Japanese Journal of Clinical Oncology 30:109-112 (2000)
© 2000 Foundation for Promotion of Cancer Research
CT-assisted Transbronchial Brachytherapy for Small Peripheral Lung Cancer
1Endoscopy Division and 2Radiation Oncology Division, National Cancer Center Hospital, Tokyo, 3Division of Thoracic Oncology, National Cancer Center East, Kashiwa, Chiba and 4Thoracic Surgery Division, National Cancer Center Hospital, Tokyo, Japan
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ABSTRACT |
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 TOP ABSTRACT INTRODUCTIONTECHNIQUEDISCUSSIONREFERENCES |
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Transbronchial brachytherapy for small peripheral lung cancer was developed with the use of the CT-guided bronchoscopy technique. Under CT guidance, an applicator carrying a dummy source was introduced into a lesion and stabilized. A radioactive source was then delivered through the applicator using a high dose rate remote afterloading system. For multiple radiation fractions, a marker was placed immediately under the pleura in a peripheral bronchus penetrating the lesion using the CT-guided barium marking technique. During brachytherapy, an applicator with a dummy source was inserted under fluoroscopic guidance up to the marker. A radioactive source was subsequently delivered. CT-assisted transbronchial brachytherapy allows radiation to be delivered from inside a lesion. This minimizes radiation damage to non-cancerous tissue and offers distinct advantages over conventional radiation techniques.
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONTECHNIQUEDISCUSSIONREFERENCES |
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Small peripheral lung cancers are increasingly detected when computed tomography (CT) is used for various purposes. The best treatment for these cancers is surgical resection. However, resection is not always possible, e.g. in patients with poor medical condition, such as insufficient pulmonary function. These situations are not rare because of the multicentricity of lung cancers and an increasingly older patient population. Furthermore, surgical resection of minute peripheral lung cancers in older people remains controversial. Their life expectancies are short and the risks of resection are not nominal. In these situations, less invasive treatment of small peripheral lung cancer is desired.
Treatment of lung cancer with high dose rate (HDR) endobronchial brachytherapy using remote afterloading systems is one treatment standard that yields relatively good results (1). HDR brachytherapy is usually applied as a boost to external irradiation (2). Additionally, limited endobronchial lung cancer can be treated by HDR brachytherapy alone. However, precise delivery of irradiation sources to the periphery of the lung is difficult using a transbronchial approach. HDR brachytherapy is therefore difficult to apply to the treatment of peripheral lung cancers.
Earlier, we developed CT-guided bronchoscopic biopsy of minute peripheral lung cancers (3). The technique is currently used on a routine basis. This permits precise approaches to peripheral lesions. An extension of the technique is CT-guided bronchoscopic barium marking for resection of fluoroscopically invisible peripheral pulmonary lesions (4). Other extension applications are anticipated. Applying CT-guided bronchoscopic biopsy and barium marking techniques, HDR transbronchial brachytherapy for small peripheral lung cancer was developed.
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TECHNIQUE |
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Case 1
A 57-year-old man had a 2.3 x 2.2 cm adenocarcinoma in the right S10a (T1N2M0 stage IIIA) and a 1.9 x 1.9 cm adenocarcinoma in the left S4b (T1N0M0). A histological diagnosis of the right lesion was established by bronchoscopy. The diagnosis of the left lesion was facilitated by CT-guided bronchoscopy. The right lesion and the mediastinum were treated with chemotherapy and concomitant external radiation. To minimize radiation pneumonitis and its attendant compromise of pulmonary function, it was decided to treat the left lesion through CT-assisted transbronchial brachytherapy. Informed consent was obtained prior to the procedure.
For all bronchoscopic procedures, a videobronchoscope was inserted orally under local anesthesia (using 4% lidocaine) after giving 0.5 mg of atropine sulfate intramuscularly. The lesion was initially marked using the CT-guided bronchoscopic barium marking technique (4). First, a transbronchial aspiration cytology (TBAC) needle whose tip had been removed was inserted into a bronchus penetrating the lesion until the TBAC needle reached the visceral pleura. The precise placement of the TBAC needle in the lesion was confirmed by high-resolution CT with a 2 mm slice thickness. A 0.2 ml volume of 100% (w/v) barium sulfate suspension in distilled water was then instilled in the peripheral bronchus directly under the visceral pleura. The marker permits the tip of an applicator carrying a dummy source to be inserted into the same bronchus under fluoroscopy guidance (no need for CT guidance). In this manner, precise delivery of a radiation source to the left lesion was possible throughout each of the planned three stages of treatment.
Nine days after the barium marking, biopsy forceps of 2.6 mm diameter were inserted through a videobronchoscope up to the marker in order to bougienage the bronchus leading to the lesion. Subsequently, a 5 Fr applicator carrying a dummy source was inserted up to the site of the barium marker through the videobronchoscope. Precise placement of the tip of the applicator at the barium marker was verified fluoroscopically. Frontal and lateral X-ray films provided the coordinates that were entered into a computer for calculation of the treatment plan (Planning Treatment Optimization–Brachytherapy Planning System, version 13.3, PLATO-BPS version 13.3; Nucletron Oldelft, Columbia, MD).
Seven days after treatment calculation, the applicator with its dummy source was re-inserted and positioned in the same manner. After fluoroscopically confirming that the tip of the dummy source in the applicator was precisely at the barium marker, the videobronchoscope was extracted and the applicator was stabilized between the pleura and the orifice of the patient’s mouth piece with appropriate tension towards the pleura. The location of the applicator with the dummy source was confirmed fluoroscopically if necessary. The dummy source was then extracted from the applicator and a radioactive source (iridium-192) was inserted into the applicator using an HDR remote afterloading system (Micro-Selectron; Nucletron Oldelft). A radiation dose of 24 Gy at a 10 mm radius from the center of the applicator was delivered in three fractions at 7 day intervals. The applicator was confirmed bronchoscopically to be in the initial location and subsequently the applicator was extracted. During brachytherapy, the patient was sedated using diazepam.
After a period of 18 months after the completion of brachytherapy, CT revealed focal radiation fibrosis at the treatment site. No change in tumor size was noted. Severe radiation fibrosis was observed in the right lung. No untoward sequelae from the brachytherapy were observed.
Case 2
A 62-year-old man had a 2.6 x 1.8 cm adenocarcinoma (Fig. 1a) in the right S2b (T1N0M0 stage I). The diagnosis was facilitated by CT-guided bronchoscopic biopsy. Earlier, he had had a left upper lobectomy for adenocarcinoma. His residual pulmonary function was considered inadequate to withstand anything except a minimally invasive procedure for the right lesion. CT-assisted transbronchial brachytherapy was performed with the patient’s informed consent.
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He was pre-medicated with 0.5 mg of atropine sulfate intramuscularly. A videobronchoscope was then inserted orally through a tracheal tube under local anesthesia (4% lidocaine). Using the CT-guided bronchoscopy technique (3), biopsy forceps of 2.6 mm diameter were inserted though the lesion up to the pleura in order to bougienage the bronchus leading to the lesion. Precise placement of the forceps in the lesion was confirmed by high-resolution CT with 2 mm thick slices. After extracting the forceps from the bronchus and the videobronchoscope, a 6 Fr applicator carrying a dummy source was inserted through the videobronchoscope and through the lesion up to the pleura. After confirming the precise location of the applicator with the dummy source by high-resolution CT (Fig. 1b), the videobronchoscope was extracted, leaving the applicator with the dummy source, and the applicator with the dummy source was stabilized between the pleura and the orifice of the tracheal tube with appropriate tension towards the pleura (Fig. 1c).
The patient was then transferred from the bronchoscopy room to the radiation treatment room. Frontal and lateral X-ray films provided information to calculate the treatment plan using PLATO-BPS version 13.3. The location of the applicator with the dummy source was confirmed fluoroscopically if necessary. After calculation, the dummy source was pulled out of the applicator. A radioactive source, iridium-192, was inserted into the applicator and a dose of 15 Gy in a single fraction was delivered at a 10 mm radius from the center using the HDR remote afterloading system. The applicator was confirmed bronchoscopically to be in the initial location and subsequently the applicator was extracted. There were no undue complications during the procedure.
The tumor size was reduced by 75% showing radiation fibrosis as determined by high-resolution CT taken 10 months after the brachytherapy (Fig. 1d). No sequelae were observed in the 10 month post-treatment period.
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DISCUSSION |
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TOPABSTRACTINTRODUCTIONTECHNIQUEDISCUSSIONREFERENCES |
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CT-assisted transbronchial brachytherapy is indicated for small peripheral lung cancers in patients whose medical condition is less than ideal to permit other therapeutic modalities. The technique has the advantage of delivering an appropriate radiation dose from inside the lesions while minimizing damage to surrounding normal tissue. As the dose is administered from inside the lesion, radiation delivery is not affected by respiratory movements or by cardiac movements. This offers a clear advantage over external irradiation, including heavy particle irradiation.
There are no contraindications to the procedure other than those that would contraindicate basic bronchoscopy. Hemorrhage from ordinary endobronchial brachytherapy for cancers located in the central bronchi or the trachea is sometimes fatal because the hemorrhage is from larger blood vessels. As is well experienced in routine bronchoscopy, hemorrhage from the peripheral lung is generally less severe than that from the central airway because the amount of blood is usually less in the peripheral hemorrhage and the peripheral hemorrhage can be controlled by certain procedures such as tamponade with fibrin glue or cotton; however, central hemorrhage is difficult to control. Likewise, with CT-assisted transbronchial brachytherapy for small peripheral lung cancer, hemorrhage is not anticipated to be clinically significant as this would be limited in volume and localized to a small peripheral region.
Likewise, CT-guided percutaneous brachytherapy can feasibly be performed with good results (5). However, the transbronchial approach allows the use of thicker catheters than those permitted by a transthoracic approach. Iatrogenic infection and pneumothorax are not significant concerns with a transbronchial approach, in contrast to a transthoracic approach. Video-assisted thoracic surgery (VATS) remains an option for patients who can tolerate a pneumothorax. In addition, once drainage for pneumothorax is performed, the discomfort might be similar to that after VATS.
The main drawback of CT-guided transbronchial brachytherapy is its technical difficulty. Small lesions are difficult to approach even under CT guidance and require a certain level of skill and experience. Due attention must be given to the patient’s comfort as the endoscopic procedure is uncomfortable unless performed under general anesthesia. This concern needs to be addressed by developing better options for sedation and anesthesia. In practice, the patient’s discomfort is much less than expected. Experience with CT-guided bronchoscopic biopsy demonstrates that delicate manipulation of the bronchoscope is required to access small lesions. This causes much less stimulation of the bronchi and much less discomfort. The latter can also be inferred from the fact that patients undergoing CT-guided bronchoscopy can keep still long enough for 2 mm thick CT images to be taken. This would be impossible if the patient coughs or moves because of discomfort.
Prior application of CT-guided bronchoscopic barium marking facilitates the performance of brachytherapy and effectively shortens the procedure time. After marking and calculation of the treatment plan, brachytherapy can be performed under fluoroscopic guidance. The latter requires less time than the CT-guided procedure. This approach is practical considering the fact that remote afterloading systems are equipped with fluoroscopy systems for guidance, not CT systems. CT-guided bronchoscopic barium marking is an ideal technique that facilitates the delivery of multiple radiation fractions to small peripheral lung cancers.
However, multiple radiation fractions eventually cause bronchitis. This could pose difficulties in inserting an applicator, as was experienced during the third radiation session with our first patient. One option to overcome this problem is to deliver a large dose in a single fraction. This is possible considering the limited area of tissue damage resulting from CT-assisted transbronchial brachytherapy for small peripheral lung cancer.
The technique is relatively new and still under development. However, experience to date indicates that CT-assisted transbronchial brachytherapy is a feasible therapeutic option for patients with less than ideal pulmonary function and medical condition.
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FOOTNOTES |
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+ For reprints and all correspondence: Toshiaki Kobayashi, Endoscopy Division, National Cancer Center Hospital, 1–1, Tsukiji 5-chome, Chuo-ku, Tokyo 104-0045, JapanAbbreviations: CT, computed tomography; HDR, high dose rate; TBAC, transbronchial aspiration cytology
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REFERENCES |
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TOPABSTRACTINTRODUCTIONTECHNIQUEDISCUSSIONREFERENCES |
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1 Barber P, Stout R. High dose rate endobronchial brachytherapy for the treatment of lung cancer: current status and indications. Thorax 1996;51:345–7.
2 Huber RM, Fischer R, Hautmann H, Poellinger B, Haeussinger K, Wendt T. Does additional brachytherapy improve the effect of external irradiation? A prospective, randomized study in central lung tumors. Int J Radiat Oncol Biol Phys 1997;38:533–40.[Web of Science][Medline]
3 Kobayashi T, Shimamura K, Hanai M, Kaneko M. Computed tomography-guided bronchoscopy with an ultrathin fiberscope. Diagn Ther Endosc 1996;2:229–32.[Medline]
4 Kobayashi T, Kaneko M, Kondo H, Nakayama H, Asamura H, Tsuchiya R, et al. CT-guided bronchoscopic barium marking for resection of a fluoroscopically invisible peripheral pulmonary lesion. Jpn J Clin Oncol 1997;27:204–5.
5 Brach B, Buhler C, Hayman MH, Joyner LR Jr, Liprie S. Percutaneous computed tomography-guided fine needle brachytherapy of pulmonary malignancies. Chest 1994;106:268–74.
Received September 6, 1999; accepted November 8, 1999.
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