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This study was performed to determine the biological effect of carbon beams on 13 human tumor cells, in comparison with 200 KVp X-rays. Carbon beams were generated by the Riken Ring Cyclotron. The RBE (relative biological effectiveness) values were distributed from 1.46 to 2.20 for LET of 20 ke V/micron, and 2.29-3.54 for 80 keV/micron. The RBEs were increased in all cell lines as the LET of carbon beams was increased from 20 to 80 keV/micron. There was no significant difference in radiosensitivity between cells from adenocarcinoma and those from squamous cell carcinoma. The relationship between the radiosensitivity of cells to X-rays and RBE was analyzed, but no significant correlation was suggested. Several survival curves of 20-40 keV/micron carbon beam irradiation showed the initial shoulders and the recovery ratios between two split doses were determined. Recovery was observed for LET of 20 keV/micron but not for that of 40 keV/micron. Furthermore, recovery ratios were 1.0-1.8, smaller than those for X-rays (1.5-2.4).

This is a retrospective analysis of 659 patients with cervical squamous cell carcinoma with a minimum follow-up of 2 years at Keio University Hospital between May 1974 and March 1990. All patients were treated with external radiation (50 Gy) and high-dose rate (HDR) intracavitary brachytherapy (20-34 Gy). The 5-year survival rates in each stage gradually decreased with the advance of the stage (I, 84%; II, 71%; III, 47%; and IVa, 12%). When 366 patients with stage III were classified into three groups according to tumor size, i.e. small (S, 102 patients), medium (M, 145) and large (L, 119), a survival gradient of small > medium > large was demonstrated and the differences between them were significant. At follow-up visits conducted between 1 and 2 months after completion of treatment, 135 patients (20%) had physical indications of residual disease. The larger the tumor size, the more likely was residual disease by 2 months. The patients with residual disease had a significantly higher rate of the pelvic failure than those without it. There was no significant correlation between radiation doses by RALS and pelvic failure rates, except in the stage III-L group. In the stage III-L group, intracavitary doses of 24 Gy or less to point A could be correlated with the higher pelvic failure rate and the lower survival rate, in contrast to doses of 27 Gy or more. The incidence of major rectosigmoid complications was 11.8% with doses of 24 Gy or less to point A, 8.1% with 27 Gy and 19.2% with doses of 30 Gy or more.(ABSTRACT TRUNCATED AT 250 WORDS)