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PubMedDate not supplied

[The brachytherapy with low dose-rate iridium for prostate cancer].

PURPOSE: Brachytherapy as an option for the treatment of prostate cancer has been commonly performed in USA. As the permanent seeding of the radioactive materials is strictly restricted by the law in Japan, brachytherapy must be performed by the temporary implant. This treatment has been performed at a few facilities in Japan mostly using high dose-rate iridium. Only our facility has been using low dose-rate iridium (LDR-Ir) for prostate cancer. This study evaluates the clinical results of the treatment. PATIENTS AND METHODS: Since December 1997 to December 1999, 26 patients with histologically diagnosed as prostate cancer (Stage B, 92%; Stage C, 8%) underwent brachytherapy. Twenty-two patients received brachytherapy alone, three were treated with a combination of brachytherapy and external beam radiotherapy (ERT) and one was treated with a combination of brachytherapy and neoadjuvant endocrine therapy. Patients ranged in age from 61 to 84 (median 76) years old. Treatment was initiated with perineal needle placement. From 10 to 14 needles were placed through the holes on the template which was fixed to the stabilizer of the transrectal ultrasound probe. After the needle placement. CT scan was performed to draw distribution curves for the treatment planning. LDR-Ir wires were introduced to the sheath and indwelled during the time calculated from dosimetry. Peripheral dose was 70 Gy for the monotherapy of brachytherapy. For the combination therapy, 40 Gy was given by brachytherapy and 36 Gy with ERT afterwards. LDR-Ir wires were removed after completion of the radiation and patients were followed with serum PSA level and annual biopsy. RESULTS: During 2 to 26 (median 12) months follow-up, 8 out of 9 patients with initial PSA level above 20 ng/ml showed PSA failure. All 13 patients with initial PSA level lower than 20 ng/ml were free from PSA failure. Eight out of 11 patients with Gleason's score 7 or higher showed PSA failure, and all 14 patients (including three patients with combined therapy) with Gleason's score 6 or less were free from PSA failure. Annual biopsy was performed in 8 patients, and 4 patients histologically revealed tumor free and 4 patients (two of them showed PSA failure) were tumor positive. No major complication was observed, however, some minor side-effect as irritability was seen in 65% of the patients. CONCLUSIONS: The results showed that brachytherapy with LDR-Ir was an acceptable treatment as long as the patients were selected strictly with PSA level and Gleason's score. A good candidate for this treatment is the patient whose PSA level is lower than 20 ng/ml and Gleason's score is 6 or less. The treatment is effective and safe, but further observation is necessary to reach the conclusion.

Aged↗

PubMed2001

[High-dose rate Iridium-192 brachytherapy with flexible applicator--a trial toward decrease of stress during treatment and improvement of quality of life].

PURPOSE: We tried to improve the materials and methods of high-dose rate Iridium-192 brachytherapy for localized prostate cancer and evaluated the stress during the treatment in 20 patients with whom the therapy was performed. MATERIALS AND METHODS: Rigid applicators made of stainless steel of 1.6 mm in diameter were indwelt with a template as usual for 30 hours in 14 patients (group A). Flexible applicators made of polyoxymethylene rosin (POM) of 2.0 mm in diameter were indwelt without a template for 30 hours after the applicator insertion in 6 patients (group B). We made inquiries about lumbago, inconvenience and necessity of assistant help and sleep in the course of therapy, and urinary incontinence and erectile function after the course of therapy as the QOL. RESULTS: The stress during the course of therapy in the patients of group B was obviously less than that of group A. There were no significant differences in urinary incontinence and erectile function after the course of therapy between group A and B. CONCLUSION: In this study, our trial successfully reduced the stress during the course of therapy in the patients with localized prostate cancer in the course of high-dose rate Iridium-192 brachytherapy.

Aged↗

PubMed1975

[Interstitial curietherapy with iridium 192 applied to small cancers of the rectum (author's transl)].

Intracavity irradiation aimed at curing cancers of the rectum mainly calls on contact radiotherapy but also on interstitial curietherapy. Iridium curietherapy has replaced Radium-therapy owing to the better homogeneousness of its' action and precise method of assay. It uses a 2 pronged fork containing 2 Iridium wires which can be very simply placed in position. It is applied on the one hand to the base of the ulcerated tumour, after abraision by contactotherapy and on the other hand as a method of prophylactic irradiation after exeresis of a malignant or degenerated polyp where the scar is badly adapted to contacto-therapy.

Iridium↗

PubMed1992

The activity of platinum, iridium and rhodium drug complexes against Leishmania donovani.

The activities of twenty seven Platinum, Rhodium and Iridium drug complexes were determined against Leishmania donovani amastigotes in mouse peritoneal macrophages in vitro. Eight compounds showed antileishmanial activity of which only three, Rh(III)-mepacrine, Ir(III) pyrrolidine dithiocarbamate and Ir(III) diethyl dithiocarbamate had ED50 values of less than 1 microM. The two Iridium complexes produced, respectively, a 50% and 39% suppression of L. donovani amastigotes in the liver of BALB/c mice following the subcutaneous administration of 200 mg/kg for 5 consecutive days. Ultrastructural studies suggest that the amastigote kinetoplast-mitochondrion complex is the primary site of action of the Ir and Rh complexes.

Animals↗

PubMed2005

Curative radiotherapy for early cancers of the lip, buccal mucosa, and nose--a simple interstitial brachytherapy technique employing angiocatheters as carriers for Iridium-192 wire implants.

OBJECTIVES: To evaluate treatment outcomes following interstitial brachytherapy for cancers of the lip, buccal mucosa, or nose. DESIGN: Retrospective study. SETTING: Regional hospital, Hong Kong. PATIENTS: A cohort of 13 patients treated uniformly by a simple interstitial brachytherapy technique employing plastic angiocatheters as carriers for Iridium-192 wires: all but one patient had T1 or T2 tumours and all but one had N0 disease. MAIN OUTCOME MEASURES: Local and loco-regional control rates. RESULTS: Six of the 13 patients received external radiotherapy prior to interstitial brachytherapy. A median brachytherapy dose of 70 Gy was delivered to those treated with brachytherapy alone, while 35 Gy was delivered after a median external radiotherapy dose of 50 Gy to those receiving combined treatment. The 3-year actuarial local control rate was 75%. No significant late complications were observed. CONCLUSIONS: Employing a simple brachytherapy technique using angiocatheters and Iridium-192 wires, in conjunction with external radiotherapy when appropriate, produces good outcomes for patients with early lip, nasal vestibule, and buccal mucosa cancers.

Adolescent↗

PubMed1991

[Breast preserving therapy: shorter treatment duration by the peroperative introduction of iridium guide needles].

In the Deventer Radiotherapeutic Institute from January 1981 through December 1989, 359 patients who had undergone a breast-saving operation were irradiated. Since 1987, iridium guiding needles were introduced peroperatively in 79 of these patients. Subsequently, irradiation was administered. With this method the total duration of treatment was 16 days shorter on average than in patients who postoperatively were treated with iridium or external irradiation; also, the patients treated peroperatively needed only to be anaesthetized once. In addition, better positioning of the needles was possible, reducing the risk of faulty localization. The follow-up was short but the preliminary results of the treatment were good (one local recurrence after an average follow-up of 20 months) and no adverse effect on wound healing was seen.

Adolescent↗

PubMed1989

[Results of temporary interstitial iridium 192 implantation in head and neck tumors].

In order to improve local tumor control in advanced head and neck tumors, a temporary interstitial iridium-192 implantation (40 to 50 cGy/h) was performed as a boost therapy (20 to 30 Gy at the surface of the target volume). This treatment was part of a multimodal therapy conception for primary tumors (N = 55) as well as for recurrences (N = 22). Local control was achieved in 89% (49/55) of patients treated for primary tumors. Complications appeared in the form of soft tissue necroses in 55% (30/55) and in the form of osteoradionecrosis of the mandible in 7% (4/55) of the patients. The authors discuss as possible reasons for this high complication rate: implantation volume too large or total activity too high, activities of the individual iridium-192 seeds to high, setting of radiation sources too close together, total dose too high, disturbed reparation capacity of sound tissues due to preceding operation and chemotherapy, premature test biopsies in the area of implantation, lacking oral hygiene and dental care by uncooperative patients. A local control rate of 50% was achieved by the treatment of recurrences, but this has no importance for the course of this tumor disease which is fatefully determined by the formation of remote metastases.

Adult↗

PubMedDate not supplied

Inhibitory effects of some organometallic complexes of rhodium(I) and iridium(I) on carrageenin paw edema in rats.

A group of 4 organometallic complexes of Rhodium (I) and 1 Iridium(I) was tested for the evaluation of their anti-inflammatory activity on carrageenin paw edema in rats. All the compounds used inhibited the development of paw edema by more than 50% at different dose-levels. The activity of the pyridinalmethylimine derivative [Rh(COD)PMI]+ Cl- had better results than that of [Rh(NBD)PMI]+ Cl- and even more than the dimeric complexes tested. The higher activity of [Ir(COD)Cl]2 as compared with [Rh(COD)Cl]2 suggests that it would be of interest to examine further Iridium(I) complexes, among which [Ir(COD)PMI]+ Cl- could be a good candidate.

Animals↗

PubMed1987

[Salvage irradiation of epidermoid carcinoma of the oropharynx by iridium 192].

Between May 1971 and March 1982, 73 patients with either recurrent or subsequent squamous cell carcinomas arising in a previously irradiated oropharynx were treated using iridium 192 wires. Although local control was achieved in 72% of these patients, only 10 remained alive at 5 years (14%). Local control was best for tonsillar arch lesions (96%), while base of tongue and glosso-tonsillar sulcus tumors were controlled in only 60%. One of the two patients with a posterior pharyngeal wall lesion is alive and well at 5 years, while the other died of an unknown cause at 20 months. Salvage implantation produced soft tissue necrosis in 36% of base of tongue implants, but only 18% of those involving the tonsillar arch. Although one necrosis was fatal, the others were successfully managed medically. Since these results compare favorably with those of previously published series, we recommend re-irradiation with iridium 192 for recurrent or new malignancies arising in a previously irradiated oropharynx. For tonsillar arch lesions, brachytherapy is the treatment of choice while in the base of tongue, it is reasonable option.

Adult↗

PubMed1986

[Curietherapy of palpebral epithelioma with iridium-192. Method and results apropos of 192 cases treated at the Claudius-Regaud Center].

Authors report a series of 192 eyelid epithelial tumors (187 patients) treated by curietherapy (192 iridium) at the Centre Claudius-Regaud, from January 1977 to December 1982. Curietherapy is an interstitial radiotherapy technique which inserts radio-active lines directly in the epithelial area. The first part of treatment consisted in using disposable vascular catheters as after loading procedure. In 90% of the cases, lesions were either on the lower lid or on the inner canthus. Tumors were mainly of basal cell type (77%). One thousand forty one tumors occurred in untreated patients: treatment was made for local recurrences in 51 cases. The control rate was 97% (186/192). Six recurrences were all observed in basal cell carcinoma. Four of them were cured by a second curietherapy, the two others needed a large surgical enucleation followed in one case by external radiotherapy. Late side effects essentially were functional and ocular. Functional side effects (19% of the series) consisted in eyelid hole reduction (5%), epiphora stenosis (6%), ectropion (4%) and loss of substance (4%). Ocular complications (3% of the series), were ulcerated cornea (one case) hypertrophic conjunctivitis (one case), iatrogenic cataract (two cases) and enucleation for recurrence (two cases). Iridium 192 curietherapy allowed a high local control rate. The best results were seen in untreated patients. Iatrogenic cataract eventually would be avoided by the use of lead contact lenses (recent utilisation not included in this series).

Adult↗

PubMed1985

[Iridium curietherapy in conservative treatment of infiltrating cancer of the bladder].

Sixty patients with infiltrating bladder cancer were treated by partial cystectomy and iridium radiotherapy between 1977 and 1982. Actuarial 5-year survival was 90% for pT1, 51% for pT2 and 34% for pT3, bladder treatment being unsuccessful in 6 cases (11%). Long-term functional results were satisfactory. Iridium provides better radioprotection than radium and stricter dosage can be established. This conservative treatment for infiltrating bladder cancer is particularly indicated for pT1 and pT2 tumors, as single lesions and with a largest diameter not exceeding 4 cm. Results are better in cases with tumors of the mobile portion of bladder, the 5-year survival in these selected cases being 85% with a minimum of sequelae. This treatment may be used, generally combined with external radiotherapy, for tumors infiltrating deeply into muscle and more distant tissues.

Adenocarcinoma↗

PubMed1979

[A projector of iridium 192 wires: motivations and preliminary studies (author's transl)].

Though the majority of procedures involved in curietherapy with Iridium 192 wires cause very few problems concerning radiation protection, this is not true in all cases: in elderly of debilitated patients, young children, or when using special techniques (curietherapy for prostate of bladder cancers for example). In these cases, the need for frequent treatments exposes the therapists to increased doses. The projector of Iridium 192 wires was conceived in order to reduce this irradiation hazard. A simple manipulation places the radioactive wires in a lead container during treatment, and then replaces them in the right position after therapy. This apparatus appears to offer the possibility of: an almost total protection of the therapists, and thus an opportunity for enlarging the indications for curietherapy; an improved quality of treatment to the patient during the application.

Aged↗

PubMed1984

[Treatment, by 192-iridium curietherapy, of epitheliomas of the penis. Apropos of 36 cases].

Since 1975, 36 patients with squamous cell carcinoma of the penis have been treated with 192 Iridium at the Centre Léon Bérard: 17 T1 lesions, 18 T2 lesions and one T3 lesion. The tumor was less than 4 cm in diameter in 31 cases. Two patients presented with local recurrences after local excision and/or external beam irradiation with 60 Cobalt. In 32 patients followed for more than one year, the rate of local control was 84% (27/32). Five local failures were controlled by subsequent salvage surgery. The rate of severe complications is 25% (8/32): 2 urethral stenoses, 4 necroses, and 2 severe fibrosis. Conservation of a functional organ was possible in 72% of cases (23/32). Amputation was necessary in the 5 patients with lesions of more than 4 cm, because of local failure or painful complications. Ten patients had palpable inguinal lymph nodes, which were found to be involved in 4 cases. Three were controlled by combined radiotherapy and surgery. Among patients off any lymphadenopathy at the time of diagnosis, only one subsequently developed an inguinal metastasis which was controlled by radiotherapy and surgery. The disease-free survival rate was 81% at 3 years (22/27) and 75% at 5 years (12/16). Only one patient died of carcinoma. Curietherapy with 192 Iridium is very suitable treatment for cancers of the penis less than 4 cm in diameter. In most patients, the quality of life will be better than with primary surgical amputation, because sexual function is preserved.

Adult↗

PubMed1980

Iridium- 191 angiocardiography for the detection and quantitation of left-to-right shunting.

An osmium- 191 leads to iridium- 191 generator that can deliver multiple doses of Ir- 191m for first-pass radionuclide angiography has been developed. Iridium- 191m has a physical half-life of 4.96 sec and decays with emission of 65-keV and 129-keV photons in 58 and 30% abundance, respectively. Using a gamma camera, Ir- 191m radionuclide angiography was carried out, in dogs and ten patients, for the detection and quantitation of left-to-right shunting. In a one-year-old patients, 25 mCi of Ir- 191m results in a whole-body radiation absorbed dose of 35 mrad. Multiple Ir- 191m angiograms can be performed, seconds to minutes apart, without interference from background. The 15.4-day half-life of Os- 191 permits transportation of the generator to centers far from the production facility. With the low radiation dose, high information density, and the ability to repeat studies with Ir- 191m, clinical use of radionuclide angiography should be expanded.

Adolescent↗

PubMed1995

Trypanosoma brucei brucei: antitrypanosomal evaluation of stilbamidinium hexachloroiridiate on the murine CNS model and iridium serum kinetics in infected sheep.

Stilbamidinium hexachloroiridiate was found trypanocidal in vitro against Trypanosoma brucei brucei IPP at 600 microM after a 1 h incubation period and 30 microM after 24 h. This activity was confirmed in mice with a subcutaneous treatment at 20 mg/kg in a single dose. It was then evaluated on T.b. brucei murine CNS model. At the early stage, a subcutaneous treatment at 2 mg/kg/day x 5 cured 50% mice where-as one single dose at 10 mg/kg was completely inactive. Higher doses failed to cure the mice. Nevertheless, hexachloroiridiate salt of stilbamidine was 3.3 fold less toxic than dihydrochloride salt. Although the compound appeared inactive at the late stage of the murine trypanosomiasis, the difference of toxicity justified its evaluation on the early stage of sheep trypanosomiasis. The compound was trypanocidal at 2 mg/kg in a single dose when administered 8 days after infection. The study of iridium serum kinetic showed that stilbamidinium hexachloroiridiate was distributed rapidly according to a monocompartmental model. Moreover, iridium persisted in serum for a long time. The compound in aqueous suspension with 1% carboxymethylcellulose acted therefore as a controlled release system with a bioavailability allowing its trypanocidal action at the early stage.

Animals↗

PubMed1996

[Good results of bladder-preserving treatment in poorly differentiated and invasive bladder carcinoma using interstitial Iridium-192 radiotherapy].

OBJECTIVE: The analyse the efficacy and safety of conservative treatment for T1G3 and T2-T3a bladder carcinoma. DESIGN: Retrospective. SETTING: National Cancer Institute/Anthoni van Leeuwenhoek Hospital, Amsterdam, the Netherlands. METHODS: Between 1987 and 1994 (7 years) 63 patients with T1G3 or T2-T3a tumours < 5 cm diameter were treated with a combined approach consisting of a transurethral resection, a course of external irradiation (30 Gy in 15 fractions) to the bladder and an Iridium-192 implant procedure. RESULTS: After a mean follow-up of 4.2 years (range 3 months to 7.2 years) 42 patients were alive without tumour. Fourteen patients died from bladder cancer and 4 patients died from intercurrent disease. Three patients were alive with non-curable cancer. Nine patients had an isolated bladder relapse. Seven of these could be salvaged with cystectomy (3 patients) or transurethral resection (4 patients). Eight patients developed distant metastases only and 7 patients distant metastases combined with bladder recurrence. The 5 year actuarial survival was 66%. Acute and late morbidity was limited and mainly related to the surgical procedure. CONCLUSION: Bladder conservation using Iridium-192 implantation is an effective and safe procedure and in selected group of patients with bladder cancer it is a good alternative to radical cystectomy.

Adult↗

PubMed1997

[Conservative surgery and iridium 192 in stage pT2 bladder tumor. A 5-year follow up].

OBJECTIVE: Study of the 5-year oncological results of a series of 24 patients treated by conservative surgery and Iridium 192 for stage pT2 bladder transitional cell carcinoma. MATERIAL AND METHODS: Retrospective study of 24 patients (mean age: 60 years) treated between March 1979 and June 1988, for a solitary bladder tumour, with a diameter less than 5 cm, without lymphadenopathy or detectable metastases at the time of treatment. Treatment successively consisted of TUR of the lesion for histological diagnosis, preoperative pelvic irradiation of 10.5 Gy, lymph node dissection in 3 patients, insertion of brachytherapy tubes at the resection site (5 cases), associated with lumpectomy (9 cases) or partial cystectomy (10 cases). 18 patients underwent a brachytherapy with doses of 45 to 60 Gy, while 6 patients received a half-dose protocol: brachytherapy 30 Gy + postoperative external beam irradiation (20 to 30 Gy to the tumour site, 30 to 40 Gy to pelvic lymph node chains). RESULTS: At 5 years, 2 out of 6 deaths were attributable to bladder cancer. 4 other patients died without recurrence, 4 patients relapsed at the site of brachytherapy and/or away from this site, requiring salvage cystectomy in one patient, and repeated TUR +/- BCG therapy in the other three patients. Overall, 18 out of 24 patients were alive at 5 years, 17 had a functional bladder, and 14 were free of recurrence. CONCLUSION: Conservative surgery associated with Iridium 192 brachytherapy can be an oncologically reasonable alternative to total cystectomy for selected pT2 bladder tumours: unifocal tumours, less than 5 cm in diameter.

Adult↗

PubMed2003

New mechanistic insights into the iridium-phosphanooxazoline-catalyzed hydrogenation of unfunctionalized olefins: a DFT and kinetic study.

The reaction mechanism of the iridium-phosphanooxazoline-catalyzed hydrogenation of unfunctionalized olefins has been studied by means of density functional theory calculations (B3LYP) and kinetic experiments. The calculations suggest that the reaction involves an unexpected Ir(III)-Ir(V) catalytic cycle facilitated by coordination of a second equivalent of dihydrogen. Thus, in the rate-determining migratory insertion of the substrate alkene into an iridium-hydride bond, simultaneous oxidative addition of the bound dihydrogen occurs. The kinetic data shows that the reaction is first order with respect to hydrogen pressure. This is interpreted in terms of an endergonic coordination of this second equivalent of dihydrogen, although a rate-determining step, in which coordinated solvent is replaced by dihydrogen, could not be ruled out. Furthermore, the reaction was found to be zeroth order with respect to the alkene concentration. This correlates well with the calculated exothermicity of substrate coordination, and the catalyst is thus believed to coordinate an alkene in the resting state. On the basis of the proposed catalytic cycle, calculations were performed on a full-sized system with 88 atoms to assess the appropriateness of the model calculations. These calculations were also used to explain the enantioselectivity exerted by the catalyst.

Journal Article↗