Relationships between acute reactions to radiotherapy in head and neck cancer patients and parameters of radiation-induced DNA damage and repair in their lymphocytes

Abstract

Purpose: To study the relationship between lymphocyte radiosensitivity measured in vitro and acute reactions to radiotherapy in patients with head and neck cancer.

Materials and methods: Acute reactions were measured in 34 patients using the Dische scale. Lymphocyte radiosensitivity was measured using the alkaline comet assay, the micronucleus assay, the nuclear division index and morphological assessment of apoptosis.

Results: There was a weak, statistically significant correlation between in vitro radiosensitivity measured as the rate of DNA damage repair and the cumulative radiation dose exerting the maximum acute reaction scored (r = −0.366, p = 0.039, n = 34). Subgroup analyses showed that for patients with a low level of radiation-induced DNA damage there was a statistically significant relationship between lymphocyte radiosensitivity measured as inhibition of proliferation and acute toxicity (r = −0.621, p = 0.007, n = 18). For patients with a high level of residual DNA damage, there was a relationship between lymphocyte radiosensitivity measured using the micronucleus assay and acute toxicity (r = −0.597, p = 0.023, n = 14).

Conclusions: Combining two measures of radiosensitivity improves the ability to correlate in vitro lymphocyte radiosensitivity and acute radiotherapy toxicity data.

Keywords:

• Radiotherapy
• prediction of healthy tissue reaction
• lymphocytes
• comet assay