Variations in radioiodine ablation: decision-making after total thyroidectomy.

BACKGROUND: The role of radioiodine treatment following total thyroidectomy for differentiated thyroid cancer is changing. The last major revision of the American Thyroid Association (ATA) Management Guidelines for Patients with Thyroid Nodules and Differentiated Thyroid Cancer in 2015 changed treatment recommendations dramatically in comparison with the European Association of Nuclear Medicine (EANM) 2008 guidelines. We hypothesised that there is marked variability between the different treatment regimens used today. METHODS: We analysed decision-making in all Swiss hospitals offering radioiodine treatment to map current practice within the community and identify consensus and discrepancies. RESULTS AND CONCLUSION: We demonstrated that for low-risk DTC patients after thyroidectomy, some institutions offered only follow-up, while RIT with significant activities is recommended in others. For intermediate- and high-risk patients, radioiodine treatment is generally recommended. Dosing and treatment preparation (recombinant human thyroid stimulation hormone (rhTSH) vs. thyroid hormone withdrawal (THW)) vary significantly among centres.

Is there need for radioimmunotherapy? results of a phase I/II study in patients with indolent B-cell lymphomas using lutetium-177-DOTA-rituximab.

AIM: The aim of the study was to explore the clinical response to 177Lutetium-DOTA-rituximab (177Lu-D-R) and to determine the maximum tolerated dose (MTD) in the treatment of patients with relapsed follicular, mantle cell or other indolent lymphomas such as marginal zone lymphoma as well as to put these results into context with other therapy options for these patients. METHODS: Treatment consisted of cold rituximab (250 mg/m2) on day 1 and day 8 and 177Lu-DOTA-Rituximab on day 8. Reassessment was done at week 10. Thirty-one patients (males=17, females=14, median number of pretreatments: 3) were treated in seven cohorts. Escalation of injected activity was carried out in steps of 5 mCi/m². Dosimetry was performed in the first 20 patients. RESULTS: The MTD was found to be 45 mCi/m2. Thrombocytopenia and leukopenia were the dose-limiting toxicities. Significant anemia only occurred at dose level 7. We observed the nadir of platelets after a median of 36 days from treatment with 177Lu-D-R and a nadir of granulocytes after a median of 50 days from 177Lu-D-R treatment. Non-hematological toxicity was negligible. We observed clinical responses at all dose levels and for all lymphoma entities. Some of the responses were durable; the longest follow up in complete remission is currently over eight years. CONCLUSION: The MTD of 177Lu-DOTA-Rituximab was found to be 45 mCi/m². Non hematologic toxicity was negligible. Responses were seen in all lymphoma entities and at all dose levels tested. Further testing seems to be most promising mainly in follicular and marginal zone lymphoma in particular as the results compare well to other therapy options for these patients with regard to effectiveness, toxicity and discomfort for the patients.

Sentinel lymph node biopsy in primary breast cancer: trust the radiolabeled colloid method and avoid unnecessary procedures.

BACKGROUND: With regard to the sentinel lymph node (SLN) procedure in breast cancer, the study analyzed the impact of discrepancies between the number of clinically and histologically identified SLN, the impact of removing additional non-hot/non-blue but clinically conspicuous lymph nodes (LN), and whether the application of blue dye for mapping is necessary. METHODS: We analyzed 391 SLN procedures in which 928 SLN were removed. In all cases, radiolabeled colloid and blue dye were used for SLN mapping. RESULTS: In 60 cases (15.3%), additional LN that were not identified by the surgeon were found by histological examination. In 22 cases (5.3%), tissue which clinically resembled an SLN but was histologically connective tissue, was removed. In 76 cases (19.4%), 133 non-hot/non-blue but clinically conspicuous LN were removed. These additionally removed LN, however, did not alter the axillary staging. In 50.8% of the cases (n = 471), the SLN were marked only by radiolabeled colloid. In 27 cases (2.9%), the surgeon identified the LN through blue coloration alone; however, in all of the latter cases, these SLN were not deciding for axillary staging. CONCLUSION: The mapping agents may accumulate in axillary tissue and mimic the existence of an SLN. The radiolabeled colloid method alone gives excellent mapping results. The additional application of blue dye is avoidable. Exact surgical preparation enables removal of the SLN only and avoids removal of LN-containing adjacent tissue. The removal of further clinically identifiable enlarged non-hot LN should only be done if there is strong suspicion of metastatic involvement.

Targeted alpha-radionuclide therapy of functionally critically located gliomas with 213Bi-DOTA-[Thi8,Met(O2)11]-substance P: a pilot trial.

PURPOSE: Functionally critically located gliomas represent a challenging subgroup of intrinsic brain neoplasms. Standard therapeutic recommendations often cannot be applied, because radical treatment and preservation of neurological function are contrary goals. The successful targeting of gliomas with locally injected beta radiation-emitting (90)Y-DOTAGA-substance P has been shown previously. However, in critically located tumours, the mean tissue range of 5 mm of (90)Y may seriously damage adjacent brain areas. In contrast, the alpha radiation-emitting radionuclide (213)Bi with a mean tissue range of 81 microm may have a more favourable toxicity profile. Therefore, we evaluated locally injected (213)Bi-DOTA-substance P in patients with critically located gliomas as the primary therapeutic modality. METHODS: In a pilot study, we included five patients with critically located gliomas (WHO grades II-IV). After diagnosis by biopsy, (213)Bi-DOTA-substance P was locally injected, followed by serial SPECT/CT and MR imaging and blood sampling. Besides feasibility and toxicity, the functional outcome was evaluated. RESULTS: Targeted radiopeptide therapy using (213)Bi-DOTA-substance P was feasible and tolerated without additional neurological deficit. No local or systemic toxicity was observed. (213)Bi-DOTA-substance P showed high retention at the target site. MR imaging was suggestive of radiation-induced necrosis and demarcation of the tumours, which was validated by subsequent resection. CONCLUSION: This study provides proof of concept that targeted local radiotherapy using (213)Bi-DOTA-substance P is feasible and may represent an innovative and effective treatment for critically located gliomas. Primarily non-operable gliomas may become resectable with this treatment, thereby possibly improving the prognosis.

Outcome of treating advanced neuroendocrine tumours with radiolabelled somatostatin analogues.

OBJECTIVES: To evaluate the initial response and outcomes (quality of life and presence of side effects) in patients with advanced neuroendocrine tumours (NET) after treatment with radiolabelled somatostatin analogues: (90)Y-DOTATyr3- octreotide ((90)Y-DOTATOC) and (177)Lu-DOTA-Tyr3- octreotate ((177)Lu-DOTATATE). MATERIAL AND METHODS: The study included 5 patients with advanced NET referred to European centres for treatment with (90)Y-DOTATOC and (177)Lu-DOTATATE after lack of response to conventional treatment. The mean age was 45.6 years (29-68 years). Response to therapy was assessed according to: (1) RECIST criteria, as complete response, partial response, stable disease or disease progression, (2) post-treatment survival time and (3) quality of life, using the Karnofsky performance index. RESULTS: All patients survived for >20 months after treatment; mean survival time was 28 months. At the time of writing, three of the patients are alive after 20, 26 and 37 months. Partial response was observed in one patient, stable disease in three and disease progression in the fifth patient. A good-to-excellent post-treatment quality of life was observed in all patients. CONCLUSION: Therapy with radiolabelled somatostatin analogues showed promising results in patients with advanced NET, with a partial response or disease stabilisation in four of the five patients, who have enjoyed an extended survival period and an improved quality of life.

Outcome of treating advanced neuroendocrine tumours with radiolabelled somatostatin analogues

OBJECTIVES: To evaluate the initial response and outcomes (quality of life and presence of side effects) in patients with advanced neuroendocrine tumours (NET) after treatment with radiolabelled somatostatin analogues: (90)Y-DOTATyr3- octreotide ((90)Y-DOTATOC) and (177)Lu-DOTA-Tyr3- octreotate ((177)Lu-DOTATATE). MATERIAL AND METHODS: The study included 5 patients with advanced NET referred to European centres for treatment with (90)Y-DOTATOC and (177)Lu-DOTATATE after lack of response to conventional treatment. The mean age was 45.6 years (29-68 years). Response to therapy was assessed according to: (1) RECIST criteria, as complete response, partial response, stable disease or disease progression, (2) post-treatment survival time and (3) quality of life, using the Karnofsky performance index. RESULTS: All patients survived for >20 months after treatment; mean survival time was 28 months. At the time of writing, three of the patients are alive after 20, 26 and 37 months. Partial response was observed in one patient, stable disease in three and disease progression in the fifth patient. A good-to-excellent post-treatment quality of life was observed in all patients. CONCLUSION: Therapy with radiolabelled somatostatin analogues showed promising results in patients with advanced NET, with a partial response or disease stabilisation in four of the five patients, who have enjoyed an extended survival period and an improved quality of life (AU)

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Radiolabeled DOTATOC in patients with advanced paraganglioma and pheochromocytoma.

AIM: Paragangliomas and pheochromocytomas are rare tumors arising from chromaffin cells. Approximately 10% are malignant. Treatment options are limited in metastatic, surgically incurable situations. These tumors often express somatostatin receptors in high density. Therefore, treatment with the radiolabeled somatostatin analogue [DOTA-Tyr(3)]-octreotide (DOTATOC) is an option. We evaluated the effectiveness and toxicity of radiolabeled DOTATOC in patients with metastatic paraganglioma and pheochromocytoma. METHODS: Twenty-eight patients (16 female and 12 male) with surgically incurable paragangliomas and pheochromocytomas were included. Twenty-five patients were scheduled for treatment with a total of 200 mCi/m(2) body surface [(90)Y]DOTATOC and 3 for one cycle with 100 mCi/m(2) [(90)Y]DOTATOC followed by 2 cycles of 200 mCi [(177)Lu]DOTATOC. Restaging was performed 8-12 weeks after the last treatment cycle, followed by regular controls every 3 to 6 months. RESULTS: The treatment was well tolerated. At restaging we found 2 partial remissions, 5 minor responses; 13 stable disease, 2 mixed responses and 6 patients remained progressive. We found 1 thrombocytopenia grade I and 1 anemia grade I. No non-hematological toxicity, especially no kidney toxicity occurred. The follow-up ranged from 6 to 50 months (mean: 19+/-14.6 months). Time to progression ranged from 3 to >42 months. Ten responses, 9 stable diseases and one partial remission, are still ongoing. CONCLUSIONS: In these 28 patients, it was shown that radiolabeled DOTATOC can be effective in patients with somatostatin receptor positive paraganglioma. However, the therapy seems to be less effective than in gastroentero-pancreatic neuroendocrine tumors. Nevertheless, DOTATOC appears to be a treatment option for surgically incurable paragangliomas, because toxicity is very low and especially the fact that long lasting remissions could be achieved justifies the treatment. The final time to progression is not yet reached after a mean follow-up time of 19 months.

Molecular imaging of reduced renal uptake of radiolabelled [DOTA0,Tyr3]octreotate by the combination of lysine and Gelofusine in rats.

AIM: In peptide receptor radionuclide therapy (PRRT) using radiolabelled somatostatin analogues, kidney uptake of radiolabelled compound is the major dose-limiting factor. We studied the effects of Gelofusine (20 mg) and lysine (100 mg) and the combination of both after injection of therapeutic doses of radiolabelled [DOTA0,Tyr3]octreotate (60 MBq 111In or 555 MBq 177Lu labelled to 15 microg peptide) in male Lewis rats. METHODS: Kidney uptake was measured by single photon emission computed tomography (SPECT) scans with a four-headed multi-pinhole camera (NanoSPECT) at 24 h, 5 and 7 days p. i. and was quantified by volume of interest analysis. For validation the activity concentration in the dissected kidneys was also determined ex vivo using a gamma counter and a dose calibrator. RESULTS: Gelofusine and lysine both reduced kidney uptake of [177Lu-DOTA0,Tyr3]octreotate significantly by about 40% at all time points. The combination of Gelofusine and lysine resulted in a 62% inhibition of kidney uptake (p < 0.01 vs. lysine alone). A weak but significant dose-response relationship for Gelofusine, but not for lysine, was found. In a study with [111In-DOTA0,Tyr3]octreotate, conclusions drawn from NanoSPECT data were confirmed by biodistribution data. CONCLUSIONS: We conclude that rat kidney uptake of radiolabelled somatostatin analogues can be monitored for a longer period in the same animal using animal SPECT. Gelofusine and lysine had equal potential to reduce kidney uptake of therapeutic doses of [177Lu-DOTA0,Tyr3]octreotate. The combination of these compounds caused a significantly larger reduction than lysine or Gelofusine alone and may therefore offer new possibilities in PRRT. The NanoSPECT data were validated by standard biodistribution experiments.

Up-regulation of somatostatin receptor density on rat CA20948 tumors escaped from low dose [177Lu-DOTA0,Tyr3]octreotate therapy.

AIM: Peptide receptor radionuclide therapy using the somatostatin analogue [(177)Lu-DOTA(0),Tyr(3)]octreotate is a convincing treatment modality for metastasized neuroendocrine tumors. Therapeutic doses are administered in 4 cycles with 6-10 week intervals. A high somatostatin receptor density on tumor cells is a prerequisite at every administration to enable effective therapy. In this study, the density of the somatostatin receptor subtype 2 (sst2) was investigated in the rat CA20948 pancreatic tumor model after low dose [(177)Lu-DOTA(0), Tyr(3)]octreotate administration resulting in approximately 20 Gy tumor radiation absorbed dose, whereas 60 Gy is needed to induce complete tumor regression in these and the majority of tumors. METHODS: Sixteen days after inoculation of the CA20948 tumor, male Lewis rats were injected with 185 MBq [(177)Lu-DOTA(0),Tyr(3)]octreotate to initiate a decline in tumor size. Approximately 40 days after injection, tumors re-grew progressively after initial response. Quantification of sst2 expression was performed using in vitro autoradiography on frozen sections of three groups: control (not-treated) tumors, tumors in regression and tumors in re-growth. Histology and proliferation were determined using HE- and anti-Ki-67-staining. RESULTS: The sst2 expression on CA20948 tumor cells decreased significantly after therapy to 5% of control level. However, tumors escaping from therapy showed an up-regulated sst2 level of 2-5 times higher sst2 density compared to control tumors. CONCLUSION: After a suboptimal therapeutic dose of [(177)Lu-DOTA(0),Tyr(3)]octreotate, escape of tumors is likely to occur. Since these cells show an up-regulated sst2 receptor density, a next therapeutic administration of radiolabelled sst2 analogue can be expected to be highly effective.

In vivo radionuclide uptake quantification using a multi-pinhole SPECT system to predict renal function in small animals.

PURPOSE: In vivo quantification of radiopharmaceuticals has great potential as a tool in developing new drugs. We investigated the accuracy of in vivo quantification with multi-pinhole single-photon emission computed tomography (SPECT) in rats. METHODS: Fifteen male Lewis rats with different stages of renal dysfunction were injected with 50 MBq 99mTc-dimercaptosuccinic acid. Four to six hours after injection, SPECT of the kidneys was acquired with a new four-headed multi-pinhole collimator camera. Immediately after imaging the rats were sacrificed and the kidneys were counted in a gamma-counter to determine the absorbed activity. SPECT data were reconstructed iteratively and regions of interest (ROIs) were drawn manually. The absolute activity in the ROIs was determined. RESULTS: Uptake values ranging from 0.71% to 21.87% of the injected activity were measured. A very strong linear correlation was found between the determined activity in vivo and ex vivo (r2=0.946; slope m=1.059). CONCLUSION: Quantification in vivo using this multi-pinhole SPECT system is highly accurate.

A comparison of (111)In-DOTATOC and (111)In-DOTATATE: biodistribution and dosimetry in the same patients with metastatic neuroendocrine tumours.

[Yttrium-90-DOTA-Tyr(3)]-octreotide (DOTATOC) and [(177)Lu-DOTA-Tyr(3)-Thr(8)]-octreotide (DOTATATE) are used for peptide receptor-mediated radionuclide therapy (PRMRT) in neuroendocrine tumours. No human data comparing these two compounds are available so far. We used (111)In as a surrogate for (90)Y and (177)Lu and examined whether one of the (111)In-labelled peptides had a more favourable biodistribution in patients with neuroendocrine tumours. Special emphasis was given to kidney uptake and tumour-to-kidney ratio since kidney toxicity is usually the dose-limiting factor. Five patients with metastatic neuroendocrine tumours were injected with 222 MBq (111)In-DOTATOC and (111)In-DOTATATE within 2 weeks. Up to 48 h after injection, whole-body scans were performed and blood and urine samples were collected. The mean absorbed dose was calculated for tumours, kidney, liver, spleen and bone marrow. In all cases (111)In-DOTATATE showed a higher uptake (%IA) in kidney and liver. The amount of (111)In-DOTATOC excreted into the urine was significantly higher than for (111)In-DOTATATE. The mean absorbed dose to the red marrow was nearly identical. (111)In-DOTATOC showed a higher tumour-to-kidney absorbed dose ratio in seven of nine evaluated tumours. The variability of the tumour-to-kidney ratio was high and the significance level in favour of (111)In-DOTATOC was P=0.065. In five patients the pharmacokinetics of (111)In-DOTATOC and (111)In-DOTATATE was found to be comparable. The two peptides appear to be nearly equivalent for PRMRT in neuroendocrine tumours, with minor advantages for (111)In/(90)Y-DOTATOC; on this basis, we shall continue to use (90)Y-DOTATOC for PRMRT in patients with metastatic neuroendocrine tumours.