Stereotactic radiotherapy is a useful treatment option for patients with medullary thyroid cancer.

The role of radiotherapy in advanced medullary thyroid carcinoma (MTC) is confined to patients in whom surgical treatment or the administration of tyrosine kinase inhibitors are not possible or contraindicated. High fractionated radiation doses during radiosurgery or fractionated stereotactic radiotherapy are applied to reduce cancer-related symptoms and stabilize irradiated lesions. This study aimed to retrospectively evaluate the therapeutic effect of stereotactic radiotherapy in MTC patients. MATERIAL AND METHODS: The study group involved 11 MTC patients, treated due to 16 cancer lesions, mainly bone metastases (10 lesions), lymph node (2 lesions) metastases, or liver metastases (2 lesions), one primary thyroid tumor, and one MTC recurrence in the thyroid bed. The fractionated and total radiation doses ranged between 5 and 12 Gy and 8-44 Gy, respectively. Six lesions were treated with a single radiation fraction, three lesions with 2 fractions, another 6 lesions with 3 fractions, whereas the remaining one metastatic lesion with 9 fractions of stereotactic radiosurgery. RESULTS: The beneficial effect of stereotactic radiosurgery was obtained in all treated lesions. None of treated lesions progressed in the further disease course. Fourteen lesions were stable (87.5 %), including eight lesions showing progression before radiosurgery (good response). Disease control was obtained in all soft-tissue metastases. Regarding bone metastases, partial regression was achieved in 20 % lesions, whereas in 30 % lesions progressive before radiotherapy, the treatment led to disease stabilization. CONCLUSIONS: Our data pointed to the effectiveness of high-dose fractionated radiotherapy in MTC. However, an observation of a larger group of patients is required to confirm it.

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.

MR spectroscopic evaluation of brain tissue damage after treatment for pediatric brain tumors.

PURPOSE: The aim of this study was to evaluate the metabolic profile of uninvolved brain tissue after treatment for pediatric brain tumors. MATERIAL: A group of 24 patients aged 4-18 years was analyzed after combined treatment for brain tumors. In this group, there were nine medulloblastomas, seven low-grade gliomas, three high-grade gliomas, two ependymomas and three children with conservatively treated diffuse brainstem gliomas. METHODS: Short echo-time (TE = 30 ms) point-resolved spectra were acquired using a 2 T clinical scanner (Elscint Prestige). The ratios of signal intensities for N-acetylaspartate (NAA), choline (Cho), myo-inositol (mI), lactate (Lac), and lipids (Lip) were calculated using the creatine (Cr) signal as an internal reference. The spectra were acquired both from the tumor bed and from contralateral uninvolved brain tissue; only control spectra were analyzed. The first examination was made between the third and sixth month after therapy (24 spectra), the second examination occurred 8-12 months after treatment (15 spectra available), and the third was performed approximately 18 months after completion of therapy (eight spectra available). The results were compared using the t-test for dependent samples. RESULTS: At all time points, the metabolite ratios showed alterations indicating brain tissue damage. The most important were the decrease of NAA/Cr and increase of Lac/Cr and Lip/Cr ratios. The mean NAA/Cr values were 0.91, 0.91, and 0.86, respectively, for the three examinations, while the Lac/Cr and Lip/Cr values were 1.66, 2.11, 1.19 and 12.24, 12.05, 5.69, respectively. Interestingly, in children with supratentorial tumors, a significant increase in NAA/Cr value was observed (from 0.82 to 1.11 in the first and second examinations, respectively; p = 0.0487), which may be indicative of neuronal function recovery. CONCLUSIONS: MRS examinations of uninvolved brain tissue indicate long-lasting metabolic disturbances. However, the NAA/Cr ratio increase may be a sign of at least partial recovery of metabolic function of the brain.

The incidence of imaging abnormalities after stereotactic radiosurgery for cerebral arteriovenous and cavernous malformations.

OBJECTIVE: The aim of the study was to evaluate the incidence of postirradiation imaging changes after stereotactic radiosurgery for arteriovenous malformations (AVM) and cerebral cavernous malformations (CCM). MATERIAL AND METHODS: A group of 85 patients treated for arteriovenous malformations (62 patients, 73%) and cavernomas (23 patients, 27%) between October 2001 and December 2005 was analyzed. All patients were treated with stereotactic radiosurgery with doses ranging from 8-28 Gy. After the irradiation, magnetic resonance imaging (MRI) or computed tomography (CT) was performed at 6 to 12-month intervals to assess the effects of the treatment. The mean follow-up time for the whole group was 27.3 months; AVM group -- 26 months; CCM group -- 30.9 months. All the imaging data were carefully reviewed to identify the radiological symptoms of postradiosurgical damage. T2 or FLAIR hyperintensity, T1-hypointensity and contrast enhancement on MRI and the presence of hypodense areas and contrast enhancement on CT examinations were assessed. RESULTS: Imaging abnormalities were found in 28 (33%) patients. The symptoms of postradiosurgical damage were observed in 21 (33.9%) patients in the AVM group and 7 (30.4%) patients in the CCM group. Radiological symptoms of radiation necrosis associated with neurological deterioration were identified in two patients with cavernomas, while no radiation necrosis was found in the AVM group. Patients in whom radiological signs of focal brain edema or gliosis existed were asymptomatic. CONCLUSIONS: Radiological symptoms of postradiosurgical damage affected about one third of the irradiated patients, typically without any clinical manifestations. Patients irradiated for CCMs seem to be more prone to develop symptomatic postradiosurgical necrosis; this observation, however, requires further investigation.

Evaluation of the late effects of CNS prophylactic treatment in childhood acute lymphoblastic leukemia (ALL) using magnetic resonance spectroscopy.

PURPOSE: The aim of the study was to evaluate the late changes seen in Magnetic Resonance Spectroscopy (MRS) of the brain in Acute Lymphoblastic Leukemia (ALL) survivors to assess neurotoxicity following prophylactic treatment with cranial irradiation (CRT) and/or intrathecal (ITMTX) and systemic MTX. MATERIALS AND METHODS: The study was performed on two groups of patients. The first group consisted of 30 children who received CRT and ITMTX, and the second group was comprised of 15 children treated only with ITMTX. All patients were ALL survivors treated between 1994 and 2002. Radiotherapy was performed using two opposite fields for a total dose of 18 Gy. The children were examined from 6 to 12 years after treatment. All children underwent a physical and neurological examination and MRI/MRS studies. (1)H-MR spectra were acquired from frontal and occipital regions of the brain. Mean values and standard deviations were calculated for following metabolite ratios: NAA/Cr, Cho/Cr, Cho/NAA, and mI/Cr. RESULTS: Three of the 45 children (11%) presented with white matter changes upon MRI examination. All children with MRI abnormalities received CRT. In 13 (31%) children, changes in (1)H-MRS metabolite ratios were seen. We observed decreased NAA/Cr and Cho/Cr ratios. MR spectroscopy showed a significant reduction (P < .05) of the mean NAA/Cr ratio in children given CRT. CONCLUSION: MRS is a sensitive detector of late metabolic changes after prophylactic treatment for ALL in childhood. It is able to detect metabolic effects of treatment in patients even when no morphologic changes are visible upon MRI.