title: Temporal lung tumor volume changes in small-cell lung cancer patients undergoing chemoradiotherapy.
abstract: OBJECTIVE
  Small-cell lung cancer is considered to be relatively chemosensitive and radiosensitive. Small-cell tumor volume changes during concurrent chemoradiotherapy have not been quantified. The purpose of this work is to quantify small-cell lung tumor volume variations in limited-stage patients undergoing chemoradiotherapy.
  
  
  METHODS
  Eligible patients had pathologically confirmed limited-stage small-cell lung cancer, underwent concurrent chemoradiotherapy, and signed study-specific consent forms. Patients underwent serial chest computed tomography (CT) scans on a CT simulator with images acquired at the same phase of patients' respiratory cycle. Computed tomography scans were obtained at the time of planning CT scan and 3 times a week during radiotherapy (RT). Gross tumor volumes (GTVs) were contoured on each CT scan. Gross tumor volumes defined on each CT scan were analyzed for volume changes relative to pre-RT scans.
  
  
  RESULTS
  We obtained 104 CT scans (median, 11.5 scans per patient). The median tumor dose was 50 Gy. The median pre-RT GTV was 98.9 cm(3) (range, 57.8-412.4 cm(3)). The median GTV at the final serial CT scan was 10.0 cm(3) (range, 4.2-81.6 cm(3)). The mean GTV relative to pre-RT volume at the end of each RT week was 53.0% for Week 1, 29.8% for Week 2, 22.9% for Week 3, 19.5% for Week 4, and 12.4% for Week 5.
  
  
  CONCLUSIONS
  Dramatic shrinkage of small-cell lung tumors occurred in patients undergoing chemoradiotherapy in this trial. Most of the observed GTV shrinkage occurred during the first week of RT.
authors.affiliation: Department of Radiation Oncology, Cross Cancer Institute, Edmonton, Alberta, Canada. dony@ualberta.ca
authors.forename: Don
authors.initials: D
authors.lastname: Yee
authors.forename: Satyapal
authors.initials: S
authors.lastname: Rathee
authors.forename: Don
authors.initials: D
authors.lastname: Robinson
authors.forename: Brad
authors.initials: B
authors.lastname: Murray
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D003131:Combined Modality Therapy / Q000379:methods; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging / Q000188:drug therapy* / Q000473:pathology / Q000532:radiotherapy*; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011879:Radiotherapy Dosage; D012119:Respiration; D055752:Small Cell Lung Carcinoma / Q000000981:diagnostic imaging / Q000188:drug therapy* / Q000473:pathology / Q000532:radiotherapy*; D014057:Tomography, X-Ray Computed; D047368:Tumor Burden / Q000187:drug effects* / Q000528:radiation effects*