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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cobalt-57-bleomycin is a diagnostically useful radiopharmaceutical, but little is known about the nature of its individual fractions in regard to their metal-binding capacity and their in vivo distribution. Bleomycin was separated by high performance liquid chromatography (HPLC) into four major components. These were labeled and the distribution studied in tumor-bearing rats at 2 and 24 hr. In vivo radiochemical purity was also determined. Of the nine HPLC systems studied, Porasil A eluted with a mobile phase of 0.3% ammonium formate in methanol gave the best separation of the fractions. These fractions were copper free and retained their biologic activity and purity. An in vitro competitive binding study of 57Co-bleomycin with either 57Co-human serum albumin (HSA) or 57Co-ethylenediaminetetraacetic acid (EDTA) showed the labeled bleomycin to be a strong chelate. The biologic distribution in tumor-bearing rats showed significantly higher concentration in tumors at 2 hr for fractions A2 and B2 as compared to the bleomycin mixture. The other fractions, A1 and demethylA2, gave lower tumor concentrations than the bleomycin mixture. The tumor-to-blood ratios for A2 and B2 were not significantly different from the bleomycin mixture, suggesting that the concentration of the bleomycin in the tumor was related to blood concentration. Tumor-to-blood ratios of greater than 10:1 at 2 hr were achieved for A2, B2, and the mixture; ratios of greater than 31:1 were achieved at 24 hr for all three. From these data it appears that the major components A2 and B2 are the most useful for diagnostic tumor imaging.
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PMID:Chemical and biologic properties of isolated radiolabeled bleomycin preparations. 5 99

Cobalt-57-bleomycin is a clinically useful tumor-localizing agent, but attempts to label bleomycin (BLEO) with other radionuclides have been made because of the long physical half-life of 57Co. As an alternative labeling approach, we iodinated BLEO both directly on the imidazole ring and indirectly by reaction with N-succinimidyl 3-(4-hydroxy, 3-iodophenyl) propionate. Directly iodinated BLEO retained antibacterial activity, but in tumor-bearing rats it showed a lower tumor-to-blood ratio (2.3) at 2 hr than did 57Co-BLEO (11.8). The antibacterial activity of the indirectly labeled BLEO was markedly reduced and this material showed a tumor-to-blood ratio of 0.55 at 2 hr. The radioiodinated bleomycins are not suitable substitutes for 57Co-BLEO as tumor-imaging radiopharmaceuticals.
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PMID:Iodinated bleomycin: an unsatisfactory radiopharmaceutical for tumor localization. 5 31

The radiochemical purity of the cobalt-57 complex of bleomycin could be enhanced by adjusting the pH of the final product to a value between 5 and 6. This radiopharmaceutical appeared to have better tumor visualizing properties compared to the not neutralized preparation. The clinical use of the cobalt-57 bleomycin complex is however limited by the long physical half-life of the label, causing a risk of radioactive contamination. It appeared to be possible to label bleomycin with radioactive cations (111In3+, 99mTc4+, 197Hg2+ and 67Cu2+) having suitable gamma ray energies and short half-lifes. These bleomycin complexes showed a high radio-chemical purity judged by their behaviour on thin layer chromatography, paper chromatography, and electrophoresis, but their application as tumor visualizing radiopharmaceutical turned out to be disappointing compared with cobalt-57 bleomycin.
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PMID:Labelling of bleomycin with cobalt-57, indium-111, technetium-99m, mercury-197, lead-203, and copper-67. 5 9

Bleomycin serves as a useful prototype for a study of the various properties required in a radiopharmaceutical for tumor imaging. Both in vitro and in vivo results using bleomycin labeled with a large number of different radionuclides have now been reported. In general, it has not been possible to predict in vivo biologic behavior solely from in vitro data. For example, 57Co-bleomycin and 111In-bleomycin both have identical patterns in several different chromatographic systems and do not break down with prolonged storage in saline, exposure to heat, or other cations. However, when the labeled bleomycin is exposed to serum transferrin (and to other as yet unidentified ligands in the body) a difference in stability becomes obvious. The stability and biologic activity of 57Co-bleomycin in humans demonstrate the validity of metal chelation as a labeling technique for this specific molecule, and also suggests that other stable chelates will have useful applications. Although 57Co-bleomycin has the most desirable biologic characteristics of all the chelates of bleomycin, the extremely long physical half-life of 57Co of 270 days creates a significant contamination problem in the hospital. Because of this, the use of 57Co-bleomycin is limited to a few specialized centers. All users have emphasized the need for a better radionuclide to produce a labeled bleomycin with the same or superior biologic characteristics to 57Co-bleomycin. Unfortunately, the elements forming the most stable chelates with bleomycin (copper, zinc, cobalt, and nickel) do not have radionuclides with suitable physical characteristics for scanning. Copper-67 may become available in the future from high-energy linear accelerators. However, even if it were available, copper will probably not have as good chemical properties as cobalt.
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PMID:Radiolabeled antitumor agents. 6 1

Bleomycin was traced by the isotope Cobalt-57. By using this radioactive substance the pharmacokinetic behaviour of the drug was examined. It was given either intravenously or intra-arterially or directly into the tumor in patients suffering from epidermoid carcinoma in the maxillo-facial region. The differences in the pharmacokinetic data are delineated. Practically, the intra-arterial route of administration is the best one because of the high adherence rate of the drug to the perfused tissue.
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PMID:Pharmacokinetic behaviour of bleomycin-cobalt-57 with special regard to intraarterial perfusion of the maxillo-facial region. 6 77

20 patients with advanced carcinomas of the oral cavity (T3NxMo) were treated at the same time with the cytostatic drugs bleomycin and methotrexate as well as with a cobalt-60-irradiation. 14 of them are tumor free after an observation period of one half to two and a half years. Among them were 4 recurrences that had to be treated surgically. 1 patient is living with a residual tumor which cannot be further treated. 5 patients died of the tumor or of other causes. The survival rate, which is 80% after 1 year, is, as a tentative result, higher than could be attained by other therapeutic measures.
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PMID:[Combination therapy by bleomycin, methotrexate, and telecobalt irradiation in carcinoma of the oral cavity (author's transl)]. 7 Aug 69

The clinical records and imaging studies of 140 patients who had 57Co-bleomycin scans were reviewed. In 53% of the patients with known tumor at the time of examination, all clinically demonstrable lesions picked up cobalt. The success rate was particularly high in carcinoma of the lung (15 of 17) and gastrointestinal tract (12 of 17). The major role of cobalt bleomycin seems to be as an early screening test for metastases in patients with carcinoma of the lung, gastrointestinal tract, and uterus. The scan is most useful in demonstrating spread to the brain, liver, and adrenals.
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PMID:The place of 57Co-bleomycin scanning in the evaluation of tumors. 7 Sep 90

Cobalt-57 bleomycin imaging was performed in 11 patients with a history of head and neck cancer. Clinical and scan findings concurred on the presence and extent of tumor in 9 patients (82%); tumor was present in 7 and absent in 2 of the 9. In 2 patients (18%) the scan demonstrated tumor in the neck but failed to show metastatic sites. Cobalt-57 bleomycin images were of good technical quality, with remarkably low background activity at 24 hours after administration. Cobalt-57 bleomycin imaging appears to be a promising technique for evaluating patients with head and neck tumors.
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PMID:Cobalt-57 bleomycin for imaging head and neck tumors. 8 53

Previous reports of radiation-related neoplasia have relied primarily upon patients treated by orthovoltage to low doses for benign disease. This survey is believed to be the first to assess the incidence of second neoplasms following megavoltage therapy. The source was the records of all long-term pediatric survivors (88 patients) who were treated with megavoltage radiation (cobalt 60) at the University of Minnesota. There was an average follow-up period of 14 years during which 7 second neoplasms were discovered (8%). Five were not associated with prior radiation. Both radiation-related neoplasms were associated with low doses and one was without significant morbidity. Two of the seven neoplasms were malignant; one was not associated with radiation while the other was associated with prolonged chemotherapy and low dose radiation (1%). The only fatal second neoplasm was not associated with radiation but developed 5 years after prolonged chlorambucil treatment. This review reveals the tendency of childhood cancer victims to develop other neoplasms regardless of radiation. The finding of neoplasia induction only at low radiation doses supports the Gray hypothesis of decreased tumor induction at high doses through increased cell killing.
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PMID:Second neoplasms following megavoltage radiation in a pediatric population. 10 Feb 7

At the invitation of the American Radium Society, Pierquin reviews his very large experience with continuous low dose rate irradiation of cancer. The target volume is treated with 6,000-7,000 rad in 3-10 days at a dose rate of 30-100 rad/hr. Preference for continuous low dose rate irradiation is based on the earlier work of Jean Pierquin, Georges Richard, Claudius Regaud, and Ralston Paterson with radium sources. Afterloading techniques with iridium-192 have been substituted allowing safer and more precise placement. An accumulated experience with 5,000 patients over the past 15 years permits conclusions that the techniques are safe, easy, inexpensive, and effective for tumors accessible to direct instrumentation. Dosimetry is based on the Paris system. Standardizing upon a dose of 7,000 rad, Pierquin concludes there is an isoeffect of continuous radiation at low dose rates of 25-100 rad/hr. The differential effect on tumor versus healthy tissue is impressive even when large volumes are irradiated, as in neck adenopathy. Stemming from this experience, three trials have been carried out of low dose rate teletherapy with cobalt-60 sources in oral cavity and oropharynx tumors, delivering 7,000 rad at rates of 90-100 rad/hr. Pierquin hopes for the same very high local control rates (in the order of 95%)achieved by iridium-192 endoradiotherapy of accessible T1, T2, T3, and T4 cancers.
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PMID:The destiny of brachytherapy in oncology. 18 39


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