tyroid cancer – an update...figure 2. age-standardised incidence of thyroid cancer in new south...

Thyroid cancer is a relatively uncommon malig-nancy that appears to be increasing in incidence.The spectrum of thyroid tumours ranges fromwell-differentiated cancers (papillary and follicu-lar), which generally have a very good prognosis,to highly aggressive tumours such as anaplasticcarcinoma, which are lethal malignancies (Figure 1).Patients with thyroid cancer require comprehensive

evaluation, multimodality treatment and long-term multidisciplinary follow up.Although the often life-long follow up is, in

most cases, primarily managed by an endocrinol-ogist, the GP has an important role is assistingwith management. Hence an understanding ofthe treatment and follow up considerations isimportant.

MedicineToday � September 2010, Volume 11, Number 9 27

RON BOVA MB BS, MS, FRACS

ANDREWWEISSBERGER MB BS, FRACP, MD

Dr Bova is a Consultant Head

and Neck Oncology Surgeon

and Dr Weissberger is a

Consultant Endocrinologist at

St Vincent’s Hospital, Sydney,

NSW.

• When thyroid nodules are detected, the challenge facing GPs is to distinguish patients

with malignancy who require referral for surgical management from patients who have

benign nodules that can be followed up nonsurgically.

• Although thyroid fine needle aspiration (FNA) is a sensitive and accurate diagnostic test,

false-negative results do occur. Hence, if there are suspicious clinical findings from the

history and/or examination that increase the probability of a nodule being malignant then

these should override the FNA result.

• Surgery is the mainstay of treatment and total thyroidectomy is indicated in most

patients. Radioactive iodine ablation and long-term thyroid stimulating hormone (TSH)

suppression therapy are useful adjuvant therapies.

• GPs should be aware of the target TSH level set by the endocrinologist to avoid inadvertently

reducing the thyroxine dose because of the mistaken interpretation that the TSH is too low.

• The increasing use of recombinant TSH is obviating the need for patients ceasing

thyroxine and being rendered temporarily hypothyroid during investigation for residual or

recurrent thyroid cancer.

• Patients with recurrent or progressive disease need comprehensive work-up and

treatment in centres with expertise in treating thyroid cancer.

IN S

UM

MARY

Thyroid canceran updatePapillary and follicular cancers are the more common types of thyroid cancer and

generally have a very good prognosis. The increasing use of recombinant thyroid

stimulating hormone means patients do not need to stop taking thyroxine and be rendered

temporarily hypothyroid during adjuvant radioactive iodine therapy and follow-up

thyroglobulin monitoring.

MedicineToday PEER REVIEWED ARTICLE POINTS: 2 CPD/2 PDP

ILLUSTRATION © CHRIS WIKOFF, 2010

Permission granted for use by Entthyroid.com.au for educational purposes. © Medicine Today 2010. Copyright for illustrations as stated.

28 MedicineToday � September 2010, Volume 11, Number 9

Thyroid cancer

continued

General considerationsThe thyroid gland consists of two main celltypes: follicular cells and parafol li cularcells. Follicular cells, which synthesisethyroglobulin and thyroid hormones,give rise to differentiated thyroid cancers(papillary and follicular) and anaplasticcarcinoma (which is poorly differenti-ated). Parafollicular cells, which secretecalcitonin, give rise to medullary carci-noma. An overview of the clinical andpathological classification of neoplasticand non-neoplastic thyroid nodules isgiven in Table 1.This article mainly focuses on the

differentiated thyroid cancers, which arethe most common type seen in clinicalpractice.

Risk factors for thyroid cancerThe risk factors for developing thyroidcancer are:

• age 30 to 50 years – the peak incidenceof thyroid cancer is in the fourth tofifth decades

• being female – thyroid cancer is threetimes more common in women thanin men`

• exposure to ionising radiation – thethyroid glands of children are

especially especially vulnerable to thecarcinogenic effects of radiation.Head and neck irradiation duringchildhood or environmentalexposure both increase the risk, andthe latency period may exceed 20 years.The Chernobyl nuclear reactoraccident in 1986 resulted in a 15- to20-fold increased incidence of thyroidcancer in the southern part of theformer Soviet Union

• family history – there is a very slightincreased risk of papillary andfollicular cancer in first-degree relativeswith thyroid cancer, suggesting apossible genetic predisposition;however, routine screening of familymembers is not recommended.

Increasing incidenceThe age-standardised incidence rates of thyroid cancer in New South Walesincreased by 40% in males and by 84% in females between 1996 and 2005,1 atrend that has been observed elsewhere,including the USA and Canada. In 2005,the incidence rate of thyroid cancer inNSW was 4.5 new cases per 100,000 formen and 14.2 for women (Figure 2).1 Themost consistent finding among theworldwide reports is that the increasedincidence occurred almost exclusivelywith papillary carcinoma, especially smallmicrocarcinomas (less than 1cm).Possible reasons for this increase

include:

• increased detection of small papillarythyroid cancers resulting fromincreased routine use of ultrasoundand fine needle aspiration (FNA)biopsy for thyroid evaluation

• incidental detection of small thyroidtumours in patients having head and neck imaging for nonthyroid-related pathology (e.g. cervical spineMRI, carotid duplex screening, totalbody CT and MRI scans, and positronemission tomography scans)

• increased number of thyroidectomiesbeing performed for multinodular

goitre and Graves’ disease, which isresulting in an increased detection of small incidental papillarymicrocarcinomas of uncertain clinicalsignificance (‘incidentaloma’);pathologists processing thyroidspecimens into thinner slices mayalso account for increased detectionof incidental microcarcinomas

• a true increase in the incidence ofpapillary thyroid cancer, withpossible contributing factors beingincreased exposure to ionisingradiation and/or changing levels ofdietary iodine intake, althoughevidence is lacking to support theseassociations.

Clinical presentationThyroid nodules are very common, and ithas been estimated that 5% of adults haveclinically palpable thyroid nodules. Fur-thermore, studies of normal healthy adultvolunteers have revealed a prevalence ofultrasound-detected nodular disease of

Figure 1. Thyroid cancer: a tumour in the

left lobe.

Table 1. Clinical andpathological classification of thyroid nodules

Non-neoplastic• Hyperplastic and colloid nodules as

seen in a benign multinodular goitre

• Inflammatory nodules as seen in

Hashimoto’s lymphocytic thyroiditis

• Thyroid cysts

NeoplasticBenign

• Follicular adenoma (may be

nonfunctioning or functioning)

Malignant

• Papillary carcinoma

• Follicular carcinoma

• Medullary carcinoma

• Anaplastic carcinoma

• Lymphoma

© CHRIS WIKOFF, 2010


© copyright


about 50%. The overwhelming majority(95%) of thyroid nodules are benign (col-loid nodules, cysts, thyroiditis and benignfollicular adenoma).Most thyroid cancers present clinically

with a palpable thyroid nodule, and areusually asymptomatic. About half of thy-roid cancers are initially noticed by thepatient, and about half are detected dur-ing routine physical examination, byserendipity on imaging studies often forunrelated medical conditions, or duringsurgery for benign thyroid disease. When thyroid nodules are detected,

the challenge facing the GP is to dis -tinguish patients with malignancy whorequire referral for surgical manage-ment from patients who have benignnodules that can be followed up non-operatively. Although most patients with thyroid

cancer are asymptomatic, certain clinicalfindings should alert the GP to a higherprobability of a thyroid nodule beingmalignant (Table 2). These clinical fea-tures include:

• large nodules (more than 4cm) • firm or hard nodules, especially iffixed to adjacent neck structures

• hoarseness due to vocal cord paralysis• rapidly growing nodules• nodules associated with enlargedcervical lymph nodes (lateral necklump).Ultrasound findings that are suspi-

cious for malignancy include:

• nodules with irregular borders• central hypervascularity• microcalcification within the nodule.

Investigating a thyroid noduleThe work-up for a patient presentingwith a thyroid nodule is summarised inTable 3 and the flowchart on page 30.

TSH assay and ultrasound scanAll patients with a thyroid nodule shouldhave a routine thyroid stimulating hormone (TSH) assay and also a thyroidultrasound scan. The vast majority of patients with

thyroid malignancy are clinically and

biochemically euthyroid. Hyperthy-roidism is rarely associated with malig-nancy; hence if the TSH is suppressed(indicating hyperthyroidism) in a patientwith a thyroid nodule, the diagnostic pos-sibilities include a solitary auto no moustoxic thyroid nodule (hyperfunctioningadenoma), toxic multinodular goitre

Figure 2. Age-standardised incidence of thyroid cancer in New South Wales, 1972 to 2005.1

Table 2. Red flags for thyroidmalignancy

• Male gender

• Extremes of age (younger than 20 or

older than 65 years)

• Exposure to ionising radiation,

especially during childhood

• Family history of thyroid cancer

• Large solitary thyroid nodule

• Hard thyroid nodules or with fixation

to adjacent neck tissues

• Symptoms of local invasion (neck

pain, hoarseness or dysphagia)

• Thyroid nodules that grow rapidly

over weeks or months

• Thyroid nodules associated with

enlarged cervical neck nodes

Table 3. Investigating apatient with a thyroid nodule

• History

• Physical examination of thyroid

and neck

• Thyroid ultrasound scan

• Serum thyroid stimulating hormone

(TSH) level measurement

• Fine needle aspiration of dominant or

suspicious nodules

• Radionuclide scan indicated only if the

patient is hyperthyroid (suppressed

TSH); routine use in euthyroid

patients should be avoided


and a solitary nodule in Grave’s disease.These patients should have a radionuclide thyroid scan and be referred to an endo -crinologist for further evaluation. In thesecases, FNA should be withheld as theinflammatory component of these hyper-cellular toxic nodules can result in anatypical cytologic appearance. A compre-hensive review of the management ofhyperthyroidism and hypothyroidismwas published in the May 2006 issue ofMedicine Today.2

Fine needle aspirationFNA has emerged as the investigation of choice for the routine diagnosis and

management of thyroid nodules. It is the most cost-efficient diagnostic test and has an accuracy rate of 95% in dif -ferentiating between benign and malig-nant nodules. Large nodules can bebiopsied without ultrasound but smallernodules are best localised and biopsiedunder ultrasound guidance. The use ofultrasound has been shown to increasethe diagnostic accuracy of thyroid FNAcompared with when performed usingdirect palpation.3

Cytopathology evaluation of an FNAbiopsy specimen categorises a thyroidnodule into several diagnostic groups,which guides the clinician towards

specific further investigation or a thera-peutic course of action. Although thyroid FNA is a sensitive

and accurate diagnostic test, false-negative results do occur in 1 to 2% ofcases. Therefore, any suspicious clinicalfindings from the history and/or exami-nation that increase the probability of anodule being malignant should overridethe FNA result.

Classification of thyroid nodulesThe diagnostic groups into which thy-roid nodules are classified according theFNA findings are listed below (see alsoTable 1).


Thyroid cancer

continued

Investigation and management of a patient with a thyroid nodule

TSH level reduced

Perform fine needle aspiration

(FNA) biopsy to classify nodule

Perform radionuclide thyroid scan

and refer to endocrinologist for

further evaluation

Malignant Atypical Benign

Benign

Nondiagnostic

NondiagnosticSurgery Surgery Conservative

management

Clinical or ultrasound

follow up in 12 months

Repeat FNA biopsy

Refer to endocrinologist

or surgeon

TSH level normal

Patient presents with athyroid nodule

Take history

Perform neck examination, thyroid stimulating

hormone (TSH) assay and ultrasound scan


• Nondiagnostic. This implies that thepathologist has not received enoughcellular material to make a diagnosis,and a repeat FNA is warranted. If arepeat FNA is nondiagnostic thendiagnostic hemithyroidectomy maybe indicated.

• Benign. Normal follicular cellsscattered in regular groups withmacrofollicular structures andabundant thin colloid are typicallyfound in benign nodules (Figure 3).Patients with these nodules can betreated conservatively unless there is another indication to proceed with surgery (such as a large nodulewith compressive symptoms).

There is a small risk of false-negativeFNA results (less than 5%) with these nodules and long-term clinicalfollow up of patients is advised.Nodules that are easily palpable canbe clinically assessed annuallywhereas those that are small ordifficult to palpate can be assessedwith repeat ultrasound after 12 months.If there is clinical or ultrasonicevidence of nodule growth (20%increase in nodule diameter), repeatFNA is appropriate. If nodule sizeremains stable, yearly clinical followup is recommended.

• Malignant. Unequivocal cytologicalfeatures of papillary, medullary or

anaplastic carcinoma warrant surgicalintervention. Cytological features ofpapillary carcinoma include anincreased degree of cellularity withcells arranged in papillary groups andnuclei that are irregularly shaped andgrooved, giving them a ‘coffee bean’appearance (Figure 4).

• Atypical. This is often reported as‘suspicious’, ‘atypical follicularpattern’, ‘follicular lesion’ or‘follicular neoplasm’. Unfortunately,cytology cannot distinguish betweenbenign follicular adenoma andfollicular carcinoma (Figure 5). Anatypical follicular pattern is associatedwith a 20% risk of malignancy, hence


Thyroid cancer

continued

Figure 3 (above left). Normal thyroid histology showing well-formed

follicles containing plentiful thin colloid.

Figure 4 (above right). Papillary carcinoma showing tumour cells

forming papillary structures. Note the ‘coffee bean’ appearance of

the nuclei.

Figure 5 (right). Follicular carcinoma with tumour infiltrating

through the tumour capsule.


patients with these findings areusually considered for diagnostichemithyroidectomy.

Staging of thyroid carcinoma The variable natural history of this rela-tively rare cancer combined with its excel-lent prognosis in most patients makes itdifficult to perform randomised con-trolled trials. Studies would require verylarge patient cohorts with follow-upperiods spanning decades in order toobtain meaningful data. Our current treatment recommenda-

tions are based on retrospective studies,and the ideal treatment for thyroid cancercontinues to be a source of controversy.Although there is no dispute that surgeryis the treatment of choice for thyroid can-cer, controversy surrounds the followingareas:

• the extent of necessary surgeryrequired, both to the thyroid and toadjacent lymph nodes, particularlyfor small primary cancers

• the routine use of adjuvant radioactiveiodine ablative therapy for low riskpatients (e.g. a patient with a small –subcentimetre – papillary carcinoma)

• the role of adjuvant external beamradiotherapy

• the role of TSH suppression therapyin low risk patients.Hundreds of publications focusing

on epidemiological, clinical and patho-logical data have been devoted to defin-ing prognostic parameters for papillaryand follicular carcinoma. Various classi -fication systems based on pretreatmentprognostic indicators have been devisedin an attempt to predict outcome and tohelp tailor treatment. Although multi-ple factors ultimately influence the outcome for patients with papillary and follicular carcinoma, the two mostimportant and consistently demonstrablefactors are patient age at the time of initialtherapy and tumour stage. It is beyondthe scope of this article to discuss stagingsystems in detail but prognostic factors

associated with poorer survival includethe following:

• older age (more than 40 years)• family history of thyroid cancer• large tumour size (more than 4cm)• tumour extension beyond thyroidcapsule

• bilateral lymph node metastases• distant metastases• aggressive histology (tall cell orcolumnar cell papillary carcinoma,widely invasive or poorlydifferentiated follicular carcinoma)

• incomplete tumour resection• delayed treatment (for more than one year).

Papillary and follicular thyroidcancers TreatmentMost patients with papillary or follicularcancer of the thyroid are treated with a combination of surgery, adjuvantradioactive iodine ablation and long-term TSH suppression therapy (see thebox on this page).

SurgerySurgery is the primary treatment for allpatients with thyroid cancer and should

be performed by experienced thyroidsurgeons.Total thyroidectomy is indicated for

most patients with thyroid cancer. Hemi -thyroidectomy alone may be consideredfor small solitary low-risk papillary cancers, although when a preoperativediagnosis of papillary carcinoma is madetotal thyroidectomy is generally recom-mended. Because preoperative FNA cannot differentiate between follicularcarcinoma and benign follicular ade-noma, patients classified as having an atypical nodule on FNA are initiallytreated with hemithyroidectomy and then proceed to completion total thy-roidectomy if the final pathology con-firms carcinoma. If there are overt signsof malignancy or the patient has a multi -nodular goitre and an atypical FNA on one side, initial total thyroidectomy isgenerally recommended.Central compartment node dissection

is commonly performed for most papil-lary carcinomas to remove the first eche-lon drainage nodes, which lie in thetracheoesophageal groove. Selective neckdissection is performed when metastaticcervical nodes are identified preopera-tively. More radical resection of adjacent


Key aspects of thyroid cancer treatment and follow up

• Surgery is the mainstay of treatment and total thyroidectomy is indicated in most

patients with papillary or follicular cancer of the thyroid. Experienced thyroid surgeons

should perform the surgery.

• Radioactive iodine ablation and long-term thyroid stimulating hormone (TSH)

suppression using thyroxine are useful adjuvant therapies. GPs need to be aware of

the target TSH level determined by the endocrinologist to avoid inadvertently reducing

the thyroxine dose because of the mistaken interpretation that the TSH is too low.

• The increasing use of recombinant TSH (rhTSH) is obviating the need for patients

having to stop taking thyroxine and being rendered temporarily hypothyroid so they

can have stimulated thyroglobulin (Tg) levels measured and/or have follow-up whole

body radioisotope thyroid scans to monitor for residual or recurrent thyroid cancer.

Use of rhTSH also avoids the patient being hypothyroid between thyroidectomy and

radioactive iodine ablation.

• External beam radiotherapy and chemotherapy are rarely indicated.


structures (larynx, trachea and oesopha-gus) is sometimes required for advancedstage thyroid cancers invading the upperaerodigestive tract.

Radioactive iodine therapy Radioactive iodine ablation is admin -istered to most patients with thyroid cancer; however, its use in patients withsmall (less than 1.5 cm) solitary tumoursis controversial. The radioactive iodine(I131) is administered following totalthyroid ectomy and is taken up by anyresidual normal and malignant thyroidcells, resulting in their death. Eradicat-ing micro scopic residual postoperativetumour cells decreases local recurrenceand mortality rates. Also, by eradicatingany residual tumour and normal thyroidtissue, the serum thyroglobulin (Tg) levelshould be undetectable and thereforesubsequent serum Tg levels can be usedto monitor for tumour recurrence. (Tg isthe protein precursor of the thyroid hormones and is produced by normalthyroid cells and by thyroid cancer cells).High levels of TSH are required to

stimulate the uptake of I131 into residualnormal and thyroid tumour cells. Thiscan be achieved by either of the methodsbelow.

• Temporarily withholding thyroxine(T4) replacement for five to six weeksfollowing total thyroidectomy untilthe TSH level rises sufficiently tofacilitate radioactive iodine therapy.This renders patients very hypothyroidin the weeks preceding the radioactiveiodine therapy, which can have anadverse effect on their ability to workand a negative impact on their qualityof life. To minimise the period ofhypothyroidism, patients are giventri-iodothyronine (T3; in the form ofthe L-isomer, liothyronine sodium),which is short-acting, for severalweeks after thyroidectomy, its usebeing ceased two weeks beforeradioactive iodine therapy.

• Admini stering rhTSH – as two

intramuscular injections on the dayspreceding radioactive iodine therapywhile patients are taking their regularthyroxine replacement therapy. Thisavoids the disruption of maintenancethyroid replacement therapy andprevents the discomfort of a period ofhypothyroidism.

TSH suppression therapyAfter ablation therapy, patients are com-menced on long-term thyroxine therapyto suppress the TSH level so that anyremaining thyroid tissue is not stimulatedto grow. The TSH level should be sup-pressed to just below the normal rangeand the T4 level maintained in the highnormal range but without rendering thepatient thyrotoxic. A greater degree ofTSH suppression is recommended forhigher risk patients, especially those withmetastatic disease. TSH suppressive therapy is best super-

vised by an endocrinologist, who willnormally advise the GP of the target TSHlevel.

External beam radiotherapyRadiotherapy is occasionally used inpatients with advanced thyroid cancer.This is especially so in those who are older(aged over 45 years) and have gross extra thyroidal extension at the time ofsurgery or positive margins, particularly if the tumour does not concentrate I131

thus limiting the utility of radioactiveiodine ablation. Radiotherapy is also used as palliation

for unresectable disease or inoperablemetastatic bone, brain or spinal disease.

Follow up All patients with thyroid cancer requirelong-term follow up by a multidisci pli -nary team including a GP, endocrinolo-gist, surgeon and nuclear medicinephysician. Papillary and follicular thyroidcancers have a long natural history andabout 5 to 20% of patients will developlocal recurrence in the thyroid bed or

regional cervical lymph nodes, with one-third of these recurrences occurring 10 ormore years after treatment. Unlike othermalignancies, where local recurrence por-tends a poor prognosis, local recurrencesin patients with thyroid carcinoma arereadily amendable to treatment withcurative intent.The intensity of follow up will vary

according to the initial tumour stage butthe principles of long-term managementinclude those listed below.

• Examination of the thyroid bed andneck, looking for evidence of localrecurrence or regional recurrence incervical lymph nodes.

• Regular thyroid function tests to assessthe adequacy of TSH suppression.The treating endocrinologist willnormally determine the frequency oftesting and the recommended TSHlevel required to achieve adequatesuppression.

• Serum thyroglobulin (Tg) assay. AsTg is normally only made by cells inthe thyroid, it serves as a useful‘tumour marker’ and has a highdegree of sensitivity and specificityafter total thyroidectomy andremnant ablation. A detectable Tglevel is suggestive of residual orrecurrent tumour. Tg is usuallymeasured after cessation of thyroxinetherapy for several weeks to allow the TSH level to increase, stimulatingTg release from any thyroid cancercells remaining in the body. Alter -natively, rhTSH can be used, whichobviates the need for discon tinuationof thyroxine therapy, as previouslymentioned. Tg levels are measured atsix and 12 months and then yearly ifpatients are apparently free of disease.Tg antibodies should always bemeasured in conjunction with serumTg because their presence can affectthe reliability of the Tg assay.

• Diagnostic whole body radioisotopescans (DWBS) are commonly used in conjunction with serum Tg assay


Thyroid cancer

continued


to monitor for thyroid cancer recur -rence (Figure 6). A small amount ofradioactive iodine is administered,which is usually readily taken up byany normal or malignant thyroidcells. Once again, patients either arewithdrawn from their thyroxinereplacement therapy or have rhTSHprior to having a DWBS. RepeatDWBS are performed at six- to 12-month intervals with concomitantradioactive iodine ablation should apersistent tumour be identified. Anegative DWBS and undetectableserum Tg are generally both requiredfor a patient to be con sidered inremission. Patients with low-risksmall cancers and those demonstratedto be disease-free can often be followedup with serum Tg assay alone, with outthe need for additional DWBS.

• Sometimes patients have tumoursthat fail to take up radioactive iodine.They may have an elevated serum Tglevel with a negative DWBS. Thiscombi nation of positive serum Tgand negative DWBS can also occur inlow-volume recurrent diseasebecause Tg is generally more sensitivethan DWBS in detecting disease.These patients require comprehensiveimaging (neck ultrasound, chest CT,bone scan or PET scan) to try todetect the site of recurrent disease. Patients with recurrent or progressive

disease need comprehensive work-upand treatment in centres with expertise intreating thyroid cancer.

Prognosis The overall prognosis of patients withpapillary or follicular carcinoma is excel-lent when they are managed according tocurrent best practice guidelines. Thosewho are younger than 45 years of age at the time of diagnosis with small papil-lary tumours (less than 4 cm) containedwithin the thyroid and who have no evi-dence of distant metastatic disease have a five-year survival rate of 99% and a

10-year survival rate of 98%. Even whendistant metastatic disease is present at thetime of diagnosis in these patients, thefive and 10-year survival rates are still99% and 85%, respectively.

Medullary thyroid carcinoma Medullary thyroid carcinoma (MTC)arises from the neuroendocrine parafol-licular calcitonin secreting cells of the thyroid, which are located predominantly in the upper portion of each thyroid lobe.Patients typically present with thyroidupper lobe nodules, and metastatic cervi-cal adenopathy is present in about half of patients at initial presentation. Anelevated serum calcitonin level confirmsthe diagnosis. Most cases of MTC are sporadic; how-

ever, about a quarter are hereditary inorigin. Hereditary MTC arises as a resultof mutation of the RET proto-oncogene,which leads to the expression of a mutatedreceptor tyrosine kinase (an enzymeinvolved in the regulation of cell growthand development). Hereditary MTCoccurs in three forms:

• multiple endocrine neoplasia 2a(MEN2a) – characterised by MTC in combination with phaeochro -mocytoma and hyperparathyroidism

• multiple endocrine neoplasia 2b(MEN2b) – characterised by MTC incombination with phaeochromo -cytoma, multiple mucosal neuromasand marfanoid habitus

• familial MTC – characterised by theabsence of other endocrinopathies orneural abnormalities in any affectedfamily member.Patients with newly diagnosed MTC

require a detailed work-up before surgery,including:

• serum calcitonin level determination• neck, chest and abdominal CTlooking for metastatic disease, and24-hour urinary catecholaminescreening to exclude a concurrentphaeochromocytoma

• serum parathyroid hormone leveldetermination to exclude coincidenthyperpara thyroidism

• genetic screening looking for the RETmutation (results of genetic screeningdo not influence initial treatment andcan be performed before or aftersurgery).Radioactive iodine ablation cannot be

used because MTC does not take upradioiodine. Surgery involves total thy-roidectomy with bilateral neck dissectionin most patients, as these patients have a


Thyroid cancer

continued

Figure 6. Diagnostic

whole-body

radioisotope (I131)

scan demonstrating

multiple foci of

avid iodine uptake

in lower neck and

chest consistent

with metastatic

thyroid cancer.

PosteriorAnterior Anterior


high incidence of bilateral metastatic cer-vical nodal disease. If patients carry the germline RET

mutation then genetic testing after appro-priate counselling should be performedon all family members. Prophylactic thy-roidectomy is usually recommended inearly childhood for known carriers of theRET gene mutation.

Anaplastic thyroid carcinomaAnaplastic carcinoma of the thyroid is ahighly lethal malignancy that is rapidlyprogressive and nearly always incurable.It tends to occur in elderly patients and is thought to arise from dedifferentiationof a longstanding papillary or follicularcarcinoma. It usually presents with arapidly expanding thyroid mass withextensive infiltration, and airway obstruc-tion is a common presenting symptom. It has a poor prognosis, with a mortal-

ity rate of 95% within two years of diag-nosis. Thyroidectomy is rarely possibleand palliation using radiotherapy andchemotherapy is standard treatment. Palliative tracheostomy is sometimesrequired.

ConclusionMost patients with papillary and follicularthyroid cancer have a very good progno-sis. Because most patients diagnosed with this cancer initially present with athyroid nodule, GPs have to be alert tothis possibility when assessing patientswith thyroid nodules. Once thyroid cancer is diagnosed, the patient should be referred promptly to a thyroid surgeonfor further assessment. Total thyroidec-tomy and adjuvant radioactive iodinethyroid remnant ablation therapy is indicated for most patients. Long-termfollow up, with input from the endocri-nologist, surgeon, nuclear medicinephysician and GP, is required to monitorfor recurrence. MT

1. Tracey E, Baker D, Chen W, Stavrou E, Bishop J.

Cancer in New South Wales: incidence, mortality

and prevalence report 2005. Sydney: Cancer

Institute NSW; 2007. p. 146-149.

2. McCormack AI, Learoyd DL. A guide to thyroid

dysfunction. Med Today 2006; 7(5): 28-35.

3. Rosen IB, Azadian A, Walfish PG, et al.

Ultrasound-guided fine-needle aspiration biopsy

in the management of thyroid disease. Am J Surg

1993; 166: 346-349.

COMPETING INTERESTS: None.

Thyroid cancer

continued

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References

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tyroid cancer – an update...figure 2. age-standardised incidence of thyroid cancer in new south...

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