Evaluation of clinical effects of chemo-radiation therapy on colorectal cancer and analysis of cell-kinetics

To evaluate the effectiveness of preoperative chemo-radiation therapy for colorectal cancer patients. Twenty patients with colorectal cancer were allocated for treatment by preoperative radiation therapy (RT group; 7 cases), chemotherapy (5-FU group; 5 cases) or combination therapy (RT and 5-FU group; 8 cases), and the DNA ploidy pattern from fresh material were compared before and after treatment. Change in DNA ploidy pattern from DNA-aneuploidy to DNA-diploidy was observed in 33.3% of the RT alone cases, 66.7% of the 5-FU alone cases and 100% of the combined group. On histological evaluation, the combined group also showed changes (p<0.05). To examine the mechanism of this combination therapy, cell-kinetics were investigated using four colorectal cell lines. There were 3 types mechanism; the enhancing effect of 5-FU (accumulated S phase), of radiation (accumulated G2 + M phase), and the enhanced combined effect by chemo-radiation therapy. (author)