Radium (Ra)

Radium is a radioactive alkaline earth metal (atomic symbol Ra) that is not a biological target molecule, such as a receptor or enzyme, but rather serves as the active component of certain radiopharmaceutical therapies [14, 20]. In clinical practice, the isotope Radium-223 is utilized as Radium-223 dichloride (Xofigo) for the treatment of metastatic castration-resistant prostate cancer (mCRPC) with symptomatic bone metastases [15, 17]. Radium-223 acts as a calcium mimetic, meaning it is chemically similar to calcium and is preferentially incorporated into the hydroxyapatite of the bone matrix at sites of high bone turnover and osteoblastic activity [4, 9, 21]. Once localized within the bone, Radium-223 emits high-energy alpha particles that travel a very short distance (less than 100 micrometers), inducing lethal, non-reparable double-strand DNA breaks in adjacent tumor cells and bone-remodeling cells like osteoblasts and osteoclasts [1, 2, 21]. This targeted alpha therapy effectively disrupts the pathological 'vicious cycle' of bone metastasis while sparing distant healthy tissues from significant radiation exposure [3, 9, 11].

Other names

Radium-223Ra-223Radium-226Radium dichlorideAlkaline earth metal

Radium-223 mimics calcium and incorporates into the bone matrix at sites of high turnover, where it emits alpha radiation to induce double-strand DNA breaks in adjacent cells [1, 4, 9].