Resultado del tratamiento quirúrgico del cáncer de tiroides Hospital Universitario Comandante "Faustino Pérez Hernández" Matanzas / Outcome of thyroid cancer surgical treatment. University Hospital ¨Comandante Faustino Pérez Hernández. Matanzas

RESUMEN Introducción: el cáncer de tiroides representa un 1% del total de todos los tipos de cáncer. Su incidencia parece aumentar un 4% cada año, y en la actualidad es el octavo cáncer más frecuente en mujeres. Objetivo: evaluar el resultado del tratamiento quirúrgico en el cáncer de tiroides. Materiales y métodos: se realizó un estudio observacional, descriptivo y retrospectivo que incluye todos los pacientes operados de cáncer tiroides en el servicio de Cirugía General del Hospital Universitario "Comandante Faustino Pérez Hernández", en el período desde enero de 1993 a diciembre del 2018. Se empleó un modelo recolector de datos con las variables de interés para el estudio y los resultados se presentaron en tablas de frecuencia, números y porciento. Resultados: el cáncer de tiroides fue más frecuente en el grupo etario de 31 a 50 años, predomino el sexo femenino, la variedad histológica papilar fue la más frecuente, la técnica quirúrgica más empleada fue la tiroidectomía total. El hipotiroidismo fue la complicación más encontrada. Conclusiones: el cáncer de tiroides es más frecuente en pacientes relativamente jóvenes y del sexo femenino, la variedad papilar, la tiroidectomía total y el hipotiroidismo como complicación posquirúrgica son los de más incidencia (AU).

SUMMARY Introduction: thyroid cancer represents 1% of the total of all kinds of cancer. Its incidence seems to increase 4% every year, and at the present time it is the eighth more frequent cancer in women. Objective: to evaluate the results of the thyroid cancer surgical treatment. Materials and methods: a retrospective, descriptive, observational study was carried out including all patients who underwent a surgery of thyroid cancer in the service of General Surgery of the University Hospital ¨Comandante Faustino Perez Hernandez¨ in the period from January 1993 to December 2018. A data collector model was used with the variables of interest for the study and the results were presented by charts of frequency, numbers and percent. Results: the thyroid cancer was more frequent in the age group of 31 to 50 years; the female sex prevailed; the most frequent variety was the histological papillary one; the most used surgical technique was total thyroidectomy. Hypothyroidism was the most commonly found complication. Conclusions: thyroid cancer is more frequent in relatively young, female patients; the papillary variety, total thyroidectomy and hypothyroidism as surgical complication are the ones with higher incidence (AU).

Primary Care Provider Involvement in Thyroid Cancer Survivorship Care.

CONTEXT: While prior research has examined how primary care providers (PCPs) can care for breast and colon cancer survivors, little is known about their role in thyroid cancer survivorship. OBJECTIVE: To understand PCP involvement and confidence in thyroid cancer survivorship care. DESIGN/SETTING/PARTICIPANTS: We surveyed PCPs identified by thyroid cancer patients from the Georgia and LA SEER registries (n = 162, response rate 56%). PCPs reported their involvement in long-term surveillance and confidence in handling survivorship care (role of random thyroglobulin levels and neck ultrasound, and when to end long-term surveillance and refer back to the specialist). We examined: 1) PCP-reported factors associated with involvement using multivariable analyses; and 2) bivariate associations between involvement and confidence in handling survivorship care. MAIN OUTCOME MEASURES: PCP involvement (involved vs not involved) and confidence (high vs low). RESULTS: Many PCPs (76%) reported being involved in long-term surveillance. Involvement was greater among PCPs who noted clinical guidelines as the most influential source in guiding treatment (OR 4.29; 95% CI, 1.56-11.82). PCPs reporting high confidence in handling survivorship varied by aspects of care: refer patient to specialist (39%), role of neck ultrasound (36%) and random thyroglobulin levels (27%), and end long-term surveillance (14%). PCPs reporting involvement were more likely to report high confidence in discussing the role of random thyroglobulin levels (33.3% vs 7.9% not involved; P < 0.01). CONCLUSIONS: While PCPs reported being involved in long-term surveillance, gaps remain in their confidence in handling survivorship care. Thyroid cancer survivorship guidelines that delineate PCP roles present one opportunity to increase confidence about their participation.

Thyroid hormone therapy in differentiated thyroid cancer.

Surgery-with or without postoperative radioiodine-is the standard of care for most patients with differentiated thyroid carcinoma (DTC). Thyroid hormone replacement therapy is the mainstay of long-term medical management. Patients treated with total thyroidectomy and some who undergo lobectomy alone require thyroid hormone therapy to restore euthyroidism with normal serum thyroid-stimulating hormone (TSH) levels. Because TSH acts as a growth factor for thyroid follicular cells (including those that are neoplastic), it can potentially affect the onset and/or progression of follicular-cell derived thyroid cancer. For this reason, some patients are placed on thyroid hormone therapy at doses that suppress secretion of TSH (suppression therapy). This mini-review looks at the potential benefits and risks of this practice in patients diagnosed with DTC. Aggressive TSH-suppressive therapy is of little or no benefit to the vast majority of patients with DTC. Practice guidelines, therefore, recommend a graded algorithm in which the potential benefits of suppression are weighed against the associated cardiovascular and skeletal risks. Large randomized controlled studies are needed to confirm the presumed oncological benefits of TSH-suppression and its causal role in adverse cardiac, skeletal, and quality of life effects and to assess the efficacy of TSH normalization in reversing or reducing these effects.

Clinical Features of Early and Late Postoperative Hypothyroidism After Lobectomy.

Context: Lobectomy is preferred in thyroid cancer to decrease surgical complications and avoid lifelong thyroid-hormone replacement. However, postoperative hypothyroidism, requiring thyroid-hormone replacement, may occur. Objective: We aimed to identify the incidence and risk factors of postoperative hypothyroidism to develop a surveillance strategy after lobectomy for papillary thyroid microcarcinoma (PTMC). Methods: This historical cohort study involved 335 patients with PTMC treated by lobectomy. Postoperative thyroid functions were measured regularly, and patients were prescribed levothyroxine according to specific criteria. Patients not satisfying hormone-replacement criteria were closely followed up. Results: Postoperative hypothyroidism occurred in 215 patients (64.2%) including 5 (1.5%) with overt hypothyroidism and 210 (62.7%) with subclinical hypothyroidism. Forty patients (11.9%) were required thyroid hormone replacement. One hundred nineteen patients (33.5%) experienced temporary hypothyroidism and spontaneously recovered to euthyroid state. High preoperative thyroid-stimulating hormone (TSH) was the most important factor predicting postoperative hypothyroidism and failure of recover from hypothyroidism (odds ratio [OR], 2.82 and 1.77; 95% confidence interval [CI], 2.07 to 3.95 and 1.22 to 2.63; P < 0.001 and 0.002, respectively). Of the 215 patients eventually developing postoperative hypothyroidism, 70 (32.6%) developed hypothyroidism after the first postoperative year. Postoperative 1-year TSH levels were able to differentiate patients developing late hypothyroidism or euthyroidism (OR, 2.29; 95% CI, 1.68 to 3.26; P < 0.001). Conclusions: Preoperative and postoperative TSH levels might be predictive for patients who develop postlobectomy hypothyroidism and identify those requiring long-term surveillance for hypothyroidism. Additionally, mild postoperative hypothyroidism cases should be followed up without immediate levothyroxine replacement with the expectation of spontaneous recovery.

Quality-of-Life Priorities in Patients with Thyroid Cancer: A Multinational European Organisation for Research and Treatment of Cancer Phase I Study.

BACKGROUND: The objectives of this study were to determine quality of life (QoL) issues that are relevant to thyroid cancer patients cross-culturally, and to identify those with highest relevance to them in addition to the more general issues covered by the core European Organisation for Research and Treatment of Cancer QoL questionnaire (EORTC QLQ-C30). METHODS: A systematic literature search provided a list of potentially relevant QoL issues to supplement the core questionnaire EORTC QLQ-C30, which is widely used in research and in care and addresses QoL issues relevant to all groups of cancer patients. A panel of experts revised this list, and thyroid cancer patients rated the issues regarding their relevance for QoL by selecting the 25 issues that they would include in a thyroid cancer-specific QoL module. RESULTS: The literature search and expert discussion provided a list of 71 QoL issues that was rated by thyroid cancer patients (n = 110) from seven countries. All issues were of high priority to at least some of the patients. The most frequently selected issues were sudden attacks of tiredness, exhaustion, quality of sleep, employment, social support, fear of cancer progression, fear of second operation, difficulties swallowing, and globus sensation. CONCLUSIONS: Thyroid cancer patients cross-culturally rate fatigue-related issues as highly important for their QoL, calling for increased efforts to find successful treatments for this problem. Vocational rehabilitation is also highly relevant for them and should therefore be an important aim of multidisciplinary care. The third important area of concern is psychological issues, especially fear of progression and of additional treatments.

Development of a disease-specific health-related quality of life questionnaire (THYCA-QoL) for thyroid cancer survivors.

BACKGROUND: To date, no valid instrument is available that focuses on specific health-related quality of life (HRQoL) issues that affect thyroid cancer survivors. The objective of this study was to develop and pretest a thyroid cancer specific HRQoL questionnaire that can be used in addition to the more general European Organization for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC QLQ-C30). MATERIAL AND METHODS: Potentially relevant issues were identified by a systematic literature review, a focus group meeting, and an issue list completed by six health care professionals (HCP) and 18 thyroid cancer survivors. Resultant issues were analyzed on importance and relevance (phase I). The issues were formulated into a long provisional list of questions (phase II). These questions were administered in combination with the EORTC QLQ-C30 to 306 Dutch thyroid cancer survivors to pretest the hypothesized scale structure (phase III). Although the development of this questionnaire was not set up as an international study, phases I-III are in agreement with the methodology of the EORTC guidelines. RESULTS: The literature search, focus group and issue list completed by HCP and survivors resulted in 75 issues. These were reduced to create a 30 item provisional list. Pretesting led to a selection of 24 items with a good range of response. This resulted in the THYCA-QoL containing 24 items and seven conceptual scales. CONCLUSION: The THYCA-QoL in combination with the EORTC QLQ-C30 is ready for a large (international) scale validation study, and will assess HRQoL issues of most relevance and concern for thyroid cancer survivors.

Optimización del tratamiento y seguimiento del cáncer de tiroides / Optimizing treatment and follow-up of thyroid cancer

Se describe una creciente incidencia de carcinoma de tiroides en todo el mundo, pero la mayor parte de estos casos corresponde a cánceres de bajo riesgo. Se necesita comprender con precisión la patología tumoral y su comportamiento biológico, para aprovechar estos parámetros en una terapia rentable con utilización adecuada de recursos. La apreciación de la importancia y el significado de los factores pronósticos y la estratificación por grupos de riesgo es esencial para el enfoque actual del carcinoma tiroideo. Se requiere discreción para la selección del tratamiento quirúrgico y la indicación de terapias adyuvantes, así como para las estrategias de vigilancia (AU)

Optimización del tratamiento y seguimiento del cáncer de tiroides / Optimizing treatment and follow-up of thyroid cancer

Se describe una creciente incidencia de carcinoma de tiroides en todo el mundo, pero la mayor parte de estos casos corresponde a cánceres de bajo riesgo. Se necesita comprender con precisión la patología tumoral y su comportamiento biológico, para aprovechar estos parámetros en una terapia rentable con utilización adecuada de recursos. La apreciación de la importancia y el significado de los factores pronósticos y la estratificación por grupos de riesgo es esencial para el enfoque actual del carcinoma tiroideo. Se requiere discreción para la selección del tratamiento quirúrgico y la indicación de terapias adyuvantes, así como para las estrategias de vigilancia

Quality of life in patients with thyroid cancer compared with the general population.

BACKGROUND: Since patients with thyroid cancer have a very good prognosis overall, clinicians may often assume that their quality of life is comparable to the general population. We hypothesized that quality of life of thyroid cancer patients is lower compared with the general population while controlling the effect of age and gender. METHODS: At the beginning of their stay at an inpatient rehabilitation clinic, a cohort of n=121 patients with thyroid cancer were assessed using the quality of life core questionnaire of the European Organisation for Research and Treatment of Cancer (QLQ-C30). Data for comparison were derived from a representative German community sample with n=2037. RESULTS: The patients reported significantly more problems than the community sample participants independent of gender and age effects in all but two domains, namely constipation and diarrhea. The strongest effects of the group (patients vs. general population) were found in the following domains: insomnia (B=-43.7, p<0.001), fatigue (B=-38.0, p=<0.001), and role functioning (B=29.7, p=<0.001). Significant interactions between age and group occurred in the social functioning, role functioning, fatigue, nausea/vomiting, and financial difficulties domains. Quality of life was unrelated to the stage of the disease, except in the physical function and global health status domains. CONCLUSIONS: At the beginning of inpatient rehabilitation, patients with thyroid cancer often experience more problems than controls from community samples, independent of their age and gender. Clinicians should be aware of the fact that quality of life is not directly related to the severity of the cancer prognosis.

Effectiveness of retinoic acid treatment for redifferentiation of thyroid cancer in relation to recovery of radioiodine uptake.

BACKGROUND: Retinoic acid (RA) treatment has been used for redifferentiation of metastatic thyroid neoplasia that have lost radioiodine (131I) uptake with heterogeneous results. AIM: Retrospective analysis of the recovery rate of 131I uptake after RA treatment in patients from 11 Spanish hospitals. METHODS: Twenty-seven patients (14 men, 13 women) with papillary [21], follicular [4], and oncocytic [2] thyroid cancer initially treated with total thyroidectomy plus 131I, and with 131I negative metastatic disease, were given 13-cis RA (0.66-1.5 mg/kg for 5-12 weeks) followed by a therapeutic 131I dose (3700-7400 MBq); 3 months later thyroglobulin levels and computed tomography imaging were performed. RESULTS: In 9 out 27 cases (33%) (8 papillary, 1 follicular) optimal positive 131I scan was observed after RA treatment; in the remaining 18, 10 had a suboptimal uptake (7 papillary, 2 follicular, 1 oncocytic) and in the rest there was no 131I uptake recovery (6 papillary, 1 follicular, 1 oncocytic). In 17 positive responses to RA (either optimal or suboptimal) in which image follow-up was available, decrease or stabilization of metastatic growth was observed in 7, while tumor mass increased at short term in the remaining 10. No major side effects were detected. CONCLUSION: Quite a high rate of 131I uptake recovery after RA treatment may be obtained in advanced differentiated thyroid cancer, but the potential modification of the natural course of the disease is uncertain. A better biological characterization of these tumors allowing the identification of potential responders to RA may improve the outcome of RA coadjuvant therapy.

Effect of cancer diagnosis on patient employment status: a nationwide longitudinal study in Korea.

BACKGROUND: Cancer diagnosis may adversely affect employment status. Our aim was to investigate whether cancer diagnosis effects employment status by comparing employment status changes in cancer patients with to that of cancer-free workers over a 5-6-year period. METHODS: All 25-55-year-old, non-self-employed, Korean workers who were diagnosed with cancer for the first time in 2001 were identified as first baseline study subjects (n=4991). Of these, those who lost their jobs within 1 year of cancer diagnosis were selected as second baseline subjects (n=1334). Sex- and age-matched cancer-free individuals from the general population were used as a reference group. We compared the time until job loss from the first baseline and the time until re-employment from the second baseline between these two groups during the 5-6-year follow-up period while adjusting for sex, age group, job-type, and equivalent household income using the National Health Insurance administrative database. RESULTS: Cancer patients were more likely to lose their jobs after cancer diagnosis and were less likely to be re-employed than cancer-free individuals in almost all sex and age groups. Most major cancer sites were also associated with decreased employment status, with the exception of thyroid cancer. CONCLUSION: Cancer diagnosis adversely affects employment status in Korea, and the effects are widespread in almost all sex and age groups. Significant efforts are needed to improve the employment status of cancer patients in Korea, as well as in developing or newly developed countries that have similar social security systems.

Long-term outcome of 495 TNM stage I or II patients with differentiated thyroid carcinoma followed up with neck ultrasonography and thyroglobulin measurements on T4 treatment.

OBJECTIVE: Recent guidelines for surveillance of patients with differentiated thyroid carcinoma emphasize TSH-stimulated serum thyroglobulin (Tg) measurements and neck ultrasonographies (US) over Tg measurements on T(4) and diagnostic whole body scans (DxWBS). We evaluated the safety and efficacy of a surveillance paradigm comprising yearly T(4)-suppressed Tg measurements and neck US every second year, with an increase in Tg to a detectable level being a prompt indication for DxWBS. DESIGN: A retrospective study with a median follow-up of 11.6 years. PATIENTS AND MEASUREMENTS: Recurrences, cancer-specific deaths and number of neck US, fine needle aspiration biopsies (FNABs) and operations performed were evaluated in 495 low-risk (TNM stage I and II) patients, the majority of whom had total thyroidectomy and radioactive iodine remnant ablation as initial treatment. RESULTS: Forty-four patients (8.9%) experienced a recurrence in the neck and one patient died. Recurrences were established histopathologically in 26 and by a new uptake in DxWBS in 16 cases. A combination of neck US and high Tg revealed 42 of 44 recurrences. Of 993 ultrasonographies, 149 led to FNAB and 28 FNABs to surgery. Serum Tg was elevated 173 times, indicating a recurrence in 23 patients. CONCLUSIONS: Although longer follow-up is still needed, monitoring low-risk differentiated thyroid carcinoma patients with neck US and T(4)-suppressed Tg appears to be safe, provided radioactive iodine remnant ablation has been given and a low-alarm threshold for Tg indicating further evaluation, is used. The number of additional studies caused by this surveillance paradigm was reasonable. DxWBS was helpful in selected cases. Comparative studies are warranted to show how much rhTSH-stimulation tests add to this surveillance scheme.

A systematic review examining the effects of therapeutic radioactive iodine on ovarian function and future pregnancy in female thyroid cancer survivors.

BACKGROUND: For women with differentiated thyroid carcinoma (DTC), the effect of radioactive iodine (RAI) therapy on gonadal and reproductive function is an important consideration. OBJECTIVE AND METHODS: We systematically reviewed controlled studies examining the gonadal and reproductive effects of RAI therapy in women and adolescents surviving DTC. We searched nine electronic databases. All abstracts and papers were independently reviewed by two reviewers. RESULTS: After reviewing 349 unique citations and 61 full-text papers, 16 papers including data from 3023 women or adolescents with DTC were included. All studies were observational, with no long-term randomized control trial data. The age at first RAI treatment varied from 8 to 50 years and the cumulative activities of RAI administered for treatment varied from 30 to 1099 mCi. Transient absence of menstrual periods occurred in 8-27% of women within the first year after RAI, particularly in older women. In addition, RAI-treated women experienced menopause at a slightly younger age than women not treated with RAI. In the first year after RAI therapy, several studies reported increased rates of spontaneous and induced abortions. However, RAI treatment for DTC was generally not associated with a significantly increased risk of long-term infertility, miscarriage, induced abortions, stillbirths, or offspring neonatal mortality or congenital defects. CONCLUSIONS: In female survivors of DTC, there is little observational evidence to suggest important adverse effects of RAI treatment on gonadal function, fertility or pregnancy outcomes beyond 12 months, with the exception of a possible slightly earlier age of menopause.

Radioiodine ablation of thyroid remnants after preparation with recombinant human thyrotropin in differentiated thyroid carcinoma: results of an international, randomized, controlled study.

CONTEXT: After surgery for differentiated thyroid carcinoma, many patients are treated with radioiodine to ablate remnant thyroid tissue. This procedure has been performed with the patient in the hypothyroid state to promote endogenous TSH stimulation and is often associated with hypothyroid symptoms and impaired quality of life. OBJECTIVE AND INTERVENTION: This international, randomized, controlled, multicenter trial aimed to compare the efficacy and safety of recombinant human TSH (rhTSH) to prepare euthyroid patients on L-thyroxine therapy (euthyroid group) to ablate remnant thyroid tissue with 3.7 GBq (100 mCi) 131I, compared with that with conventional remnant ablation performed in the hypothyroid state (hypothyroid group). Quality of life was determined at the time of randomization and ablation. After the administration of the 131-I dose, the rate of radiation clearance from blood, thyroid remnant, and whole body was measured. RESULTS: The predefined primary criterion for successful ablation was "no visible uptake in the thyroid bed, or if visible, fractional uptake less than 0.1%" on neck scans performed 8 months after therapy and was satisfied in 100% of patients in both groups. A secondary criterion for ablation, an rhTSH-stimulated serum thyroglobulin concentration less than 2 ng/ml, was fulfilled by 23 of 24 (96%) euthyroid patients and 18 of 21 (86%) hypothyroid patients (P = 0.2341). Quality of life was well preserved in the euthyroid group, compared with the hypothyroid group, as demonstrated by their lower pretreatment scores on the Billewicz scale for hypothyroid signs and symptoms, 27 +/- 7 vs. 18 +/- 4 (P < 0.0001) and their significantly higher Short Form-36 Health Assessment Scale scores in five of eight categories. Euthyroid patients had a statistically significant one third lower radiation dose to the blood, compared with patients in the hypothyroid group. CONCLUSIONS: This study demonstrates comparable remnant ablation rates in patients prepared for 131I remnant ablation with 3.7 GBq by either administering rhTSH or withholding thyroid hormone. rhTSH-prepared patients maintained a higher quality of life and received less radiation exposure to the blood.

Quality of life of well-differentiated thyroid carcinoma patients.

The thyroid gland is the second most common site for malignancy in the head and neck region. Quality of life (QOL) of thyroid cancer patients has not been studied directly. The QOL of long-term thyroid carcinoma patients was investigated. A standardized set of questions based on the University of Washington QOL questionnaire for head and neck cancer with specific domains associated with thyroid disease was created. This questionnaire was mailed to patients who underwent total thyroidectomy for well-differentiated cancer in the department of Otolaryngology--Head and Neck surgery at the Chaim Sheba Medical Centre in Israel between the years 1994-2000. Seventy-eight patients undergoing total thyroidectomy were identified. Forty-eight patients were excluded and 20 out of the 30 remaining patients responded to the questionnaires. Six were male and 14 female, 12 were under the age of 45 (these 12 patients were staged as stage 1). Eleven patients underwent neck dissection. General health and QOL were significantly better for the younger age group and so was the calcium balance score. General health and QOL were significantly better for patients undergoing neck dissection. The overall QOL score was 3.8 conforming with 'good' in the questionnaire. Surgery and initial radioiodine treatment scored 6.75 and 6.9 respectively in the distressing scale (0-10 range: 10 = most distressing). The highest distress was encountered during withdrawal from thyroid hormone. Women rated the importance of proper replacement therapy significantly higher than men. Global low scores were found for employment and for effective L-thyroxine replacement therapy. Overall, QOL in these patients was good although lower than expected when compared with other forms of cancer. Age and gender-related differences were noted. Better QOL in neck dissection patients is probably associated with age under 45 years. High distress scores for hormone withdrawal during periodical imaging correspond with former reports and supports use of Thyrogen. Better hormone balance is warranted for this group.

[Drainage after thyroid surgery: 264 patients]. / Drainage dans la chirurgie thyroïdienne.

OBJECTIVES: A prospective study was conducted in 1996-1997 in 100 patients who underwent thyroid surgery and who were randomly assigned to receive drainage or not. No statistical difference in complication rate was observed. The aim of the present retrospective study was to assess the consequences of this attitude in patients undergoing surgery since that time and to determine the number of postoperative complications, length of hospital stay, and type of thyroidectomy where cervical drains still appear to be indicated. PATIENTS AND METHODS: Total or partial thyroid surgery was performed in 264 patients between June 1997 and October 2000. Neck dissection was associated with 24 patients. RESULTS: Cervical drains were used in 29 patients (10.9%). Postoperative complications were comparable to those commonly reported. CONCLUSION: Except for neck dissection and mediastinal extension, thyroidectomy can be safely performed without drainage. This attitude reduces the overall hospital stay.

Tratamientos no Quirúrgicos del Cáncer de Tiroides / Non surgical treatments of thyroid cancer

En la búsqueda constante de soluciones más efectivas para el tratamiento del cáncer de tiroides, y por lo tanto para mejorar la calidad de vida de nuestros pacientes, se encuentran a nuestro alcance actualmente varias alternativas además del tratamiento quirúrgico, las principales son: El tratamiento con yodo radioactivo (I 131), que puede utilizarse solo, combinado con radioterapia externa, quimioterapia o radioterapia intersticial; la radiación con megavoltaje usando fotones; la radiación intersticial por medio de implantes removibles o permanentes y por último, la terapia hormonal utilizando diferentes preparados de hormona tiroidea como terapia de suplencia o de supresión. En este artículo se hace una supresión de cada uno de estos tratamientos, además, se explican sus indicaciones y beneficios con el fin de emplear el procedimiento más adecuado para las diferentes presentaciones de carcinoma tiroideo