Apoptosis and p53 overexpression in human rectal cancer; relationship with response to hyperthermo-chemo-radiotherapy

Hyperthermo-chemo-radio (HCR) therapy has been found to be effective for rectal cancer. Biomarkers for predicting the effect of HCR therapy are important in determining optimum treatment regimens. Hyperthermo-chemo-radiotherapy (HCR therapy), consisting of hyperthermia at 42 degrees C to 45 degrees C 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 mg), were prescribed pre-operatively for 29 patients with rectal cancer, using tissue specimens collected at pre-treatment biopsy. Apoptosis and overexpression of p53 protein were investigated histopathologically and immunohistochemically. On termination of HCR therapy, all the tumors were surgically resected and effectiveness of the therapy was evaluated histologically. Spontaneous apoptosis was evident in the pre-treatment cancer tissues of 14 patients (48.2%). In this apoptosis-positive group, the positive rate of expression of the p53 protein (21.4%, 3 out of 14) was lower as compared to findings in the apoptosis-negative group (66.7%, 10 out of 15). The response to HCR therapy was better in the apoptosis-positive group than in the apoptosis-negative group. We propose that spontaneous apoptosis is closely related to the function of wild-type p53 protein and is also a predictive biomarker of the effect of HCR therapy for patients with rectal cancer.