title: Conventional four-field pelvic radiotherapy technique without computed tomography-treatment planning in cancer of the cervix: potential geographic miss and its impact on pelvic control.
abstract: OBJECTIVE
  To evaluate the impact of inadequate margins on pelvic control using the conventional four-field pelvic portals without computed tomography (CT)-treatment planning.
  
  
  METHODS
  Between 1986 and 1991, 34 patients with invasive cancer of the cervix were eligible for outcome study of conventional four-field radiation therapy (10 Stage I, 16 Stage II, 8 Stage III). The eligibility for this study includes four-field pelvic technique, definitive radiation therapy, and diagnostic CT scan of the pelvis. For this study, an inadequate margin is arbitrarily defined as < or = 1.0 cm of normal tissue around the CT-defined tumor volume.
  
  
  RESULTS
  All 34 patients had adequate margins for anterio-posterior/posterio-anterior portals. However, 19 patients had an inadequate margin at the posterior border (S2-S3 interspace) and/or custom-shaped rectal block for lateral pelvic portals. Two patients had inadequate margins at the anterior border (level of symphysis pubis) due to an enlarged uterus. With a median follow-up of 36 months, pelvic control for adequate margins and inadequate margins was 100% and 71% for Stage IB disease and 88% and 50% for Stage IIB disease, respectively. However, pelvic control for Stage IIIB disease was 50% for both groups. There was no difference in total dose to point A or point B between the two groups.
  
  
  CONCLUSIONS
  Our preliminary data show higher local failure in patients with an inadequate margin. For four-field pelvic radiation therapy, we strongly recommend CT-treatment planning. Otherwise, anterio-posterior/posterio-anterior pelvic therapy is the most reliable treatment for cancer of the uterine cervix.
authors.affiliation: Department of Radiation Oncology, University of Alabama Medical Center, Birmingham 35233.
authors.forename: R Y
authors.initials: RY
authors.lastname: Kim
authors.forename: L S
authors.initials: LS
authors.lastname: McGinnis
authors.forename: S A
authors.initials: SA
authors.lastname: Spencer
authors.forename: R F
authors.initials: RF
authors.lastname: Meredith
authors.forename: R L
authors.initials: RL
authors.lastname: Jennelle
authors.forename: M M
authors.initials: MM
authors.lastname: Salter
mesh_terms: D005260:Female; D006801:Humans; D011879:Radiotherapy Dosage; D011881:Radiotherapy, Computer-Assisted; D014057:Tomography, X-Ray Computed; D002583:Uterine Cervical Neoplasms / Q000175:diagnosis / Q000473:pathology / Q000532:radiotherapy*