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The metallothionein (MT) family is a class of low-molecular-weight, cysteine-rich proteins (MT-1, MT-2, MT-3, and MT-4) with high affinity for metal ions. Apart from their involvement in metal ion homeostasis and detoxification, protection against oxidative damage, and cell proliferation and apoptosis, they are also implicated in drug and radiotherapy resistance and several aspects of the carcinogenic process. Variable MT expression has been observed in different cancer types, reaching statistically significant correlation with clinicopathological parameters in some cases; nevertheless, MT expression as a marker of prognosis or as a predictor for the response to either chemotherapy or radiotherapy remains unclear. The present review examines the expression of MT in different human tumors in correlation with resistance to radiation therapy or chemotherapy and patients' final outcome. Detailed studies focused on the expression of MT isoforms and isotypes in different tumor types could elucidate the role of this group of proteins in patients' prognosis and resistance to treatment strategies.

Radiotherapy is one of the effective treatments of cancers. External irradiation, however, often causes damages to healthy tissues. It has been reported that 17Y₂O₃-19Al₂O₃-64SiO₂ (mol%) glass microspheres 20-30 μm in diameter are useful for in situ irradiation of cancers. This glass microsphere is already clinically used for treatment of liver cancer in Canada etc. The number of yttrium ions present in this glass microsphere is, however, not very large. In the present study, pure Y₂O₃ microspheres with smooth spherical shape 20-30 μm in diameter were successfully obtained by the inductively thermal plasma melting technique. They were essentially composed of crystalline Y₂O₃ particles. They little released yttrium into water at 95°C for 7 d, but a large amount of it into pH 4-buffered solution. After they were coated with SiO₂ film by plasma chemical vapor deposition (CVD) method, they hardly released yttrium into the pH 4-buffered solution as well as into the water. The SiO₂-coated Y₂O₃ microspheres showing high chemical durability even in the low pH environment are believed to be more effective for cancer treatment than the Y₂O₃-Al₂O₃-SiO₂ glass microspheres.

The world's first hospital-based proton treatment center opened at Loma Linda University Medical Center in 1990, following two decades of development. Patients' needs were the driving force behind its conception, development, and execution; the primary needs were delivery of effective conformal doses of ionizing radiation and avoidance of normal tissue to the maximum extent possible. The facility includes a proton synchrotron and delivery system developed in collaboration with physicists and engineers at Fermi National Accelerator Laboratory and from other high-energy-physics laboratories worldwide. The system, operated and maintained by Loma Linda personnel, was designed to be safe, reliable, flexible in utilization, efficient in use, and upgradeable to meet demands of changing patient needs and advances in technology. Since the facility opened, nearly 14,000 adults and children have been treated for a wide range of cancers and other diseases. Ongoing research is expanding the applications of proton therapy, while reducing costs.

The history and technology of medical linacs are reviewed, focusing on machine requirements for radiotherapy. Configurations used in modern machines are described and operational aspects of a gantry-style linac system are illustrated with reference to the state of the art. Aspects of structure design, modeling and testing are discussed.