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.