Predictive factors for late toxicity after endobronchial brachytherapy: a multivariate analysis

PURPOSE

To determine the predictive factors associated with hemoptysis and radiation bronchitis after endobronchial brachytherapy by univariate and multivariate analyses

METHODS AND MATERIALS

One hundred forty-nine patients underwent endobronchial brachytherapy and were divided into three therapeutic groups: group 1: patients treated with palliative intent (n=47); group 2: patients treated with curative intent (small endobronchial tumors without mediastinal or general dissemination: n=73); group 3: patients also receiving external irradiation (n=29). One hundred twelve patients had previously received external irradiation. Brachytherapy was delivered with a dose per fraction ranging from 4 to 7 Gy and a prescription point between 0.5 and 1.5 cm, usually 1 cm from the source center. Two to six fractions were delivered according to the therapeutic group and clinical situation. The influence of the following variables on the incidence of hemoptysis or radiation bronchitis was studied: age, sex, Karnofsky score, therapeutic group, histologic type, endoscopic tumor length, dose per fraction, total brachytherapy dose, total external beam irradiation dose, total dose (brachytherapy dose plus external irradiation dose), volumes of the 100% and 200% isodoses, and volumes of the 7 and 14 Gy isodoses.

RESULTS

We observed 11 hemoptyses (7.4%), 10 were lethal. All but one occurred in patients with progressive disease. Two clinical factors were significantly associated with hemoptysis by univariate analysis: palliative group (p=0.009) and endobronchial tumor length (p=0.004). No technical factors seem to be implicated in the occurrence of hemoptysis. Only endobronchial tumor length remained in the multivariate model (p=0.02). Radiation bronchitis was observed in 13 cases (8.7%). By univariate analysis, a good Karnofsky score (p=0.02), curative treatment (p=0.02), and tumor location on trachea and main stem bronchus (p=0.002) were significantly associated with this complication. Two technical factors were also incriminated: the total dose (p=0.04) and the 100% isodose volume (p=0.02). By multivariate analysis, only the tumor location retained statistical significance (p=0.009).

CONCLUSION

Hemoptysis is most likely due to disease progression, with the bleeding being facilitated by brachytherapy. Some rare cases could be a direct complication of brachytherapy itself, particularly when tumors are located in the upper lobes. In contrast, radiation bronchitis occurred more frequently in patients with controlled disease, and was significantly influenced by tumor location and technical factors (dose and volumes treated). Technical improvements should increase the therapeutic ratio.

Alterations in the expression of chemokine mRNA levels in fibrosis-resistant and -sensitive mice after thoracic irradiation

Fibrosis, characterized by the accumulation of collagen, is a consequence of a chronic inflammatory response. The purpose of this study was to determine if the mRNA expression of the chemokines, lymphotactin (Ltn), RANTES, eotaxin, macrophage inflammatory protein (MIP)-1 alpha, -1 beta, and -2, interferon-inducible protein 10 (IP-10), and monocyte chemotactic protein-1 (MCP-1), are altered during the development of radiation-induced pneumonitis and fibrosis. Further, we wished to determine if these changes differ between two strains of mice that vary in their sensitivity to radiation fibrosis. Fibrosis-sensitive (C57BL/6) and fibrosis-resistant (C3H/HeJ) mice were irradiated with a single dose of 12.5 Gy to the thorax. Total lung RNA was prepared and hybridized utilizing RNase protection assays. Data were quantified by phosphorimaging and results normalized to a constituitively expressed mRNA L32. 8 weeks post-irradiation most chemokines measured were elevated to varying degrees. The degree of elevation of each chemokine was identical in both strains. This suggested that chemotactic activity for neutrophils, macrophages, and lymphocytes were occurring during pneumonitis. By 26 weeks post-irradiation, messages encoding Ltn, RANTES, IP-10, and MCP-1 were elevated only in fibrosis sensitive (C57BL/6) mice. In situ hybridization demonstrated that MCP-1 and RANTES transcripts were produced predominantly from macrophages and lymphocytes. These studies suggest that lymphocytic recruitment and activation are key components of radiation-induced fibrosis.

Molecular and cellular basis of radiation fibrosis

PURPOSE

Recent data from the literature and the experimental work of the authors clearly indicate that TGF-beta1 is a key modulator of cellular events, for example, induction of terminal differentiation, resulting in radiation-induced fibrosis. Therefore, the present study analysed which cellular processes induced by exogenously added TGF-beta could be responsible for the induction, development and manifestation of the fibrotic phenotype in culture.

MATERIALS AND METHODS

Rat lung fibroblast cultures (passage 1) were used. As a function of treatment with TGF-beta and/or anti-TGF-beta-antibody, the clonogenic activity and differentiation pattern were analysed by colony-formation assays.

RESULTS

It could be demonstrated that treatment of rat lung progenitor fibroblasts with TGF-beta1 resulted in a pronounced shift in the differentiation pattern, i.e. induction of post-mitotic fibrocytes. This TGF-beta1-dependent terminal differentiation could be abolished by simultaneous treatment with a neutralizing antibody directed against TGF-beta1.

CONCLUSIONS

The data presented indicate that TGF-beta1 is one major candidate mediating the accelerated terminal differentiation of progenitor fibroblasts to post-mitotic functional fibrocytes, which results in the fibrotic phenotype of this cell system.

[The inhalation versus systemic prevention of pneumonitis during thoracic irradiation]

BACKGROUND

Pneumonitis is a typical subacute reaction of healthy bronchial tissue to thoracic irradiation. The purpose of the present trial was to show whether prophylactic application of steroids in the course of and following radiotherapy would reduce the incidence of pneumonitis.

PATIENTS AND METHODS

Fifty-seven patients receiving thoracic irradiation for bronchial carcinoma were assigned to 2 therapeutic groups; half of the patients were given 10 mg of oral prednisolone per day, while the other half received daily inhalative beclomethasone. All patients were evaluated for radiographic signs of pneumonitis. Thirty-two patients received additional investigations for pulmonary diffusion capacity of carbon monoxide.

RESULTS

The overall incidence of pneumonitis was 17.6% (10/57 patients). Neither total radiation dose nor mode of fractionation did significantly contribute to the incidence of pneumonitis. Those patients showing a pulmonary diffusion capacity for carbon monoxide of less than 60% prior to radiotherapy had a significantly higher risk of developing pneumonitis (4/7) than patients with a higher diffusion capacity (3/25, p = 0.026). In follow-up period we did not see significant changes in diffusion capacity neither with patients who developed pneumonitis nor with those patients showing no evidence of pulmonary injury. Comparing the chest X-ray there were less radiographic changes consistent with pneumonitis in the inhalative beclomethasone (2/28) than in the oral prednisolone group (8/29, p = 0.045).

DISCUSSION

In order to reduce the incidence of pneumonitis in patients receiving thoracic irradiation we support a continuous application of steroids in the course of and following radiotherapy. The inhalative use of beclomethasone has proved to be superior to oral prednisolone due to better local efficacy and decreased unwanted side effects.

Risk factors of pneumonitis following chemoradiotherapy for lung cancer

The purpose of this retrospective study was to identify risk factors associated with development of pneumonitis following chemoradiotherapy (CRT). We examined 60 patients (pts) who received CRT from May 1993 to August 1995. Factors evaluated included total radiation dose, field-size, irradiated site, type of chemotherapy, pulmonary fibrosis and treatment schedule (concurrent versus sequential). There were 17 pts (28.3%) who had > or = Grade 2 pulmonary toxicity. There was no significant relationship between total radiation dose, field-size > or = 200 cm2, pulmonary fibrosis or treatment schedule and risk of pneumonitis. In the sequential treatment group (22 pts), no relationship was noted between any factor and the risk of pneumonitis, while in the concurrent treatment group (38 pts), the incidence of pneumonitis was more frequent (53.8%) in patients with field-size > or = 200 cm2 than in patients with field-size < 200 cm2 (P < 0.05). In those who received concurrent treatment, including weekly CPT-11, pneumonitis was more frequent (56.3%) than in those without CPT-11 (13.6%, P < 0.01). When the lower lung field was included in the radiation site, the incidence of pneumonitis was 70% compared with 20% for other sites (P < 0.01). Multivariate analysis revealed a significant relationship between radiation site and the risk of pneumonitis (P = 0.0096). CPT-11 was significant (P = 0.038) only in the concurrent group. Pneumonitis was reversible in all but one pt by steroid therapy. Thus, irradiated site (included lower lung field) and concurrent CRT used with weekly CPT-11 were treatment factors significantly associated with a higher risk of pneumonitis following CRT.

[Intrabronchial curietherapy. Experiences at Hôpital Saint-Louis after the treatment of 149 patients]

Endobronchial tumour obstruction threatens to occur in cases of carcinoma of the bronchus throughout the course of the disease. Such patients can benefit from relief of the bronchial obstruction by several techniques which are currently available. We have treated 149 patients with endobronchial radiotherapy. Seventy three patients were treated with a view to cure, 47 with a palliative dose and 29 received endobronchial radiation in complement with external irradiation. The treatment was carried out in series repeated every 15 days until a maximum of three treatments, consisting of two sessions at 24 hour intervals delivering at each session and irradiating of 7 Gy with a 1 cm catheter. All the clinical signs were relieved and in 79% of patients there was a symptomatic benefit. One hundred and thirty two patients were evaluated by control endoscopy two months after the treatment and 64 had a complete histological remission. The median survival was 14.4 months for patients treated with intent to cure. Obtaining a histological remission was a gauge for prolonged survival (median survival 26.5 months), 11 (7.4%) had massive hemoptysis and 13 (8%) irradiation pneumonitis, all of which occurred some time after the therapeutic procedure. The results confirm the feasibility and the good results of endobronchial irradiation in this field and encourage the idea of controlled multi-centre trials in order to assess a placed of endobronchial radiotherapy in the therapeutic strategy of bronchial cancer.

[Radiation- and chemically-induced respiratory manifestations]

There are frequently respiratory complications with cancer particularly in primary lung carcinoma. Among these are bronchopulmonary infections with or without endobronchial obstruction, carcinomatous lymphangitis, thromboembolic disease and haemorrhagic disease as well. Radiotherapy and chemotherapy may induce various respiratory complications which diagnosis can be of varying shades of difficulty. The classical post radiation pneumonitis occurring exclusively in the field of radiation hardly poses any problem unless it could be masking a recurrence. Certain clinical manifestations address very difficult problems of differential diagnosis by their lack of specificity and by their often unforeseeable character (except for bleomycin fibrosis which is perfectly dose dependent). Moreover patients often have multiple treatments and the identification of the single responsible agent becomes very difficult. We will not discuss here the infectious or secondary haemorrhagic complications of radiotherapy or chemotherapy but rather the anaphylactic manifestations, diffuse interstitial pneumonia with lymphocytic alveolitis or fibrosis, eosinophilic pneumonia, non-cardiogenic pulmonary oedema, bronchiolitis obliterans with organising pneumonia and the rare pulmonary vascular disorders such as pulmonary veno-occlusive disease.

Biological effects of inhaled 238PuO2 in beagles

Beagle dogs exposed to 238PuO2 aerosols (136 dogs, 13-22 per group, mean initial lung depositions of 0.0, 0.13, 0.68, 3.1, 13, 52 and 210 kBq) were observed throughout life to determine tissues at risk and dose-effect relationships. The pulmonary retention of 238Pu was represented by the sum of two exponentially decreasing components of the initial lung deposition; about 84% cleared with a 174-day half-time; the half-time of the remainder was 908 days. The average percentages of final body burden found in lung, skeleton, liver and thoracic lymph nodes in the 30 longest-surviving dogs (mean survival 14 years) were 1, 46, 42 and 6%, respectively. Of 116 beagles exposed to plutonium, 34 (29%) developed bone tumors, 31 (27%) developed lung tumors, and 8 (7%) developed liver tumors. Although lungs accumulated a higher average radiation dose than skeleton, more deaths were due to bone tumors than to lung tumors. Deterministic effects included radiation pneumonitis, osteodystrophy, hepatic nodular hyperplasia, lymphopenia, neutropenia and sclerosing tracheobronchial lymphadenitis. Hypoadrenocorticism was also observed in a few dogs. Increased serum alanine aminotransferase, indicative of liver damage, was observed in groups with > or =3.1 kBq initial lung deposition. Estimates of cumulative tissue dose in a human exposed to airborne 238PuO2 for 50 years at a rate of one annual limit on intake each year were derived based on a comparison of the data on metabolism for humans and beagles. The 50-year dose estimates for humans are an order of magnitude lower than doses at which increased incidence of neoplasia was observed in these dogs, whereas the projected doses to humans from 50-year exposure at the annual limit of intake are of similar magnitude to those at which deterministic effects were seen in the beagles.

Is the time interval between surgery and radiotherapy important in operable nonsmall cell lung cancer? A retrospective analysis of 340 cases

PURPOSE

To evaluate the influence of prognostic factors in postoperative radiotherapy of NSCLC with special emphasis on the time interval between surgery and start of radiotherapy.

METHODS AND MATERIALS

Between January 1976 and December 1993, 340 cases were treated and retrospectively analyzed meeting the following criteria: complete follow-up; complete staging information including pathological confirmation of resection status; maximum interval between surgery (SX) and radiotherapy (RT) of 12 weeks (median 36 days, range 18 to 84 days); minimum dose of 50 Gy (R0), and maximum dose of 70 Gy (R2). Two hundred thirty patients (68%) had N2 disease; 228 patients were completely resected (R0). One hundred six (31%) had adenocarcinoma, 172 (51%) squamous cell carcinoma.

RESULTS

In univariate analysis, Karnofsky performance status (90+ >60-80%; p = 0.019 log rank), resection status stratified for nodal disease (R+ <R0; p = 0.046), and the time interval between SX and RT were of significant importance. Patients with a long interval (37 to 84 days) had higher 5-year survival rates (26%) and a median survival time (MST: 21.9 months, 95% C.I. 17.2 to 28.6 months) than patients with a short interval (18 to 36 days: 15%; 14.9 months, 13 to 19.9 months; p = 0.013). A further subgroup analysis revealed significant higher survival rates in patients with a long interval in N0/1 disease (p = 0.011) and incompletely resected NSCLC (p = 0.012). In multivariate analysis, the time interval had a p-value of 0.009 (nodal disease: p = 0.0083; KPI: p = 0.0037; sex: p = 0.035).

CONCLUSION

Shortening the time interval between surgery and postoperative radiotherapy to less than 6 weeks even in R+ cases is not necessary. Survival of patients with a long interval between surgery and start of radiotherapy was better in this retrospective analysis as compared to patients with a short interval.

Stage IA-IIB Hodgkin's disease: management and outcome of extensive thoracic involvement

PURPOSE

To examine the presentation, management, and outcome of patients with extensive intrathoracic involvement in early-stage Hodgkin's disease.

PATIENTS AND METHODS

One hundred seventy-two patients with clinical Stage IA-IIB Hodgkin's disease and extensive intrathoracic involvement were studied. Extensive intrathoracic disease was defined as either large mediastinal adenopathy (LMA, defined as the width of the mass greater than one-third the maximum thoracic diameter, n = 154) or as extensive (> 10 cm) cephalocaudad intrathoracic disease that did not fulfill formal chest radiograph criteria for LMA (n = 18). Patients were divided into three groups based on staging and extent of treatment. Forty-seven patients were treated with radiation alone after a laparotomy (RT-lap), 47 patients received combined modality therapy after laparotomy (CMT-lap), and 78 patients were treated with combined modality therapy without staging laparotomy (CMT-no lap). MOPP was used in 82% of the CMT patients. Low-dose whole-cardiac RT was used in nearly 50% of patients treated either with RT or CMT.

RESULTS

The 10-year actuarial freedom from relapse rates were 54% with RT alone and 88% with CMT (p = 0.001); overall survival rates were 84 and 89%, respectively (p = NS). The median time to relapse was only 17 months. Over 80% of relapses occurred within the first 3 years. The most common site of relapse in all patients was the mediastinum. Relapses below the diaphragm were rare, even in CMT patients who did not receive abdominal radiation treatment. The principal acute morbidity was symptomatic pneumonitis, which occurred in 29% of patients receiving any part of their chemotherapy after RT, compared to 13% if all the chemotherapy was given before RT and 11% if RT alone was administered. There was a low late risk of myocardial infarction (3%) in the two groups with the longest follow up (RT-lap, CMT-lap), but a higher risk of second malignancy in the CMT-lap group (21%) compared with the RT-lap group (2%).

CONCLUSION

Extensive intrathoracic involvement is a distinctive presentation of early-stage HD that has a high relapse risk if treated with RT alone. The introduction of CMT has been associated with improvements in freedom from relapse. The low rate of peripheral relapse with CMT suggests that reductions in field size may be achievable. The use of low-dose whole-heart RT with modern techniques is not associated with a high risk of late cardiac complications and should be used in patients who present with extensive pericardial disease or cardiophrenic lymphadenopathy. The high rate of second malignancy in the CMT group with the longest follow-up suggests that careful long-term surveillance for such patients is warranted.

Risk factors for development of radiation pneumonitis following radiation therapy with or without chemotherapy for lung cancer

PURPOSE

To determine the risk factors contributing to development of radiation pneumonitis (RP) in patients with lung cancer who undergo radiation therapy to the thorax.

METHODS AND MATERIALS

Development and severity of RP were retrospectively analyzed for 89 patients with lung cancer who underwent radiation therapy with or without chemotherapy at the National Shikoku Cancer Center Hospital between 1991 and 1995. The severity of RP was determined using a modified grading scale based on that of the Radiation Therapy Oncology Group and the European Organization for the Research and Treatment of Cancer.

RESULTS

Fifty-two (58%) patients developed RP: 34 patients with Grade 1, 5 with Grade 2, 8 with Grade 3, and 5 with Grade 5 RP. Severe RP tended to develop earlier than less severe RP, but not to a significant extent (p = 0.151). On logistic regression analysis including both patient condition and treatment factors, development of Grade 1 or more severe RP was most frequently observed for Stage I-II disease (p = 0.011). The use of chemotherapy, large daily radiation dose, and once-daily fractionation (vs. twice-daily fractionation) were possibly related to the development of RP (p = 0.057, p = 0.069, and p = 0.092, respectively). For the group of 48 patients who underwent chemoradiation therapy, the use of large daily radiation dose was a significant risk factor for RP (p = 0.014). In addition, the use of once-daily fractionation was a marginally significant risk factor (p = 0.052). Among chemotherapy drugs administered, cisplatin was a favorable factor (p = 0.011), while adriamycin was a risk factor (p = 0.061).

CONCLUSIONS

In radiation therapy for lung cancer, administration of a large daily dose should be avoided in order to prevent RP, particularly when radiation therapy is combined with chemotherapy.

[Pneumonitis after radiotherapy of bronchial carcinoma: incidence and influencing factors]

BACKGROUND

The most important side effect in radiotherapy of lung cancer is pneumonitis. The incidence of pneumonitis was evaluated in a retrospective study in the patient collective of the University of Heidelberg. Therapy related and therapy independent factors have been evaluated.

PATIENTS AND METHODS

In 348 of 392 cases with lung cancer who were treated by local irradiation between January 1989 and January 1992 the patient's records were evaluable for response and toxicity. All patients were treated by megavolt equipment with a conventional fractionation in most cases. Standard target volumes were irradiated including the lymphatic drainage. From a dose of above 30 Gy a technique sparing the spinal cord was chosen. Retrospectively pneumonitis was classified into 4 grades starting from slight symptoms to respiratory insufficiency requiring O2. Grade I and II were summarized to slight, grade III and IV to severe pneumonitis.

RESULTS

Regarding the treatment prior to irradiation patients with primary irradiation were affected in 26.5% (17% slight, 9.5% severe), with postoperative irradiation in 14% (9.3% slight, 4.7% severe), with radiochemotherapy of small cell lung cancer (SCLC) in 15.4% (12% slight, 3.4% severe) by this side effect. These differences were not significant (p = 0.32). The median onset of pneumonitis was 31 days after end of irradiation (severe 23 days, slight 44 days, p = 0.026). By a univariate analysis the total dose at the prescription point was the most important factor (30 to 50.5 Gy 11%, 52 to 59 Gy 15%, 60 to 74 Gy 26%, p = 0.007). High single doses (2.5 Gy) were only applied within a study of radiochemotherapy with a randomised sequential and alternating schedule. So that the increased rate of pneumonitis (42%) is not clearly separable from other influencing variables. A correlation between the applied techniques and the irradiated volume (measured by planimetric methods) was not demonstrable. Regarding the independent factors a high age, female sex and a low FeV1 were unfavourable. However, age and sex corrected FeV1 was not predictive.

CONCLUSIONS

The observed incidence is within the range of literature. By a clinical point of view the total dose is an obvious factor. Also single doses above 2 Gy have to be seen critically (a total dose of 50 Gy). The results confirm the fact that patients with a low FeV1 are not suitable to a high dose irradiation of the chest. In this connection old patients and women also should be seen as patients at risk.

[Effect of daily administration of oral etoposide for non-small cell lung cancer treated with concurrent radiation therapy]

The purpose of this study was to explore the effect of daily administration of oral etoposide (25 mg) for patients with non-small cell lung cancer treated with concurrent radiation therapy. Planned endpoints were response, survival and toxicity. Forty-one patients with non-small cell lung cancer were divided into 25 patients given daily oral etoposide (25 mg) with concurrent radiation therapy (ERT group) and 16 patients given radiation therapy alone (RT group). Etoposide was administrated in the morning throughout radiation therapy. The median total irradiated dose was 63.1 Gy in the ERT group and 64.0 Gy in the RT group. Twenty-four patients completed therapy in the ERT group and 16 in the RT group. Three (15%) ERT patients achieved complete response (CR) and 9 (45%) achieved partial response (PR). In the RT group, no patients achieved CR and 9 (69%) achieved PR. One-year survival was 22.6% with ERT and 23.0% with RT. The prognosis of stage III patients in the ERT group was worse than that in the RT group because radiation pneumonitis and radiation esophagitis were more severe with ERT. In conclusion, the ERT group had better local response but worse in survival than the RT group. Complications of ERT were severe enough to cause death in some patients. ERT had no clear advantage over RT.

[Influence of reduction of radiation dosage on the incidence of radiation-induced pneumonitis, pulmonary fibrosis and pericarditis after mediastinal irradiation in the treatment of lymphogranulomatosis]

BACKGROUND

The amount of radiation dose applied in the treatment of Hodgkin's disease is associated with the incidence of complications including radiation-induced pneumonitis, lung fibrosis and pericarditis. Therefore, from the beginning of 1986, we have started to apply a radiation therapy approach with reduced doses in order to minimize complications while maintaining effective treatment.

PATIENTS AND METHOD

From 1983 through 1992 141 patients suffering from Hodgkin's disease were included in the present study. All of them were treated by radiation of mediastinum. In 126 cases polychemotherapy was applied before radiation. From 1986 we used a reduced radiation dose in cases that were treated by radiation alone (affected nodal regions with 40 Gy instead of 45 Gy and unaffected nodal regions with 36 Gy instead of 40 Gy) as well as after application of chemotherapy (affected nodal regions 36 Gy instead of 40 Gy and unaffected nodal regions with 30 Gy instead of 36 Gy). Ninety-five patients were treated according to the new therapy protocol. Forty-six patients had been treated with the higher dosages and served as the historical control group. Radiation therapy included Co-60, 15-MV and 9-MV photons, and 15-MeV and 9-MeV electrons. Serial thoracic X-ray controls were performed. CT scans, echocardiographic and electrocardiographic investigations were added in selected cases.

RESULTS

During the period from 1983 to 1992, we diagnosed radiation-induced pneumonitis in 31% of the patients who underwent radiation therapy of the mediastinum. In addition, 16% demonstrated lung fibrosis and 10% pericarditis. After implementation of the reduced radiation dosages, the incidence of pneumonitis decreased from 35% to 24% (nearly significant in the 5% range), lung fibrosis from 24% to 12% (p < 0.05) and pericarditis from 26% to 2% (p < 0.01). The efficacy of treatment remained unaffected by the new therapy approach as has been demonstrated for cumulative survival data and recurrence-free intervals.

CONCLUSIONS

Reduction of radiation dose in patients with Hodgkin's disease who undergo mediastinal radiation leads to a decrease in the incidence of radiation-induced complications (pneumonitis, lung fibrosis, pericarditis) whereas treatment efficacy remains unchanged.

Clinical evaluation of the partition model for estimating radiation doses from yttrium-90 microspheres in the treatment of hepatic cancer

Radiation doses to the tumour and non-tumorous liver compartments from yttrium-90 microspheres in the treatment of hepatic cancer, as estimated by a partition model, have been verified by correlation with the actual doses measured with a beta probe at open surgery. The validity of the doses to the lungs, the tumour and non-tumorous liver compartment as estimated by the partition model was further evaluated in clinical settings. On the basis of the observation that one of three patients who received more than 30 Gy from a single treatment and one of two patients who received more than 50 Gy from multiple treatments developed radiation pneumonitis, it was deduced that an estimated lung dose < 30 Gy from a single treatment and a cumulative lung dose < 50 Gy from multiple treatments were probably the tolerance limits of the lungs. Three of five patients who received lung doses > 30 Gy as estimated by the partition model and were predicted to develop radiation pneumonitis, did so despite the use of partial hepatic embolization to reduce the degree of lung shunting. Furthermore, a higher radiological response rate and prolonged survival were found in the group of patients who received higher tumour doses, as estimated by the partition model, than in the group with lower estimated tumour doses. Thus the radiation doses estimated by the partition model can be used to predict (a) complication rate, (b) response rate and (c) duration of survival in the same manner as the actual radiation doses measured with a beta probe at open surgery. The partition model has made selective internal radiation therapy using 90Y microspheres safe and repeatable without laparotomy.

[Bilateral pneumonia after localized irradiation of a thymoma. Description of a case]

Acute pneumonitis characterized by fever, coughing and moderate dyspnea can appear from 6 to 12 weeks after irradiation. Most patients later show signs of fibrosis confined to the irradiated field. An entity that has been under recent discussion is "radiation-induced sporadic pneumonitis", a bilateral lymphocytic alveolitis of autoimmune origin that leads to generalized pulmonary response after local irradiation. The prognosis for such cases is good. We report a case of early post-irradiation pneumonitis of the type described, which led unexpectedly to the patient's death.

Radiation pneumonitis complicating mediastinal radiotherapy postpneumonectomy

Radiation pneumonitis is a well-characterized clinicopathological syndrome. The severity of radiation-induced lung injury correlates, among other factors, with the extent of lung volume incorporated within the field of radiation. The present article describes the cases of two patients with radiation pneumonitis following pneumonectomy and mediastinal radiotherapy. Postpneumonectomy pulmonary-mediastinal shift of the remaining lung towards the operated side, with inclusion of lung parenchyma within the "mediastinal" radiation portals, resulted in a substantial (albeit clinically unsuspected) radiation pneumonitis. Chest computed tomography in the postpneumonectomy patient may be helpful to evaluate the degree of pulmonary-mediastinal shift and optimization of the radiotherapy field.

Radiation doses during pediatric radiofrequency catheter ablation procedures

Because RF catheter ablation procedures may be lengthy and are commonly performed in young patients, concern has arisen about radiation dose in this group of patients. This article investigates radiation doses in pediatric patients undergoing RF catheter ablation. Standard fluoroscopic equipment used for diagnostic electrophysiological catheterization studies is technologically capable of dose rates as high as 90 milligray (mGy) per minute to skin and adjacent lung and 260 mGy/min to vertebral bone. Dose rates of this magnitude when used for extended periods of time have been known to cause erythema, pneumonitis, and retardation of bone growth. We measured skin dose rates of nine pediatric patients undergoing RF catheter ablation for tachycardia and calculated doses to the skin using standard dosimetric methods. Fluoroscopic techniques and equipment were studied using a patient simulating phantom. Overlap of fluoroscopic fields was checked using radiotherapy portal verification film, and regions in which doses overlapped from multiple angle exposures were verified using a treatment planning computer. Patient skin dose rates ranged from 6.2-49 mGy/min for patients ranging in age from 2-20 years. Maximum skin doses ranged from 0.09-2.35 Gy. Our data demonstrate the need to directly measure dose rates for individual fluoroscopic equipment and procedural techniques in order to determine whether limitations need to be set for procedural times.

Effects of radiation on the lung

Since the beginning of the twentieth century, radiation has been employed as a tool to cure or palliate malignancy. Unfortunately, soon after its discovery, the harmful effects of radiation were recognized as well. As our understanding of the physiologic responses to radiation increases, we can refine the routes of delivery and dosages of radiation administered. The use of three-dimensional treatment planning and the manipulation of the biochemical response with drugs and synthesized cytokines offers promise in curtailing the undesirable effects of irradiation. Side effects will be minimized and benefits maximized with further technologic developments that will more accurately control the delivery of and response to radiation.

Entire hemithorax irradiation following complete resection in patients with stage II-III invasive thymoma

PURPOSE

To evaluate the feasibility and efficacy of prophylactic entire hemithorax irradiation (EH) in addition to mediastinal irradiation (MRT) following a complete resection in Stage II-III invasive thymoma.

METHODS AND MATERIALS

Forty-three patients with invasive thymoma treated with surgery and radiation therapy between 1978 and 1993 were analyzed retrospectively. All 43 patients underwent a complete surgical resection and were judged to have Masaoka's Stage II-III invasive thymoma. Of these, 23 patients received EH and MRT (EH-MRT) and the remaining 20 received MRT. Of the 23 patients with EH-MRT, 11 were Stage II and 12 Stage III. Of the 20 with MRT, 11 were Stage II and 9 Stage III. In most cases, EH was 15 Gy per 15 fractions over 3 weeks (without lung compensation calculation). In both the EH-MRT and MRT group, the total radiation doses to the mediastinum were similar with a median of 40 Gy. The median follow-up time after surgery was 63 months and no patients were lost to follow-up.

RESULTS

Only one of the 23 patients with EH-MRT relapsed. On the other hand, eight of the 20 with MRT relapsed, six of whom died of disease. The pleura was the most common site of failure. At 5 years, the relapse-free rate was 100% for those receiving EH-MRT and 66% for those with MRT (p = 0.03); the overall survival rate was 96% for those with EH-MRT, and 74% for those with MRT (p: not significant). The only significant treatment-related complication was radiation pneumonitis requiring treatment, in one patient who received MRT and three who received EH-MRT, including one death of a 72-year-old man and one 68-year-old woman with severe lung fibrosis.

CONCLUSION

Except for elderly patients, EH-MRT following a macroscopically complete resection appears to be safe and feasible, and can reduce intrathoracic relapses.