Purpose. To describe tumor shrinkage of nonirradiated lung metastases in a patient with non-small cell lung cancer. Case Report. The patient had a concurrent autoimmune condition, bullous pemphigoid, which was clinically exacerbated during radiotherapy of mediastinal and axillary lymph node metastases. He also developed a series of infections during and after irradiation, and we hypothesize that the immunological events during this phase might have influenced the size of the nonirradiated metastases. Conclusion. Ionizing radiation generates inflammatory signals and, in principle, could provide both tumor-specific antigens from dying cells and maturation stimuli that are necessary for dendritic cells' activation of tumor-specific T cells. Even if the detailed mechanisms causing nontargeted immune modulatory effects in individual patients are poorly understood, clinical development of radioimmunotherapy is underway.