title: Association between XRCC1 G399A Polymorphism and Late Complications to Radiotherapy in Saudi Head and Neck Cancer Patients.
abstract: BACKGROUND
  It has been hypothesized that patient to patient variation in normal tissue reactions to radiotherapy is associated with the presence of polymorphic variations in genes involved in DNA repair.
  
  
  OBJECTIVE
  To test for a possible association between two single-nucleotide polymorphisms (SNPs), XRCC1 399 G>A Arg/Gln and XRCC3 241 C>T Thr/Met and late reactions to radiotherapy.
  
  
  METHODS
  In this case control study, 50 Head and Neck cancer patients were retrospectively recruited. The grade (G) of fibrosis, a late complication to radiotherapy, was scored using the RTOG/EORTC grading system. Radiosensitive patients with moderate to severe subcutaneous and deep tissue fibrosis (cases, G2-3, n=25) where matched with patients with minimal fibrotic reactions (control, G0-1, n=25). The two nonsynonymous SNPs were genotyped by direct sequencing of DNA extracted from blood or cultured fibroblasts.
  
  
  RESULTS
  Allelic frequency showed significant association with grade of fibrosis for XRCC1 399 G/A (p=0.05), but not for XRCC3 241 C>T (p=0.10).
  
  
  CONCLUSIONS
  This pilot study corroborates the association between XRCC1 399 G>A and risk of late normal tissue complications following radiotherapy in our patients. Large studies are required to unravel more SNPs that can influence radiosensitivity and ascertain the associations with reactions to radiotherapy in order to be used as genetic predictive biomarkers of individual radiosensitivity.
  
  
  BACKGROUND
  Single nucleotide polymorphism - Radiosensitivity - Late reactions to radiotherapy - XRCC1 - XRCC3.
authors.affiliation: The Departments of Biomedical Physics, King Saud University, Riyadh, Saudi Arabia.
authors.forename: Ghazi Atiyeh
authors.initials: GA
authors.lastname: Alsbeih
authors.forename: Medhat Mohamed
authors.initials: MM
authors.lastname: El-Sebaie
authors.forename: Nasser Mohamed
authors.initials: NM
authors.lastname: Al-Rajhi
authors.forename: Najla Mohamed
authors.initials: NM
authors.lastname: Al-Harbi
authors.forename: Khaled Saleh
authors.initials: KS
authors.lastname: Al-Hadyan
authors.forename: Muneera Hamad
authors.initials: MH
authors.lastname: Al-Buhairi
authors.forename: Belal Ali
authors.initials: BA
authors.lastname: Moftah
authors.forename: Mohammad Othman
authors.initials: MO
authors.lastname: Al-Shabanah
authors.forename: Khaled Kader
authors.initials: KK
authors.lastname: Abu-Amero