Ablation with low-dose radioiodine and thyrotropin alfa in thyroid cancer

Detection and management of cervical lymph nodes in papillary thyroid cancer

Lymph node metastases in papillary thyroid cancer are a common occurrence; however, the management of clinically negative cervical lymph nodes remains controversial. Preoperative neck ultrasound mapping is crucial, and complete dissection of a nodal compartment is recommended for any metastatic lymph nodes. The role of prophylactic central neck dissection remains controversial. The BRAF V600E mutation is a common mutation in papillary thyroid cancer, and has been associated with more aggressive tumor behavior. Evaluating the BRAF status of tumors may have implications for treatment and surveillance. New areas of research continue to focus on risk stratification and identifying which patients benefit from a more aggressive treatment, such as prophylactic central lymphadenectomy and radioiodine ablation and more intense surveillance strategies.

Thyroid nodules and differentiated thyroid cancer: update on the Brazilian consensus

Thyroid nodules are frequent findings, especially when sensitive imaging methods are used. Although thyroid cancer is relatively rare, its incidence is increasing, particularly in terms of small tumors, which have an uncertain clinical relevance. Most patients with differentiated thyroid cancer exhibit satisfactory clinical outcomes when treatment is appropriate, and their mortality rate is similar to that of the overall population. However, relapse occurs in a considerable fraction of these patients, and some patients stop responding to conventional treatment and eventually die from their disease. Therefore, the challenge is how to identify the individuals who require more aggressive disease management while sparing the majority of patients from unnecessary treatments and procedures. We have updated the Brazilian Consensus that was published in 2007, emphasizing the diagnostic and therapeutic advances that the participants, representing several Brazilian university centers, consider most relevant in clinical practice. The formulation of the present guidelines was based on the participants' experience and a review of the relevant literature.

Long-term outcomes following low-dose radioiodide ablation for differentiated thyroid cancer

CONTEXT

Randomized trials show that low-dose (1.1 GBq [30 mCi]) radioiodide (RAI) has efficacy equivalent to high-dose RAI (3.7 GBq [100 mCi]) in thyroid remnant ablation (TRA) for differentiated thyroid cancer. Long-term follow-up is required to ensure detection of late recurrences and to confirm equivalence in terms of survival end points. However, median follow-up duration within randomized trials is currently limited.

PATIENTS AND SETTING

We studied 53 patients undergoing TRA for differentiated thyroid cancer with long-term follow-up in the Thyroid Unit of The Royal Marsden Hospital (Sutton, United Kingdom).

INTERVENTION

Patients were treated with TRA using low-dose (1.1 GBq) RAI.

MAIN OUTCOME MEASURES

Disease-free survival, overall survival, and the incidence of second malignancies were measured. Multivariable analysis was used to determine clinical risk factors for failure to achieve TRA after low-dose RAI.

RESULTS

Median follow-up was 24 (range, 4-34) years. Low-dose RAI TRA was successful in 26 (49%) patients (successful ablation [SA] group), whereas 27 (51%) patients required further treatment (unsuccessful ablation [UA] group). Thirty-year disease-free survival was 92% in the SA group vs 87% in the UA group (P = .601). Thirty-year overall survival was 81% in the SA group vs 62% in the UA group (P = .154). Nine (17%) patients developed second malignancies (4 in the SA group and 5 in the UA group). Predictors of failure to achieve TRA with low-dose RAI were male sex and stage pT4 disease.

CONCLUSIONS

There is no evidence from long-term follow-up of our cohort that treatment outcomes are compromised for patients that fail TRA with low-dose RAI and subsequently receive high-dose RAI.

Low- or high-dose radioiodine remnant ablation for differentiated thyroid carcinoma: a meta-analysis

CONTEXT

There is uncertainty over the dose of (131)I required for thyroid remnant ablation. Most previous studies have been inadequately powered to establish the best fixed dose of (131)I for effective ablation.

OBJECTIVE

The aim of the study was to assess the effects of low- vs high-dose regimens of radioiodine in thyroid remnant ablation for patients with differentiated thyroid carcinoma.

DATA SOURCES

Sources included the Cochrane Library, MEDLINE, EMBASE, and SCOPUS (all until September 2012).

STUDY SELECTION

Randomized controlled trials that assess the efficacy of low- or high-dose of radioiodine ablation of thyroid remnants were collected.

DATA EXTRACTION

Two authors performed the data extraction independently.

DATA SYNTHESIS

Nine randomized controlled trials involving 2569 patients were included. The 1100-MBq vs the 3700-MBq radioiodine showed no statistically significant difference in successful thyroid remnant ablation (risk ratio [RR], 0.91 [0.79 to 1.04]; P = .15), both the 1100 vs the 1850 MBq (RR, 0.95 [0.83 to 1.10]; P = .52) and the 1850 vs the 3700 MBq (RR, 1.00 [0.85 to 1.17]; P = .98) also showed no significant differences (95% confidence intervals were calculated for each estimate). Also, no significant differences existed in quality-of-life scores on the SF-36 between different (131)I-dose groups both on the day of ablation (RR, 0.15 [-0.65 to 0.96], P = .71; I(2) = 29%, P = .24) and 3 months after ablation (RR, -1.1 [-2.37 to 0.17], P = .09; I(2) = 22%, P = .26). A low dose of 1100 MBq radioiodine showed significant benefits in reducing adverse effects (total RR, 0.65 [0.55 to 0.77], P < .1; I(2) = 31%, P =.14) and shorter hospital isolation (RR, 0.4 [0.32 to 0.50]; P < .05).

CONCLUSIONS

The low dose of 1100 MBq radioiodine activity is sufficient for thyroid remnant ablation as compared to 3700 MBq radioiodine activity with similar quality of life, less common adverse effects, and a shorter hospital stay.

Controversies in primary treatment of low-risk papillary thyroid cancer

In many parts of the world, incidence of papillary thyroid cancer is increasing faster than any other malignancy. Most papillary thyroid cancers that are diagnosed are small and are generally regarded as being low risk, with little or no effect on mortality. Papillary thyroid cancer is a clinical challenge because it is difficult to prove benefit from the traditional therapeutic triad for this disorder (ie, total thyroidectomy with or without prophylactic central neck dissection, radioiodine remnant ablation, and suppression of serum thyroid-stimulating hormone with levothyroxine). However, risk of disease recurrence might be reduced by these therapies in a subset of patients with more aggressive disease. In the past decade, professional societies and other groups have established evidence-based clinical practice guidelines for management of papillary thyroid cancer, but these efforts have been made difficult by a paucity of randomised controlled trials. In this review, we summarise epidemiological data for disease incidence, discuss some controversies in disease management, and outline a therapeutic framework founded in the best available medical evidence and existing recommendations from clinical practice guidelines.

Progress in molecular-based management of differentiated thyroid cancer

Substantial developments have occurred in the past 5-10 years in clinical translational research of thyroid cancer. Diagnostic molecular markers, such as RET-PTC, RAS, and BRAF(V600E) mutations; galectin 3; and a new gene expression classifier, are outstanding examples that have improved diagnosis of thyroid nodules. BRAF mutation is a prognostic genetic marker that has improved risk stratification and hence tailored management of patients with thyroid cancer, including those with conventionally low risks. Novel molecular-targeted treatments hold great promise for radioiodine-refractory and surgically inoperable thyroid cancers as shown in clinical trials; such treatments are likely to become a component of the standard treatment regimen for patients with thyroid cancer in the near future. These novel molecular-based management strategies for thyroid nodules and thyroid cancer are the most exciting developments in this unprecedented era of molecular thyroid-cancer medicine.

Current and Future Perspectives in Thyroid Carcinoma Treatment

Thyroid nodules are a common clinical problem and evaluation with neck and thyroid ultrasound and fine-needle aspiration biopsy are the most accurate methods for evaluating and identifying those that require surgical resection. The surgical treatment of differentiated thyroid carcinoma is the most common and recommended approach. Post-operative ¹³¹I remnant ablation is used to eliminate the post-surgical thyroid remnant and may facilitate the early detection of recurrence. The conclusion of two important recent studies is that the use of recombinant human thyrotropin and low ¹³¹I dose, 30 mCi, for post-operative ablation may be sufficient for the management of low-risk thyroid cancer. Recently, multi-targeted kinase inhibitors have emerged as promising treatments for metastatic differentiated thyroid cancers based on mutation detection in samples from thyroid cancer. Motesanib, sorafenib, vandetanib, sunitinib, lenvatinib, imatinib and cabozantinib are multi-kinase inhibitors that have the ability of inhibiting the rearranged during transection (RET) and vascular endothelial growth factor receptor (VEGFR), and other kinases, and have been used in advanced differentiated thyroid carcinoma. By contrast, axitinib and pazopanib seem to act only as anti-angiogenic agents. Anaplastic thyroid carinoma is often advanced and metastatic at diagnosis. Patients with localised disease not amenable to surgical resection can be treated with adjuvant chemoradiotherapy.

Controversies in the management and followup of differentiated thyroid cancer: beyond the guidelines

Thyroid cancer is among the most common endocrine malignancies. Genetic and environmental factors play an important role in the pathogenesis of differentiated thyroid cancer. Both have good prognosis but with frequent recurrences. Cancer staging is an essential prognostic part of cancer management. There are multiple controversies in the management and followup of differentiated thyroid cancer. Debate still exists with regard to the optimal surgical approach but trends toward a more conservative approach, such as lobectomy, are being more favored, especially in papillary thyroid cancer, of tumor sizes less than 4 cm, in the absence of other high-risk suggestive features. Survival of patients with well-differentiated thyroid cancer was adversely affected by lymph node metastases. Prophylactic central LN dissection did improve accuracy in staging and decrease postop TG level, but it had no effect on small-sized tumors. Conservative approach was more applied with regard to the need and dose of radioiodine given postoperatively. There have been several advancements in the management of radioiodine resistant advanced differentiated thyroid cancers. Appropriate followup is required based on risk stratification of patients postoperatively. Many studies are still ongoing in order to reach the optimal management and followup of differentiated thyroid cancer.

Radioiodine thyroid remnant ablation after recombinant human thyrotropin or thyroid hormone withdrawal in patients with high-risk differentiated thyroid cancer

To supplement limited relevant literature, we retrospectively compared ablation and disease outcomes in high-risk differentiated thyroid carcinoma (DTC) patients undergoing radioiodine thyroid remnant ablation aided by recombinant human thyrotropin (rhTSH) versus thyroid hormone withdrawal/withholding (THW). Our cohort was 45 consecutive antithyroglobulin antibody- (TgAb-) negative, T3-T4/N0-N1-Nx/M0 adults ablated with high activities at three referral centers. Ablation success comprised negative (<1 μg/L) stimulated serum thyroglobulin (Tg) and TgAb, with absent or <0.1% scintigraphic thyroid bed uptake. “No evidence of disease” (NED) comprised negative unstimulated/stimulated Tg and no suspicious neck ultrasonography or pathological imaging or biopsy. “Persistent disease” was failure to achieve NED, “recurrence,” loss of NED status. rhTSH patients (n = 18) were oftener ≥45 years old and higher stage (P = 0.01), but otherwise not different than THW patients (n = 27) at baseline. rhTSH patients were significantly oftener successfully ablated compared to THW patients (83% versus 67%, P < 0.02). After respective 3.3 yr and 4.5 yr mean follow-ups (P = 0.02), NED was achieved oftener (72% versus 59%) and persistent disease was less frequent in rhTSH patients (22% versus 33%) (both comparisons P = 0.03). rhTSH stimulation is associated with at least as good outcomes as is THW in ablation of high-risk DTC patients.

To treat or not to treat: the role of adjuvant radioiodine therapy in thyroid cancer patients

Radioactive iodine (RAI) is used in treatment of patients with differentiated papillary and follicular thyroid cancer. It is typically used after thyroidectomy, both as a means of imaging to detect residual thyroid tissue or metastatic disease, as well as a means of treatment by ablation if such tissue is found. In this paper, we discuss the indications for and the mechanisms of RAI in the treatment of patients with thyroid cancer. We discuss the attendant risks and benefits that come with its use, as well as techniques used to optimize its effectiveness as an imaging tool and a therapeutic modality.

Thyroglobulin autoantibodies in patients with papillary thyroid carcinoma: comparison of different assays and evaluation of causes of discrepancies

CONTEXT

Thyroglobulin autoantibodies (TgAb) have been proposed as a surrogate marker of thyroglobulin in the follow-up of differentiated thyroid carcinoma. Commercially available TgAb assays are often discordant. We investigated the causes of discrepancy.

DESIGN

TgAb were measured by three noncompetitive immunometric assays and three competitive RIA in 72 patients with papillary thyroid carcinoma and associated lymphocytic thyroiditis (PTC-T), 105 with papillary thyroid carcinoma and no lymphocytic thyroiditis (PTC), 160 with Hashimoto's thyroiditis, and in 150 normal subjects. The results of the six assays were correlated. TgAb epitope pattern, evaluated by inhibition of serum TgAb binding to thyroglobulin by TgAb-Fab regions A, B, C, and D, were compared in sera which were positive in all six assays (concordant sera) and positive in only one to five assays (discordant sera) were compared. TgAb International Reference Preparation (IRP) was measured in 2007 and 2009.

RESULTS

The correlations of the six assays ranged from -0.01 to 0.93 and were higher in PTC-T and Hashimoto's thyroiditis than in PTC and normal subjects. Two uncorrelated components, one including the three immunometric assays, the other the three RIA, explained 40 and 37% of the total variance of the results of the six assays. The levels of inhibition were higher in concordant sera than in discordant sera by TgAb-Fab region B (27.0%, 21.2-34.0 vs. 6.0%, and 2.7-12.7%) and region C (30.5%, 21.3-37.7 vs. 4.0%, and 1.0-6.5%); thus, the epitope pattern was more homogeneous in concordant sera than in discordant sera. TgAb IRP ranged from 157 to 1088 (expected 1000) IU/ml in 2009; results in 2007 were similar in all but two assays.

CONCLUSIONS

TgAb assays are highly discordant. Discrepancy is lower when comparing assays with similar methodology. Results of TgAb from PTC-T are more concordant than those from PTC because their epitope pattern is more restricted. The internal standardization of TgAb is generally, but not completely, satisfactory.

Is recombinant human TSH as effective as thyroid hormone withdrawal in the detection and treatment of metastatic differentiated thyroid cancer?

Evaluation of: Van Nostr D, Khorjekav GR, O'Neil J et al. Recombinant human thyroid-stimulating hormone versus thyroid hormone withdrawal in the identification of metastasis in differentiated thyroid cancer with ¹³¹I planar whole body imaging and ¹²⁴I PET. J. Nucl. Med 53(3), 359-362 (2012). In a recent article, Van Nostrand et al. compared two methods of patient preparation, that is, recombinant human thyroid-stimulating hormone and thyroid hormone withdrawal, for the detection of metastasis in patients previously treated for differentiated thyroid cancer, using both ¹³¹I whole-body imaging and ¹²⁴I positron emission tomography. The major finding of this prospective study was that the number of patients and the number of foci for patient positive at ¹³¹I whole-body imaging and ¹²⁴I PET performed after thyroid hormone withdrawal was significantly higher when compared with that related to patients prepared with recombinant human thyroid-stimulating hormone.

Radioactive iodine therapy

PURPOSE OF REVIEW

Review of the management decisions that must be made by the endocrinologist during the use of radioactive iodine (RAI) therapy of hyperthyroidism and differentiated thyroid cancer.

RECENT FINDINGS

Since the 1940s radioactive (131)I (RAI) therapy has been a major component of the treatment of hyperthyroidism and differentiated thyroid cancer. RAI is the most common definitive treatment of hyperthyroidism. Pretherapy decisions including use of antithyroid medication and low-iodine diet will be discussed with the relevant supportive literature. The method of semi-quantitative calculation used for RAI treatment of hyperthyroidism will be described. Evidence-based guideline for the management of differentiated thyroid cancer by the American Thyroid Association, new drug development and recent randomized controlled trials have changed current practice of how RAI is used for remnant ablation and adjuvant therapy of differentiated thyroid cancer.

SUMMARY

RAI is a common tool for the endocrinologist in the management of hyperthyroidism and differentiated thyroid cancer. Review of the management decisions and practice of RAI therapy will educate the endocrinologist of the literature supporting current RAI use in hyperthyroidism and new developments in limiting the radiation exposure to the patients with differentiated thyroid cancer.