Management of low-

risk thyroid cancer

John T. Koutsikos, MD, PhD

Department of Nuclear Medicine

401 General Military Hospital of Athens

Definition of low risk thyroid cancer

according to different staging systems

Papillary/Follicular Thyroid

Cancer Staging

Stage I

• In patients younger than 45 years of age: Cancer (any size) is located in the thyroid gland. It may also be present in nearby neck (cervical) lymph nodes and/or nearby neck tissue. However, it has not spread to distant sites.

• In patients 45 years of age or older: Cancer is located in the thyroid gland only and is less than 2 centimeters (about 1 inch) in size. It is not in nearby neck tissue or lymph nodes. It has not spread to any distant sites.

Stage II

• In patients younger than 45 years of age: Cancer has spread beyond the thyroid and neck area (i.e., there are distant metastases).

• In patients 45 years of age or older: Cancer is in the thyroid only and is 2 to 4 cm (about 1 to 2 inches) in size. It has not spread to lymph nodes, nearby neck tissue, or distant sites.

Personal Point of View

• There are many staging systems.

• None is perfect or captures all the essential issues that

prognosticate for thyroid cancer.

• Also, the staging systems are static, focusing on only

one point in time.

• They do not reassess the patient 2 years or 12 years

after treatment.

• Because of these limitations, can we rely on staging

systems very much?

Staging and Treatment of DTC

• The recommended treatment depends on the

stage of differentiated thyroid cancer.

• May differ from the general statements, for

reasons related to patients’ individual

circumstances.

Staging and Risk Levels

POST SURGICAL RADIOIODINE (RAI) [preliminary ATA GL 2015]

Limited Use Selected Use Definite Use

ATA low-risk ATA low-

intermediate risk

ATA high-risk

<45 yrs

<2 cm

≥45 yrs

≥2cm

Gross invasion

Residual disease

No LN or invasion Positive LN LN invasion

Distant mets

No RAI

(or 30mCi?)

rhTSH RAI

(30-50 mCi)

Wthdr RAI

(dosimetry?)

Remnant

Ablation

Adjuvant

Therapy

Therapy

Thyroid cancer

Incidence and mortality

• Incidence: rising (average 100%) in

both sexes worldwide

men 1.0 – 3.5

women 1.9 – 12.1

(Kilfoy BA et al, Cancer Causes

Control 2009)

• Mortality: stabilised (fairly)

SEER:

Surveillance, Epidemiology & End Results

incidence

mortality

Prevalence of micro (≤10 mm) and macro-PTC cases

during 3 recent chronological periods (n=852 PTC

patients)

0

10

20

30

40

50

60

70

80

1963-1982 1983-1992 1993-2007

macroPTC

microPTC

Alevizaki et al, Thyroid 2009

n=132 n=306 n=414

Prevalence of micro- and macro-PTC according to pre-

existing thyroid disease – many are “incidental”

0

10

20

30

40

50

60

70

80

goitre cold nodule hot nodule

(%

)

macropapillary

micropapillary

p<0.001, Pearson x2

Alevizaki et al, Thyroid 2009

0

10

20

30

40

50

60

70

80

90

100

1982 1983-1992 1993-2007

papillary

follicular

6%

Alevizaki et al, Thyroid 2009

Overdiagnosis

vs.

Diagnosis

Korea's Thyroid-Cancer “Epidemic”

Screening and Overdiagnosis

Ahn et al

N Engl J Med

2014; 371:1765-

1767

Geographical differences in thyroid cancer incidence by district (2004-2006)

3

Males and

females

Wallonia: 8.3/100 000 PY

Flanders: 4.1/100 000 PY

ESR: 5.8/100 000 PY 664 new cases per year

Variability of screening and diagnostic procedures

Belgium (/ 1 000

py)

Walloon Region

Flemish Region

Brussels Region

P value

TSH 340 350 338 321 0.256

Neck US (+/- TSH)

8 12.5 5.1 10.5 <0.0001

Carotid duplex 12 14 11 16 <0.0001

High-tech imaging (CT/MRI/PET CT)

59 71 50 73 0.0002

Standardized rates; in population without history of thyroid disease

9

These exams can potentially unmask indolent or very small thyroid tumours

Study conclusion (1):

• Higher imaging rates

• More surgery for thyrotoxicosis/nodular disease

• Higher surgical rates

• ~ higher probability of indolent cancers

High incidence region

Van den Bruel et al. JCEM 2013, 98(10):4063-4071

Low incidence region

From overdiagnosis to

overtreatment

JCEM 2015

Frangos, et. alEJNMMI, in press

• “… putatively “low-risk” DTC patients frequently

had higher-risk features, or characteristics

confounding risk stratification. This finding

suggests that outside international centres of

excellence, limitations in surgical experience and

completeness and in histopathology reporting

may cast important doubt on such patients’ “low-

risk” classification.”

Treatment in low risk DTC

• Surgical removal via a lobectomy or near-total/total thyroidectomy. A near-total/total thyroidectomy is more common than a lobectomy.

• A central compartment neck dissection may also be done. This means surgical removal of lymph nodes next to the thyroid.

• In the lowest-risk patients, surgery may be the only treatment. The cure rate for lowest-risk patients with only surgery is excellent.

• Some patients receive radioactive iodine (RAI) treatment after the thyroidectomy. The patient’s age and other factors affect the decision about radioactive iodine.

• Thyroid hormone replacement therapy after thyroidectomy, with a dosage appropriate for a lower-risk patient.

Conclusion (I)

• Small (≤1 cm) intrathyroidal unifocal DTC with a

favorable histology and no node metastases

should not be submitted to RRA because of the

low risk of relapse and cancer specific mortality.

• Conversely, RRA is indicated in patients with a

higher risk level since it seems to reduce

recurrence rates and mortality.

The recent demonstration that the RRA

preparation with rhTSH is as effective as

THW using either high (100 mCi) or low (30

mCi) 131I activities suggests that rhTSH

preparation and low activity of 131I should

be considered as the standard of care for

low-risk DTC patients in the near future.

Conclusion (II)