Radiation-associated changes in the length of telomeres in peripheral leukocytes from inpatients with cancer

Purpose: The telomere length of somatic cells shortens with age and with other endogenous and exogenous pathogenic factors. However, the effects of radiation therapy on telomere DNA of non-cancer tissue have not been thoroughly investigated. This study analyzed the telomere length of inpatients with cancer treated with radiation therapy to see whether the telomere lengths change in response to therapeutic radiation. Materials and methods: Twenty-five patients were enrolled in the study. The patients had lung cancer, prostate cancer, thyroid cancer, hepatoma, or rectal cancer. They received radiation therapy with a dose range of 15-74 Gy. The telomere lengths and telomere length distribution in peripheral leukocytes were analyzed by using a Southern blot-based method. Results: The telomere length and the telomere length distribution of the peripheral leukocytes did not change after radiation therapy. However, there was a significant proportional decrease in the short telomere fraction (< 4.4 kb) per day and per Gy. Conclusions: This observation suggested that the telomere length distribution of peripheral leukocytes could be affected by radiation therapy, and that the effect of radiation tends to appear in cells with short telomeres. Radiation therapy-associated somatic telomere length change within a short range of time, about three months or shorter, can be detected by analyzing the mean telomere length and telomere length distribution.