Treating patients with high-dose radiotherapy after chemotherapy and surgery for malignant pleural mesothelioma does not achieve improvements in local relapse and overall survival, according to data from a prospective randomised phase II trial presented at ESMO 2014 Congress in Madrid.

“Mesothelioma remains a difficult disease to find better treatment options for, so we asked whether high-dose hemithoracic radiotherapy would decrease the rate or delay the time of local recurrence after chemotherapy and radical surgery,” says lead author Prof Rolf A. Stahel, from the Clinic and Policlinic for Oncology, at the University Hospital Zurich, Switzerland, and current President of the European Society for Medical Oncology.

The multicentre trial included 153 patients with surgically-treatable malignant pleural mesothelioma, who were first treated with three chemotherapy cycles of cisplatin and pemetrexed, followed by surgical removal of affected lung tissue, with the goal of complete removal of the cancerous areas of lung.

In a second part of the study, researchers randomly assigned 54 patients to receive either radiotherapy or no further treatment, with the primary endpoint being the duration of relapse-free survival.

While there had been preliminary evidence suggesting that the addition of radiotherapy might improve outcomes, the study failed to find any differences in relapse-free survival between patients treated with the additional radiotherapy, and those who were not.

Stahel says researchers were hoping for a more positive signal from the study.

“We aimed for a six month delay in local recurrence, which would be meaningful because it’s an aggressive treatment for patients.”

In summary, Stahel says, “It demonstrates that, like in other solid tumours, when two modalities are not sufficient it’s very rare that the third modality added would make a benefit.”

Commenting on the results, Dr Paul Baas, from the Department of Thoracic Oncology, The Netherlands Cancer Institute, Amsterdam, says the combined modality of chemotherapy followed by major surgery and irradiation of high volumes of the chest is one of the accepted treatments in very fit patients, however it is a combination associated with high morbidity.

“The study by Stahel et al. indicates that the contribution of radiation does not improve time to recurrence of the disease,” says Baas.

However he also stressed that the results did not lead him to conclude that there was no role for adjuvant radiation in this setting, pointing out that this was a phase II trial, and therefore not necessarily the final conclusion, and that selection of patients with differing pathology, stage and performance could influence outcome.

“Times are changing and this is also true for the way that radiation therapy can be administered to the patient, so new approaches (intensity modulated radiation) can improve the local control and reduce toxicity.”

Source: ESMO