title: Interaction of 2-Gy equivalent dose and margin status in perioperative high-dose-rate brachytherapy.
abstract: OBJECTIVE
  To determine patient, tumor, and treatment factors predictive of local control (LC) in a series of patients treated with either perioperative high-dose-rate brachytherapy (PHDRB) alone (Group 1) or with PHDRB combined with external-beam radiotherapy (EBRT) (Group 2).
  
  
  METHODS
  Patients (n = 312) enrolled in several PHDRB prospective Phase I-II studies conducted at the Clínica Universidad de Navarra were analyzed. Treatment with PHDRB alone, mainly because of prior irradiation, was used in 126 patients to total doses of 32 Gy/8 b.i.d. or 40 Gy/10 b.i.d. treatments after R0 or R1 resections. Treatment with PHDRB plus EBRT was used in 186 patients to total doses of 16 Gy/4 b.i.d. or 24 Gy/6 b.i.d. treatments after R0 or R1 resections along with 45 Gy of EBRT with or without concomitant chemotherapy.
  
  
  RESULTS
  No dose-margin interaction was observed in Group 1 patients. In Group 2 patients there was a significant interaction between margin status and 2-Gy equivalent (Eq2Gy) dose (p = 0.002): (1) patients with negative margins had 9-year LC of 95.7% at Eq2Gy = 62.9Gy; (2) patients with close margins of >1 mm had 9-year LC of 92.4% at Eq2Gy = 72.2Gy, and (3) patients with positive/close <1-mm margins had 9-year LC of 68.0% at Eq2Gy = 72.2Gy.
  
  
  CONCLUSIONS
  Two-gray equivalent doses ≥70 Gy may compensate the effect of close margins ≥1 mm but do not counterbalance the detrimental effect of unfavorable (positive/close <1 mm) resection margins. No dose-margin interaction is observed in patients treated at lower Eq2Gy doses ≤50 Gy with PHDRB alone.
authors.affiliation: Department of Oncology, Clínica Universitaria de Navarra, University of Navarre, Navarre, Spain. rmartinezm@unav.es
authors.forename: Rafael
authors.initials: R
authors.lastname: Martínez-Monge
authors.forename: Mauricio
authors.initials: M
authors.lastname: Cambeiro
authors.forename: Marta
authors.initials: M
authors.lastname: Moreno
authors.forename: Miren
authors.initials: M
authors.lastname: Gaztañaga
authors.forename: Mikel
authors.initials: M
authors.lastname: San Julián
authors.forename: Juan
authors.initials: J
authors.lastname: Alcalde
authors.forename: Matías
authors.initials: M
authors.lastname: Jurado
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001918:Brachytherapy / Q000379:methods*; D002648:Child; D019583:Dose Fractionation, Radiation; D005260:Female; D005833:Genital Neoplasms, Female / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy / Q000601:surgery; D006258:Head and Neck Neoplasms / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy / Q000601:surgery; D006801:Humans; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy; D009369:Neoplasms / Q000401:mortality / Q000473:pathology* / Q000532:radiotherapy* / Q000601:surgery; D011446:Prospective Studies; D012509:Sarcoma / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy / Q000601:surgery; D012737:Sex Factors; D047368:Tumor Burden; D055815:Young Adult