Present review article describes use of radiation and radionuclides on cancer and cancer cell therapeutics. It also sketches out cumulative effects of radiation exposure received by the patients during cancer diagnostics. Though, in cancer therapeutics a selected and permissible dose is provided in several cycles to ablate the neoplastic cells and improve the condition of patient, but radiation harms surrounding cells and imparts negative effects on biology of cells. Ionizing radiation (IR) promotes cancer cell death through cytotoxicity. This article emphasizes both remedial effects and biological effects of radiation and radio-resistance in cells. It suggests safe use of radionucleides by encapsulating them in nanomaterials so as to use it alternate to chemotherapy to destroy various cancer types to enhance the survival of normal cells. This article explains effect of ionizing and non-ionizing radiation on cellular metabolism and genetics.