title: Electron and high-dose-rate brachytherapy boost in the conservative treatment of stage I-II breast cancer first results of the randomized Budapest boost trial.
abstract: OBJECTIVE
  To evaluate the effect of electron and high-dose-rate brachytherapy (HDR BT) boost on local tumor control (LTC), side effects and cosmesis after breast-conserving surgery (BCS) in a prospective randomized study.
  
  
  METHODS
  207 women with stage I-II breast cancer who underwent BCS were treated by 50 Gy irradiation to the whole breast and then randomly assigned to receive either a boost to the tumor bed (n = 104) or no further radiotherapy (n = 103). Boost treatments consisted of either 16 Gy electron irradiation (n = 52) or 12-14,25 Gy HDR BT (n = 52). Breast cancer-related events, side effects, and cosmetic results were assessed.
  
  
  RESULTS
  At a median follow-up of 5.3 years, the crude rate of local recurrences was 6.7% (7/104) with and 15.5% (16/103) without boost. The 5-year probability of LTC, relapse-free survival (RFS), and cancer-specific survival (CSS) was 92.7% vs. 84.9% (p = 0.049), 76.6% vs. 66.2% (p = 0.044), and 90.4% vs. 82.1% (p = 0.053), respectively. There was no significant difference in LTC between patients treated with electron or HDR BT boost (94.2% vs. 91.4%; p = 0.74). On multivariate analysis, patient age < 40 years (RR: 4.53), positive margin status (RR: 4.17), and high mitotic activity index (RR: 3.60) were found to be significant risk factors for local recurrence. The incidence of grade 2-3 side effects was higher in the boost arm (17.3% vs. 7.8%; p = 0.03). However, the rate of excellent/good cosmetic results was similar for the two arms (85.6% vs 91.3%; p = 0.14). Cosmesis was rated as excellent/good in 88.5% of patients treated with HDR BT and 82.7% of patients with electron boost (p = 0.29).
  
  
  CONCLUSIONS
  Boost dose significantly improves LTC and RFS in patients treated with BCS and radiotherapy. In spite of the higher incidence of late side effects in the boost arm, boost dose is strongly recommended for patients at high risk for local recurrence. Positive or close margin status, high mitotic activity index, and young patient age should be viewed as absolute indications for tumor bed boost. LTC and cosmesis are excellent and similar to patients boosted with either HDR BT or electrons.
authors.affiliation: Department of Radiotherapy, National Institute of Oncology, Budapest, Hungary. polgar@oncol.hu
authors.forename: Csaba
authors.initials: C
authors.lastname: Polgár
authors.forename: János
authors.initials: J
authors.lastname: Fodor
authors.forename: Zsolt
authors.initials: Z
authors.lastname: Orosz
authors.forename: Tibor
authors.initials: T
authors.lastname: Major
authors.forename: Zoltán
authors.initials: Z
authors.lastname: Takácsi-Nagy
authors.forename: László Csaba
authors.initials: LC
authors.lastname: Mangel
authors.forename: Zoltán
authors.initials: Z
authors.lastname: Sulyok
authors.forename: András
authors.initials: A
authors.lastname: Somogyi
authors.forename: Miklós
authors.initials: M
authors.lastname: Kásler
authors.forename: György
authors.initials: G
authors.lastname: Németh
mesh_terms: D001918:Brachytherapy; D001943:Breast Neoplasms / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D003131:Combined Modality Therapy; D018450:Disease Progression; D018572:Disease-Free Survival; D019583:Dose Fractionation, Radiation; D004583:Electrons / Q000627:therapeutic use*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006814:Hungary; D009364:Neoplasm Recurrence, Local / Q000209:etiology / Q000401:mortality; D011446:Prospective Studies; D018714:Radiotherapy, Adjuvant; D011882:Radiotherapy, High-Energy / Q000379:methods*; D012307:Risk Factors