Observational Study of Immune Responses in Prostate, Lung, Melanoma and Breast Cancer Patients Following Stereotactic Body Radiotherapy (SBRT), Intensity Modulated Radiotherapy (IMRT) or Brachytherapy

Success of cancer immunotherapy is limited by the ability of solid tumors to evade local and systemic antitumoral immune responses. Several mechanisms of tumor immune evasion have been identified, including low intratumor expression of antigens and elevated expression of inhibitory co-regulatory molecules. An effective immunotherapy is one which would induce necrotic cell death and accompanying proinflammatory cytokine induction. Stereotactic Body Radiotherapy (SBRT) or Intensity Modulated Radiotherapy (IMRT) or brachytherapy, which is capable of delivering high, conformal radiation doses (>8 Gy) of tumor ablative radiation may be an effective means of conditioning a tumor bed to a state favorable to the initiation of robust antitumoral immune responses.