High Dose-Rate Intraluminal Irradiation in Bronchogenic Carcinoma: Materials and Methods
Between June 1990 and April 1992, there were 32 patients who underwent 80 high dose-rate endobronchial applications. The median age was 59 years, with a range from 49 to 80 years. Thirty had primary malignant neoplasms of the lungs, and two had nonpulmonary tumors, one primary cervical carcinoma and one primary carcinoma of the colon metastatic to the bronchus. Twenty-two, including the patient with cervical primary carcinoma, had squamous cell carcinoma; five, including the patient with carcinoma of the colon, had adenocarcinoma; three had large cell carcinoma; one had a carcinoid tumor; and one had both adenocarcinoma and squamous cell carcinoma. The patients were divided into two groups. Group 1 consisted of 17 patients who were treated with endobronchial brachytherapy as a boost to primary external-beam irradiation. All had ASCC stage IIIB. The remaining 15 comprised group 2 and were treated for endobronchial recurrence after prior irradiation with an external beam. The pulmonary neoplasms were all stage IIIB. The cervical carcinoma was T3B. The carcinoma of the colon patient was stage III. The median external-beam dose prior to intraluminal treatment was 5,000 cGy. The range for group 1 was 5,000 to 6,000 cGy, and the range for group 2 was 4,000 to 5,000 cGy. Intraluminal brachytherapy was only performed when bronchoscopy revealed an endobronchial component of primary or recurrent tumor. canadianneighborpharmacy.com
The most severe presenting symptom for each patient included hemoptysis in 47 percent (15/32), persistent cough in 22 percent (7/32), and dyspnea in the remaining 31 percent (10/ 32). A combination of symptoms was seen in 25 patients. The following tabulation shows the numbers of patients by histologic findings and presenting sy mptoms (numbers within parentheses are percents):
Sauamous cell carcinoma 22 (69)
Adenocarcinoma 5 (16)
Large cell carcinoma 3 (9)
Carcinoid 1 (3)
Adenocarcinoma and squamous 1 (3)
Hemoptysis 15 (47)
Cough 7 (22)
Dyspnea 10 (31)
Combination of above 25 (78)
Of the 32 patients treated, 2 presented with Eastern Cooperative Oncology Group (ECOG) performance status (PS) of 4, twelve with PS of 3, ten with a PS of 2, seven with a PS of 1, and one with a PS of 0.
External-beam irradiation in all patients was administered with megavoltage apparatus using conventional fractionation and treatment plans based on computed tomography (CT) when appropriate.
For group 1, the median time between completion of external-beam irradiation and intraluminal application was 7 days. For group 2, it was an average of 6 months after external-beam therapy.
Endobronchial irradiation was delivered using a remote afterloader (Microselection) with an iridium 192 10-Ci high-activity source. All treatments were delivered on an outpatient basis. A flexible bronchoscope was passed down the bronchial tree toward the area involved with tumor. The tumors, which were generally exophytic, were examined. The location and extent of the tumor were documented. The distance of the lesion from the incisors is determined by holding the tip of the bronchoscope at the most distal point of the tumor. A cable with lead markers was then introduced into the afterloading catheter, which is then placed through the suction channel of the bronchoscope and advanced 1 cm past the tumor as determined at bronchoscopy or by thin-slice CT scan. A chest radiograph is taken, and the target region with a 1-cm proximal and distal margin is determined with the aid of the lead marker images. The proximal end of the afterloading catheter is then connected to the treatment machine. The technical details of the procedure have been described by us previously.- A uniform dose of 500 cGy per fraction for 28 patients and 400 cGy for 4 patients was prescribed at a distance of 1 cm from the central axis of the catheter. The length of treatment varied from 4 to 7 cm, with a median length of 5 cm. The majority of patients received 3 to 4 fractions, with a time interval between fractions of 1 week. Figure 1 shows a transverse, coronal, and sagittal reconstruction of isodose distribution for a typical endobronchial high dose-rate treatment.
Figure 1. Transverse, coronal, and sagittal reconstruction of isodose distribution for typical endobronchial high-dose treatment.