Papillary Microcarcinoma of the Thyroid T.T. Law Queen Mary Hospital Joint Hospital Surgical Grand Round 16th January, 2010

Papillary Microcarcinoma of the Thyroid

T.T. Law Queen Mary Hospital

Joint Hospital Surgical Grand Round16th January, 2010

112/04/18 Free template from www.brainybetty.com 2

Background

• Papillary thyroid carcinoma (PTC) is the most common type of thyroid cancer.

• Papillary thyroid microcarcinoma (PTMC) represents a particular variant of papillary thyroid carcinoma.


Definitions

World Health Organization (WHO) definition of PTMC:

– Papillary carcinomas of the thyroid with maximal diameter of ≤1.0cm

Hedinger C et al. WHO international histologcial Classification of tumors, vol 11.


Incidence

• Wide range of prevalence: ranging from 3 -36% in autopsies studies – Number of sectioning levels – Histologic criteria for diagnosis – Possible population/geographical

variation

Harach HR et al. Cancer 1985;56:531-8


Incidence

• Increase in incidence in recent years• 30-40% of patients had PTMC among all

patients with PTC • 2-24% of patients after thyroidectomy for

presumbly benign thyroid disease• Increase use of ultrasound (USG) and USG-

guided fine-needle aspiration (FNA)

Bramley MD, et al. Br J Surg 1996;83:1674-83

Fink A, et al. Mod Pathol 1996;9:816-20


USG Features

• Hypoechoic or heterogenous

• Microcalcifications within lesion

• Irregular margins• Taller than wider dimension• Intranodular vascularity

Hubbard GH et al. Endocrine Surgery. Springer 2009

Transverse (A) and longitudinal (B) thyroid USG images of a suspicious thyroid nodule

(A)

(B)


Management

• Controversies in the management: 1. Total/near-total thyroidectomy versus

lobectomy

2. Need for neck dissection

3. Need for radioiodine (RAI)


Clinical Scenarios

1. Pre-operative diagnosis of PTMC suspected or confirmed (overt PTMC)

– US – Fine-needle aspiration of suspicious thyroid

nodules or lymph nodes (LN)

2. Incidental finding of PTMC in thyroidectomy specimen for presumbly benign disease (occult PTMC)


Overt PTMC

• Total or near-total thyroidectomy than lobectomy is preferred – High incidence of multifocal disease – Avoids risk of reoperation – Possibility of better monitoring post-op by

scintigraphic scan and thyroglobulin measurements

Sakorafas GH et al. Cancer Treat Rev 2005;31:423-38


Overt PTMC - Neck

• Routine central neck dissection (CND) or selective approach?

• Pre-operative confirmed lymph node metastases -> therapeutic central neck dissection

• Pre-operative no lymph node metastases + intra-operative no suspicious lymph nodes ->

? Prophylactic neck dissection


Anatomy of Cervical LN


Overt PTMC – Central Neck Dissection

Proponents Opponents •High incidence of LN metastases in PTMC noted after prophylactic neck dissection

•Increased risk of injuring the recurrent laryngeal nerve and parathyroid glands

•CND provides pathologic information on nodal metastases, which may assist the post-op RAI planning

•Central node metastases unrelated to disease-free survivalIto Y et al. World J Surg 2006;30:91-9

•No need for wound extension •Low incidence of central compartment recurrence in patients without LN dissection

•RAI decreased LN recurrence rate from 7% to 0% in patients with negative LN on presentation and no neck dissectionChow SM et al. Cancer 2003;98:31-40


Overt PTMC - RAI

• Is the use of RAI after total thyroidectomy associated with lower rate of recurrence in PTMC?

• Japan: restricted use of RAI, Japanese surgeons support prophylactic neck dissection

Ito Y et al. World J Surg 2008;32:729-39


Overt PTMC - RAI

• RAI may reduce recurrence rate in high risk patient, yet it remains a controversial issue

• Unfavorable prognostic factors: – Older age (>45 years)– Distant metastases– Capsular invasion, vascular invasion – Lymph node metastases – Uncapsulated tumor – Multifocality – Non-incidental cancer

Sakorafas GH Cancer Treat Rev. 2005;31:423-38


Overt PTMC - RAI

• RAI may reduce nodal recurrence in patients who were negative for lymph node metastasis at presentation and who were not treated with neck dissection2

• Speculation: RAI may eradicate microscopic metastases in LNs, yet the clinical significance of these micrometastases is difficult to predict

• RAI is indicated for patients with distant metastases

Chow SM et al. Cancer 2003;98:31-40


Occult PTMC

• Excellent prognosis• Patients died of other diseases than of occult PTMC

Lo CY et al. World J Surg 2006;30:759-66


Occult PTMC

• A benign disease?• Is completion thyroidectomy indicated if

PTMC is incidentally discovered following a limited thyroid surgery?

• Controversial topic


Occult PTMC

• Very low incidence of lymph node metastases or tumor recurrence in clinically occult PTMC treated with thyroidectomy alone

• Neck dissection and RAI generally not indicated

Lo CY et al. World J Surg 2006;30:759-66

Besic N et al. Ann Surg Oncol 2009;16:920-8


PTMC – Suppression therapy

• Is suppressive T4 treatment necessary for patients with PTMC (especially for those with hemithyroidectomy)?

• Recommended by some authors1 but other2 showed that patients who discontinued TSH suppression within a few years did not had significantly higher incidence of recurrence

1Bramley MD et al. Br J Surg 1996;83:1674-83

2Noguchi S et al. World J Surg 2008;32:747-53


Follow up

• Clinical exam • Neck USG • Measurements of thyroglobulin (Tg) serum

levels • Long term surveillance is necessary as

recurrence may occur after many years


Social/Psychological Impact

• Should we mention the diagnosis of “carcinoma” to patients who have a completely excised PTMC?

• Important to discuss with patient about the nature of the disease, its high curability rate and excellent prognosis


Conclusion

• Incidence of PTMC is increasing due to use of USG and USG-guided FNA for small thyroid lesions

• Prognosis is excellent for the majority of patients with PTMC

• Optimal treatment is important to decrease risk of lymph node recurrence and distant metastases in clinically overt PTMC

• Optimal treatment for occult PTMC is debatable



PTMC – Endoscopic thyroidectomy

• Several retrospective studies of endoscopic thyroidectomy for PTMC

• 499 patients with PTMC were enrolled between 2005-2007• 275 patients underwent gasless endoscopic thyroidectomy

via the axillary route (endo group)• 224 patients underwent conventional open thyroidectomy

(open group) • Statistically significant longer operating time in endo group

(138.5 +/- 49.0 min vs. 105.5 +/- 41.6 min; P < 0.0001)• Smaller number of lymph nodes were retrieved in the endo

group compared to the open group (5.05 +/- 2.94 vs. 5.96 +/- 4.50, P = 0.007)

• Short term oncological results were comparable between 2 groups

Jeong JJ et al. J Surg Oncol 2009 Nov(1) 100(6)477-80


Occult PTMC - Observation

• Is observation and non-operative management feasible in occult PTMC?

• Japanese study: 162 patients with PTMC treated with observation alone

• Mean follow up: 46.5 months • >70% tumors no change in size, 10.2% increase

in size by >10mm, 1.2% lymph node metastases in lateral compartment

• Surgical treatment only when tumor is progressing -> not late according to investigators

Ito Y et al. Thyroid 2003;13:381-7

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Papillary Microcarcinoma of the Thyroid T.T. Law Queen Mary Hospital Joint Hospital Surgical Grand Round 16th January, 2010