Biological predictors of response to radiotherapy in cervical carcinomas

On 21 patients with T1b-T3b tumours subjected to external radiotherapy and brachytherapy, the expression of P53 and glutathione S-transferase pi [GST-pi], immunohistochemically detected, the S-phase cells fraction (H-3-thymidine labeling index, TLI) and DNA content evaluated by image analysis were determined on biopsies before and after the first 10 Gy. P53 accumulation was reduced in 60% of P53-overexpressing tumours and not induced in P53-negative tumours, GST-pi was induced in about 40% of pretreatment GST-pi-negative cases, TLI was reduced in 70% of the cases regardless of pretreatment values, and DNA profiles remained unchanged in two-thirds of the cases. P53 accumulation was a predictor of 3-year relapse-free survival after radiotherapy, followed by GST-pi expression, whereas TLI did not influence prognosis.