title: Local recurrence rates in breast cancer patients treated with intraoperative electron-boost radiotherapy versus postoperative external-beam electron-boost irradiation. A sequential intervention study.
abstract: OBJECTIVE
  The purpose of this sequential intervention study was to determine the rate of local recurrences and the rate of distant metastases in patients with invasive breast cancer who had been treated with breast-conserving surgery and postoperative radiation therapy to the whole breast either with postoperative electron boost in group 1 or with intraoperative electron boost (IORT) in group 2.
  
  
  METHODS
  After breast-conserving surgery, 378 women with invasive breast cancer of tumor sizes T1 and T2 received 51-56.1 Gy of postoperative radiation therapy to the whole breast in 1.7-Gy fractions. 188 of those patients additionally received a postoperative electron boost of 12 Gy in group 1 from January 1996 to October 1998. Consecutively, from October 1998 to March 2001, 190 patients received intraoperative electron-boost radiotherapy of 9 Gy to the tumor bed in group 2. The groups were comparable with regard to age, menopausal status, tumor size, grading, and nodal status. All statistical tests were two-sided.
  
  
  RESULTS
  During a median follow-up period of 55.3 months in group 1 and 25.8 months in group 2, local recurrences were observed in eight of 188 patients (4.3%) in group 1, and no local recurrence was seen in group 2 (p=0.082). Distant metastases occurred in 15 of the 188 patients (7.9%) in group 1 and in two of the 190 patients (1.1%) in group 2 (p=0.09). The 4-year actuarial rates of local recurrence were 4.3% (95% confidence interval, 1.8-8.2%) and 0.0% (95% confidence interval, 0.0-1.9%) and the 4-year actuarial rates of distant metastases were 7.9% (95% confidence interval, 4.5-12.8%) and 1.1% (95% confidence interval, 0.1-3.8%).
  
  
  CONCLUSIONS
  Immediate IORT boost yielded excellent local control figures in this prospective investigation and appears to be superior to conventional postoperative boost in a short-term follow-up.
authors.affiliation: Department of Senology, General Hospital, Salzburg, Austria. r.reitsamer@lks.at
authors.forename: Roland
authors.initials: R
authors.lastname: Reitsamer
authors.forename: Florentia
authors.initials: F
authors.lastname: Peintinger
authors.forename: Michael
authors.initials: M
authors.lastname: Kopp
authors.forename: Christian
authors.initials: C
authors.lastname: Menzel
authors.forename: H Dieter
authors.initials: HD
authors.lastname: Kogelnik
authors.forename: Felix
authors.initials: F
authors.lastname: Sedlmayer
mesh_terms: D000328:Adult; D000368:Aged; D001918:Brachytherapy / Q000379:methods*; D001943:Breast Neoplasms / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery*; D044584:Carcinoma, Ductal / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery*; D002285:Carcinoma, Intraductal, Noninfiltrating / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery*; D018275:Carcinoma, Lobular / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery*; D003131:Combined Modality Therapy; D018572:Disease-Free Survival; D019583:Dose Fractionation, Radiation; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D015412:Mastectomy, Segmental; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000209:etiology* / Q000473:pathology; D009367:Neoplasm Staging; D011183:Postoperative Complications / Q000209:etiology*; D011879:Radiotherapy Dosage; D018714:Radiotherapy, Adjuvant; D021701:Sentinel Lymph Node Biopsy