[Tumor progression and tumor stem cell heterogeneity in relation to tumor radioresistance]

Intertumor heterogeneity among human tumors of similar size and of narrowly defined type has been evidenced as a shallow dose-response relationship for local tumor control. Tumor progression in variable degrees and its resultant tumor stem cell heterogeneity are considered as major factors for the intertumor heterogeneity. Various factors including abnormal ploidy, thymidine labeling index and oncogene amplification are discussed in relation to tumor progression. Predictive and quantitative method of assay for tumor progression is considered important for the selection of treatment modalities.