Abstract
Radiotherapy (RT) which is a treatment regime for cancer patients may cause genetic instability and side effects. Etiological associations exist amongst autophagy-related gene (ATG) mutation and cancer. RT increases the rate of autophagy previously proven in vitro. The aforementioned background diverted us to conduct exon mutation analysis for ATG5, ATG12, and ATG9B genes of colorectal cancer patients who were receiving neoadjuvant RT. Peripheral blood DNA from different time points (before/middle/after RT) of the same patients was isolated and most tandem repeat-containing exons of ATG5, ATG12, and ATG9B were polymerase chain reaction-amplified and examined for mutations by Sanger sequencing. CA19-9/CEA (Tumor marker of colorectal cancer/Carcinoembryonic Antigen) serum levels were retrieved from the clinic. No exon variations detected for ATG5 and ATG12 genes. However, 4 patients (17.4%) showed frameshift mutation for ATG9B gene. Exon variation analysis of 2 (8.7%) patients resulted in GGG deletion at 8G mononucleotide tandem repeat region of ATG9B. Assigning patients as before RT and after RT, CA19-9 levels in ATG9B (Mutation) patients were higher compared to ATG9B (Wild Type) patients. ATG9B is highly likely to mutate during RT and ATG9B mutation correlates to higher CEA and CA19-9 levels and patients show poor prognosis. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s12291-023-01177-6.