Brain metastases in patients with differentiated thyroid carcinoma

Brain Metastases in Differentiated Thyroid Cancer: Clinical Presentation, Diagnosis, and Management

Background: Brain metastases (BM) are the most common intracranial neoplasms in adults and are a significant cause of morbidity and mortality. The brain is an unusual site for distant metastases of thyroid cancer; indeed, the most common sites are lungs and bones. In this narrative review, we discuss about the clinical characteristics, diagnosis, and treatment options for patients with BM from differentiated thyroid cancer (DTC). Summary: BM can be discovered before initial therapy due to symptoms, but in most patients, BM is diagnosed during follow-up because of imaging performed before starting tyrosine kinase inhibitors (TKI) or due to the onset of neurological symptoms. Older male patients with follicular thyroid cancer (FTC), poorly differentiated thyroid cancer (PDTC), and distant metastases may have an increased risk of developing BM. The gold standard for detection of BM is magnetic resonance imaging with contrast agent administration, which is superior to contrast-enhanced computed tomography. The treatment strategies for patients with BM from DTC remain controversial. Patients with poor performance status are candidates for palliative and supportive care. Neurosurgery is usually reserved for cases where symptoms persist despite medical treatment, especially in patients with favorable prognostic factors and larger lesions. It should also be considered for patients with a single BM in a surgically accessible location, particularly if the primary disease is controlled without other systemic metastases. Additionally, stereotactic radiosurgery (SRS) may be the preferred option for treating small lesions, especially those in inaccessible areas of the brain or when surgery is not advisable. Whole brain radiotherapy is less frequently used in treating these patients due to its potential side effects and the debated effectiveness. Therefore, it is typically reserved for cases involving multiple BM that are too large for SRS. TKIs are effective in patients with progressive radioiodine-refractory thyroid cancer and multiple metastases. Conclusions: Although routine screening for BM is not recommended, older male patients with FTC or PDTC and distant metastases may be at higher risk and should be carefully evaluated for BM. According to current data, patients who are suitable for neurosurgery seem to have the highest survival benefit, while SRS may be appropriate for selected patient.

Interleukin-6-controlled, mesenchymal stem cell-based sodium/iodide symporter gene therapy improves survival of glioblastoma-bearing mice

New treatment strategies are urgently needed for glioblastoma (GBM)-a tumor resistant to standard-of-care treatment with a high risk of recurrence and extremely poor prognosis. Based on their intrinsic tumor tropism, adoptively applied mesenchymal stem cells (MSCs) can be harnessed to deliver the theranostic sodium/iodide symporter (NIS) deep into the tumor microenvironment. Interleukin-6 (IL-6) is a multifunctional, highly expressed cytokine in the GBM microenvironment including recruited MSCs. MSCs engineered to drive NIS expression in response to IL-6 promoter activation offer the possibility of a new tumor-targeted gene therapy approach of GBM. Therefore, MSCs were stably transfected with an NIS-expressing plasmid controlled by the human IL-6 promoter (IL-6-NIS-MSCs) and systemically applied in mice carrying orthotopic GBM. Enhanced radiotracer uptake by 18F-Tetrafluoroborate-PET/magnetic resonance imaging (MRI) was detected in tumors after IL-6-NIS-MSC application as compared with mice that received wild-type MSCs. Ex vivo analysis of tumors and non-target organs showed tumor-specific NIS protein expression. Subsequent 131I therapy after IL-6-NIS-MSC application resulted in significantly delayed tumor growth assessed by MRI and improved median survival up to 60% of GBM-bearing mice as compared with controls. In conclusion, the application of MSC-mediated NIS gene therapy focusing on IL-6 biology-induced NIS transgene expression represents a promising approach for GBM treatment.

Clinical characteristics, treatment, and long-term outcome of patients with brain metastases from thyroid cancer

Brain metastases (BM) in patients with thyroid cancer (TC) are rare with an incidence of 1% for papillary and follicular, 3% for medullary and up to 10% for anaplastic TC (PTC, FTC, MTC and ATC). Little is known about the characteristics and management of BM from TC. Thus, we retrospectively analyzed patients with histologically verified TC and radiologically verified BM identified from the Vienna Brain Metastasis Registry. A total of 20/6074 patients included in the database since 1986 had BM from TC and 13/20 were female. Ten patients had FTC, 8 PTC, one MTC and one ATC. The median age at diagnosis of BM was 68 years. All but one had symptomatic BM and 13/20 patients had a singular BM. Synchronous BM at primary diagnosis were found in 6 patients, while the median time to BM diagnosis was 13 years for PTC (range 1.9-24), 4 years for FTC (range 2.1-41) and 22 years for the MTC patient. The overall survival from diagnosis of BM was 13 months for PTC (range 1.8-57), 26 months for FTC (range 3.9-188), 12 years for the MTC and 3 months for the ATC patient. In conclusion, development of BM from TC is exceedingly rare and the most common presentation is a symptomatic single lesion. While BM generally constitute a poor prognostic factor, individual patients experience long-term survival following local therapy.

Prognostic factors to predict the efficacy of surgical interventions against brain metastasis secondary to thyroid cancer

Introduction

Brain metastasis in differentiated thyroid cancer (DTC) is rare (frequency < 1%) and has a poor prognosis. Treatment strategies for brain metastasis are not well established.

Objectives

We conducted a retrospective analysis to identify predictive factors for patient outcomes and verify surgical indications for patients with brain metastasis and DTC.

Methods

The study included 34 patients with pathologically confirmed DTC with brain metastasis from March 2008 to November 2020. The associations between overall survival (OS) and clinical factors were evaluated. Cox regression analysis was used to determine the relationship between clinical factors and OS. To assess the survival benefit of craniotomy, Kaplan-Meier survival analysis was performed for each variable whose statistical significance was determined by Cox regression analysis.

Results

The median OS of the entire patient sample was 11.4 months. Survival was affected by the presence of lung metastasis (P = 0.033) and the number of brain metastases (n > 3) (P = 0.039). Only the subgroup with the number of brain metastases ≤3 showed statistical significance in the subgroup analysis of survival benefit following craniotomy (P = 0.048).

Conclusions

The number of brain metastases and the existence of lung metastasis were regarded more essential than other clinical factors in patients with DTC in this study. Furthermore, craniotomies indicated a survival benefit only when the number of brain metastases was ≤3. This finding could be beneficial in determining surgical indications in thyroid cancer with brain metastasis.

Brain Metastases From Differentiated Thyroid Carcinoma: Prevalence, Current Therapies, and Outcomes

BACKGROUND AND OBJECTIVE

The brain is an unusual site for distant metastases of differentiated thyroid carcinoma (DTC). The aim of this study was to document the prevalence of brain metastases from DTC at our institutions and to analyze the current therapies and the outcomes of these patients.

METHODS

We performed a retrospective chart review of patients with DTC and secondary neoplasia of the brain.

RESULTS

From 2002 to 2016, 9514 cases of thyroid cancer were evaluated across our institutions and 24 patients met our inclusion criteria, corresponding to a prevalence of 0.3% of patients with DTC. Fourteen (58.3%) were female and 10 (41.7%) were male. Fifteen patients had papillary thyroid cancer (PTC) (62.5%). Brain metastases were diagnosed 0 to 37 years (mean ± SD, 10.6 ± 10.4 years) after the initial diagnosis of thyroid cancer. Patients undergoing surgery had a median survival time longer than those that did not undergo surgery (27.3 months vs 6.8 months; P = 0.15). Patients who underwent stereotactic radiosurgery (SRS) had a median survival time longer than those that did not receive SRS (52.5 months vs 6.7 months; P = 0.11). Twelve patients (50%) were treated with tyrosine kinase inhibitors (TKIs), and they had a better survival than those who have not used a TKI (median survival time, 27.2 months vs 4.7 months; P < 0.05).

CONCLUSION

The prevalence of brain metastases of DTC in our institutions was 0.3% over 15 years. The median survival time after diagnosis of brain metastases was 19 months. In our study population, the use of TKI improved the survival rates.

Brain metastases: epidemiology

Brain metastases (BM) are the most commonly diagnosed type of central nervous system tumor in the United States. Estimates of the frequency of BM vary significantly, as there is no nationwide reporting system for metastases. BM may be the first sign of a previously undiagnosed cancer, or occur years or decades after the primary cancer was diagnosed. Incidence of BM varies significantly by primary cancer site. Lung, breast, and melanoma continue to be the leading cause of BM. These tumors are increasingly more common as new therapeutics, advanced imaging, and improved screening have led to lengthened survival after primary diagnosis for cancer patients. BM are difficult to treat, and for most individuals the diagnosis of BM generally portends a poor prognosis.

Prognostic indicators for papillary thyroid carcinoma

Differentiated thyroid cancer (DTC) includes more than 90% of all thyroid carcinoma and its incidence is growing, mainly due to an increase in the incidence of papillary thyroid cancer (PTC) for the widespread use of neck ultrasonography. Areas covered: Several prognostic factors should be considered during the management of PTC in order to provide the most effective treatment. The most important prognostic factors in PTC include personal and pathological features such as patient's age, gender, hystotype, tumor size, extrathyroidal extension, lymph node involvement, presence of local or distant metastases and molecular analyses. We performed a search in the PubMed database for studies published in English since 1960 using the terms: 'thyroid cancer', 'prognostic factors', 'age', 'gender', 'hystotype', 'tumor size', 'extrathyroidal extension', 'lymph node', 'metastases' and 'molecular analyses'. Expert commentary: Prognostic factors can guide clinicians during the treatment and follow-up of DTC patients, but it is now evident that the risk of recurrence or death must be evaluated periodically, on the basis of individual risk, according to the response to initial therapy or the subsequent therapy required during follow-up.

Metastatic cerebellar tumor of papillary thyroid carcinoma mimicking cerebellar hemangioblastoma

INTRODUCTION

Well-differentiated papillary thyroid carcinoma generally (PTC) have a favorable prognosis. This metastasis is rare in the central nervous system. Brain metastasis has a relatively poor prognosis. We present a rare case of cerebellar metastasis, one that mimics a solid type cerebellar hemangioblastoma and because of which it was very hard to reach accurate preoperative diagnosis. Accurate diagnosis was challenging because of the similar imaging and histopathological findings for these two tumors.

CASE DESCRIPTION

A brain lesion was detected by routine medical checkup of the brain with MRI in a 49-year-old woman 2 years after thyroidectomy for well-differentiated PTC. Gadolinium-enhanced MRI showed a homogeneous prominently enhanced lesion with surrounding enhanced dilated vessels in the left cerebellar hemisphere. Digital subtraction angiography showed a strongly stained lesion fed by the peripheral branch of the left posterior inferior cerebellar artery with drainage into the inferior vermian vein, revealing arteriovenous shunting. The most like likely preoperative diagnosis was felt to be that of a solid cerebellar hemangioblastoma. Gross total resection of the tumor was achieved by bilateral suboccipital craniotomy, and intraoperative pathological analysis suggested hemangioblastoma. Histopathological findings showed proliferation of vacuolated sheeted tumor cells with clear and eosinophilic cytoplasm and numerous thin-walled microvessels, consistent with hemangioblastoma. However, the final diagnosis was brain metastasis of the follicular variant of PTC due to a partial thyroid follicle-like pattern including eosinophilic fluid pathologically and positive TTF-1 immunostaining.

DISCUSSION AND EVALUATION

Since presented rare case of cerebellar metastasis of PTC was very similar to solid type cerebellar hemangioblastoma on imaging and histopathological findings, accurate diagnosis was challenging. Moreover, it is extremely rare for a cerebellar metastasis to occur as an initial distant metastasis of PTC, and hemangioblastoma is the most common primary cerebellar neoplasm in adults. This epidemiological data was also one of the reason of difficulty to reach preoperative accurate diagnosis.

CONCLUSIONS

To the best of our knowledge, there are no other reports of challenging diagnosis case of these two tumors in the literature. Brain metastasis of a well-differentiated PTC could be a relatively poor prognostic factor, and accurate diagnosis and suitable surgical therapy or radiotherapy are needed.

The Largest Known Survival Analysis of Patients with Brain Metastasis from Thyroid Cancer Based on Prognostic Groups

PURPOSE

To analyze the clinical features and prognostic factors associated with the survival of patients with a very rare occurrence of brain metastasis (BM) from differentiated thyroid cancer (DTC).

METHODS AND MATERIALS

A total of 37 patients with DTC who were diagnosed with BM between 1995 and 2014 were included. We reviewed the clinical characteristics, treatment modalities, and image findings of BM. Factors associated with survival were evaluated, and the patients were divided into three prognostic groups (Groups A, B, and C) for comparative analysis.

RESULTS

The median age at BM was 63 years, and the median time from initial thyroid cancer diagnosis to BM was 3.8 years. The median survival and the 1-year actuarial survival rate after BM were 8.8 months and 47%, respectively. According to univariate and multivariate analyses, four good prognostic factors (GPFs) were identified including age ≤ 60 years, PS ≤ ECOG 2, ≤ 3 BM sites, and without extracranial metastasis prior to BM. Three prognostic groups were designed based on age and number of remaining GPFs: patients ≤ 60 years of age with at least 2 GPFs (Group A) had the most favorable prognosis with a median survival of 32.8 months; patients ≤ 60 years of age with fewer than 2 GPFs and those > 60 years of age with at least 2 GPFs (Group B) had an intermediate prognosis with a median survival of 9.4 months; and patients > 60 years of age with fewer than 2 GPFs (Group C) had the least favorable prognosis with a median survival of 1.5 months.

CONCLUSIONS

The survival of patients with BM form DTC differed among the prognostic groups based on the total number of good prognostic factors.

Long-term survival in a patient with brain metastases of papillary thyroid carcinoma

We present the case of a 43-year-old woman who underwent total thyroidectomy with bilateral lymphadenectomy for a papillary thyroid carcinoma (PTC), solid variant (T4bN1bMx), with V600E BRAF mutation. After ablative therapy, she presented undetectable thyroglobulin (Tg) but progressively increasing anti-Tg antibodies (TgAbs). During follow-up, nodal, lung and brain metastases were identified. She was submitted to surgical excision of lung lesions, radiosurgery of brain metastases and five radioiodine treatments. The latest brain MRI showed no lesions, pulmonary CT showed stable micronodules and there was progressive reduction in TgAbs. This is a peculiar case of a PTC with lung and brain metastatic lesions detected through TgAbs. Initial histological and molecular study suggested a more aggressive clinical behaviour, which was eventually confirmed. Although PTC brain metastases are extremely rare and present poor prognosis, our patient presented a good response to treatment and longer survival than usually reported for similar cases.

Clinical characteristics and follow-up of intracranial metastases from thyroid cancer

BACKGROUND

Intracranial metastasis from thyroid cancer is extremely rare. However, less is known about the risk factors for intracranial metastasis and its treatment from few retrospective studies. The aim of this study was to contribute to the understanding of this disease by analyzing patients with intracranial metastases from thyroid cancer.

METHODS

Between 2001 and 2014, the database of the National Cancer Center of Korea was searched for thyroid cancer patients. The clinical characteristics and site of distant metastasis according to the histological type were evaluated in the thyroid cancer cohort. Among the patients with intracranial metastases, the characteristics, histological type of primary cancer and metastatic brain tumor, additional synchronous or previous distant metastasis, treatment modalities, locations and characteristics on radiologic findings, time interval between the first diagnosis of the primary thyroid cancer and brain metastasis, thyroglobulin level at the first detection of intracranial metastasis and survival were reviewed.

RESULTS

A total of 10 (0.032 %) out of 3,090 thyroid cancer patients in the National Cancer Center database were identified as having intracranial metastases. The histological types of the primary thyroid cancers were papillary for six patients, follicular for three, and poorly differentiated carcinoma for one. Six of these ten patients underwent surgical resection for intracranial lesions. Whole-brain radiotherapy or tyrosine kinase inhibitors were applied to the patients as postoperative adjuvant treatment, and stereotactic radiosurgery was considered for recurrent or surgically inoperable lesions. The overall median survival time was 33 months (range, 0.5-78 months) after diagnosis of intracranial metastasis.

CONCLUSIONS

Surgical resection and adjuvant treatments in the contemporary era seem to result in improved survival after intracranial metastases compared with what has been reported in past studies. Considering the grave course of intracranial metastasis, the early detection and aggressive treatment of patients with a good performance status are crucial.

Choroid Plexus Metastasis of Follicular Thyroid Carcinoma Diagnosed due to Intraventricular Hemorrhage

Choroid plexus metastasis (CPM) is extremely rare and originates most frequently from renal cell carcinoma (RCC). We herein report the case of a 58-year-old man who developed a solitary CPM lesion derived from follicular thyroid carcinoma in addition to intraventricular hemorrhage. Computed tomography revealed acute hydrocephalus as a result of the hemorrhage, and we planned endoscopic hematoma evacuation. Since it was too difficult to reach the hematoma, we considered the possibility of a neoplasm and performed a biopsy of the lesion, the results of which led to an accurate diagnosis of CPM in this case. We also review previous reports of CPM originating from thyroid carcinoma compared with RCC.

Brain metastasis from papillary thyroid carcinomas

Papillary thyroid carcinoma (PTC) is the most common type of thyroid carcinoma and has a relatively favorable prognosis. PTC brain metastases are rare, occurring in 0.1–5% of cases in previous studies. In the present study, we treated 5 cases of PTC brain metastasis in our institute and retrospectively evaluated these patients. A retrospective database was generated from the patient medical records of our institution for the years between 1976 and 2011. The mean patient age at diagnosis was 64.6 years and the average duration from PTC resection to the detection of a brain metastasis using magnetic resonance imaging (MRI) or computed tomography (CT) was 91.7 months. The patients were treated with various combinations of surgery and radiation therapy. All 5 patients died and the mean overall survival following the diagnosis of a brain metastasis was 9.0 months. One patient succumbed to an intratumoral hemorrhage of the metastatic brain tumor. The remaining patients died following metastasis to other organs. Our findings suggest that PTC brain metastases may occur at the end-stage of patient treatment and result in an unfavorable prognosis. Patients with brain metastases also succumbed to the development of metastases to the fetal organs rather than brain.

Brain metastases from thyroid carcinoma: a retrospective study of 21 patients

BACKGROUND

Brain metastases (BM) from differentiated thyroid carcinoma (DTC) are uncommon, and many questions about their management remain unsolved. The objective of this retrospective study was to analyze the characteristics, treatments, and outcomes of patients with BM from DTC.

METHODS

Among the 1523 patients with a DTC prospectively recorded in institutional databases between 1989 and 2012, 21 patients (1.4%) with BM were retrospectively retrieved. Patient characteristics, histological findings on initial thyroidectomy specimen, treatments, and time to death were reviewed. Overall survival (OS) was calculated using the Kaplan-Meier method. Survival curves for various subgroups of patients according to baseline characteristics and treatment received were compared.

RESULTS

The mean age at initial and BM diagnosis was, respectively, 52.7 and 63.2 years. World Health Organization performance status (PS) at BM diagnosis was good (<2) for 12 patients and poor (≥2) for 9. The initial carcinoma was papillary for 12 patients, follicular for 5, and poorly differentiated for 4. Eighteen patients had other previous and/or synchronous distant metastases: lung (11), bone (10), and others (2 peritoneum, 1 liver, 1 adrenal gland, and 1 uterine cervix). The average interval between the first metastasis and the BM was 3 years (range 0-35.6 years). The mean number and the mean size of BM were, respectively, 2.8 (range 1-10) and 22.5 mm (range 3-44 mm). Surgery was performed for 10 patients and radiotherapy (RT) for 18, with 2 stereotactic radiosurgery (SRS), 2 conformal RT limited to the metastasis, and 15 whole-brain RT. The median OS after BM was 7.1 months. OS at 1 and 2 years were 41.6% and 35.6%. PS and realization of surgery or SRS had an impact on survival, with OS of 27 months when PS <2 versus 3 months when PS ≥2 (p=0.0009), and OS of 11.9 months after surgery or SRS versus 3.6 months in their absence (p=0.04).

CONCLUSIONS

BM from thyroid cancer may have an indolent evolution with survival of one to two years or longer for specific groups of patients. Therefore, aggressive treatment options such as neurosurgery and RT should be strongly considered in patients with good PS.

Toward determining the lifetime occurrence of metastatic brain tumors estimated from 2007 United States cancer incidence data

Few population estimates of brain metastasis in the United States are available, prompting this study. Our objective was to estimate the expected number of metastatic brain tumors that would subsequently develop among incident cancer cases for 1 diagnosis year in the United States. Incidence proportions for primary cancer sites known to develop brain metastasis were applied to United States cancer incidence data for 2007 that were retrieved from accessible data sets through Centers for Disease Control and Prevention (CDC Wonder) and Surveillance, Epidemiology, and End Results (SEER) Program Web sites. Incidence proportions were identified for cancer sites, reflecting 80% of all cancers. It was conservatively estimated that almost 70 000 new brain metastases would occur over the remaining lifetime of individuals who received a diagnosis in 2007 of primary invasive cancer in the United States. That is, 6% of newly diagnosed cases of cancer during 2007 would be expected to develop brain metastasis as a progression of their original cancer diagnosis; the most frequent sites for metastases being lung and bronchus and breast cancers. The estimated numbers of brain metastasis will be expected to be higher among white individuals, female individuals, and older age groups. Changing patterns in the occurrence of primary cancers, trends in populations at risk, effectiveness of treatments on survival, and access to those treatments will influence the extent of brain tumor metastasis at the population level. These findings provide insight on the patterns of brain tumor metastasis and the future burden of this condition in the United States.

Effective radiovirotherapy for malignant gliomas by using oncolytic measles virus strains encoding the sodium iodide symporter (MV-NIS)

Engineered measles virus (MV) strains deriving from the vaccine lineage represent a promising oncolytic platform and are currently being tested in phase I trials. In this study, we have demonstrated that MV strains genetically engineered to express the human sodium iodide symporter (NIS) have significant antitumor activity against glioma lines and orthotopic xenografts; this compares favorably with the MV strain expressing the human carcinoembryonic antigen, which is currently in clinical testing. Expression of NIS protein in infected cells results in effective concentration of radioactive iodine, which allows for in vivo monitoring of localization of MV-NIS infection by measuring uptake of (123)I or (99m)Tc. In addition, radiovirotherapy with MV-NIS followed by (131)I administration resulted in significant increase of MV-NIS antitumor activity as compared with virus alone in both subcutaneous (p=0.0003) and orthotopic (p=0.004) glioblastoma models. In conclusion, MV-NIS-based radiovirotherapy has significant antitumor activity against glioblastoma multiforme and represents a promising candidate for clinical translation.

Stereotactic radiosurgery in the management of brain metastases from primary thyroid cancers

Patients with metastatic well-differentiated thyroid cancer have a generally favorable long-term outcome although multi-organ involvement is a known marker of poor prognosis. Brain metastases are rare, occurring in less than 1% of patients with thyroid cancer. Few patients have been managed with stereotactic radiosurgery (SRS). A retrospective database of 5,067 patients treated for brain metastases between 1985 and 2007 was generated from 11 institutions. Thyroid cancer patients were identified in this database and, when possible, additional information was obtained from further chart review. Patients were excluded if they had incomplete treatment or follow-up information. Two validated prognostic indices, Graded prognostic Assessment (GPA) and Recursive Partitioning Analysis (RPA), were calculated for each patient. The overall survival times were calculated by the Kaplan-Meier method. Twenty-three thyroid cancer patients were identified (51% male, 48% female). Median age was 63 years (range 20-81). Pathology of the primary thyroid disease was available for twelve patients; the majority were diagnosed with differentiated thyroid cancer (n = 9 papillary, n = 2 Hürthle cell; 92%) and one had medullary subtype (8%). Median time from diagnosis of primary disease to brain metastasis was 41.8 months (range 0-516). Fifteen (65%) patients underwent SRS as part of their initial treatment with a median number of lesions treated of 1.5 (range 1-9). The median follow-up time for living patients was 35.2 months. Overall median survival time was 20.8 months (40% alive at last follow-up) and 37.4 months for SRS-treated patients (P = NS). A poor Karnofsky performance status was predictive of worse outcome (P = 0.001). GPA and RPA did not provide additional prognostic information. In conclusion, patients treated with SRS for brain metastases from primary thyroid cancer have a favorable prognosis with an expected median survival greater than 3 years. It is unclear as to whether current prognostic indices are relevant to this patient population.

Brain metastases: epidemiology and pathophysiology

Metastases are the most common tumors of the central nervous system (CNS), but cancer databases are often incomplete leading to underestimation of the incidence of even symptomatic brain metastases. Brain imaging studies are not routinely performed on neurologically asymptomatic cancer patients and autopsy studies are outdated. Furthermore, while incidence rates for cancers are stable and mortality is decreasing due to earlier detection and better therapy, the incidence of brain metastases appears to be increasing. The pathophysiology of brain metastases is a complex multistage process, mediated by molecular mechanisms; from the primary organ, cancer cells must transform, grow and be transported to the CNS where they can lay dormant for various lengths of time before invading and growing further. Understanding the pathophysiology of brain metastases is of great importance, because it may lead to the development of more efficient therapies to combat brain tumor growth or to possibly make the CNS an undesirable environment for tumor progression.

Management of brain metastases from thyroid carcinoma: a study of 16 pathologically confirmed cases over 25 years

BACKGROUND

Brain metastasis is an uncommon, morbid complication of metastatic thyroid carcinoma. Because of its rarity, management often is problematic. To help contribute to the management of this disease entity, the authors present herein what to their knowledge is the largest series reported to date in which all patients had biopsy proven confirmation of their brain metastases.

METHODS

The authors report a series of 16 patients with metastatic thyroid carcinoma to the brain who were treated between 1976-2000. The Mayo Clinic database was used to locate and review charts and radiology and pathology reports, and all biopsy specimens were reviewed by one pathologist. The histologic types of carcinoma included 10 papillary carcinomas, 2 follicular carcinomas, 1 Hürthle cell carcinoma, 1 medullary carcinoma, 1 insular carcinoma, and 1 anaplastic carcinoma. Given the small sample size, statistical analyses were not performed.

RESULTS

Surgical resection of brain metastases was associated with a trend toward longer survival (20.8 months vs. 2.7 months for no surgical intervention in selected patients) Whole brain external beam radiation therapy produced disease regression in three of the four evaluable patients. Gamma knife radiosurgery and radioactive iodine therapy appear to play limited, but beneficial, therapeutic roles. Overall, survival after the diagnosis of brain metastasis is reported to be longer than that noted with other solid tumors (17.4 months), and the majority of patients die of their extracranial disease (85% in the current series).

CONCLUSIONS

The results of the current study indicate that local therapies appear to control brain metastases in the large majority of thyroid carcinoma patients with metastases to the brain.

Single brain metastasis from thyroid cancer: report of twelve cases and review of the literature

Brain metastases from thyroid carcinoma is unusual, with a frequency of 1%. We report twelve patients, with single brain metastases and with a karnofsky performance scale score >60 at admission. No metastasis was seen during the uptake of iodine-131, even in the cases from differentiated thyroid carcinoma, suggesting absence of differentiation between primary and metastasic disease. The histopathology of thyroid carcinomas was anaplastic in five cases, differentiated in six, and medullary in one. Only in four patients, brain was the unique site of metastatic spread; in others, bones and lungs were also involved. All metastases were surgically removed, and all patients were treated with radiotherapy (45 Gy) in the postoperative course. The survival average was 19.8 months, and the quality of life was satisfactory in all patients. One patient remained alive till 5 years. Anaplastic histopathology and size of the primitive, and also bone involvement of thyroid disease were significant risk factors in our cases (p < 0.05). According to the literature, surgery is the best therapeutical choice. Alternative strategies in the management of brain metastasis, such as iodine-131 therapy, are discussed, paying particular attention to the relevant side effects.

Solitary follicular thyroid carcinoma of the skull base and its differentiation from ectopic adenoma--review, use of galectin-3 and report of a new case

With only four histologically proven cases in the literature, solitary skull base metastasis of thyroid carcinoma is extremely rare. Having treated another patient harboring a lesion with osseous destruction in the petroclival region and downward soft tissue extension we analyzed this case in conjunction with previous reports. In contrast to parenchymal brain metastasis that usually consists of the papillary type, histological examination revealed differentiated follicular tumors in all cases. All were located around the clivus. The radiographic picture resembled that of chordomas or chondrosarcomas. In the tissue obtained during thyroidectomy no evidence of primary malignancy was found in any of the cases according to standard histological criteria. In our case, a recently developed immunocytological marker - galectin-3 - was applied to differentiate between ectopic thyroid adenoma and carcinoma. The results were indicative of anaplastic growth. Tumor remnants responded well to postoperative 131I internal radiation and TSH suppression therapy. Distant metastasis of follicular thyroid carcinoma has to be considered in the differential diagnosis of destructive skull base lesions. Histological evaluation should include immunohistochemistry or clonal analysis to differentiate between adenomatous and carcinomatous growth and initiate effective radiotherapy early. Prognosis is by far not as poor as in brain metastases and appears to depend largely on location, size and histological appearance.

Thyroglobulin antibodies in differentiated thyroid cancer

A retrospective review of patients with differentiated thyroid cancer (DTC) who were seen between 1984 and 1996 at the Royal Marsden Hospital identified 40 patients with serum thyroglobulin antibodies (TgAb). These antibodies can interfere with the immunoradiometric assay for serum thyroglobulin (Tg) used at this hospital, with resulting underestimation of the Tg level. A review of the case notes was carried out to ascertain the clinical significance of TgAb. The median follow-up from diagnosis of DTC was 26 months (range 3-401). The median age at diagnosis of DTC was 50 years (range 13-83). Patients were grouped according to the TgAb titre (high titre: TgAb >1/100, n = 28; low titre TgAb <1/100, n = 12). Thirteen patients relapsed, 11 in the high titre group and two in the low titre group. Sites of recurrence were: neck (n = 9), lung (n = 5), bone (n = 4) and brain (n = 2). No patient in the high titre group showed an elevated Tg with recurrence. One patient in the low titre group showed a Tg response to recurrence. Overall, the Tg assay failed to detect 92% of recurrences. Eight patients in the high titre group developed TgAb, apparently in response to tumour progression. In a third patient in the low titre group, the TgAb also acted as a 'tumour marker'. Thus, overall TgAb acted as a tumour marker in nine of the 40 (22.5%) patients in whom it was detected, and in nine of the 470 (1.9%) patients on follow-up during this time period. The overall survival of the whole group was 69% at 10 years. For patients with papillary carcinoma (n = 34) overall survival was 78% at 10 years. Laboratories should report routinely the presence of TgAb, with a caution indicating the direction of possible error (which depends on the assay used). Clinicians should appreciate that Tg measurements are unreliable in the presence of TgAb and that the development of TgAb can indicate active tumour.