title: Reduced Mortality With Partial-Breast Irradiation for Early Breast Cancer: A Meta-Analysis of Randomized Trials.
abstract: With earlier detection and more effective treatment, mortality from breast cancer continues to fall and it has become increasingly important to reduce the toxicity of treatments. Partial-breast radiation therapy, which focuses radiation to the tumor bed, may achieve this aim. We analyzed mortality differences in randomized trials of partial-breast irradiation (PBI).
  
  
  
  We included data from published randomized trials of PBI (alone or as part of a risk-adapted approach) versus whole-breast irradiation (WBI) for invasive breast cancer suitable for breast-conserving therapy. We identified trials using PubMed and Google searches with the terms "partial breast irradiation" OR "intraoperative radiotherapy" OR "IMRT" OR ("accelerated" AND "radiation") AND "randomised/randomized," as well as through discussion with colleagues in the field. We calculated the proportion of patients who had events in each randomized arm at 5 years' follow-up and created a forest plot using Stata, version 14.1.
  
  
  
  We identified 9 randomized trials of PBI versus WBI in invasive breast cancer; 5-year outcomes were available for non-breast cancer mortality in 5 trials (n=4489) and for breast cancer mortality in 4 trials (n=4231). The overall mortality was 4.9%. There was no detectable heterogeneity between the trials for any of the outcomes. There was no difference in the proportion of patients dying of breast cancer (difference, 0.000% [95% confidence interval (CI), -0.7 to +0.7]; P=.999). Non-breast cancer mortality with PBI was lower than with WBI (difference, 1.1% [95% CI, -2.1% to -0.2%]; P=.023). Total mortality with PBI was also lower than with WBI (difference, 1.3% [95% CI, -2.5% to 0.0%]; P=.05).
  
  
  
  Use of PBI instead of WBI in selected patients results in a lower 5-year non-breast cancer and overall mortality, amounting to a 25% reduction in relative terms. This information should be included when breast-conserving therapy is proposed to a patient.
authors.affiliation: Division of Surgery and Interventional Science, University College London, London, UK; Department of Surgery, Royal Free Hospital, London, UK; Department of Surgery, Whittington Health, London, UK. Electronic address: jayant.vaidya@ucl.ac.uk.
authors.forename: Jayant S
authors.initials: JS
authors.lastname: Vaidya
authors.affiliation: Department of Biostatistics, University of Notre Dame, Fremantle, WA, Australia.
authors.forename: Max
authors.initials: M
authors.lastname: Bulsara
authors.affiliation: Department of Radiation Oncology, University Medical Centre Mannheim, University of Heidelberg, Mannheim, Germany.
authors.forename: Frederik
authors.initials: F
authors.lastname: Wenz
authors.affiliation: Department of Surgery, Great Western Hospital, Swindon, UK.
authors.forename: Nathan
authors.initials: N
authors.lastname: Coombs
authors.affiliation: Department of Clinical Oncology, The Princess Alexandra Hospital, Harlow, UK.
authors.forename: Julian
authors.initials: J
authors.lastname: Singer
authors.affiliation: Croydon University Hospital, Croydon, UK.
authors.forename: Stephen
authors.initials: S
authors.lastname: Ebbs
authors.affiliation: National Cancer Institute, Centro di Riferimento Oncologico, Aviano, Italy.
authors.forename: Samuele
authors.initials: S
authors.lastname: Massarut
authors.affiliation: School of Surgery, University of Western Australia, Perth, WA, Australia.
authors.forename: Christobel
authors.initials: C
authors.lastname: Saunders
authors.affiliation: Department of Surgery, Kings College London, London, UK.
authors.forename: Michael
authors.initials: M
authors.lastname: Douek
authors.affiliation: Division of Surgery and Interventional Science, University College London, London, UK.
authors.forename: Norman R
authors.initials: NR
authors.lastname: Williams
authors.affiliation: Departments of Radiation Oncology, and Surgery, Sir Charles Gairdner Hospital, Perth, WA, Australia.
authors.forename: David
authors.initials: D
authors.lastname: Joseph
authors.affiliation: Department of Clinical Oncology, University College London Hospitals, London, UK.
authors.forename: Jeffrey S
authors.initials: JS
authors.lastname: Tobias
authors.affiliation: Division of Surgery and Interventional Science, University College London, London, UK.
authors.forename: Michael
authors.initials: M
authors.lastname: Baum
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000401:mortality* / Q000532:radiotherapy*; D019317:Evidence-Based Medicine; D005260:Female; D006801:Humans; D008875:Middle Aged; D059351:Organ Sparing Treatments / Q000401:mortality* / Q000706:statistics & numerical data*; D015995:Prevalence; D016032:Randomized Controlled Trials as Topic / Q000706:statistics & numerical data; D055502:Secondary Prevention / Q000706:statistics & numerical data*; D015996:Survival Rate; D016896:Treatment Outcome