Effect of Radiotherapy on Chromosomal Aberration in Cancer Patients

Chun, Hachung; Lee, Myung Za; Yoo, Myung Soo

Abstract

We evaluated frequency and types of chromosomal aberrations by ionizing radiation in cancer patients treated with radiotherapy in our institution. Twenty-five patients with various types of carcinomas such as lung, uterine cervix, esophagus, rectum, head and neck and pancreatic cancers were studied immediately before and after external beam radiotherapy. The frequency of aberrant metaphase prior to treatment was 4.93%, which was higher than that of control group. Especially in lung cancer, the frequency of aberrant metaphase was three times higher than control group. A comparison of chromosomal abnormalities observed before and after radiotherapy demonstrated that proportion of aberrant metaphases was significantly increased to 22.13%. Major chromosomal aberrations like structural abnormalities showed remarkable increase from 65.45 to 88.45% after the treatment. Also the numbers of chromosomal alterations per cell were increased by a factor of 6.5. Aberrations with two or more break points were more prominently increased, compared with aberrations with single break point. The number of chromosomal break points was noted to be higher than expected value in No.1, 3, 8 and 11 chromosomes and lower in No. 13, 15, 17 and 21 chromosomes. Based on this study, we believe that the distribution of chromosomal breakage is related with gene and chromosomal rearrangement which could resu1t in the development of cancers.