Malignant pleural mesothelioma with long-term tumor disappearance of a local relapse after surgery: a case report

INTRODUCTION: There have been few reports of spontaneous regression of malignant pleural mesothelioma, but the mechanism for this is unknown. We present a case report on a patient with malignant pleural mesothelioma showing apparent tumor disappearance in a local relapse after surgery. CASE PRESENTATION: A 73-year-old man presented with malignant pleural mesothelioma in the right thoracic cavity. A pleurectomy was performed, and as expected, the tumor locally relapsed with increasing chest pain. However, the symptoms suddenly improved while the tumor was apparently reduced, and spontaneous tumor regression was initially considered. The patient confessed that he had self-administered a mushroom extract with alternative parasympathetic nerve stimulation therapy thereafter. The complete disappearance of the tumor was clinically achieved during a 29-month follow-up with continuing self-treatment. CONCLUSION: This is the first report describing a malignant pleural mesothelioma patient in Japan showing long-term complete disappearance of a local relapse after surgery. This event was a tumor regression possibly due to an immunological effect of combined complementary and alternative therapy.