Estimation of tumor proliferative activity according to expression of cell-cycle-related antigen and selection of fractionation schema in radiation therapy.

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We have performed various basic and clinical studies on tumor proliferation and radiation therapy,1)To understand better the repopulation kinetics of tumor cells after radiotherapy (RT), we investigated changes in cell proliferative parameters after single-dose irradiation of murine tumors. As one of conclusions, recruitment of previously quiescent cells into the proliferative pool in the tumors was suggested to contribute to repopulation after RT.(ref.2)2)Combined effects of an antiangiogenic agent (TNP-470) with fractionated RT were investigated using a murine tumor. The tumor control probability decreased by administrating TPN-470 during fractionated RT in air. This unexpected result may be contributable to partial inhibition of reoxygenation by TNP-470, because no significant changes in TCD-50 under hypoxic conditions by TNP-470. (ref.6)3)The effects of overall treatment time (OTT) on local control of RT were evaluated to consider optimal OTT in RT.Local control rates and acute and … More late toxicities of esophageal cancer, glottic cancer, and uterine cervical cancer were analyzed. In the multivariate analysis, OTT was a significant prognostic factor for local control. In conclusion, OTT should be kept as short as Possible wiyhin the limits of tolerance of normal tissues and patients. (ref.4)4)The relationship of immunohistochemical indices of proliferating cell nuclear antigen (PCNA) and Ki-67 to local control and survival rates for patients with esophageal squamous cell carcinomas treated by definitive radiotherapy (RT) was investigated. Biopsy materials before RT were obtained from 65 patients with esophageal cancer. The PCNA LI was independent of known prognostic factors on local control for esophageal cancer. Patients with the PCNA LI of<50% or the Ki-67 LI of<45% showed significantly higher local recurrence rates than those with higher LIs (p<0.05). In conclusion, PCNA LI and Ki-67 LI were significantly correlated with local control probabilities in esophageal. squamous cell carcinomas treated by definitive RT.PCNA LI may be a useful parameter for selecting the fractionation scheme of esophageal cancers. Less