Pulmonary Medicine

Interventional Bronchoscopy: Brachytherapy

General description of procedure, equipment, technique

Brachytherapy

Initially defined in 1995 and subsequently described in European Respiratory Society (ERS) and American Thoracic Society (ATS) guidelines, interventional pulmonology is "the art and science of medicine as related to the performance of diagnostic and invasive therapeutic procedures that require additional training and expertise beyond that required in a standard pulmonary medicine training program." Clinical entities encompassed within the discipline include complex airway management, benign and malignant central airway obstruction, pleural diseases, and pulmonary vascular procedures.

Diagnostic and therapeutic procedures pertaining to these areas include rigid bronchoscopy, transbronchial needle aspiration, autofluorescence bronchoscopy, endobronchial ultrasound, transthoracic needle aspiration and biopsy, laser bronchoscopy, endobronchial electrosurgery, argon-plasma coagulation, cryotherapy, airway stent insertion, balloon bronchoplasty and dilatation techniques, endobronchial radiation (brachytherapy), photodynamic therapy, percutaneous dilatational tracheotomy, transtracheal oxygen catheter insertion, medical thoracoscopy, and image-guided thoracic interventions. This presentation focuses on brachytherapy.

Endobronchial radiation therapy by the use of an implanted source of ionizing radiation (brachytherapy) was first used in the 1920s. Yankauer reported on the implantation of radium into an endobronchial tumor using a bronchoscope, with the radium in capsules attached to a string that exited through the mouth.

In the mid-1980s, publications distinguished low-dose-rate (LDR) from high-dose-rate (HDR) brachytherapy. LDR brachytherapy is usually defined as delivery of less than two gray (Gy) per hour and a total dose between 1500 and 5000 Gy, given over three days. HDR entails delivery of more than ten Gy per hour, in which the total dose and the dose per session varies from approximately 300 to 1000 Gy, and total dose from approximately 500 to 4000 Gy. Development of the "remote afterloading device" reduced the radiation exposure to the healthcare staff.

Subsequently, use of the flexible bronchoscope and the polyethylene catheter that holds the radioactive material for brachytherapy was described, along with a description of Iridium-192, the current radiation source.

Indications and patient selection

The indications for brachytherapy are similar to those for the other endobronchial therapies. The therapeutic goal is palliation of symptoms caused by airway obstruction by tumor. However, brachytherapy may also be used as an adjunct to external beam radiotherapy for treatment of otherwise unresectable lung cancers. Some investigators have used the technique in patients who have histologically positive surgical margins following surgical resection.

Contraindications

Absolute contraindications for endobronchial brachytherapy include known fistulas to non-bronchial tissue areas and lesions that have not been proved to be malignancies. Because of the potential for post-radiation edema and total airway obstruction, patients with endotracheal carcinoma that causes high-grade obstruction should be treated with Nd: YAG laser and possible stent placement prior to brachytherapy.

Details of how the procedure is performed

Intraluminal brachytherapy currently uses fiberoptic bronchoscopy for the placement of the radiation source after it is loaded into a polyethylene catheter. Loading of the catheter with the radiation source may be performed manually or through use of a remote after loader. Placement of the radiation source is verified by bronchoscopy and radiography.

The dose rate of brachytherapy depends on the radioactivity of the radionuclide used. The apparatus designed to deliver HDR brachytherapy uses iridium 192, which is the radionuclide of choice. HDR brachytherapy is usually delivered as fractionated doses in order to maximize its safety and effectiveness.

Treatment schedules vary in clinical practice because the procedure requires bronchoscopy and placement of endobronchial catheters during each session. Most patients are treated once per week or once per two weeks, rather than once daily, in order to minimize patient discomfort.

Interpretation of results

Not applicable

Performance characteristics of the procedure (applies only to diagnostic procedures)

Not applicable.

Outcomes (applies only to therapeutic procedures)

Most studies of brachytherapy have reported on its use in combination with external beam radiation therapy. Subjective improvement after brachytherapy has ranged from 20 percent to 100 percent, depending on the symptoms. Hemoptysis is relieved in more than 90 percent of patients, but cough and dyspnea are only moderately or minimally relieved, probably because of underlying of chronic bronchitis or radiation fibrosis. Most studies report greater than 50 percent improvement in airway patency, and positive responses usually persist for six months or more.

Conventional external-beam radiation therapy relieves symptoms of hemoptysis, dyspnea, or chest pain in 50-80 percent of patients for three to four months. No studies have directly compared external-beam radiation therapy with endobronchial brachytherapy. However, based on existing data, endobronchial brachytherapy has been relegated to a second-line treatment option that offers effective palliation.

Alternative and/or additional procedures to consider

Not applicable.

Complications and their management

Brachytherapy has both early complications and late complications. The two most serious complications are massive hemoptysis and fistula formation to the mediastinum. Several large series have reported a rate of serious complications of 0-42 percent. Risk of massive pulmonary hemorrhage is likely related to the proximity of pulmonary arteries to the left upper lobe bronchus. In one report, massive hemoptysis following treatment occurred at a rate of 32 percent in patients with recurrent tumors in the right upper lobe bronchus, the right mainstem bronchus, and the left upper lobe bronchus.

What’s the evidence?

Burt, PA, O' Driscoll, BR, Notely, HM. "Intraluminal irradiation for the palliation of lung cancer with the high dose rate microselectron". Thorax. vol. 45. 1990. pp. 765-768.

A description of the use of high-dose irradiation for palliation of endobronchial tumors.

Golling, SW, Burt, PA, Barber, PV. "High dose rate intraluminal radiotherapy for carcinoma of the bronchus: Outcome of treatment of 406 patients". Radiother Oncol. vol. 33. 1994. pp. 310-349.

A large series describing outcomes with brachytherapy.

Henschke, UK, Hilaris, BS, Mahan, GD. "Remote after loading with intracavitary applicators". Radiology. vol. 83. 1964. pp. 344-345.

Early description of the technique of brachytherapy.

Khanavka, B, Stern, P, Alberti, W. "Complication associated with brachytherapy alone or with laser in lung cancer". Chest. vol. 99. 1991. pp. 1062-1065.

A discussion of the complications associated with brachytherapy.

Mendiondo, DA, Dillon, M, Beach, U. "Endobronchial brachytherapy in the treatment of recurrent bronchogenic carcinoma". Int J Radiat Oncol Biol Phys. vol. 9. 1983. pp. 579-582.

A historical perspective on the use of brachytherapy in treatment of lung cancer.

Nori, U, Allison, R, Kaplan, B. "High dose-rate intraluminal irradiation in bronchogenic carcinoma". Chest. vol. 104. 1993. pp. 1006-1011.

A report confirming the value of brachytherapy in the treatment of bronchogenic carcinoma.

Sutedja, G, Bans, G, Van Zandwijk, N. "High-dose rate brachytherapy has a curative potential in patients with intraluminal squamous cell lung cancer". Respiration. vol. 61. 1993. pp. 167-168.

A description of the use of endobronchial brachytherapy for possible cure in lung cancer.

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