Phosphorus-32 interstitial radiotherapy for recurrent craniopharyngioma: Expressions of vascular endothelial growth factor and its receptor-2 and imaging features of tumors are associated with tumor radiosensitivity

To investigate the relationship of the expression of vascular endothelial growth factor (VEGF)/vascular endothelial growth factor receptor-2 (VEGFR-2) and imaging features with the therapeutic efficacy of Phosphorus-32 colloid interstitial radiotherapy in recurrent craniopharyngioma.Thirty-two patients with recurrent craniopharyngioma underwent phosphorus-32 colloid interstitial radiotherapy. The tumor imaging features were classified into 4 types according to the thickness of the cyst wall and signals of the cyst contents as shown by computed tomography (CT) and magnetic resonance imaging (MRI) images. Protein expressions of VEGF and VEGFR-2 in craniopharyngioma tissues were evaluated with immunohistochemistry before radiotherapy. The tumor radiosensitivity was determined at 12 months after the interstitial radiotherapy.VEGF mainly expressed in the tumor cytoplasm, and VEGFR-2 expressed either in vascular endothelial cells or in tumor endothelial cells. VEGF/VEGFR-2 expressions varied significantly in cases sensitive or insensitive to the radiotherapy (VEGF: P = .028; VEGFR-2: P = .017). Tumor imaging features were associated with the therapeutic efficacy of interstitial radiotherapy (P = .000). VEGF expression had no association with the imaging features of tumors (P = .226), but VEGFR-2 expression was associated with the imaging features of tumors (P = .008).Our results confirmed the association among imaging features, VEGFR-2 expressions, and tumor radiosensitivity in craniopharyngiomas. Imaging features and VEGFR-2 expressions may add useful data to the radiosensitive assessment of craniopharyngiomas.

Intracystic bleomycin for cystic craniopharyngiomas in children

BACKGROUND

Craniopharyngiomas are the most common benign histological tumours to involve the hypothalamo-pituitary region in childhood. Cystic craniopharyngiomas account for more than 90% of the tumours. The optimal treatment of cystic craniopharyngioma remains controversial. Radical resection is the treatment of choice in patients with favourable tumour localisation. When the tumour localisation is unfavourable, a gross-total or partial resection followed by radiotherapy is the main treatment option in adults. However, it presents a risk of morbidity, especially for children. Intracystic bleomycin has been utilised potentially to delay the use of radiotherapy or radical resection, to decrease morbidity. This review is the second update of a previously published Cochrane review.

OBJECTIVES

To assess the benefits and harmful effects of intracystic bleomycin in children from birth to 18 years with cystic craniopharyngioma when compared to placebo (no treatment), surgical treatment (with or without adjuvant radiotherapy) or other intracystic treatments.

SEARCH METHODS

We searched the electronic databases CENTRAL (2016, Issue 1), MEDLINE/PubMed (from 1966 to February 2016) and EMBASE/Ovid (from 1980 to February 2016) with pre-specified terms. In addition, we searched the reference lists of relevant articles and reviews, conference proceedings (International Society for Paediatric Oncology 2005-2015) and ongoing trial databases (Register of the National Institute of Health and International Standard Randomised Controlled Trial Number (ISRCTN) register) in February 2016.

SELECTION CRITERIA

Randomised controlled trials (RCTs), quasi-randomised trials or controlled clinical trials (CCTs) comparing intracystic bleomycin and other treatments for cystic craniopharyngiomas in children (from birth to 18 years).

DATA COLLECTION AND ANALYSIS

Two review authors independently performed the study selection, data extraction and 'Risk of bias' assessment. We used risk ratio (RR) for binary data and mean difference (MD) for continuous data. If one of the treatment groups experienced no events and there was only one study available for the outcome, we used the Fischer's exact test. We performed analysis according to the guidelines in the Cochrane Handbook for Systematic reviews of Interventions.

MAIN RESULTS

We could not identify any studies in which the only difference between the treatment groups was the use of intracystic bleomycin. We did identify a RCT comparing intracystic bleomycin with intracystic phosphorus(32) ((32)P) (seven children). In this update we identified no additional studies. The included study had a high risk of bias. Survival could not be evaluated. There was no clear evidence of a difference between the treatment groups in cyst reduction (MD -0.15, 95% confidence interval (CI) -0.69 to 0.39, P value = 0.59, very low quality of evidence), neurological status (Fisher's exact P value = 0.429, very low quality of evidence), third nerve paralysis (Fischer's exact P value = 1.00, very low quality of evidence), fever (RR 2.92, 95% CI 0.73 to 11.70, P value = 0.13, very low quality of evidence) or total adverse effects (RR 1.75, 95% CI 0.68 to 4.53, P value = 0.25, very low quality of evidence). There was a significant difference in favour of the (32)P group for the occurrence of headache and vomiting (Fischer's exact P value = 0.029, very low quality of evidence for both outcomes).

AUTHORS' CONCLUSIONS

Since we identified no RCTs, quasi-randomised trials or CCTs of the treatment of cystic craniopharyngiomas in children in which only the use of intracystic bleomycin differed between the treatment groups, no definitive conclusions could be made about the effects of intracystic bleomycin in these patients. Only one low-power RCT comparing intracystic bleomycin with intracystic (32)P treatment was available, but no definitive conclusions can be made about the effectiveness of these agents in children with cystic craniopharyngiomas. Based on the currently available evidence, we are not able to give recommendations for the use of intracystic bleomycin in the treatment of cystic craniopharyngiomas in children. High-quality RCTs are needed.

Phosphorus-32, a clinically available drug, inhibits cancer growth by inducing DNA double-strand breakage

Radioisotopes that emit electrons (beta particles), such as radioiodine, can effectively kill target cells, including cancer cells. Aqueous ³²P[PO₄] is a pure beta-emitter that has been used for several decades to treat non-malignant human myeloproliferative diseases. ³²P[PO₄] was directly compared to a more powerful pure beta-emitter, the clinically important ⁹⁰Y isotope. In vitro, ³²P[PO₄] was more effective at killing cells than was the more powerful isotope ⁹⁰Y (P ≤ 0.001) and also caused substantially more double-stranded DNA breaks than did ⁹⁰Y. In vivo, a single low-dose intravenous dose of aqueous elemental ³²P significantly inhibited tumor growth in the syngeneic murine cancer model (P ≤ 0.001). This effect is exerted by direct incorporation into nascent DNA chains, resulting in double-stranded breakage, a unique mechanism not duplicatable by other, more powerful electron-emitting radioisotopes. ³²P[PO₄] should be considered for human clinical trials as a potential novel anti-cancer drug.

Intracystic bleomycin for cystic craniopharyngiomas in children

BACKGROUND

Craniopharyngiomas are the commonest benign histological tumours to involve the hypothalamo-pituitary region in childhood. Cystic craniopharyngiomas comprise more than 90% of the tumours. The optimal treatment of cystic craniopharyngioma remains controversial. Radical resection is the treatment of choice in patients with favourable tumour localisation. When the tumour localisation is unfavourable, a gross-total or partial resection followed by radiotherapy is the main treatment option in adults. However, it presents a risk of morbidity, especially for children. Intracystic bleomycin has been utilised potentially to delay the use of radiotherapy or radical resection, to decrease morbidity. This review is an update of a previously published Cochrane review.

OBJECTIVES

To assess the benefits and harmful effects of intracystic bleomycin in children from birth to 18 years with cystic craniopharyngioma when compared to placebo (no treatment), surgical treatment (with or without adjuvant radiotherapy) or some other intracyctic treatments.

SEARCH METHODS

We searched the electronic databases CENTRAL (2014, Issue 1), MEDLINE/PubMed (from 1966 to March 2014) and EMBASE/Ovid (from 1980 to March 2014) with pre-specified terms. In addition, we searched the reference lists of relevant articles and reviews, conference proceedings (International Society for Paediatric Oncology 2005-2013) and ongoing trial databases (Register of the National Institute of Health and International Standard Randomised Controlled Trial Number (ISRCTN) register) in May 2014.

SELECTION CRITERIA

Randomised controlled trials (RCTs), quasi-randomised trials or controlled clinical trials (CCTs) comparing intracystic bleomycin and other treatments for cystic craniopharyngiomas in children (from birth to 18 years).

DATA COLLECTION AND ANALYSIS

Two review authors independently performed the data extraction and 'Risk of bias' assessment. We used risk ratio (RR) for binary data and mean difference (MD) for continuous data. We planned that if one of the treatment groups experienced no events and there was only one study available for the outcome, we would use the Fischer's exact test.

MAIN RESULTS

We could not identify any studies in which the only difference between the treatment groups was the use of intracystic bleomycin. We did identify a RCT comparing intracystic bleomycin with intracystic phosphorus(32) ((32)P) (n = 7 children). The trial had a high risk of bias. Survival could not be evaluated. There was no evidence of a significant difference between the treatment groups in cyst reduction (MD -0.15, 95% confidence interval (CI) -0.69 to 0.39, P value = 0.59), neurological status (Fisher's exact P value = 0.429), 3rd nerve paralysis (Fischer's exact P value = 1.00), fever (RR 2.92, 95% CI 0.73 to 11.70, P value = 0.13) or total adverse effects (RR 1.75, 95% CI 0.68 to 4.53, P value = 0.25). There was a significant difference in favour of the (32)P group for the occurrence of headache and vomiting (Fischer's exact P value = 0.029 for both outcomes).

AUTHORS' CONCLUSIONS

Since we identified no RCTs, quasi-randomised trials or CCTs of the treatment of cystic craniopharyngiomas in children in which only the use of intracystic bleomycin differed between the treatment groups, no definitive conclusions could be made about the effects of intracystic bleomycin in these patients. Only one low-power RCT comparing intracystic bleomycin with intracystic (32)P treatment was available, but no definitive conclusions can be made about the effectiveness of these agents in children with cystic craniopharyngiomas. Based on the currently available evidence, we are not able to give recommendations for the use of intracystic bleomycin in the treatment of cystic craniopharyngiomas in children. High-quality RCTs are needed.

[Efficacy of CO2 laser combined with 32P-patch contact brachyradiotherapy for the treatment of keloids]

OBJECTIVE

To investigate the efficacy of CO2 laser combined with 32P-patch contact brachyradiotherapy for the treatment of keloids.

METHODS

From 2001 to 2006, 121 cases with 151 keloids, which reoccurred after treatment with more than 2 methods, underwent continuous CO2 laser treatment to remove the hypertrophic scar tissue, following by ultra-pulse CO2 laser to treat the fresh granulation tissue. After wound healing, 32P-patch contact brachyradiotherapy was used for the lesion, 0.5-1 MBQ/cm2 for 72-96 hours, every 1-2 months. 2-3 treatment were applied.

RESULTS

Among the 151 keloids, good result was achieved in 111 keloids, and effective result in 40 keloids. Adverse effect included hyperpigmentation in 21 lesions and hypopigmentation in 32 lesions. The patients were followed up for 2-6 years without relapse.

CONCLUSION

CO2 laser combined with 32P-patch contact brachyradiotherapy is an effective and safe method for the treatment of recalcitrant keloids.

Clinical dosimetry in the treatment of bone tumors: old and new agents

Treatment of multisite, sclerotic bone metastases is successfully performed by radionuclide therapy. Pain palliation is the most common aim for the treatment. Two radiopharmaceuticals are currently approved by the European Medicines Agency ((153)Sm-EDTMP and (89)Sr-Cl₂) whilst other radiopharmaceuticals are at different stages of development, or are approved in some European countries ((186)Re-HEDP, (117)Snm-DTPA and (223)Ra-Cl₂). The tissues at risk for the treatment are bone marrow and normal bone. A review of the methods applied for dosimetry for these tissues and for tumours is performed, including the calculation of S values (the absorbed dose per decay) and optimal procedures on how to obtain biodistribution data for each radiopharmaceutical. The dosimetry data can be used to individualise and further improve the treatment for each patient. Dosimetry for radionuclide therapy of bone metastases is feasible and can be performed in a routine clinical practice.

[A 32P application device for the treatment of condyloma acuminatum in the rectum]

OBJECTIVE

To investigate the use of a 32P application device (AD) in the treatment of condyloma acuminatum (CA) in the rectum, and to compare its clinical effect with that of the microwave therapy.

METHODS

This study included 107 cases of CA in the rectum, 99 males and 8 females, aged 21-58 (33.6 +/- 9.4) years. Forty-six of the patients (the AD group) were treated with a self-made 32P application device, which, as a tube-shaped carrier of radionuclide 32P colloid, was fixed in the rectum at the diseased part for medication at 4.9-8.2 Gy for 3-5 hours once and 1-2 times a week. The other 61 (the microwave group) were treated by microwave burning under local anesthesia. Both groups of patients were followed up for over 3 months for comparison of the therapeutic results and observation of the stability and reliability of the 32P application device.

RESULTS

The rates of cure, reoccurrence and adverse reaction were 84, 8%, 13.0% and 8.7% in the AD group, compared with 40.3%, 55.7% and 75.4% in the microwave group, with statistically significant differences between the two groups (P < 0.01).

CONCLUSION

The 32P application device, with its advantages of low cost, easy operation, good effect, high safety and reliability, low recurrence, fewer adverse events and good acceptability, is highly valuable for the treatment of CA in the rectum.

32P as an adjunct to standard therapy for locally advanced unresectable pancreatic cancer: a randomized trial

This prospective randomized trial was undertaken to determine the added efficacy of (32)P in treating locally advanced unresectable pancreatic cancer. Thirty patients with biopsy proven locally advanced unresectable adenocarcinoma of the pancreas were assessable after receiving 5-fluorouracil and radiation therapy with or without (32)P, followed by gemcitabine. Intratumoral (32)P dose was determined by tumor size and volume and was administered at months 0, 1, 2, 6, 7, and 8. Tumor cross-sectional area and liquefaction were determined at intervals by computed tomography scan. Tumor liquefaction occurred in 78% of patients receiving (32)P and in 8% of patients not receiving (32)P, although tumor cross-sectional area did not decrease. Serious adverse events occurred more often per patient for patients receiving (32)P (4.2 +/- 3.1 vs. 1.8 +/- 1.9; p = 0.03) leading to more hospitalizations. Death was because of disease progression (23 patients), gastrointenstinal hemorrhage (4 patients), and stroke (1 patient). One patient not receiving (32)P and one receiving (32)P are alive at 28 and 13 months, respectively. (32)P did not prolong survival (7.4 +/- 5.5 months with (32)P vs. 11.5 +/- 8.0 months without (32)P, p = 0.16). (32)P promoted tumor liquefaction, but did not decrease tumor size. Intratumoral (32)P was associated with more serious adverse events and did not improve survival for locally advanced unresectable pancreatic cancer.

Development of samarium [32P] phosphate colloid for radiosynoviorthesis applications: Preparation, biological and preliminary clinical studies experience

A new therapeutic radio colloid for radiosynoviorthesis (RS) applications is reported. The method of preparation involves the reaction of SmCl3 carrier with carrier added [32P]H3PO4 in the presence of gelatin. The pure colloid was recovered by dialysis purification leading to radiochemical yield of around 90%. The radiochemical purity of the pure colloid formulated in isotonic saline was over 98%, for the usage period of 14 days, as assessed by paper chromatography. Ninety percent of colloid particles were in the size of 1-10 microm as evident from the laser diffraction particle size analysis, ideally suitable for the intended end use. Animal studies revealed complete retention of the radio colloid in the rabbit knee joint. The results of clinical trials in humans are satisfactory and encouraging, satisfactory retention of the colloid in the knee joint and negligible leakage into the systemic circulation.

Novel decapeptides that bind avidly and deliver radioisotope to colon cancer cells

BACKGROUND

The rapidly growing field of targeted tumor therapy often utilizes an antibody, sometimes tagged with a tumor-ablating material such as radioisotope, directed against a specific molecule.

METHODOLOGY/PRINCIPAL FINDINGS

This report describes the discovery of nine novel decapeptides which can be radioactively labeled, bind to, and deliver (32)P to colon cancer cells. The decapeptides vary from one another by one to three amino acids and demonstrate vastly different binding abilities. The most avidly binding decapeptide can permanently deliver very high levels of radioisotope to the adenocarcinoma cancer cell lines at an efficiency 35 to 150 times greater than to a variety of other cell types, including cell lines derived from other types of cancer or from normal tissue.

CONCLUSIONS/SIGNIFICANCE

This experimental approach represents a new example of a strategy, termed peptide binding therapy, for the potential treatment of colorectal and other adenocarcinomas.

Determination of biological vector characteristics and nanoparticle dimensions for radioimmunotherapy with radioactive nanoparticles

Radioimmunotherapy with biological vector labeled with radioactive nanoparticles is investigated from a dosimetric point of view. Beta (32P, 90Y) and low-energy X-ray radionuclides (103Pd) are considered. Dose distributions inside solid tumors have been calculated using MCNPX 2.5.0. Nanoparticle dimensions and biological vector characteristics are also determined in order to reach the 50 Gy prescribed dose inside the entire tumor volume. The worst case of an avascular tumor is considered. Results show that for beta-emitting nanoparticles, a set of data (covering fraction, biological half-life, and nanoparticle radius) can be found within acceptable ranges (those of classical radioimmunotherapy). These sources (with Emax approximately few MeV) can be used for the treatment of tumors with a maximum diameter of about 1 cm. Low-energy X-rays (E<25 keV) can be used to extend the range of tumor diameter to 4-5 cm but require very tight biological vector characteristics.

Low-dose P32 therapy in essential thrombocythemia

We present a case of an 85-year-old woman with medically refractory essential thrombocythemia and subsequent venous thrombosis. She received conservative phosphorus-32 sodium phosphate therapy for 3 mCi, approximately half the usual dose. One month later, she received a second intravenous phosphorus-32 treatment of 3.5 mCi. She responded successfully to both treatments with drops in her platelet count and experienced no adverse effects. Our case is noteworthy in the effectiveness from a conservative dose while avoiding hematologic complications.

Diffuse pigmented villonodular synovitis: preliminary results with intralesional resection and p32 synoviorthesis

Because of the high local recurrence rate associated with surgical resection alone, patients with diffuse intraarticular pigmented villonodular synovitis were treated with surgical resection followed by colloidal chromic P32 synoviorthesis. The medical records of nine consecutive patients treated in this manner were reviewed retrospectively to determine the recurrence rate of pigmented villonodular synovitis. All patients had either one or two surgical resections (arthroscopy in one patient, open resection in seven, arthroscopy and open resection in one). The involved joints included six knees and one each, ankle, elbow, and hip. Eight of the nine patients remained recurrence free at a mean followup of 38 months (range, 19-60 months) after surgery. One patient had a suspected asymptomatic recurrence documented by magnetic resonance imaging 29 months after surgery. Seven patients reported their normal activities as unrestricted. Five reported improved activity levels, one reported the activity level remained the same, and one reported activity as the same or better. None reported reduced activity levels. In these patients synoviorthesis with colloidal chromic P32 following gross resection of all obvious pigmented villonodular synovitis provided local disease control in all but one.

(32)P radioisotope therapy for recurrent pilocytic astrocytoma

(32)P is a pure beta-emitter that has a depth of penetration of 2-3 mm and can be useful in the treatment of cystic lesions. Its effectiveness in the treatment of a selected brain tumor is illustrated here.

Improving patient-specific dosimetry for intravascular brachytherapy

PURPOSE

Accurate patient-specific dosimetry in intravascular brachytherapy (IVBT) is generally difficult due to the extremely high-dose gradient, complexity of treatment device, and patient-specific geometry (e.g., calcification, stent, curvature, movement of target). The purpose of this study is to analyze quantitatively and systematically the dose effects of calcification, stent, guidewire, and source curvature on clinical dosimetry in an IVBT procedure, and propose a method that can be used to assess these effects in routine clinical practice.

METHODS AND MATERIALS

Monte Carlo techniques were used to calculate 3-D dose distribution in both homogeneous and inhomogeneous media for three most commonly used IVBT sources: (90)Sr beta (Novoste), (192)Ir gamma (Cordis/Best), and (32)P beta (Guidant). Dosimetric perturbations in the presence of metallic stents, calcified plaques, metallic guide wires, and source curvature were studied for situations commonly encountered in the clinic. The importance of each of these perturbations and their practical influence on patient-specific dosimetry were analyzed. Factors (plaque, stent, guidewire, and curvature) that may be used to correct/reduce these perturbations were introduced to prevent dosimetric cold spots during IVBT. Practical methods of using these correction factors are proposed.

RESULTS

Dose perturbations are significant due to the presence of source curvature, metallic stents, calcified plaques, and metallic guide wires, especially for beta sources. These perturbations can be as high as 30% under normal clinical conditions, although they can be much higher in extreme situations. Empirical relationships of plaque factor with the thickness of calcified plaque, stent factor with stent metallic surface area, guidewire with guidewire thickness, and curvature factor with the bending angle are derived. These relationships are found to be useful in improving clinical dose accuracy in IVBT treatment planning or dose evaluation after treatment.

CONCLUSIONS

Significant dose perturbations due to the presence of source curvature, metallic stents, calcified plaques, and guide wires have been found in IVBT for in-stent restenosis. Because it has been reported that, with the current prescriptions for IVBT, higher doses consistently improve treatment outcomes, the empirical method derived from this work can be used to assess cold spots dosimetrically, thus improving patient-specific dosimetry for IVBT.

Increased dosage during intracoronary irradiation due to overlapped source stepping shows no long-term adverse changes in vessel morphology

PURPOSE

The purpose of this analysis was to evaluate if overdosage during intracoronary irradiation due to overlapped source stepping may result in long-term morphologic changes in vessel anatomy.

METHODS

Baseline angiograms of patients with in-stent restenosis undergoing coronary reintervention followed by intracoronary irradiation with source stepping were analyzed. Overlapping was considered present for the segment with overlapped reference isodose length (RIL) (RIL = segment with > or = 90% of reference dose at 1 mm vessel wall depth). Baseline and 6-months follow-up volumetric intravascular ultrasound (IVUS) analysis were performed for the overlapped segment and for proximal and distal segments of equal length.

RESULTS

Overlapping was found in six patients (three patients: (32)P treatment; three patients: (90)Sr/Y treatment); final analysis was performed in four patients. Comparison of the baseline and follow-up IVUS volumetric parameters revealed no significant change in lumen or vessel volumes at segments of overlaps in comparison to proximal and distal reference segments.

CONCLUSION

Increased dosage due to overlapping during source stepping is not associated with morphologic changes in vessel anatomy at follow-up.

Feasibility study and dosimetric assessment of radiolabeled drugs injected to the coronary arterial wall to prevent restenosis

PURPOSE

Intramural delivery of a P-32 radiolabeled oligonucleotide (ODN) using an infiltrating catheter has been proposed recently to potentially reduce restenosis in coronary arteries and tested on a limited number of human subjects. However, because of the low efficiency of drug retention (approximately 2-5%) after the initial washout period from this technique, the dose levels to nontarget organs may be significant and thus may require a detailed investigation. The radiation dose distributions resulting from this technique is investigated using the MIRD formalism and Monte Carlo calculations.

MATERIALS AND METHODS

The total activity of the P-32 ODN to be injected during treatment to deliver a therapeutic dose of approximately 30 Gy to the arterial wall is estimated taking into account the drug delivery efficacy of the infiltrating device (approximately 2-5% typical). Using pharmacokinetic data for P-32 ODN, we estimate the dose to healthy organs resulting from the systemic fraction that is released into the circulatory system during washout (>95% typical). Variabilities in the biological parameters are also identified as important sources of error in the prescribed dose.

RESULTS

A limitation to this technique is the poor accuracy in delivering the prescribed dose due to variability in the amount of drug delivered. Dose to organs is also an important limitation. For example, our calculation indicate that approximately 37 MBq (1 mCi) of P-32 labeled ODN are needed to deliver 30 Gy to the arterial wall assuming a delivery efficiency of 2-5% and a 24-h residence time. This may result in doses of approximately 1 Gy to the spleen and 0.2-0.4 Gy to the liver, kidneys and lungs (95% confidence interval).

CONCLUSION

This novel therapy suffers from serious limitations. It is doubtful that a therapeutic dose can be delivered accurately, safely and effectively to the arterial wall because of the poor delivery efficacy and extreme variability found in drug delivery experiments. Also, dose levels to healthy organs appears to be too high to recommend the use of this technique in human experiments.

Endovascular Treatment of Intracranial Aneurysms With Radioactive Coils

Background and Purpose— Endovascular treatment of intracranial aneurysms is safe and effective but is associated with angiographic recurrences. Beta radiation prevents recanalization after coil embolization in experimental models. We wanted to assess the feasibility of using radioactive coil embolization to improve long-term results of endovascular treatment.

Methods— Platinum coils were ion-implanted with 0.13 to 0.26 μCi/cm of 32 P. Forty-one patients aged 34 to 84 years with 44 aneurysms with a high propensity for recurrences were included. Radioactive coils were introduced into aneurysms to reach a target volumetric activity of 0.018 μCi/mm 3 . Nonradioactive coils were also used to ensure the same safety and the same angiographic results as the standard procedure. Angiographic results, procedure-related complications, and neurological events during follow-up were recorded. Angiographic follow-up data are available in 36 lesions 6 months after treatment.

Results— Forty of 44 aneurysms (91%) could be treated with radioactive coils. Target activities could be reached in 88% of lesions that could actually be coiled (35/40). Total activities ranged from 1.72 to 80.9 μCi, for a mean of 20.13±20.80 μCi. Procedure-related complications occurred in 7% of patients. Initial angiographic results were satisfactory (complete occlusions or residual necks) in 75% of lesions. Angiographic recurrences occurred in 11 (31%) of patients followed, within the expected range for standard coils. There was no complication from beta radiation during a mean follow-up period of 10 months.

Conclusions— Radioactive coil embolization is feasible; target volumetric activities can be reached in most aneurysms considered for endovascular treatment.

Beta radiation and inhibition of recanalization after coil embolization of canine arteries and experimental aneurysms: how should radiation be delivered?

BACKGROUND AND PURPOSE

Beta radiation prevents recanalization after coil embolization. We sought to determine the effects of varying coil caliber, length, activity of 32P per centimeter of coil or per volume, and spatial distribution of coils on recanalization.

METHODS

We studied the angiographic evolution of 81 canine maxillary, cervical, and vertebral arteries implanted with a variety of nonradioactive (n=29 arteries) or radioactive (n=52) devices. We compared 1- or 2-caliber 0.015 or 0.010 coils ion-implanted or not with 3 different activity levels (0.05 to 0.08, 0.06 to 0.12, 0.18 to 0.32 microCi/cm) of 32P and totaling 4, 8, and 16 cm in length for the same arterial volume. We also compared inhibition of recanalization by beta radiation delivered by stents, after coil occlusion proximal to or within the stent, with that delivered by coils placed within nonradioactive stents. We finally studied the angiographic evolution of canine lateral wall carotid aneurysms treated with 1 or 2 stents of various activity levels positioned inside the parent artery across the neck. Animals were killed at 4 and 12 weeks for macroscopic photography and pathological examination.

RESULTS

All arteries (29 of 29) occluded with nonradioactive devices were recanalized, while 49 of 52 arteries (94%) implanted with 32P devices were occluded at 4 weeks. All aneurysms treated with stents, radioactive or not, demonstrated residual filling of the sac or of channels leading to the aneurysms at follow-up angiography at 4 weeks.

CONCLUSIONS

The recanalization process found in the canine arterial occlusion model is minimally affected by coil caliber, number, and length or packing density. Beta radiation reliably inhibits this process, but thrombosis is an essential condition for the efficacy of a radioactive coil strategy.

32P liquid sources—comparison of the effectiveness of postangioplasty versus poststenting intravascular brachytherapy in hypercholesterolemic rabbits

PURPOSE

Endovascular application of ionizing radiation is a promising but still not sufficiently studied means of restenosis prevention. To test the effects of radiation on restenosis, and especially their dependence on whether the angioplasty was followed by stent implantation or not, we performed an in-stent versus no-stent intravascular brachytherapy study in an animal model. Balloon-based, continuous and self-centering, liquid 32P sources seemed the most convenient for the purpose.

METHOD

The radial dose distribution around angioplasty balloons filled with solutions of Na(2)H32PO(4) was calibrated by thermoluminescence dosimetry, both in the absence and presence of stents. The animal experiments were performed on rabbits with induced hypercholesterolemia. The balloons containing 32P were introduced into iliac artery immediately after stent implantation or after angioplasty alone. Radiation effects were evaluated postmortem by comparing thickness of various components of the artery wall.

RESULTS

In the presence of titanium stents (TTS), irradiation with 16 Gy dose at 1.0 mm from the balloon surface was no less effective in reducing hypertrophy in every active layer of the artery wall than without a stent.

CONCLUSION

In the animal model, IVBT basing on P(32) liquid sources was no less effective in the stented arteries than in the nonstented ones.

Wire or coated balloon? Searching for an optimal source for intravascular brachytherapy with beta emitters using (32)P as an example

This study identifies basic dosimetric differences between two designs for intravascular brachytherapy (IVBT) in current clinical practice and ongoing trials and their clinical implications within beta emitting systems using P-32 as an example. The two designs are (i) the wire-type source, where the radioactive source material is confined to a wirelike structure within the vessel lumen, and (ii) the balloon-surface source, where the radioactive source material is distributed over a surface area (balloon-wall) which is brought in close proximity with the vessel wall. Using Monte Carlo simulations with the EGS4 code, the target coverage, the influence of centering errors, and the perturbation of the dose distribution caused by metallic stents have been compared. The radial dose fall-off in the target region was found to be steeper for balloon surface systems compared with wire systems. The inner lumen wall dose for a balloon surface source was 25% higher than that for a wirelike source (2.5 mm vessel diameter). However, the comparably shallower fall-off from wire-type systems is very sensitive to centering uncertainties. A 0.5 mm displacement, for example, will cause the dose to change by a factor of 2 at the inner vessel wall and by a factor of 1.8 at the prescription point. It is shown that the interference from metallic stents is more significant for wire-type systems than it is for balloon-surface-type systems, where double the dose variation beyond the stent at the radial prescription distance may occur. Centering uncertainties dominate the dose perturbation effects for wire-type systems. Balloon-surface-type designs show a more predictable dose distribution that features, however, a higher inner vessel surface dose. Since a direct clinical comparison of systems of both types is not likely, these findings should be considered when interpreting clinical results from treatments with either type of source and, possibly, for future source design.

[Radioactive stents: problems and potential solutions]

BACKGROUND

The implantation of radioactive stents was the first procedure of a coronary brachytherapy in Europe examined in multicenter clinical trials.

PROBLEMS OF RADIOACTIVE STENTS

After more than 400 patients with radioactive stents were analyzed, it became clear that overall restenosis rates were not reduced. A new phenomenon called the "edge effect" or "candy-wrapper" effect was discovered, which later was also described for catheter-based brachytherapy. Currently, the implantation of radioactive stents for the prevention of restenosis cannot be recommended.

DRUG ELUTING STENTS

Although technical improvements of radioactive stents are theoretically possible, novel drug coated stents may overcome any future research of stent-based radiotherapy. Drug eluting stents induce antiproliferative effects beyond the stent margins. Edge effects were not observed in preliminary trials. However, long-term results need to be awaited.

Combined treatment with stereotactic intracavitary irradiation and gamma knife surgery for craniopharyngiomas

OBJECT

To evaluate the effectiveness of the combined treatment of stereotactic intracavitary irradiation and Gamma Knife surgery on craniopharyngiomas.

PATIENTS AND METHODS

Combined treatment with stereotactic instillation of radioisotopes and Gamma Knife surgery was performed on 46 patients with craniopharyngioma between October 1996 and June 1999. There were 13 solid tumors and 33 mixed solid and cystic tumors.

RESULTS

38 patients (10 solid and 28 mixed) were followed up from 6 months to two years. The tumor control rate was 90% in solid tumors, 85.7% in mixed tumors, 92.1% in the solid segment and 89.5% in total.

CONCLUSIONS

Gamma Knife surgery plays an important role in the treatment of the solid component of craniopharyngiomas and the combination of treatment is a simple, safe and effective method for treatment of craniopharyngiomas, especially for the recurrent mixed solid and cystic tumors.

[Treatment of nuclein 32P colloid perfusion with chronic suppurative maxillary sinusitis]

OBJECTIVE

To determine the effect of nuclein 32P colloid in treatment of chronic maxillary sinusitis (CMS).

METHOD

22 patients (31 sides) with CMS after washing of sinucavity were perfused with nuclein 32P in sinucavity. 20 patients (31 sides) with routine conservative treatment were served as a control group. Two groups were followed up for one year.

RESULT

In nuclein group, 27 sides were cured, 4 sides were recurred and the rate of cure was 87%. In routine group, 19 sides were cured, 12 sides were recurred and the rate of cure is 61%. There is significant difference between the two groups (P < 0.01). The treatment active of nuclein group is better than that of routine group.

CONCLUSION

Nuclein 32P colloid with the function of ionizing radiation can increase the pathogenic tissue immunocompetence and metabolic course, obstruct the microvascular and promote the absorption of inflammatory exudation and edema subsidence. It can also make the proliferous tissue atrophy thence accelerate the rate of cure of CMS.

"Edge Effect" of (32)p radioactive stents is caused by the combination of chronic stent injury and radioactive dose falloff

BACKGROUND

Radioactive stents have been reported to reduce in-stent neointimal thickening. An unexpected increase in neointimal response was observed, however, at the stent-to-artery transitions, the so-called "edge effect." To investigate the factors involved in this edge effect, we studied stents with 1 radioactive half and 1 regular nonradioactive half, thereby creating a midstent radioactive dose-falloff zone next to a nonradioactive stent-artery transition at one side and a radioactive stent-artery transition at the other side.

METHODS AND RESULTS

Half-radioactive stents (n=20) and nonradioactive control stents (n=10) were implanted in the coronary arteries of Yucatan micropigs. Animals received aspirin and clopidogrel as antithrombotics. After 4 weeks, a significant midstent stenosis was observed by angiography in the half-radioactive stents. Two animals died suddenly because of coronary occlusion at this mid zone at 8 and 10 weeks. At 12-week follow-up angiography, intravascular ultrasound and histomorphometry showed a significant neointimal thickening at the midstent dose-falloff zone of the half-radioactive stents, but not at the stent-to-artery transitions at both extremities. Such a midstent response (mean angiographic late loss 1.0 mm) was not observed in the nonradioactive stents (mean loss 0.4 to 0.6 mm; P< 0.01).

CONCLUSIONS

The edge effect of high-dose radioactive stents in porcine coronary arteries is associated with the combination of stent injury and radioactive dose falloff.

32P chromic phosphate radiosynovectomy for chronic haemophilic synovitis

The principal medical consequence of haemophilia is the development of arthropathy, initiated by a haemarthrosis giving rise to chronic synovitis. Traditional methods of synovectomy include open excision and arthroscopy each of which require substantial amounts of clotting factor concentrate for several weeks, and in the case of open synovectomy, is often associated with loss of range of motion and arthrofibrosis. Radiosynovectomy, the intra-articular injection of low penetration radiocolloids, has been utilized outside the United States for over 20 years. Since 1988, our centre has performed 170 radiosynovectomies utilizing 32P chromic phosphate (32P). This study reports results of 130 32P radiosyovectomies with an average follow-up of 36.5 months (6-140 months). For primary procedures, excellent and good results (haemarthrosis reduction from 75 to 100%) were obtained in 79.2% of cases at 6 months to 8 years. For repeat procedures a combination of excellent and good results were obtained in 62.4% of cases at 6 months to 3 years. Regression analysis showed no correlation between results and age or degree of arthropathy. Radiation was well contained within the joint. There were no observed or identified complications. The procedure is highly cost effective in comparison to open surgical or arthroscopic synovectomy.

A novel balloon angioplasty catheter impregnated with beta-particle emitting radioisotopes for vascular brachytherapy to prevent restenosis; first in vivo results

BACKGROUND

According to early clinical trials, vascular brachytherapy performed prior to or shortly after angioplasty is very effective in reducing restenosis rates. The purpose of this study was to investigate the effects of a novel radioactive catheter that allows simultaneous balloon angioplasty and beta-particle irradiation in the prevention of restenosis.

MATERIAL AND METHODS

The balloon surface of an angioplasty catheter was impregnated with the radioisotope(32)P. Dosimetry calculations using a Monte Carlo method were performed at a radial distance of 0.2 mm from the balloon surface. Rabbit iliac arteries were dilated and simultaneously irradiated with a dose of 20 Gy delivered to the adventitia. Control arteries were only dilated and not irradiated. Neointimal areas, cell numbers and the perimeter of the arteries were measured by histomorphometry after 6 weeks.

RESULTS

Neointima formation was reduced after balloon dilatation and simultaneous beta-particle irradiation using the(32)P impregnated angioplasty catheter as compared to balloon dilatation alone with a non-impregnated catheter (0.09+/-0.06 vs 0.27+/-0.09 mm(2)neointimal area and 168+/-45 vs 360+/-133 cells/0.05 mm(2)neointima, P<0.001 vs control, respectively). In addition, balloon dilatation with the(32)P impregnated angioplasty catheter increased the vessel perimeter as compared to balloon dilatation with a non-impregnated catheter (4. 7+/-0.2 vs 3.9+/-0.3 mm, P<0.001 vs control).

CONCLUSIONS

Simultaneous balloon dilatation and vascular brachytherapy with a novel(32)P impregnated angioplasty catheter markedly reduces restenosis in vivo by preventing neointimal hyperplasia and constrictive vascular remodelling.

[The relationship between effects and radiation doses of intra-arterial phosphorus-32 glass microspheres embolization therapy for patients with advanced liver cancer]

OBJECTIVE

To evaluate the relationship between effects and internal radiation of phosphorus-32 glass microspheres embolization therapy for liver cancer patients.

METHODS

From 1994 to 1998, 44 patients with unresectable liver cancer received intra-arterial radio-embolization therapy using (32)P-GMS. Preoperative and postoperative function and energy level of the liver were tested by liver function test and arterial blood ketone body ratio (AKBR). CT, single photon emission computer tomography (SPECT), and AFP were used to judge the effect of the therapy; multivariate analysis was made.

RESULTS

In the moderate dose group, low incidence of complication, high tumor shrinking rate and AFP decreasing rate, and long-term survival rate were observed. In the larger dose group, high incidence of liver failure, high tumor shrinking rate and AFP decreasing rate, and long-term survival rate were also observed. In the low dose group, low incidence of complication, but low tumor shrinking rate and AFP decreasing rate and long-term survival rate were not observed.

CONCLUSIONS

The reasonable radiation doses for liver cancer patients may be about 30 Gy; if liver cirrhosis is serious, the doses can be reduced.

Late clinical, plain X-ray and magnetic resonance imaging findings in haemophilic joints treated with radiosynoviorthesis

The clinical, plain X-ray and magnetic resonance imaging (MRI) findings were studied in 13 haemophilic joints previously treated with radiosynoviorthesis. (32)P had been injected into the joints at a median of 16 years earlier in an attempt to halt recurrent haemorrhage. Prior to (32)P injection, the majority of joints demonstrated bone damage evident on plain X-ray, secondary to recurrent haemorrhage. At the follow-up evaluation we found plain X-rays were adequate to identify cysts, erosions and cartilage loss in these very damaged joints. MRI was superior to clinical examination and plain X-ray in identifying synovial hyperplasia and effusions.

Inhibition of restenosis with beta-emitting radiotherapy: Report of the Proliferation Reduction with Vascular Energy Trial (PREVENT)

BACKGROUND

Intracoronary gamma- and beta-radiation have reduced restenosis in animal models. In the clinical setting, the effectiveness of beta-emitters has not been studied in a broad spectrum of patients, particularly those receiving stents.

METHODS AND RESULTS

A prospective, randomized, sham-controlled study of intracoronary radiotherapy with the beta-emitting (32)P source wire, using a centering catheter and automated source delivery unit, was conducted. A total of 105 patients with de novo (70%) or restenotic (30%) lesions who were treated by stenting (61%) or balloon angioplasty (39%) received 0 (control), 16, 20, or 24 Gy to a depth of 1 mm in the artery wall. Angiography at 6 months showed a target site late loss index of 11+/-36% in radiotherapy patients versus 55+/-30% in controls (P:<0.0001). A low late loss index was seen in stented and balloon-treated patients and was similar across the 16, 20, and 24 Gy radiotherapy groups. Restenosis (>/=50%) rates were significantly lower in radiotherapy patients at the target site (8% versus 39%; P:=0.012) and at target site plus adjacent segments (22% versus 50%; P:=0.018). Target lesion revascularization was needed in 5 radiotherapy patients (6%) and 6 controls (24%; P:<0.05). Stenosis adjacent to the target site and late thrombotic events reduced the overall clinical benefit of radiotherapy.

CONCLUSIONS

beta-radiotherapy with a centered (32)P source is safe and highly effective in inhibiting restenosis at the target site after stent or balloon angioplasty. However, minimizing edge narrowing and late thrombotic events must be accomplished to maximize the clinical benefit of this modality.

The impact of stent design and delivery upon the long-term efficacy of radioisotope stents

Both gamma and beta irradiation delivered via a radioactive catheter-based line source have been shown to have efficacy in reducing restenosis. However, these catheter-based treatments have some limitations, including the safety of handling sources ranging from 30 mCi to 500 mCi. Alternatively, one could use a stent as the platform for local radiation delivery as a means to prevent restenosis. Experimental studies have demonstrated that stents ion implanted with the b-particle emitter 32P can reduce neointima formation. Clinical evaluation of the radioisotope stent began in the fall of 1996. Dose escalation studies have now been completed in approximately 250 patients with 32P, b-particle emitting stents ranging from 0.5 microCi to 24 microCi. Overall, these feasibility trials have demonstrated a clear, dose-dependent reduction of neointimal hyperplasia within the stent structure, but with an unanticipated finding of a relatively high incidence of restenosis at the stent margins. The purpose of this paper is to review the current status of radioactive stents, with an emphasis on the key elements of stent design and stent delivery that could impact the long-term efficacy of this device.

[Hepatic arterial infusion of 32P-radionuclide microspheres for radiation therapy of hepatocellular carcinoma]

OBJECTIVE

To investigate the efficacy of internal radiation of (32)P-glass microspheres ((32)P-GMS) in unresected hepatocellular carcinoma (HCC) via subcutaneous arterial port.

METHODS

Hepatic arterial (99)technetium-macroaggregate albumin ((99)Tc-MAA) scanning via subcutaneous arterial port was undertaken to measure lung/liver shunting ratio and tumor/liver ratio. Hepatic arterial infusion of (32)P-GMS was performed in 17 cases of HCC with a dose from 1.11 to 1.30 GBq. Twenty cases of HCC undergoing hepatic arterial chemoembolization (HACE) in the same period served as controls group.

RESULTS

There was no treatment-related death in the 17 cases. In 7 of the 17 cases, AFP level and/or tumor size decreased by 50% after treatment, with a response rate of 64.7%. The median survival time was 5.5 months, and the 3-, 6-, 9-, 12-month survival rates were 94.1%, 44.1%, 31.0%, 24.4%, respectively. The therapeutic efficacy was better than that of HACE. The survival time was significantly longer in patients with T/N ratio >or= 2 than in those with T/N < 2 (P < 0.05).

CONCLUSIONS

Hepatic arterial infusion of (32)P-GMS is an alternative treatment for unresected HCC.

The effect of various therapeutic solutions including colloidal chromic 32P via an intratumoral injection on the tumor physiological parameters of AsPC-1 human pancreatic tumor xenografts in nude mice

To overcome the physiological barrier in solid tumors (i.e., tumor hypertension), a large volume of material is required via an intratumoral injection. Alternatively, a method of reduction in tumor hypertension is also feasible. In this study, we focused on the physiological response after an intratumoral infusion of various therapeutic agents. Tumor interstitial fluid pressure (TIFP) was intermittently monitored for up to 7 days after treatment using AsPC-1 human pancreatic tumors in nude mice. Macroaggregated albumin (MAA), colloidal chromic 32P (32P-CP), albumin, dexamethasone, 5-fluoro-2'deoxyuridine, dextrose, saline, and trypan blue increased TIFP within approximately 5 min, and TIFP returned to the original level within 1 h, except in the case of MAA and 32P-CP. We also found that the maximal uptake for AsPC-1 tumors in both the exponential and plateau growth phases occurred at approximately 100 min postincubation; the maximum value in the exponential growth phase was approximately 2 times less than that of plateau growth phase (P < 0.01). Therefore, this study supports intralesional 32P-CP brachytherapy for nonresectional pancreatic cancer patients. This may offer a promising treatment modality for delivering high doses of tumor-selective radiation, mainly due to two physiological mechanisms: (a) the high adherence of 32P-CP to the infused regions; and (b) reduction in either tumor blood flow or TIFP by this therapeutic colloid.

Intraluminal irradiation for TIPS stenosis: preliminary results in a swine model

PURPOSE

To evaluate the ability of 32phosphorus intraluminal irradiation to reduce pseudointimal hyperplasia in a transjugular intrahepatic portosystemic shunt (TIPS).

MATERIALS AND METHODS

TIPS were successfully placed in 11 swine with normal portal pressures. Six animals received 15.2 Gy intraluminal irradiation to the hepatic parenchyma and venous outflow tract at the time of TIPS placement with use of a NA32P-filled balloon angioplasty catheter. Five control animals underwent TIPS and balloon angioplasty with saline. All animals were followed up for 28 days, at which time percutaneous portography was performed, the animals were killed, and the tissue around the TIPS stent was processed for histologic analysis. Maximum pseudointimal hyperplasia as a percentage of estimated TIPS diameter was calculated for each animal.

RESULTS

At the time of euthanasia, all five control TIPS and all but one irradiated TIPS were occluded. Histologic analysis demonstrated considerable variability in the degree of pseudointimal hyperplasia within each TIPS and between animals. No statistically significant difference was found in the maximum pseudointimal hyperplasia, measured as a percentage of stent radius, between control (80.2%+/-17.4%) and irradiated animals (69.2%+/-25.2%).

CONCLUSIONS

Irradiation of TIPS with 15.2 Gy 32P delivered at the time of TIPS placement did not significantly improve TIPS patency or reduce the degree of pseudointimal hyperplasia in swine with normal portal pressures.

Toxicology of intrahepatic arterial administration of interventional phosphorus-32 glass microspheres to domestic pigs

OBJECTIVE

To evaluate the toxic response to intrahepatic arterial administration of radioactive phosphorus-32 glass microspheres (32P-GMS) in domestic pigs.

METHODS

Through selective catheterization of hepatic artery, 32P-GMS was infused to 5 healthy domestic pigs in a dosage equivalent to the therapeutic dose for human being, and 31P-GMS was infused to other 5 healthy domestic pigs. Two pigs served as the whole course blank controls. One pig from each group was surrendered to euthanasia at week 1, 2, 4, 8 and 16, respectively, and liver biopsies were performed on the rest of pigs at the corresponding time points. Liver tissues from different sites were taken for light and electron microscopy. The ultrastructural histopathological changes were evaluated semiquantitatively.

RESULTS

The accumulative amount of 32P-GMS in the target tissue attained more than 90% of the total dose administrated. Histologically, abnormal hepatocytes were easily found at week 1 or 2. At week 4 they were less than at week 1 or 2, and endothelium of the sinuses were damaged prominently. At week 8 they were scarcely seen, and liver tissue recovered gradually. The histological features of liver tissue restored to normal at week 16. Semiquantitative analysis of ultrastructural morphology in the experimental group showed no statistical difference (P > 0.50) between the nuclear abnormality (Nabn) and mitochrondrial variability (Mvar) at week 1 or 2, but revealed prominent difference (P < 0.01, P < 0.001) as compared with those in other groups. In the experimental group the Nabn in tissues showed no significant difference (P > 0.20) between week 8 and week 16.

CONCLUSION

32P-GMS internal irradiation at the dosage equivalent to human therapeutic dosage exerts reversible injury to domestic pig liver tissue, and it takes more than 8 weeks for the injured liver tissue to recover.

Chemical digestion and radionuclidic assay of TiNi-encapsulated 32P intravascular brachytherapy sources

A very quantitative, destructive assay procedure was devised for accurately measuring the 32P activity content of TiNi-encapsulated intravascular brachytherapy sources and was applied to four different sources (termed 'seeds') which were developed and provided by Guidant Intravascular Intervention (formerly NeoCardia). These seeds are intended for use in the prophylactic treatment of restenosis following balloon angioplasty in heart-disease patients. The assays involved the dissolution of the TiNi jacket, extraction of the activity from the internal 32P-containing source material, quantitative solution transfers, and a gravimetrically based dilution; followed by liquid scintillation (LS) spectrometry of the resulting master solution with 3H-standard efficiency tracing using composition-matched LS cocktails. The LS spectrometry utilized a previously-developed method for resolving the always-present 33P impurity. The protocol included provisions for accounting for all possible losses of 32P in the digestion procedure (based on radiochemical tracing experiments), for any unrecovered activity in the remaining source material, and for any residual activity in the solution-transfer and containing vessels. Sections of the TiNi jackets adjacent to the cut-off active seed portions were also assayed for any contained activity. Such destructive assays were required for relating measurements of the absorbed dose spatial distribution for the seeds to theoretic dose modelling and for establishing calibration factors for subsequent non-destructive radionuclidic measurements on the seeds.

An early phase II study of intratumoral P-32 chromic phosphate injection therapy for patients with refractory solid tumors and solitary metastases

BACKGROUND

In this early Phase II study, the authors investigated the efficacy of intratumoral injection of P-32 chromic phosphate in 17 patients with refractory solid tumors or solitary metastases in terms of response rates and overall survival.

METHODS

Seventeen patients (median age, 60 years) with either cytostatic drug-resistant tumors or tumors known to be primarily chemotherapy-resistant were entered into the study. After sonographic determination of the tumor volume, P-32 chromic phosphate (74-555 MBq) was injected into the central part of the tumor under sonographic guidance. Follow-up investigations included serial scintigraphy, sonographic examinations, and hematologic studies.

RESULTS

Injection of P-32 chromic phosphate into refractory tumors resulted in remarkable regression. The median survival of all patients was 13 months (range, 8-25 months). The response rate was 71% (12 patients). A complete remission was seen in 7 patients (41%), and the rate of partial remissions was 29% (5 patients). However, 5 patients (30%) did not respond to the treatment. In one patient thrombocytopenia was observed, but no other side effects were apparent. Important pathologic and anatomic changes within the tumor tissue were demonstrated in solitary liver metastases of gastrointestinal malignancies excised in second-look operations. In all cases examined, formation of a cyst within the area of central activity, surrounded by a centrifugal necrotic ring and a marginal fibrotic structure, was found.

CONCLUSIONS

Lack of persistent systemic or local side effects, as well as noteworthy efficacy, are properties of this optimal regional treatment modality with P-32 chromic phosphate. This modality deserves consideration for further clinical trials.

Relative efficacy of 32P and 89Sr in palliation in skeletal metastases

32p and 89Sr have been shown to produce significant pain relief in patients with skeletal metastases from advanced cancer. Clinically significant pancytopenia has not been reported in doses up to 12 mCi (444 MBq) of either radionuclide. To date, no reports comparing the relative efficacy and toxicity of the two radionuclides in comparable patient populations have been available. Although a cure has not been reported, both treatments have achieved substantial pain relief. However, several studies have used semiquantitative measures such as "slight," "fair," "partial" and "dramatic" responses, which lend themselves to subjective bias. This report examines the responses to treatment with 32P or 89Sr by attempting a quantification of pain relief and quality of life using the patients as their own controls and compares toxicity in terms of hematological parameters.

METHODS

Thirty-one patients with skeletal metastases were treated for pain relief with either 32P (16 patients) or 89Sr (15 patients). Inclusion criteria were pain from bone scan-positive sites above a subjective score of 5 of 10 despite analgesic therapy with narcotic or non-narcotic medication, limitation of movement related to the performance of routine daily activity and a predicted life expectancy of at least 4 mo. The patients had not had chemotherapy or radiotherapy during the previous 6 wk and had normal serum creatinine, white cell and platelet counts. 32P was given orally as a 12 mCi dose, and 89Sr was given intravenously as a 4 mCi (148 MBq) dose. The patients were monitored for 4 mo.

RESULTS

Complete absence of pain was seen in 7 of 16 patients who were given 32P and in 7 of 15 patients who were given 89Sr. Pain scores fell by at least 50% of the pretreatment score in 14 of 16 patients who were given 32P and 14 of 15 patients who were given 89Sr. Mean duration of pain relief was 9.6 wk with 32P and 10 wk with 89Sr. Analgesic scores fell along with the drop in pain scores. A fall in total white cell, absolute granulocyte and platelet counts occurred in all patients. Subnormal values of white cells and platelets were seen in 5 and 7 patients, respectively, with 32P, and in 0 and 4 patients, respectively, after 89Sr therapy. The decrease in platelet count (but not absolute granulocyte count) was statistically significant when 32P patients were compared with 89Sr patients. However, in no instance did the fall in blood counts require treatment. Absolute granulocyte counts did not fall below 1000 in any patient. There was no significant difference between the two treatments in terms of either efficacy or toxicity.

CONCLUSION

No justification has been found in this study for the recommendation of 89Sr over the considerably less expensive oral 32P for the palliation of skeletal pain from metastases of advanced cancer.

Evaluation of cellular uptake, tumor retention, radiation response, and tumor pathophysiology in experimental solid tumors after an intratumoral infusion of colloidal 32P

BACKGROUND

Order et al. successfully deposited > 85% of radionuclides in pancreatic carcinoma patients using an intratumoral (i. t.) infusion of macroaggregated albumin (MAA) prior to the i. t. infusion of colloidal 32P (32P-CP), apparently due to MAA-induced transient blockade. However, no studies regarding physiologic response and the inhibitory tumor growth of solid tumors after treatment with 32P-CP with or without MAA have been performed.

METHODS

First, the authors determined the cellular uptake of 32P-CP in 10 cell lines. They then evaluated the relationship between tumor retention and radiation response in vivo. Third, they evaluated the changes in physiologic parameters such as tumor interstitial fluid pressure (TIFP) and tumor blood flow (TBF) after an i. t. infusion of MAA.

RESULTS

In the plateau growth phase of both H4IIE and LS174T tumors, maximal uptake occurred at approximately 100 minutes after treatment with 10 microCi of 32P-CP, but uptake in LS174T was approximately 2 times higher than that in H4IIE. In animal experiments, 32P-CP alone significantly inhibited the tumor growth of H4IIE. However, additional i. t. infusion of MAA did not improve the growth delay induced by 32P-CP, mainly due to insignificant differences in retention of radioactivity when using 32P-CP with or without MAA. It was speculated that when the outflow of the tumor vasculature was obstructed by clamping (or an i. t. infusion of MAA), it would reduce TBF and increase TIFP. However, neither increased TIFP nor decreased TBF was observed when MAA was given i. t. to tumors.

CONCLUSIONS

The authors concluded that an MAA-induced transient blockade of tumor vasculature after an i. t. infusion of MAA did not occur in experimental solid tumors.

Contamination of the pleural surfaces in childhood sarcoma. Use of colloidal P-32 to reduce radiation dose to the whole lung

Children with pulmonary sarcomas who have diffuse contamination of the pleural cavity present a difficult management problem for the radiation oncologist. Doses required to control even microscopic disease exceed lung tolerance. We report on the use of intracavity colloid P-32 in an attempt to treat the pleural surface and spare normal lung parenchyma and tissues of the chest wall. Three children--18 months, 12 years, and 3 years of age--had spillage of pulmonary sarcomas into the chest cavity. All children were treated with systemic chemotherapy. Initially, 0.5 mCi of technetium sulfur colloid (99mTc-sulfur colloid) was instilled into the pleural space to ascertain even distribution of isotope. This was then followed by installation of 5.0 mCi of colloidal P-32. Uniform distribution was then confirmed by bremsstrahlung scanning. All three patients are in complete remission 3.5 years, 3 years, and 1 year after treatment, respectively. The major toxicity was asymptomatic pleural thickening, which could be confused with disease. This was confirmed histologically to be fibrous in the first patient. The process diminished or stabilized with time in all 3 patients over the period of observation. In this small series, intrapleural colloidal P-32 appeared to be safe and well tolerated and would be expected to be less toxic than wide-field external beam in the treatment of spilled pulmonary sarcomas.

Advantages and limitations of radioactive stents

The concept of radioactive stents was initiated to prevent restenosis after angioplasty in patients with coronary artery disease. We review the modes of fabrication, dosimetry and the biological effects of radioactive stents. Radioactive stents deliver ionizing radiation continuously at very low-dose rates according to the half-life of the incorporated radioisotopes. The activity levels of radioactive stents are up to 10,000 times lower than activity levels of sources used for catheter-based vascular brachytherapy. Radioactive stents allow uniform dose distribution and precise dosimetry because of the direct source contact with the circumference of the vessel. Animal studies show that these stents can potently inhibit smooth muscle cell proliferation and neointimal hyperplasia. A persistent inhibition of neointimal hyperplasia appears to be dose dependent. Local or systemic side effects related to the irradiation were not observed. A limitation of radioactive stents could be the dose-dependent delay in stent endothelialization which, however, did not cause thrombotic vessel occlusion in animal experiments. Whether a delay in stent endothelialization is associated with an increased rate of occlusive stent thrombosis in humans requires further studies.

The dose distribution produced by a 32P source for endovascular irradiation

PURPOSE

Percutaneous transluminal coronary angioplasty (PTCA) is one of the most common therapies for obstructive coronary artery disease. Unfortunately, subsequent restenosis after percutaneous balloon angioplasty occurs in 30-50% of patients and remains one of the major unsolved problems of contemporary cardiology. The study of endovascular irradiation has been greatly stimulated by the discovery that the process of restenosis may be impaired by irradiation. The objective of this study was to examine a custom-made commercial 32P wire and to determine whether the present source presentation is suitable for this application.

METHODS AND MATERIALS

Measurements of the dose distribution around a 3 mm long 32P source with an activity of 0.414 GBq (11.2 mCi) were made by using LiF thermoluminescent dosimeters and a scintillation detector. The source had the dimensions of 0.3 mm in diameter and 3 mm in length, and was first encapsulated by a plastic tube and then encapsulated in a specially manufactured Ni-Ti wire with a diameter of 0.4 mm and a length of 2.6 m. The detector size effect is removed from the measurements calculation. Loevinger's equation for the dose distribution around a 32P source was used for the calculations.

RESULTS

The dose rate at a radial distance of 1.5 mm was 53 cGy/s per GBq (1.96 cGy/s per mCi) and fell off rapidly perpendicularly to the axis of the source in an approximately exponential manner, from 53-5.3 cGy/s per GBq (approximately 2 to 0.2 cGy/s per mCi) as radial distances increased from 0.2 to 0.4 g/cm2 (1.5 to 3.5 mm away from the center of the source). The treatment length parallel along the wire could be as long as 24 mm for eight source dwell positions with the average dose rate of 59 cGy/s per GBq (2.2 cGy/s per mCi) and a variation of +/- 2.3% at a radial distance of 1.5 mm.

CONCLUSIONS

Our experiments show that the dose distribution is ideal for endovascular irradiation. The source was incorporated in the end of a flexible cable and with a half-life of 14.3 days is suitable for endovascular irradiation.

Dosimetric considerations for catheter-based beta and gamma emitters in the therapy of neointimal hyperplasia in human coronary arteries

PURPOSE

Recent data indicate that intraluminal irradiation of coronary arteries following balloon angioplasty reduces proliferation of smooth muscle cells, neointima formation, and restenosis. We present calculations for various isotopes and geometries in an attempt to identify suitable source designs for such treatments.

METHODS AND MATERIALS

Analytical calculations of dose distributions and dose rates are presented for 192Ir, 125I, 103Pd, 32P, and 90Sr for use in intracoronary irradiation. The effects of source geometry and positioning accuracy are studied.

RESULTS

Accurate source centering, high dose rate, well-defined treatment volume, and radiation safety are all of concern; 15-20 Gy are required to a length of 2-3 cm of vessel wall (2-4 mm diameter). Dose must be confined to the region of the angioplasty, with reduced doses to normal tissues. Beta emitters have radiation safety advantages, but may not have suitable ranges for treating large diameter vessels. Gamma emitters deliver larger doses to normal tissues and to staff. Low energy x-ray emitters such as 125I and 103Pd reduce these risks but are not available at high enough activities. The feasibility of injecting a radioactive liquid directly into the angioplasty balloon is also explored.

CONCLUSIONS

Accurate source centering is found to be of great importance. If this can be accomplished, then high energy beta emitters such as 90Sr would be ideal sources. Otherwise, gamma emitters such as 192Ir may be optimal. A liquid beta source would have optimal geometry and dose distribution, but available sources, such as 32P are unsafe for use with available balloon catheters.

Oligoradionuclidetherapy using radiolabelled antisense oligodeoxynucleotide phosphorothioates

Radiolabelled antisense oligodeoxynucleotides have been used for in vivo biokinetic studies in AIDS and cancer patients. The therapeutic possibilities are still unknown and the major question in therapeutic use of radio-oligonucleotide is the optimal source of radiation. We studied the pharmacokinetics and in vivo tissue distribution for oligodeoxynucleotide phosphorothioates by using the data from three different radionuclides: sulphur-35 (t1/2 = 87.4 days, maximum beta-energy = 167 keV), phosphorus-33 (t1/2 = 24.4 days, maximum beta-energy = 250 keV) and phosphorus-32 (t1/2 = 14.3 days, maximum beta-energy = 2270 keV). The absorbed doses of 32P-, 33P- and 35S-labelled oligonucleotides were estimated using the published biodistribution data for several oligonucleotides in two animal models for both tumour xenografts and AIDS. The local energy absorption of 33P turned out to be higher than that of 32P if the mass was smaller than approximately 300 micrograms, and the local absorption of 35S was higher than that of 32P when the mass was <80 micrograms. In a mouse tumour xenograft model an i.v. injected activity seemed to achieve sufficient radiation doses in the tumour: in a 1 g tumour 4.9 Gy for 32P, 5.1 Gy for 33P and 5.5 Gy for 35S were calculated when the kidney dose was kept as 5 Gy. In the same model in smaller tumours the doses were for a 1 mg tumour 0.73 Gy (32P), 5.1 Gy (33P) and 5.5 Gy (35S), and for a 1 microgram tumour 0.08 Gy (32P), 3.1 Gy (33P) and 3.9 Gy (35S). Thus, 33P and 35S have more beneficial radiotherapeutic characteristics than 32P. Relative advantage factors (33P and 35S versus 32P) for kidney and liver doses using these nuclides varied from 0.997 to 1.001 for a 1 g tumour and there was no difference in the radiation dose to normal organs. Therefore, we conclude that in oligonucleotide radiotherapy tumours >1 g should be treated with 32P, whereas smaller tumours should be treated with 33P or 35S. There is no significant difference between 33P and 35S, and either radionuclide could be selected according to labelling properties.

Risk of leukaemia, carcinoma, and myelofibrosis in 32P- or chemotherapy-treated patients with polycythaemia vera: a prospective analysis of 682 cases. The "French Cooperative Group for the Study of Polycythaemias"

An analysis of the risk of progression towards leukemia, carcinoma and myelofibrosis was performed in 93 patients treated by 32P alone (PVSG protocols) since 1970-1979, 395 patients over the age of 65 years treated by 32P with or without maintenance therapy using hydroxyurea (French protocol) since 1980-1994, and 202 patients under the age of 65 treated by either hydroxyurea or pipobroman since 1980. The risk of leukemia, or myelodysplasia, or lymphoma in the 32P-treated patients was 10% at the 10th year, but increase after that time to reach a value of about 30% at the 20th year, in the surviving case. This risk was not dose-related. Despite a marked reduction of the cumulative 32P dose in the patients maintained by hydroxyurea, the actuarial risk was 19% at the 10th year. In the patients treated exclusively by non radio-mimetic agents (hydroxyurea or pipobroman) a risk of 10% at the 10th year was observed. The risk of carcinoma (excluding skin cancers) was about 15% at the 10th year in the 32P-treated cases, a value similar to that generally reported by the French statistics. There was no prevalence of digestive carcinomas. In contrast, the patients receiving 32P and hydroxyurea as maintenance had an excess risk: 29% at the 10th year. In the relatively young cases treated by non radio-mimetic agents, the risk was similar in both arms: 9% at the 10th year, similar to the expected incidence at this age. The risk of myelofibrosis with myeloid metaplasia was still relatively low at the 10th year, about 15% in all arms, but increased towards a value higher than 30% in the patients surviving at the 20th year. At the present time, but in only a few cases with long-term following, no myelo-fibrosis with splenic metaplasia has been observed in the pipobroman-treated cases. The present results, which need to be confirmed (the present analysis has been done in spring 95) suggest that:-the use of non radio-mimetic agents does not protect against leukemic transformation, which may be a consequence of the disease; rather than of the treatment,-maintenance therapy after initial use of 32P increases the risk of both leukemia and carcinoma,-and hydroxyurea does not delay the risk of developing myelo-fibrosis, in comparison with 32P alone.