Therapeutic strategies and long-term results in differentiated thyroid cancer

Should central lymph node dissection be considered for all papillary thyroid microcarcinoma?

BACKGROUND

Central lymph node dissection (CLND) in patients with papillary thyroid microcarcinoma (PTMC) is still controversial. The aim of this study was to examine the risk factors and the incidence of central lymph node metastases (CLNMs) in patients with PTMC who underwent thyroidectomy and CLND.

PATIENTS AND METHODS

Between 2002 and 2013, 613 patients were enrolled who underwent thyroidectomy with routine CLND for PTMC at the Korea University Medical Center, Ansan Hospital and risk factors and the incidence of CLNM were analyzed. In addition, we also evaluated the complications after thyroidectomy with CLND.

RESULTS

Out of 613 patients, 239 (39.0%) were found to have CLNM. Male sex (p = 0.012), tumor size ≥ 0.5 cm (p = 0.001), capsular invasion or extrathyroidal extension (p = 0.029), and multifocality (p = 0.004) were independent risk factors for CLNM. Among the 69 patients who had PTMC without these risk factors, CLNM was identified in 12 (17.4%). In this study group, two (0.3%) had permanent recurrent laryngeal nerve injury, two (0.3%) had persistent hypocalcemia, and two (0.3%) developed postoperative hemorrhage.

CONCLUSION

CLNM in PTMC is highly prevalent in male sex, tumor size ≥ 0.5 cm, extrathyroidal extension, and multifocality. Even in PTMC patients without these risk factors, the incidence of CLNM is rather higher than expected, and the complication rate of thyroidectomy with CLND is acceptable. Thus, CLND should be considered in all patients with PTMC.

Specific features of differentiated thyroid carcinoma in patients over 70 years of age

BACKGROUND AND OBJECTIVES

Among the geriatric population, there is a lower incidence of thyroid carcinoma (TC), but it accounts for 30% of all thyroid disorders compared to 6-8% in younger subjects. Prognosis, moreover, is worse in the elderly, as demonstrated by the fact that 81% of deaths related to these tumors occur in patients over 55. The aim of this retrospective study was to identify the characteristics of differentiated thyroid carcinoma (DTC) peculiar to the elderly.

METHODS

Of 638 patients who underwent surgery for DTC over a period of 30 years, 46 were more than 70 years old. All the elderly patients had undergone radioioidine and TSH-suppression therapy following surgical resection.

RESULTS AND CONCLUSIONS

Despite these measures, the rate of recurrence was 26.5% at 5 years and 63.6% at 10 years. The 5- and 10-year disease-specific survival rates were 87.8% and 63.6%, respectively. On an average, survival was 55.1 months when death was disease-related, and with regard to histological type, it was longer in papillary carcinoma than in the follicular variant, and longest of all in occult sclerosing carcinoma. Survival was greatest in patients with tumors less than 2 cm in diameter, characterized by the absence of extraglandular spread and by lymph node metastasis.

Lymph node surgery in papillary thyroid carcinoma

BACKGROUND

The impact of nodal disease remains controversial in papillary thyroid carcinoma (PTC).

STUDY DESIGN

One surgeon treated 159 unselected patients, who were followed up for 1 to 27 years. We present a retrospective analysis with respect to nodal disease. Occult nodal disease was investigated, including metachronous nodal disease (mpN(1)) in primarily node negative patients (pN(0), clinical [c]N(0)).

RESULTS

Therapeutic lymphadenectomies, prophylactic lymphadenectomies, or no lymphadenectomy were carried out in 42 (cN(1)), 29 (cN(0)), and 88 (cN(0)) patients, respectively, with stage pN(1) in 41 (98%), in 5 (17%), and in 2 (2.3%) patients, respectively (17% versus 2.3% p < 0.005). Sensitivity and specificity of clinical staging were 85% and 99%, respectively. More frequent prophylactic lymphadenectomy during the study period (p = 0.002) led to a nonsignificant increase in stage pN(1) (26% versus 30%). Immunohistochemistry led to upstaging of only 3% of histologically negative nodes and one (4%) pN(0) patient. Nodal recurrence occurred in 8 of 156 patients (5%) treated for cure, in 12% of pN(1) versus 3% of pN(0) cN(0) tumors (p = 0.009), in 15% of TNM high-versus 3% of low-risk patients (p = 0.006), and in 5% each of patients, younger than 45 and 45 years or more. In TNM high-risk patients, tumor-related survival was 50% for stage pN(1) versus 86% for stage pN(0), cN(0) (p = 0.03) (100% and 100% in low-risk patients).

CONCLUSIONS

The rate of occult nodal disease might be relatively low, and it does not frequently progress to clinical recurrent disease. Clinical nodal status might be valid for deciding the extent and radicality of node dissection. Prophylactic (central) lymphadenectomy should be carried out without radicality-associated morbidity. Macroscopic nodal disease warrants more rigorous, compartment-oriented lymphadenectomy. There is no rationale for detection of occult disease and micrometastasis by frozen section or immunohistochemistry.

Intraoperative lymphatic mapping and sentinel lymph node biopsy in patients with papillary carcinoma of the thyroid gland

We examined the feasibility of sentinel lymph node biopsy for thyroid cancer. Thirty-eight patients with papillary thyroid carcinoma underwent intraoperative lymphatic mapping and sentinel lymph node biopsy. At surgery, we exposed the thyroid gland and used a tuberculin syringe to inject 0.2 ml of 1% patent blue dye directly into the thyroid mass. The lymphatics and the lymph node dyed with blue dyes, was excised as a sentinel lymph node. Modified radical neck dissection was performed following sentinel lymph node biopsy and the diagnostic ability of sentinel lymph node biopsy was examined. A sentinel lymph node was identified successfully in 27 (71%) of 38 patients. Sentinel lymph node biopsy removed one to three lymph nodes (median, two nodes). Eighteen patients had paratracheal sentinel lymph nodes, five patients had jugular sentinel lymph nodes, and four patients had both. Histological nodal metastasis was recognized in 16 of 27 cases. The positive rate of cancer metastases in sentinel lymph nodes was 58%, which was significantly higher than 11% in non-sentinel lymph nodes. Diagnostic ability of sentinel lymph node biopsy showed that accuracy was 89%, sensitivity was 84%, and specificity was 100%. Our preliminary study indicated that sentinel lymph node biopsy was available on detection of non-palpable nodal metastasis in the patients with thyroid cancer; however, further experience and refinement are needed.

Polymerase chain reaction in the detection of tumor cells: new approaches in diagnosis and follow-up of patients with thyroid cancer

Thyroid cancers are the most common endocrine malignancies and are being diagnosed with increasing frequency. In addition to other measures, diagnosis is based on fine-needle aspiration cytology examination. Recently, new assays using reverse transcription-polymerase chain reaction (PCR) are being tested to improve sensitivity and specificity of primary diagnosis and detection of recurrent thyroid cancer. In the preoperative diagnosis of thyroid cancer, several tissue- and/or tumor-specific mRNA have been described and in several cases, a higher sensitivity and specificity could be achieved using molecular techniques compared to conventional methods. In the postoperative follow-up of patients with thyroid cancer, conflicting data have been published and the use of PCR techniques revealed several problems of the molecular approach, which are based on some technical as well as biologic limitations. Despite these problems, which are discussed in detail in this review, molecular techniques may nevertheless improve the sensitivity and accuracy of fine-needle aspiration of thyroid nodules, fine-needle aspiration of metastases, and detection of recurrent disease in peripheral blood samples.

The use of recombinant human TSH in the follow-up of differentiated thyroid cancer: experience from a large patient cohort in a single centre

BACKGROUND

Periodic evaluation of serum thyroglobulin (Tg) and whole body 131I imaging (131I-WBS) are essential in the follow-up of differentiated thyroid carcinoma (DTC); both diagnostic modalities require stimulation by high levels of TSH. Administration of recombinant human TSH (rhTSH) is an alternative to the withdrawal of thyroid hormone therapy.

OBJECTIVE

The aim of this study was to report our experience in the use of rhTSH for the management of patients with DTC.

PATIENTS

One hundred and four patients were enrolled in the study. A dose of 10 U of rhTSH therapy was injected intramuscularly for 2 consecutive days; 24 h after the second dose of rhTSH the patients were administered 4--5 mCi of 131I and, 48 h later, WBS was performed.

RESULTS

In all patients, baseline mean serum Tg and TSH levels were 2.4 +/- 1.9 ng/ml and 0.0153 +/- 0.0232 mIU/l, respectively. Basal Tg levels were detectable in 58 out of 104 patients. After rhTSH injection, mean serum TSH levels rose to 122.67 +/- 47.36 mIU/l. Stimulated serum Tg levels increased to greater-than-or-equal 5 ng/ml and the 131I-WBS showed an uptake in 18 patients (17.4%). Among them there were three with bone metastases and one with brain metastases, who reported violent skeletal pain and a severe headache, respectively. These were caused by the growth of tumour mass of metastases induced by rhTSH administration.

CONCLUSIONS

The use of rhTSH avoids the debilitating effects of hypothyroidism and its use successfully promotes iodine uptake and increases the sensitivity of serum Tg testing. The risk of causing serious side-effects recommends performing skull magnetic resonance and radionuclide bone scan in cases of suspected brain or skeletal metastases.

Molecular detection of thyroglobulin mRNA transcripts in peripheral blood of patients with thyroid disease by RT-PCR

The sensitive detection of circulating tumour cells in patients with differentiated thyroid cancer may precede the detection of relapse by other diagnostic studies--such as serum thyroglobulin-and thus may have important therapeutic and prognostic implications. We performed reverse transcription-polymerase chain reaction (RT-PCR) on blood samples from patients diagnosed with thyroid disease using two different RT-PCR sensitivities. Additionally, tissue specificity of TG mRNA-expression was determined using RNA extracts from 27 different human tissues. The lower limit of detection was 50-100 TG mRNA producing cells/ml blood using a 'normal' RT-PCR sensitivity and 10-20 cells/ml blood using a 'high' sensitivity. With the normal sensitivity TG mRNA was detected in 9/13 patients with thyroid cancer and metastasis, 63/137 patients with a history of thyroid cancer and no metastasis, 21/85 with non-malignant thyroid disease and 9/50 controls. With the high sensitivity TG mRNA was detected in 11/13 patients with thyroid cancer and metastasis, 111/137 patients with a history of thyroid cancer and no metastasis, 61/85 with non-malignant thyroid disease and 41/50 controls. Interestingly, using the normal RT-PCR sensitivity TG mRNA transcripts are specific for thyroid tissue and detectable in the peripheral blood of controls and patients with thyroid disease, which correlates with a diagnosis of metastasized thyroid cancer. However, with a high RT-PCR sensitivity, TG mRNA expression was found not to be specific for thyroid tissue and was not correlated with a diagnosis of thyroid cancer in patients. As a consequence, to date TG mRNA detected by RT-PCR in the peripheral blood cannot be recommended as a tumour marker superior to TG serum-level.