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

2015/5/18Free template from 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.

2015/5/18Free template from 3 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.

2015/5/18Free template from 4 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

2015/5/18Free template from 5 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: Fink A, et al. Mod Pathol 1996;9:816-20

2015/5/18Free template from 6 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)

2015/5/18Free template from 7 Management Controversies in the management: 1.Total/near-total thyroidectomy versus lobectomy 2.Need for neck dissection 3.Need for radioiodine (RAI)

2015/5/18Free template from 8 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)

2015/5/18Free template from 9 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

2015/5/18Free template from 10 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

2015/5/18Free template from 11 Anatomy of Cervical LN

2015/5/18Free template from 12 Overt PTMC – Central Neck Dissection ProponentsOpponents 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 survival Ito Y et al. World J Surg 2006;30:91-9 No need for wound extensionLow 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 dissection Chow SM et al. Cancer 2003;98:31-40

2015/5/18Free template from 13 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

2015/5/18Free template from 14 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

2015/5/18Free template from 15 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 dissection 2 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

2015/5/18Free template from 16 Occult PTMC Excellent prognosis Patients died of other diseases than of occult PTMC Lo CY et al. World J Surg 2006;30:759-66

2015/5/18Free template from 17 Occult PTMC A benign disease? Is completion thyroidectomy indicated if PTMC is incidentally discovered following a limited thyroid surgery? Controversial topic

2015/5/18Free template from 18 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: Besic N et al. Ann Surg Oncol 2009;16:920-8

2015/5/18Free template from 19 PTMC – Suppression therapy Is suppressive T4 treatment necessary for patients with PTMC (especially for those with hemithyroidectomy)? Recommended by some authors 1 but other 2 showed that patients who discontinued TSH suppression within a few years did not had significantly higher incidence of recurrence 1 Bramley MD et al. Br J Surg 1996;83: Noguchi S et al. World J Surg 2008;32:747-53

2015/5/18Free template from 20 Follow up Clinical exam Neck USG Measurements of thyroglobulin (Tg) serum levels Long term surveillance is necessary as recurrence may occur after many years

2015/5/18Free template from 21 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

2015/5/18Free template from 22 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

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2015/5/18Free template from 24 PTMC – Endoscopic thyroidectomy Several retrospective studies of endoscopic thyroidectomy for PTMC 499 patients with PTMC were enrolled between 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 ( / min vs / min; P < ) Smaller number of lymph nodes were retrieved in the endo group compared to the open group (5.05 +/ vs /- 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

2015/5/18Free template from 25 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