title: Acceleration of telomere loss by chemotherapy is greater in older patients with locally advanced head and neck cancer.
abstract: OBJECTIVE
  Chronic viral infection and combinations of chemotherapeutic drugs have been reported to accelerate telomere erosion. Here, we asked if chemoradiotherapy, using the single agent cisplatin, would accelerate telomere loss in head and neck cancer patients, and whether loss was linked to smoking status, age, gender, or stage of disease at diagnosis.
  
  
  METHODS
  Blood samples were collected from 20 patients with squamous cell cancer of the head and neck before, during, and after chemoradiotherapy. Following DNA isolation from peripheral blood mononuclear cells, telomere length was measured by terminal restriction fragment analysis.
  
  
  RESULTS
  Chemoradiotherapy increased the rate of telomere erosion>100-fold. Telomere length before treatment in chemoradiotherapy patients was similar to age-matched controls. Although smokers began with significantly shorter telomeres, smoking status did not affect chemoradiotherapy-induced attrition, nor did gender or stage of disease. We also make the novel observation that a significantly greater telomere loss occurred in response to treatment in older patients, with those younger than 55 years losing an average of 400 bp of telomeric DNA compared with the 880 bp lost by those over 55 years.
  
  
  CONCLUSIONS
  The lack of telomere length difference before treatment suggests that shortened telomeres may not be a risk factor for development of head and neck cancer in the age range we examined. Chemoradiotherapy caused a severe telomere length reduction in all patients. The significant difference seen in the elderly (P=0.018) suggests that chemoradiotherapy may have more severe effects on the replicative capacity of blood cells in older patients.
authors.affiliation: Department of Biochemistry, The University of Calgary Health Sciences Centre, Canada.
authors.forename: Brad M
authors.initials: BM
authors.lastname: Unryn
authors.forename: Desiree
authors.initials: D
authors.lastname: Hao
authors.forename: Stefan
authors.initials: S
authors.lastname: Glück
authors.forename: Karl T
authors.initials: KT
authors.lastname: Riabowol
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000970:Antineoplastic Agents / Q000627:therapeutic use; D002945:Cisplatin / Q000627:therapeutic use; D005260:Female; D006258:Head and Neck Neoplasms / Q000473:pathology* / Q000628:therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D018307:Neoplasms, Squamous Cell / Q000473:pathology* / Q000628:therapy*; D011878:Radiotherapy; D012737:Sex Factors; D016615:Telomere / Q000187:drug effects / Q000473:pathology* / Q000528:radiation effects
chemical_list: D000970:Antineoplastic Agents; D002945:Cisplatin