International Journal of Radiation Oncology*Biology*Physics
Clinical InvestigationsFactors influencing the outcome of radiotherapy in malignant mesothelioma of the pleura—a single-institution experience with 189 patients
Introduction
Malignant mesothelioma is an aggressive tumor that arises from the pleura and peritoneal surfaces and is linked to exposure to asbestos fibers (1). Because the period between asbestos exposure and presentation of the disease can be up to 40 years, the increasing incidence of malignant mesothelioma is expected to continue in the light of widespread, mainly industrial, exposure during the previous decades 2, 3.
Malignant mesothelioma of the pleura (MM) is almost invariably a fatal illness and median survival ranges from 9–12 months 4, 5. Important predictors for long-term survival include the performance status, histological subtype, and disease extent at the time of diagnosis 6, 7. Radical surgery is seldom possible because MM commonly exhibits diffuse pleural spread (8), but surgery has a role in selected patients who present with early disease (9). Local tumor progression can occur despite radiotherapy (RT) to doses of up to 70 Gy (10). Response rates to chemotherapy are commonly less than 20%, and combination chemotherapy has shown no advantage over single agents (11). In the light of these findings, it is not surprising that untreated patients have been reported to survive as long as treated ones 6, 7, and palliation remains the main goal of treatment for the majority of patients presenting with MM.
Chest pain is a frequent symptom and RT has been reported to provide palliation in between 50 to 68% of patients with MM 12, 13. However, the optimal dose and fractionation is unclear and no clear dose-response relationship for palliation has been established. We reviewed the results in 189 patients with MM who were treated with RT at the Daniel den Hoed Cancer Centre to determine the factors influencing the outcome of RT.
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Patients
Between 1979 and 1996, a histological diagnosis of mesothelioma was made in 303 patients who were referred to our center. A total of 189 patients were treated with external RT for pleural mesothelioma (MM), and they received a total of 227 RT series. The remaining 114 patients included patients with MM who received only chemotherapy and/or immunotherapy (n = 59), supportive care only (n = 40), intrapleural radioactive phosphorus only (n = 3), and patients with peritoneal mesothelioma (n = 13).
Results
A univariate analysis showed that the stage of disease and performance status were prognostic factors for survival Fig. 1, Fig. 2. The majority of patients in this series had locally advanced or Stage III disease (Table 1). Despite the fact that 82% of patients had a performance status of ECOG 2 or better, the median survival was only 5 months from the start of radiotherapy, and only 17% of patients were alive at 1 year posttreatment. Patients with symptomatic disease showed a poorer
Discussion
In patients with MM, RT has been evaluated in curative, adjuvant, and palliative settings. The poor responses, even with high-dose RT 5, 10, have led to a purely palliative role for RT in many centers. Although prophylactic RT of thoracoscopy or biopsy sites reduces the incidence of subsequent chest wall recurrence 15, 16, this has not been shown to influence the course of the disease. It has long been advocated that RT techniques should minimize toxicity by using “high fraction size and small
Conclusion
These data confirm that RT is an active single agent in the palliation of MM; the use of hypofractionated RT schemes that are limited to sites of symptomatic disease can provide palliation of pain in at least 50% of patients. However, low response rates and the short duration of responses to RT indicate that relatively nontoxic measures such as HT added to RT should be further evaluated as palliative treatment of MM. In the light of the poor prognosis of patients with MM, such studies should
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