Surgical Management of Well-Differentiated Thyroid Cancer: State of the Art
Section snippets
Epidemiology
Thyroid cancer, although relatively rare (2% of all cancers), is the most common endocrine malignancy and there has been a steady increase in its incidence over the past 15 to 20 years. The incidence of thyroid cancer has risen faster in women than any other cancer over the last decade and the rising incidence in men exceeds that of all but 2 cancers.8 In the United States, the incidence is increasing fastest in the northeast as well as in southern parts of the country.9 The distribution of the
Risk factors
The most pronounced environmental risk factor for thyroid cancer is exposure to ionizing radiation (energy from the high-frequency electromagnetic spectrum such as gamma rays or x-rays). Ionizing radiation is either due to medical treatment (childhood radiation therapy for benign or malignant disease, adult treatment of malignancies) or nuclear fallout (atomic bomb/testing survivors, nuclear energy accidents). Ionizing radiation may exert this effect through several changes to the cell,
Genetic susceptibility and molecular pathogenesis
Although not well defined, there most certainly exists a genetic component to WDTC. In fact a family history of thyroid carcinoma may increase an individual's risk 3-fold when a parent has the disease and up to 6-fold if a sibling has the disease.22 Thyroid cancer may be associated with germline mutation syndromes such as familial adenomatous polyposis/Gardner syndrome (APC gene mutation), Cowden disease (PTEN gene mutation), Carney syndrome (PRKAR1A gene), and Werner Syndrome (WRN gene
National and international guidelines for treatment
The surgical management of WDTC continues to be controversial in the absence of prospective randomized trials of treatment to guide the clinician. Because of the overall good prognosis and indolent course of the disease, such trials would take decades to complete. As such, clinicians must use the best available evidence that generally consists of retrospective reviews of large case series.
Well-established evidenced-based guidelines for the treatment of thyroid cancer in North America come from
Clinical Presentation
Evaluation of the patient with a suspected thyroid cancer first begins with thorough history taking to evaluate what risk factors the patient may have for malignancy. In general, patients commonly self-diagnose a lump in their neck found during palpation. Other patients may present with a thyroid nodule detected incidentally on imaging ordered for a different medical reason (thyroid incidentaloma). Key aspects of the history include the presence of symptoms (dysphagia, voice change, coughing,
Laboratory
The initial investigation required in all patients with a thyroid lesion is biochemical assessment of thyroid function, as clinical assessment of thyroid function is not a reliable indicator of thyroid status. Ideally the thyrotropin level should be known before FNA, as an aspirate from a hyperfunctioning nodule may lead to confounding results. If the nodule is simply a hyperfunctioning one, the risk of malignancy may be so low that excision to rule out malignancy is rarely if ever warranted.
Fine-Needle Aspiration
Ultrasound
It cannot be overemphasized that manual palpation of thyroid nodules is extremely variable between even experienced clinicians and as such imaging with ultrasound, especially surgeon-performed ultrasound, has become essential to the evaluation of the thyroid gland. Surgeon-performed ultrasound is rapidly becoming an extension of the physical examination, adding images containing objective information to the subjective palpation by the surgeon's hands. Whereas there are some ultrasound
Staging
The historical stage distribution and corresponding 5-year survival based on SEER data is summarized in Table 2.8 There are other multiple staging and prognostic systems for WDTC. Some of the most commonly used systems include the sixth edition of the American Joint Committee on Cancer (AJCC) TNM (Tumor, Node, Metastasis) system, AMES (Age, Metastases, Extent, Size), AGES (Age, Grade, Extent, Size), EORTC (European Organization for Research and Treatment of Cancer), and MACIS (Metastasis, Age,
Follow-up care: therapy, surveilance, and recurrence
Whereas it is true that the vast majority of patients with WDTC will do very well, treatment still requires a multidisciplinary approach. Treatment of thyroid cancer continues to evolve and now is best done through a team approach to combine surgical therapy, expert pathology review, long-term thyrotropin suppression, radioactive iodine therapy, and in select cases external beam radiotherapy. Ideally, this will involve having experienced thyroid specialists in surgery, pathology, endocrinology,
Children
Pediatric thyroid cancer accounts for 1% to 2% of malignancies in children and, like that of adult WDTC, is the most common endocrine malignancy.79, 80 SEER data from 1988 to 2000 noted 566 cases of pediatric thyroid carcinoma, with 90% being PTC or follicular variant of PTC, 84% of patients female, and 37% of patients with nodal disease present at diagnosis.81 Of the histologic subtypes of papillary thyroid cancer, the diffuse sclerosing subtype is more common in young patients, especially
Summary
With proper initial surgery planned and performed by experienced thyroid surgeons and follow-up treatment with thyrotropin suppression and radioiodine ablation, patients can now expect to achieve clinical disease-free status. There is, however, a subset of patients who present with advanced disease that must be treated aggressively. There is no accurate method for predicting preoperatively which patient will develop metastatic or recurrent disease. As a result of this an aggressive initial
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Imaging in Thyroid Cancer
2022, Oncologic Imaging: A Multidisciplinary ApproachPhysiology and Diseases of the Thyroid Gland in the Elderly: Thyroid Cancer
2020, Endocrinology of Aging: Clinical Aspects in Diagrams and ImagesMorbidity comparison of Primary and Completion Total thyroidectomy for differentiated thyroid cancer in relation to the extent of Redo surgery
2015, International Journal of Surgery OpenCitation Excerpt :This requires a greater number of completion thyroidectomies to be performed for differentiated thyroid cancers, diagnosed at an initial, lesser degree of thyroid surgery. Redo thyroid surgery has been associated with a higher morbidity rate in some studies when compared to the primary total thyroidectomy [2–4]. However most studies do not precisely take into account the stage of local disease when comparing the outcomes, and also the extent, of redo surgery performed, i.e. one side neck exploration versus both sides or a performance of simultaneous neck dissection in completion surgeries [1,5].
Imaging in Thyroid Cancer
2012, Oncologic Imaging: A Multidisciplinary Approach Expert ConsultImaging in thyroid cancer
2012, Oncologic Imaging: A Multidisciplinary Approach