Different tumor cells irradiated with 12C6+ ion beams show special advantages of tumor therapy with heavy ions

The study was performed to investigate the feasibility and advantages of tumor therapy with heavy ions by observing the radiosensitivity and its discrepancy for two kinds of human malignant tumor cell line after respectively irradiated with 60Co γ-rays and 12C6+ ions with high LET. After exposed to 60Co γ-rays and 12C6+ ions, cell survival of two human carcinoma cell lines, SMMC-7721 and A375, was determined by an in vitro clonogenic assay. The survival fractions of cells irradiated with 12C6+ were considerably lower than those of cells irradiated with γ-rays in both single irradiation and dividual irradiation. For cells irradiated with heavy ions, there was an evidently decreasing discrepancy of radiosensitivity and there was not an obviously increasing survival as dividually irradiated. The assay showed that heavy ions with high LET could kill tumor cells more efficiently and decrease the discrepancy of radiosensitivity between different cell lines, as well as lead a lower repair of cells. Associated with the depth-dose curve of heavy ions, tumor therapy with heavy ions demonstrates special advantages. (authors)