A comparison of forward and inverse treatment planning for intensity-modulated radiotherapy of head and neck cancer.

BACKGROUND AND PURPOSE: To compare intensity-modulated treatment plans of patients with head and neck cancer generated by forward and inverse planning. MATERIALS AND METHODS: Ten intensity-modulated treatment plans, planned and treated with a step&shoot technique using a forward planning approach, were retrospectively re-planned with an inverse planning algorithm. For this purpose, two strategies were applied. First, inverse planning was performed with the same beam directions as forward planning. In addition, nine equidistant, coplanar incidences were used. The main objective of the optimisation process was the sparing of the parotid glands beside an adequate treatment of the planning target volume (PTV). Inverse planning was performed both with pencil beam and Monte Carlo dose computation to investigate the influence of dose computation on the result of the optimisation. RESULTS: In most cases, both inverse planning strategies managed to improve the treatment plans distinctly due to a better target coverage, a better sparing of the parotid glands or both. A reduction of the mean dose by 3-11Gy for at least one of the parotid glands could be achieved for most of the patients. For three patients, inverse planning allowed to spare a parotid gland that had to be sacrificed by forward planning. Inverse planning increased the number of segments compared to forward planning by a factor of about 3; from 9-15 to 27-46. No significant differences for PTV and parotid glands between both inverse planning approaches were found. Also, the use of Monte Carlo instead of pencil beam dose computation did not influence the results significantly. CONCLUSION: The results demonstrate the potential of inverse planning to improve intensity-modulated treatment plans for head and neck cases compared to forward planning while retaining clinical utility in terms of treatment time and quality assurance.     

Fibrosarcoma in Children: A Rare Tumour with Long-Term Survival even with Advanced Disease A Report of 3 Cases

Fibrosarcoma is a rare tumour in children. The potential of malignancy has been questioned. We present three cases of fibrosarcoma in children. The follow-up periods range from 10 to 37 years. The first patient had pulmonary metastases at the time of diagnosis in 1958. The primary tumour in fossa ischio-rectalis was resected in 1960. Lung metastases were resected in 1960 and 1989. Radiotherapy was given in 1992. He is still alive with metastases 37 years after the first manifestation of disease. The second patient had a primary tumour and several local recurrences in the mandible. He is alive without evidence of disease 4 years after resection of pulmonary metastases and 21 years after resection of the primary tumour. The third patient has no signs of recurrence or metastasic spread 10 years after a wide excision of subcutanous tumours of the left upper arm. The cases demonstrate a special tumour-entity of low-grade malignancy, which show a good prognosis and a wide spectrum of biological behaviour.     

Metabolism and disposition of imatinib mesylate in healthy volunteers.

Imatinib mesylate (GLEEVEC, GLIVEC, formerly STI571) has demonstrated unprecedented efficacy as first-line therapy for treatment for all phases of chronic myelogenous leukemia and metastatic and unresectable malignant gastrointestinal stromal tumors. Disposition and biotransformation of imatinib were studied in four male healthy volunteers after a single oral dose of 239 mg of (14)C-labeled imatinib mesylate. Biological fluids were analyzed for total radioactivity, imatinib, and its main metabolite CGP74588. Metabolite patterns were determined by radio-high-performance liquid chromatography with off-line microplate solid scintillation counting and characterized by liquid chromatography-mass spectrometry. Imatinib treatment was well tolerated without serious adverse events. Absorption was rapid (t(max) 1-2 h) and complete with imatinib as the major radioactive compound in plasma. Maximum plasma concentrations were 0.921 +/- 0.095 mug/ml (mean +/- S.D., n = 4) for imatinib and 0.115 +/- 0.026 mug/ml for the pharmacologically active N-desmethyl metabolite (CGP74588). Mean plasma terminal elimination half-lives were 13.5 +/- 0.9 h for imatinib, 20.6 +/- 1.7 h for CGP74588, and 57.3 +/- 12.5 h for (14)C radioactivity. Imatinib was predominantly cleared through oxidative metabolism. Approximately 65 and 9% of total systemic exposure [AUC(0-24 h) (area under the concentration time curve) of radioactivity] corresponded to imatinib and CGP74588, respectively. The remaining proportion corresponded mainly to oxidized derivatives of imatinib and CGP74588. Imatinib and its metabolites were excreted predominantly via the biliary-fecal route. Excretion of radioactivity was slow with a mean radiocarbon recovery of 80% within 7 days (67% in feces, 13% in urine). Approximately 28 and 13% of the dose in the excreta corresponded to imatinib and CGP74588, respectively.     

Expression, localization, and function of the carnitine transporter octn2 (slc22a5) in human placenta.

L-carnitine is assumed to play an important role in fetal development, and there is evidence that carnitine is transported across the placenta. The protein involved in this transfer, however, has not been identified on a molecular level. We therefore characterized localization and function of the carnitine transporter OCTN2 in human placenta. Significant expression of OCTN2 mRNA was detected in human placenta applying real-time polymerase chain reaction technology. Confocal immunofluorescence microscopy using an antibody directed against the carboxy terminus of OCTN2 protein revealed that it is predominantly expressed in the apical membrane of syncytiotrophoblasts. This was confirmed by the costaining of organic anion-transporting polypeptide B and MRP2, which are known to be expressed mainly in the basal and apical syncytiotrophoblasts membrane, respectively. To further support this finding, we performed transport studies using basal and apical placenta membrane vesicles. We could demonstrate that the carnitine uptake into the apical vesicles was about eight times higher compared with the basal ones. Moreover, this uptake was sodium- and pH-dependent with an apparent K(m) value of 21 muM and inhibited by verapamil, which is in line with published data for recombinant OCTN2. Finally, experiments using trophoblasts in cell culture revealed that expression of OCTN2 paralleled human choriogonadotropin production and thus is modulated by cellular differentiation. In summary, we show expression and function of OCTN2 in human placenta. Moreover, several lines of evidence indicate that OCTN2 is localized in the apical membrane of syncytiotrophoblasts, thereby suggesting a major role in the uptake of carnitine during fetal development.     

Increased fluorine-18 2-fluoro-2-deoxy-D-glucose (FDG) uptake in childhood CNS tumors is correlated with malignancy grade: a study with FDG positron emission tomography/magnetic resonance imaging coregistration and image fusion.

PURPOSE Positron emission tomography (PET) has been used in grading of CNS tumors in adults, whereas studies of children have been limited. PATIENTS AND METHODS Nineteen boys and 19 girls (median age, 8 years) with primary CNS tumors were studied prospectively by fluorine-18 2-fluoro-2-deoxy-D-glucose (FDG) PET with (n = 16) or without (n = 22) H(2)(15)O-PET before therapy. Image processing included coregistration to magnetic resonance imaging (MRI) in all patients. The FDG uptake in tumors was semiquantitatively calculated by a region-of-interest-based tumor hotspot/brain index. Eight tumors without histologic confirmation were classified as WHO grade 1 based on location, MRI, and clinical course (22 to 42 months). Results Four grade 4 tumors had a mean index of 4.27 +/- 0.5, four grade 3 tumors had a mean index of 2.47 +/- 1.07, 10 grade 2 tumors had a mean index of 1.34 +/- 0.73, and eight of 12 grade 1 tumors had a mean index of -0.31 +/- 0.59. Eight patients with no histologic confirmation had a mean index of 1.04. For these 34 tumors, FDG uptake was positively correlated with malignancy grading (n = 34; r = 0.72; P < .01), as for the 26 histologically classified tumors (n = 26; r = 0.89; P < .01). The choroid plexus papilloma (n = 1) and the pilocytic astrocytomas (n = 3) had a mean index of 3.26 (n = 38; r = 0.57; P < .01). H(2)(15)O-uptake showed no correlation with malignancy. Digitally performed PET/MRI coregistration increased information on tumor characterization in 90% of cases. CONCLUSION FDG PET of the brain with MRI coregistration can be used to obtain a more specific diagnosis with respect to malignancy grading. Improved PET/MRI imaging of the benign hypermetabolic tumors is needed to optimize clinical use.     

Treatment of refractory Hodgkin's lymphoma patients with an iodine-131-labeled murine anti-CD30 monoclonal antibody.

PURPOSE: Hodgkin's lymphoma (HL) has been demonstrated to be a good target for immunotherapy since lymphocyte activation markers such as CD30 are expressed in high numbers on the malignant cells. Thus, we developed a new radioimmunoconjugate consisting of the murine anti-CD30 monoclonal antibody (MAb) Ki-4 labeled with iodine-131 ((131)I). PATIENTS AND METHODS: The biodistribution of (131)I-Ki-4 was assessed via dosimetry after preinfusion of 5 mg native Ki-4 followed by 250 to 300 MBq (131)I-labeled Ki-4. Whole-body scintigraphy was performed 1 hour, 24 hours, 48 hours, 72 hours, and 6 days after the infusion. Dosimetry was calculated using the programs NucliDose ICON-IDL (version 5.0.2; Siemens, Erlanger, Germany) and MIRDOSE (version 3.1; Oak Ridge National Laboratories; Oak Ridge, TN). The therapeutic dose was given on day 8 after preinfusion of unlabeled Ki-4. RESULTS: We treated 22 patients with relapsed or refractory CD30-positive HL. Preinfusion of 5 mg native Ki-4 was sufficient to bind the soluble CD30. Imaging demonstrated localization of involved areas measuring 5 cm in diameter or more in four patients and 2.5 cm in one patient. Patients received total body doses of 0.035 Gy to 0.99 Gy. Acute toxicity was mild with grade 1 fatigue in 19 of 22 assessable patients. Seven patients experienced grade 4 degrees hematotoxicity 4 to 8 weeks after treatment. Response included one complete remission, five partial remissions, and three minor responses. CONCLUSION: Treatment with (131)I-Ki-4 is effective but can be associated with severe hematotoxicity.