Update on external beam radiation therapy in thyroid cancer

Clinical Outcomes of Radioactive Iodine Redifferentiation Therapy in Previously Iodine Refractory Differentiated Thyroid Cancers

Objective: Redifferentiation therapy (RDT) can restore radioactive iodine (RAI) uptake in differentiated thyroid cancer (DTC) cells to enable salvage 131I therapy for previously RAI refractory (RAIR) disease. This study evaluated the clinical outcomes of patients who underwent RDT and identified clinicopathologic characteristics predictive of RAI restoration following RDT. Methods: This is a retrospective case series of 33 patients with response evaluation criteria in solid tumors (RECIST)-progressive metastatic RAIR-DTC who underwent RDT between 2017 and 2022 at the Mayo Clinic (Rochester, MN). All patients underwent genomic profiling and received MEK, RET or ALK inhibitors alone, or combination BRAF-MEK inhibitors for 4 weeks. At week 3, those with increased RAI avidity in metastatic foci received high-dose 131I therapy. Baseline and clinicopathologic outcomes were comprehensively reviewed. Results: Of the 33 patients, 57.6% had restored RAI uptake following RDT (Redifferentiated subgroup). 42.1% (8/19) with papillary thyroid cancers (PTC), 100% (4/4) with invasive encapsulated follicular variant PTCs (IEFV-PTCs), and 100% (7/7) with follicular thyroid cancers (FTC) redifferentiated. All (11/11) RAS mutant tumors redifferentiated compared with 38.9% (7/18) with BRAF mutant disease (6 PTC and 1 IEFV-PTC). 76.5% (13/17) of redifferentiated and 66.7% (8/12) of non-redifferentiated patients achieved a best overall RECIST response of stable disease (SD) or non-complete response/non-progressive disease. Both subgroups had a median 12% tumor shrinkage at 3 weeks on drug(s) alone. The redifferentiated subgroup, following high-dose 131I therapy, achieved an additional median 20% tumor reduction at 6 months after RDT. There were no statistically significant differences between both groups in progression free survival (PFS), time to initiation of systemic therapy, and time to any additional therapy. Of the entire cohort, 6.1% (2/33) experienced histologic transformation to anaplastic thyroid cancer, 15.1% (5/33) died, and all had redifferentiated following RDT and received 131I therapy. Conclusion: RDT has the potential to restore RAI avidity and induce RECIST responses following 131I therapy in select patients with RAIR-DTC, particularly those with RAS-driven "follicular" phenotypes. In patients with PTC, none of the evaluated clinical outcomes differed statistically between the redifferentiated and non-redifferentiated subgroups. Further studies are needed to better characterize the long-term survival and/or safety outcomes of high-dose RAI following RDT, particularly whether it could be associated with histologic anaplastic transformation.

The role of external beam radiation therapy in the management of thyroid carcinomas: A retrospective study in Iran Cancer Institute

BACKGROUND

Thyroid cancers are histologically classified into three types; differentiated thyroid carcinoma (DTC), medullary thyroid carcinoma (MTC), and anaplastic thyroid carcinoma (ATC). Among the several therapeutic strategies for treatment and management of thyroid cancer, surgical resection in combination with radioactive iodine therapy (RAI) is indicated for moderate to high-risk differentiated thyroid cancer (DTC) patients- according to current guidelines. However, external radiation therapy (EBRT) can be a viable alternative treatment option for these patients and scarce evidence is available regarding the efficacy and effectiveness of EBRT on thyroid cancer.

AIM

This study aims at evaluating the role of EBRT in the management of thyroid carcinomas.

METHODS AND RESULTS

In this retrospective cohort study, the records of 59 patients with thyroid cancer were accessed who were treated by EBRT from 2008 to 2016. The indications for EBRT included unresectable primary (definitive) or loco-regional recurrences (salvage) not suitable for RAI, palliation for local disease or metastatic foci (palliative), and the adjuvant treatment for suspected residual disease following resection. Progression-free survival (PFS) and overall survival (OS) were calculated for different types of cancer. PFS was measured from the start of EBRT to the last uneventful follow-up, recurrence, or death. Kaplan-Meier model was used for the survival analysis. Fifty-nine patients were evaluated. The histopathology of the tumors was differentiated and poorly-differentiated, medullary and anaplastic thyroid carcinomas in 22 and 6, 15 and 16 patients, respectively. Twenty-seven patients received external beam radiotherapy (EBRT) as adjuvant therapy and 18 of the cases as palliative therapy while the remaining received salvage or definitive primary EBRT. The stage of patients' cancer was as follows: stage II in 3 and III in 1, IVA in 18 and IVB in 18 and IVC in 19. Stage-based median overall survival was 26 months for IVA, 44 for IVB, and 29 for IVC. The median PFS was 18, 22 and 21 months for stages IVA, IVB and IVC, respectively.

CONCLUSION

Based on our findings, EBRT may still play a role in the management of patients with thyroid carcinoma and should be considered in the armamentarium against thyroid cancers.

External Radiotherapy for Locoregional Control in Thyroid Carcinoma

Most patients with well-differentiated thyroid cancers (WDTC) are adequately treated with surgery, radioactive iodine, and TSH suppression by thyroxine. External radiotherapy (ERT) is reserved for selected cases and for older patients. Some of the indications for ERT to neck include adjuvant treatment for gross or microscopic disease after surgery, palliation of locally advanced unresectable tumor, or as salvage for recurrent disease which is not amenable to surgery or does not uptake radioactive iodine. High radiation dose of at least 60Gy is required for locoregional control of gross or microscopic residual disease. As even patients with recurrent or metastatic disease can have long survival, it is important to minimize late radiation-induced morbidity without compromising local control. Modern ERT technique like intensity-modulated radiotherapy allows high radiation dose to be delivered to the large, complex target volume while protecting the adjacent critical normal structures like the trachea, larynx, esophagus, and cervical spinal cord.

Case of papillary thyroid cancer presenting with an inoperable cervical mass successfully treated with high-dose radiation therapy

External-beam radiation therapy (EBRT) for differentiated thyroid cancer has been controversial. Palliative irradiation is usually recommended for patients with treatment-resistant relapse and/or distant metastases, but high-dose EBRT is not often indicated in this situation. A 50-year-old man had treatment-resistant recurrence of an inoperable cervical mass and multiple lung metastases after total thyroidectomy and neck dissection. Because the patient had good performance status and no other life-threatening metastases, he received high-dose intensity-modulated radiation therapy (IMRT). Remarkably, the tumour shrank during treatment. After 3 months, he had bleeding from the internal carotid artery. The bleeding was outside the high-dose irradiation site and was likely due to infection; emergency interventional radiology was performed. The post-EBRT clinical course was favourable and the cervical mass almost disappeared. The patient remained alive for 3 years post treatment. It is possible to extend the indication of high-dose intensity-IMRT in selected patients with differentiated thyroid cancer.

The revised clinical practice guidelines on the management of thyroid tumors by the Japan Associations of Endocrine Surgeons: Core questions and recommendations for treatments of thyroid cancer

The Japan Associations of Endocrine Surgeons has developed the revised version of the Clinical Practice Guidelines for Thyroid Tumors. This article describes the guidelines translated into English for the 35 clinical questions relevant to the therapeutic management of thyroid cancers. The objective of the guidelines is to improve health-related outcomes in patients with thyroid tumors by enabling users to make their practice evidence-based and by minimizing any variations in clinical practice due to gaps in evidential knowledge among physicians. The guidelines give representative flow-charts on the management of papillary, follicular, medullary, and anaplastic thyroid carcinoma, along with recommendations for clinical questions by presenting evidence on the relevant outcomes including benefits, risks, and health conditions from patients' perspective. Therapeutic actions were recommended or not recommended either strongly (◎◎◎ or XXX) based on good evidence (😊)/good expert consensus (+++), or weakly (◎, ◎◎ or X, XX) based on poor evidence (😣)/poor expert consensus (+ or ++). Only 10 of the 51 recommendations given in the guidelines were supported by good evidence, whereas 35 were supported by good expert consensus. While implementing the current guidelines would be of help to achieve the objective, we need further clinical research to make our shared decision making to be more evidence-based.

The role of postoperative adjuvant radiotherapy in the local control in medullary thyroid carcinoma

BACKGROUND

The value of postoperative radiotherapy in the treatment of medullary thyroid carcinoma (MTC) has not been unequivocally demonstrated. Therefore our study aimed to answer the question of whether adjuvant radiotherapy showed any impact on the risk of local recurrence and whether there were any differences in response to radiotherapy between hereditary and sporadic MTC.

METHODS

A retrospective analysis involved 254 MTC patients, among them 73 patients with a hereditary disease. Two hundred and twenty-four patients, including 43 persons at high risk of local relapse, underwent only initial surgery, 18 other patients were operated due to MTC recurrences, whereas the remaining 12 patients had cytoreductive procedure or were not amenable for surgery. Radiotherapy was carried out in 132 patients. One hundred and twenty patients underwent adjuvant radiotherapy, among them 102 patients after initial surgery. The median follow up was 10 years (range 0.5-29 years).

RESULTS

Local recurrence occurred in 107/254 patients, among them in 63 subjects after prior radiotherapy. The frequency of relapse showed significant, increasing trend toward higher MTC stages (p<0.001). More relapses were noticed in patients with lymph node metastases at diagnosis. Adjuvant radiotherapy was associated with a lower risk of nodal recurrence only in high-risk patients, particularly if lymph node metastases were present at MTC diagnosis. The differences between hereditary and sporadic subgroups were not significant.

CONCLUSIONS

Adjuvant radiotherapy has a limited importance in MTC treatment. It should be considered in high-risk MTC patients. The presence of RET mutation does not influence the response to radiation.

Targeting autophagy in thyroid cancers

Thyroid cancer is one of the most common endocrine malignancies. Although the prognosis for the majority of thyroid cancers is relatively good, patients with metastatic, radioiodine-refractory or anaplastic thyroid cancers have an unfavorable outcome. With the gradual understanding of the oncogenic events in thyroid cancers, molecularly targeted therapy using tyrosine kinase inhibitors (TKIs) is greatly changing the therapeutic landscape of radioiodine-refractory differentiated thyroid cancers (RR-DTCs), but intrinsic and acquired drug resistance, as well as adverse effects, may limit their clinical efficacy and use. In this setting, development of synergistic treatment options is of clinical significance, which may enhance the therapeutic effect of current TKIs and further overcome the resultant drug resistance. Autophagy is a critical cellular process involved not only in protecting cells and organisms from stressors but also in the maintenance and development of various kinds of cancers. Substantial studies have explored the complex role of autophagy in thyroid cancers. Specifically, autophagy plays important roles in mediating the drug resistance of small-molecular therapeutics, in regulating the dedifferentiation process of thyroid cancers and also in affecting the treatment outcome of radioiodine therapy. Exploring how autophagy intertwines in the development and dedifferentiation process of thyroid cancers is essential, which will enable a more profound understanding of the physiopathology of thyroid cancers. More importantly, these advances may fuel future development of autophagy-targeted therapeutic strategies for patients with thyroid cancers. Herein, we summarize the most recent evidence uncovering the role of autophagy in thyroid cancers and highlight future research perspectives in this regard.

Locoregional disease control after external beam radiotherapy in 91 patients with differentiated thyroid carcinoma and pT4 tumor stage - a single institution experience

Background Locoregional recurrence is common in patients with locally advanced differentiated thyroid carcinoma (DTC). Our aim was to find out the rate of locoregional control of the disease after external beam radiotherapy (EBRT) of the neck and mediastinum in patients with DTC and pT4 tumor. Patients and methods Altogether 91 patients (47 males, 44 females, median age 61 years) with DTC had EBRT of the neck and mediastinum as part of the multimodal treatment of pT4 tumor (63 cases pT4a, 28 cases pT4b) from the year 1973 to 2015. Data on clinical factors, histopathology and recurrence were collected. Disease-free, disease-specific and overall survival was calculated. Results Median tumor size was 5 cm (range 1-30 cm). Out of 91 patients, 23 had distant and 38 regional metastases. A total or near-total thyroidectomy, lobectomy, subtotal thyroidectomy and lymph node dissection was performed in 70%, 14%, 2% and 30% of cases, respectively. Thirteen percent of patients were not treated with surgery. All patients had EBRT and 39 had chemotherapy. Radioiodine (RAI) ablation of thyroid remnant and RAI therapy was applied in 90% and 40% of cases, respectively. Recurrence was diagnosed in 29/64 patients without a persistent disease: locoregional and distant in 16 and 13 cases, respectively. Five-year and ten-year disease-free survival rate was 64% and 48%, respectively. Conclusions The majority of patients with DTC and pT4 tumors who were treated with EBRT of the neck and mediastinum region as part of multimodal treatment have long-lasting locoregional control of the disease.

Outcome of Treatment for Medullary Thyroid Carcinoma-a Single Centre Experience

We conducted this study to evaluate the demography, clinical presentation, management and outcomes of medullary thyroid carcinoma (MTC) from the Indian context. This was a retrospective study of patients with MTC managed between January 2008 and December 2016. All pertinent data was collected and the results were analysed using STATA (v.13.1). MTC accounted for 90/2022 (4.45%) patients managed with thyroid cancer during the study period. The mean age of presentation was 40 years (range 14-70 years) with 47 males and 43 females. The most common presentation included goitre with cervical lymphadenopathy seen in 60 patients (66.7%). There were 11 patients (12.2%) with systemic metastasis at presentation. Rearranged during transfection (RET) testing was performed in 71 patients and was positive in 25 (35.2%). The mutations among these patients were seen in the following codons: 634 (12), 804 (8), 790 (3) and 618 (2). Persistent hypercalcitoninemia (calcitonin > 50 pg/ml) was observed in 62/80 (77.5%) patients. Forty patients underwent a meta-iodo-benzyl-guanidine (MIBG) scan in the postoperative period, 10 were positive. The mean duration of follow-up was 32 months and 10 patients defaulted from follow-up. Sixteen patients developed metastasis during the period of follow-up while eight patients expired. The mean survival was 85.75 months (95% CI 78.7-92.7). MTC accounted for 4.5% of thyroid carcinomas in this cohort among which 35% were hereditary. Persistent hypercalcitoninemia following surgery is seen in more than 70% of patients but this does not affect survival. RET screening should be performed for all patients with MTC as curative surgery can be offered for mutation positive offspring.

Patterns of failure in anaplastic and differentiated thyroid carcinoma treated with intensity-modulated radiotherapy

BACKGROUND

The radiotherapy (rt) volumes in anaplastic (atc) and differentiated thyroid carcinoma (dtc) are controversial.

METHODS

We retrospectively examined the patterns of failure after postoperative intensity-modulated rt for atc and dtc. Computed tomography images were rigidly registered with the original rt plans. Recurrences were considered in-field if more than 95% of the recurrence volume received 95% of the prescribed dose, out-of-field if less than 20% received 95% of the dose, and marginal otherwise.

RESULTS

Of 30 dtc patients, 4 developed regional recurrence: 1 being in-field (level iii), and 3 being out-of-field (all level ii). Of 5 atc patients, all 5 recurred at 7 sites: 2 recurrences being local, and 5 being regional [2 marginal (intramuscular to the digastric and sternocleidomastoid), 3 out-of-field (retropharyngeal, soft tissues near the manubrium, and lateral to the sternocleidomastoid)].

CONCLUSIONS

In dtc, locoregional recurrence is unusual after rt. Out-of-field dtc recurrences infrequently occurred in level ii. Enlarged treatment volumes to level ii must be balanced against a potentially greater risk of toxicity.

Radioactive Iodine Therapy and Glucose Tolerance

Radioactive iodine therapy is commonly used as an adjuvant therapy in follicular and papillary thyroid carcinoma (PTC) and in the treatment of Graves’ disease (GD). The basis of this therapy is the accumulation of radioactive iodine by the sodium-iodide symporter (NIS) in the thyroid gland. Expression of NIS by extrathyroidal tissues such as islets of pancreas has been reported. Radioactive iodine uptake by pancreatic beta-cells can potentially damage these cells. In this study, we discuss the possible associations between radioactive iodine and glucose intolerance. Overall, radioactive iodine uptake by the pancreas may damage beta-cells and predispose patients to glucose intolerance or type 2 diabetes, particularly in patients exposed to radioactive iodine therapy following total thyroidectomy. Further studies are needed to clarify and confirm this association.

Lenvatinib: A Review in Refractory Thyroid Cancer

Lenvatinib (Lenvima®) is an oral, multi-targeted tyrosine kinase inhibitor (TKI) of vascular endothelial growth factor (VEGF) receptors 1, 2 and 3, fibroblast growth factor receptors 1, 2, 3 and 4, platelet-derived growth factor receptor alpha, and RET and KIT signalling networks, which are implicated in tumour growth and maintenance. In the EU and USA, lenvatinib is indicated for the treatment of locally recurrent or metastatic progressive, radioiodine-refractory differentiated thyroid cancer (RR-DTC). This approval was based on the results of the randomized, double-blind, multinational, phase 3 SELECT study, in which lenvatinib significantly improved median progression-free survival (PFS) and overall response rate compared with placebo in patients with RR-DTC. The PFS benefit with lenvatinib was seen in all pre-specified subgroups, including patients who had received either one or no prior VEGF-targeted therapy. Moreover, the PFS benefit with lenvatinib was maintained regardless of BRAF or RAS mutation status. The safety and tolerability profile of lenvatinib in SELECT was consistent with that of other VEGF/VEGF receptor-targeted therapies and was mostly manageable. Hypertension was the most common treatment-related adverse event in lenvatinib-treated patients, but only infrequently led to discontinuation of the drug. Although not collected in SELECT, information on quality of life would be useful in assessing the overall impact of therapy on the patient. This notwithstanding, the data which are available indicate that lenvatinib is an effective and generally well-tolerated treatment option for patients with RR-DTC. Lenvatinib, therefore, offers an acceptable alternative to sorafenib--currently, the only other TKI approved for this indication.

Does radiation dose matter in thyroid cancer?: Patterns of local-regional failure in recurrent and metastatic well-differentiated thyroid cancers treated with dose-painted intensity-modulated radiation therapy

INTRODUCTION

Due to complex multimodal treatments and a lengthy natural history of disease, the impact of radiation therapy for well-differentiated thyroid cancer (WDTC) is challenging to evaluate. We analysed the effect of dose escalation, as enabled by intensity-modulated radiation therapy (IMRT), on preventing local-regional failure (LRF) of microscopic and macroscopic WDTC.

METHOD

We performed a retrospective review of WDTC patients treated with IMRT from 1998-2011. Diagnostic imaging demonstrating first LRF was registered to the simulation CT containing the treated radiation isodose volumes. Areas of disease progression were contoured and the relationships of LRFs with isodose volumes were recorded.

RESULTS

Thirty patients had a median follow-up of 56 months (range = 1-139). Seventeen (57%) had gross residual, five (17%) had microscopic residual and eight (27%) had clear margins at the time of IMRT. Nine patients (30%) developed LRF, at a median time of 44 months (range = 0-116). Of these, six (67%) had been radiated to gross disease and one (11%) had microscopic residual. In the seven analysable cases, only one (14%) LRF occurred within the 70 Gy isodose volume. Marginal LRFs were: four (57%) outside 70 Gy, one (14%) outside 60 Gy and one (14%) outside 50 Gy. All but one recurrence (86%) occurred in the perioesophageal region.

CONCLUSIONS

Local-regional failure was seen most in patients who had gross disease at the time of IMRT, almost always occurred outside of the 70 Gy volume and was frequently in the area of oesophageal sparing. Meticulous surgical dissection, especially in the perioesophageal region, should be prioritised to prevent long-term LRF.

The Role of Adjuvant Radiation Therapy for Locoregionally Advanced Papillary Thyroid Carcinoma

OBJECTIVES

To investigate the role of adjuvant radiation therapy in locoregional control in patients with locoregionally advanced papillary thyroid carcinoma (pT4 or pN1b) based on a comparison of a group that received radiation therapy and a group that did not receive radiation therapy.

METHODS

A retrospective analysis was performed on 165 patients with locoregionally advanced papillary thyroid carcinoma who underwent treatment between 2002 and 2011. Of these, 32 patients received adjuvant radiation therapy, and 133 patients did not receive radiation therapy.

RESULTS

The median follow-up period was 7.2 years (range, 3.4-13.6) for the overall study population. The 10-year locoregional recurrence-free survival rates for patients in the radiation therapy and no radiation therapy groups were 83.9 and 60.8%, respectively (p = 0.037). The overall survival rate and distant recurrence-free survival rate were not different between the two groups (p = 0.076 and p = 0.813, respectively). Multivariate analysis showed that adjuvant radiation therapy was an independent prognostic factor for locoregional recurrence-free survival (p = 0.040).

CONCLUSIONS

Adjuvant radiation therapy for patients with either pT4 or pN1b disease improved locoregional recurrence-free survival and might be of benefit for patients with these high-risk features by reducing the need for additional salvage treatment after locoregional recurrence.

Engineering Multi-Walled Carbon Nanotube Therapeutic Bionanofluids to Selectively Target Papillary Thyroid Cancer Cells

BACKGROUND

The incidence of papillary thyroid carcinoma (PTC) has risen steadily over the past few decades as well as the recurrence rates. It has been proposed that targeted ablative physical therapy could be a therapeutic modality in thyroid cancer. Targeted bio-affinity functionalized multi-walled carbon nanotubes (BioNanofluid) act locally, to efficiently convert external light energy to heat thereby specifically killing cancer cells. This may represent a promising new cancer therapeutic modality, advancing beyond conventional laser ablation and other nanoparticle approaches.

METHODS

Thyroid Stimulating Hormone Receptor (TSHR) was selected as a target for PTC cells, due to its wide expression. Either TSHR antibodies or Thyrogen or purified TSH (Thyrotropin) were chemically conjugated to our functionalized Bionanofluid. A diode laser system (532 nm) was used to illuminate a PTC cell line for set exposure times. Cell death was assessed using Trypan Blue staining.

RESULTS

TSHR-targeted BioNanofluids were capable of selectively ablating BCPAP, a TSHR-positive PTC cell line, while not TSHR-null NSC-34 cells. We determined that a 2:1 BCPAP cell:α-TSHR-BioNanofluid conjugate ratio and a 30 second laser exposure killed approximately 60% of the BCPAP cells, while 65% and >70% of cells were ablated using Thyrotropin- and Thyrogen-BioNanofluid conjugates, respectively. Furthermore, minimal non-targeted killing was observed using selective controls.

CONCLUSION

A BioNanofluid platform offering a potential therapeutic path for papillary thyroid cancer has been investigated, with our in vitro results suggesting the development of a potent and rapid method of selective cancer cell killing. Therefore, BioNanofluid treatment emphasizes the need for new technology to treat patients with local recurrence and metastatic disease who are currently undergoing either re-operative neck explorations, repeated administration of radioactive iodine and as a last resort external beam radiation or chemotherapy, with fewer side effects and improved quality of life.

Management of invasive well-differentiated thyroid cancer: an American Head and Neck Society consensus statement. AHNS consensus statement

BACKGROUND

Invasive differentiated thyroid cancer (DTC) is relatively frequent, yet there is a paucity of specific guidelines devoted to its management. The Endocrine Committee of the American Head and Neck Society (AHNS) convened a panel to provide clinical consensus statements based on review of the literature, synthesized with the expert opinion of the group.

METHODS

An expert panel, selected from membership of the AHNS, constructed the manuscript and recommendations for management of DTC with invasion of recurrent laryngeal nerve, trachea, esophagus, larynx, and major vessels based on current best evidence. A Modified Delphi survey was then constructed by another expert panelist utilizing 9 anchor points, 1 = strongly disagree to 9 = strongly agree. Results of the survey were utilized to determine which statements achieved consensus, near-consensus, or non-consensus.

RESULTS

After endorsement by the AHNS Endocrine Committee and Quality of Care Committee, it received final approval from the AHNS Council.

Indications for the use of external beam radiation in thyroid cancer

PURPOSE OF REVIEW

The role of external beam radiation therapy (EBRT) in the management of thyroid cancer is not clearly defined. In the absence of randomized studies, the review aims to identify any recent literature that helps define the role.

RECENT FINDINGS

In differentiated thyroid cancer, single institutional studies report durable locoregional disease control in patients considered to be at high risk of local relapse after EBRT and recent guidelines are consistent in their recommendations. In medullary thyroid cancer, the evidence is more limited but again there is benefit in selected cases. In anaplastic thyroid cancer, multimodality therapy is superior to surgery alone in achieving local control and possibly survival but the benefit must be weighed against the toxicity. Newer radiation techniques may help reduce toxicity.

SUMMARY

Although surgery is the main treatment for thyroid carcinoma, EBRT has a role in the adjuvant setting following surgery in high-risk patients and in unresectable cancer. Advances in the delivery of external beam radiotherapy, including intensity-modulated radiotherapy reduces toxicity.

Referral patterns for patients with high-risk thyroid cancer

OBJECTIVE

Knowledge of referral patterns for specialty cancer care is sparse. Information on both the need and reasons for referral of high-risk, well-differentiated thyroid cancer patients should provide a foundation for eliminating obstacles to appropriate patient referrals and improving patient care.

METHODS

We surveyed 370 endocrinologists involved in thyroid cancer management. From information in a clinical vignette, respondents were asked to identify the reasons they would need to refer a high-risk patient to a more specialized facility for care. We performed multivariable analysis controlling for hospital and physician characteristics.

RESULTS

Thirty-two percent of respondents reported never referring thyroid cancer patients to another facility. Of those that would refer a high-risk patient to another facility, the opportunity for a patient to enter a clinical trial was the most common reason reported (44%), followed by high-dose radioactive iodine (RAI) with or without dosimetry (33%), lateral neck dissection (24%), and external beam radiation (15%). In multivariable analysis, endocrinologists with a higher percentage of their practice devoted to thyroid cancer care were significantly less likely to refer patients to another facility (P = .003).

CONCLUSION

The majority of endocrinologists treating thyroid cancer patients report referring a high-risk patient to another facility for some or all of their care. Knowledge of the patterns of physician referrals and the likelihood of need for referral are key to understanding discrepancies in referral rates and obstacles in the referral process.

Vitamin D in thyroid tumorigenesis and development

Besides its classical role in bone and calcium homeostasis, 1,25-dihydroxyvitamin D3 (1,25(OH)2D3), the active form of vitamin D, has many non-classical effects; antiproliferative, anti-apoptotic and prodifferentiating effects of 1,25(OH)2D3 have been described in several tumour types in preclinical models. This review focuses on the insights gained in the elucidation of the role of 1,25(OH)2D3 in the normal thyroid and in the pathogenesis, progression and treatment of thyroid cancer, the most common endocrine malignancy. An increasing amount of observations points towards a role for impaired 1,25(OH)2D3-VDR signalling in the occurrence and progression of thyroid cancer, and a potential for structural analogues in the multimodal treatment of dedifferentiated iodine-resistant thyroid cancer. A role for vitamin D in thyroid-related autoimmunity is less convincing and needs further study. Altered 1,25(OH)2D3-VDR signalling does not influence normal thyroid development nor thyrocyte function, but does affect C-cell function, at least in rodents. If these findings also apply to humans deserves further study.

Quality of life impact of external beam radiotherapy for advanced thyroid carcinoma

BACKGROUND

External beam radiotherapy (XRT) has an established role in the management of recurrent or advanced well-differentiated thyroid carcinoma (WDTC). The goal of this study was to investigate the impact of this additional intervention on the quality of life (QOL) compared with total thyroidectomy (TT), with or without adjuvant radioactive iodine (RAI).

METHODS

A cross-sectional analysis using validated QOL instruments was performed. Patients receiving XRT between 1992 and 2008 for WDTC were identified and offered study participation. The Quality of Life Radiation Therapy Instrument and the Head and Neck Companion Module were administered retrospectively (N=13). For a comparison, patients previously treated with TT (N=11) alone as well as TT with postoperative RAI (N=11) for WDTC were also evaluated.

RESULTS

Thirty-four patients were included in the analysis. The XRT group reported significant decreases in chewing, swallowing, and appetite, and significant increase in pain, compared with both the RAI group and the TT group. Significant differences were reported for questions with regard to peace of mind, feeling discouraged, saliva, taste, ability to eat regular food, and concerns for the appearance of the neck in both RAI and XRT groups compared with TT patients. Subscale analysis of head and neck specific questions demonstrated significant overall differences for both RAI and XRT groups compared with thyroidectomy alone, with no differences observed between RAI and XRT groups in a direct comparison.

CONCLUSIONS

RAI therapy results in a measurable decrease in head and neck specific QOL measures compared with TT alone. The addition of XRT results in additional measurable morbidity secondary to pain and dysphagia.

Update on thyroid cancer treatment

Surgery and radioiodine therapy are usually effective for most patients with differentiated thyroid cancer. However, poorly differentiated and anaplastic thyroid carcinomas represent a challenge to physicians on the basis of the current cancer treatment modalities. These cancer subtypes are often lethal and refractory to radioiodine therapy as well as most of the common chemotherapy drugs. Several kinase inhibitors are promising targeted therapies for these malignancies; however, clinical trials involving these drugs have provided controversial results and their clinical use is still under debate. Advanced medullary thyroid carcinomas may also be refractory to conventional therapies and novel kinase inhibitors may also be useful to control tumor progression in certain patients. Novel evidence is emerging that thyroid cancer is a stem cell disease, thereby implying that the driving force of thyroid cancers is a subset of undifferentiated cells (thyroid cancer stem cells) with unlimited growth potential and resistance to conventional therapeutic regimens. Thyroid cancer stem cells have been proposed as responsible for tumor invasiveness, metastasis, relapse and differentiation. Therefore, drugs that selectively target these cells could serve as a cornerstone in the treatment of poorly differentiated thyroid cancer.

Anaplastic thyroid carcinoma

Thyroid cancers represent about 1% of all human cancers. Differentiate thyroid carcinomas (DTCs), papillary and follicular cancers, are the most frequent forms, instead Anaplastic Thyroid Carcinoma (ATC) is estimated to comprise 1-2% of thyroid malignancies and it accounts for 14-39% of thyroid cancer deaths. The annual incidence of ATC is about one to two cases/million, with the overall incidence being higher in Europe (and area of endemic goiter) than in USA. ATC has a more complex genotype than DTCs, with chromosomal aberrations present in 85-100% of cases. A small number of gene mutations have been identified, and there appears to be a progression in mutations acquired during dedifferentiation. The mean survival time is around 6 months from diagnosis an outcome that is frequently not altered by treatment. ATC presents with a rapidly growing fixed and hard neck mass, often metastatic local lymph nodes appreciable on examination and/or vocal paralysis. Symptoms may reflect rapid growth of tumor with local invasion and/or compression. The majority of patients with ATC die from aggressive local regional disease, primarily from upper airway respiratory failure. For this reason, aggressive local therapy is indicated in all patients who can tolerate it. Although rarely possible, complete surgical resection gives the best chance of long-term control and improved survival. Therapy options include surgery, external beam radiation therapy, tracheostomy, chemotherapy, and investigational clinical trials. Multimodal or combination therapy should be useful. In fact, surgical debulking of local tumor, combined with external beam radiation therapy and chemotherapy as neoadjuvant (before surgery) or adjuvant (after surgery) therapy, may prevent death from local airway obstruction and as best may slight prolong survival. Investigational clinical trials in phase I or in phase II are actually in running and they include anti-angiogenetic drugs, multi-kinase inhibitor drugs.