Relationship between radiosensitivity and normal tissue complications in Saudi cancer patients treated with radiotherapy.

Purpose: To assess the variations in radiosensitivity, its relationship with clinical complications and the potential application of predictive testing in Saudi radiotherapy patients. Materials and Methods: Forty-one patients included in this study, during (17) or after (24) their radiation treatment for head and neck (26), breast (9), gynecological (3) or other (3) cancer. Skin fibroblasts were established and radiosensitivity was measured. The surviving fraction at 2 Gy (SF2) was calculated and compared to the maximum grade of acute (erythema, desquamation, mucositis, ulceration) and late reactions (atrophy, fibrosis, xerostomia, telangiectasia). Follow-up ranged between 12 and 178 months (median 30). Results: SF2 ranged between 0.16 and 0.56 (mean 0.34). The inter-patients coefficient of variation (CV) was 26%. The intra-patient CV was 18%. There was a statistically significant correlation between fibroblasts SF2 and the maximum grade of late (p = 0.012; 40 patients), but not acute complications (p = 0.70; 36 patients). There was no correlation between acute and late reactions ( p > 0.05; 34 patients). Conclusions: These data revealed wide variations in cellular radiosensitivity that correlated with late reactions to radiation treatment. Radiotherapy patients, particularly those at risk to sustain severe complications may well benefit from individualizing the doses prescription. However, a predictive test alternative to SF2 is required.