Apoptosis and p53 overexpression in human rectal cancer; Relationship withresponse to hyperthermo-chemo-radiotherapy

Hyperthermo-chemo-radio (HCR) therapy has been found to be effective for re ctal cancer. Biomarkers for predicting the effect of HCR therapy are import ant in determining optimum treatment regimens, Hyperthermo-chemo-radiothera py (HCR therapy), consisting of hyperthermia at 42 degreesC to 45 degreesC for 40 minutes (twice per week for two weeks), a total of 60 Gy irradiation and administration of 1-hexylcarbamoyl-5-fluorouracil (HCFU) (total 8400 m g), were prescribed pre-operatively for 29 patients with rectal cancer, usi ng tissue specimens collected at pre-treatment biopsy. Apoptosis and overex pression of p53 protein were investigated histopathologically and immunohis tochemically. On termination of HCR therapy, all the tumors were surgically resected and effectiveness of the therapy was evaluated histologically. Sp ontaneous apoptosis was evident in the pre-treatment cancer tissues of 14 p atients (48.2%). In this apoptosis-positive group, the positive rate of exp ression of the p53 protein (21.4%, 3 out of 14) was lower as compared to fi ndings in the apoptosi/s- negative group (66.7%, 10 out of 15). The respons e to HCR therapy was better in the apoptosis-positive group than in the apo ptosis-negative group. We propose that spontaneous apoptosis is closely rel ated to the function of wildtype p53 protein and is also a predictive bioma rker of the effect of HCR therapy for patients with rectal cancer.