THE INTRINSIC RADIOSENSITIVITY OF NORMAL AND TUMOR-CELLS

Purpose: To examine whether in vitro measurements of normal and tumour cell radiosensitivity can be used as prognostic factors in clinical o ncology. Materials and methods: Stage I-III cervix carcinoma patients were treated with radical radiotherapy with a minimum of 3 years' foll ow-up. Lymphocyte and tumour radiosensitivities were assayed using, re spectively, a limiting dilution and soft agar clonogenic assay to obta in surviving fraction at 2 Gy (SF2). The results were related, in an a ctuarial analysis, to late morbidity assessed using the France-Italian glossary. Results: Patients with radiosensitive lymphocytes had a sig nificantly increased risk of developing late complications (n=93, p=0. 002). Increasing tumour radiosensitivity was associated with an increa sed risk of morbidity (n=113, p=0.032). ii significant correlation was found between fibroblast and tumour cell radiosensitivity (r=0.57, p= 0.03), but a weak inverse association was found between lymphocyte and tumour cell radiosensitivity (r= -0.32, p=0.03). Patients with radios ensitive lymphocytes and tumour cells had higher levels of late compli cations than those whose cells were radioresistant. Conclusion: The wo rk described highlights the importance of cellular radiosensitivity as a parameter determining the clinical response to radiotherapy.