); thyroglobulin concentration has been found markedly increased. It is suggested that in "serum like" the formation of the cysts occurs in the interstitium, whereas in the "denatured" type cyst the hemorrhagic necrosis appears to be the consequence of a massive damage of the follicular tissue.

Hypothyroidism and thyroid autoimmunity in acute myocardial infarction (AMI).

It has been suggested that subjects with thyroid autoimmunity are more frequently affected by acute myocardial infarction (AMI), than the general population (Lancet ii, 155-158, 1977). Serum thyroid antibodies (microsomal and thyroglobulin) were measured in a cohort of 132 males admitted consecutively to the Coronary Unit of Clinica Medica II Univ. "La Sapienza" of Rome with AMI. In the AMI group the thyroid autoimmunity was twice as frequent as in an age matched random population (9.1 vs 17.4%), but the association was statistically weak (p less than 0.05). In the group over 60 y two cases of overt hypothyroidism were found and none in the control group. The prevalence of 2.5% is higher than that reported in previous surveys carried out in elderly populations. No differences have been demonstrated in concentration of serum cholesterol, triglycerides, apolipoprotein A and B between patients with and without thyroid autoimmunity, although the serum cholesterol of AMI patients and those with asymptomatic thyroiditis was significantly higher than that of the general population. It is concluded that the prevalence of thyroid autoimmunity and hypothyroidism are increased in AMI and migth thus contribute to development of hypercholesterolemia and/or immune mechanisms.

[Imaging diagnosis in the study of the hypophysis in congenital hypothyroidism]. / La diagnostica per immagini nello studio dell'ipofisi nell'ipotiroidismo congenito.

A high incidence of empty sella was found, by CT.HR and MR, in 18 patients with congenital hypothyroidism studied by plain skull radiographs, hormonal and radioimmunoassays and scintiscan. From a pathogenetic point of view, it is interesting to note that all patients had been given inadequate therapy for a long period. A significant incidence of cerebral atrophy was found in young congenital hypothyroid subjects. Radiographic examination is still useful, mainly in the screening of these lesions. In fact, morphologic and/or volumetric alterations of the sella, corresponded in all cases to the finding of an empty sella, as demonstrated by CT.HR and MR. Both these techniques have a high diagnostic accuracy in identifying the lesion. The contribution of imaging techniques is even greater in view of the fact that the clinical and biohumoral picture of empty sella is still ill-defined.

Low prevalence of thyroid antibodies in a Somalian population.

Prevalence rates of serum thyroid antibodies in a Somalian population have been compared with those of an Italian population. Thyroid antibodies have been evaluated by passive haemagglutination (microsomal antigen) and by 125I-thyroglobulin binding. In the Italian survey 13% of all subjects were positive for thyroid antibodies. A significantly lower prevalence of thyroid antibody positive subjects was found in the Somalian group (2,07%, P less than 0.001). It is suggested that the observed difference between Somalian and Italian populations could reflect nutritional or genetic causes which influence the antithyroid autoimmune response.

A retrospective study of audiological function in a group of congenital hypothyroid patients.

A retrospective survey has been carried out on audiological function in 46 congenital hypothyroid cases; mental and physical development were also assessed, as well as the adequacy of substitutive therapy. Using traditional audiometry it was found that 50% of the congenital hypothyroid patients were hypocusic. Severe and profound hearing loss (5 cases) was found in the group of hypothyroid patients with dyshormonogenesis, whereas only one-third of patients with thyroid agenesis presented a mild or moderate hearing loss not related to the time of diagnosis and treatment. The hearing loss was twice as frequent in the patients with clinical hypothyroidism. Using electrophysiological techniques, the early or slow potentials were comparable between hypocusic or normocusic patients; however a longer latency of the slow vertex responses was observed in the hypothyroid group as compared to the normal population. The mean estimated I.Q. was about 2 standard deviations below the average; however 30% of subjects had normal or above normal intellectual level, this percentage rises to 55% if only patients below 16 years are considered. The height was significantly shorter only in the late treated patients (1 year). No correlations were found among audiological and psychological variables, nor between these variables and height. All patients were on desiccated thyroid, but therapy was inadequate in 26% of cases and subclinical hypothyroidism was found in 33% of cases.