title: Nomogram for predicting the risk of locoregional recurrence in patients treated with accelerated partial-breast irradiation.
abstract: OBJECTIVE
  To develop a nomogram taking into account clinicopathologic features to predict locoregional recurrence (LRR) in patients treated with accelerated partial-breast irradiation (APBI) for early-stage breast cancer.
  
  
  METHODS
  A total of 2000 breasts (1990 women) were treated with APBI at William Beaumont Hospital (n=551) or on the American Society of Breast Surgeons MammoSite Registry Trial (n=1449). Techniques included multiplanar interstitial catheters (n=98), balloon-based brachytherapy (n=1689), and 3-dimensional conformal radiation therapy (n=213). Clinicopathologic variables were gathered prospectively. A nomogram was formulated utilizing the Cox proportional hazards regression model to predict for LRR. This was validated by generating a bias-corrected index and cross-validated with a concordance index.
  
  
  RESULTS
  Median follow-up was 5.5 years (range, 0.9-18.3 years). Of the 2000 cases, 435 were excluded because of missing data. Univariate analysis found that age <50 years, pre-/perimenopausal status, close/positive margins, estrogen receptor negativity, and high grade were associated with a higher frequency of LRR. These 5 independent covariates were used to create adjusted estimates, weighting each on a scale of 0-100. The total score is identified on a points scale to obtain the probability of an LRR over the study period. The model demonstrated good concordance for predicting LRR, with a concordance index of 0.641.
  
  
  CONCLUSIONS
  The formulation of a practical, easy-to-use nomogram for calculating the risk of LRR in patients undergoing APBI will help guide the appropriate selection of patients for off-protocol utilization of APBI.
authors.affiliation: Department of Radiation Oncology, Beaumont Health System, Royal Oak, Michigan.
authors.forename: Jessica L
authors.initials: JL
authors.lastname: Wobb
authors.affiliation: Department of Radiation Oncology, Beaumont Health System, Royal Oak, Michigan. Electronic address: PChen@beaumont.edu.
authors.forename: Peter Y
authors.initials: PY
authors.lastname: Chen
authors.affiliation: Department of Radiation Oncology, Summa Health System, Akron, Ohio.
authors.forename: Chirag
authors.initials: C
authors.lastname: Shah
authors.affiliation: Department of Therapeutic Radiology, Yale School of Medicine, Norwich, Connecticut.
authors.forename: Meena S
authors.initials: MS
authors.lastname: Moran
authors.affiliation: Department of Radiation Oncology, MD Anderson Cancer Center, Houston, Texas.
authors.forename: Simona F
authors.initials: SF
authors.lastname: Shaitelman
authors.affiliation: Department of Radiation Oncology, Michigan Healthcare Professionals/21st Century Oncology, Farmington, Michigan.
authors.forename: Frank A
authors.initials: FA
authors.lastname: Vicini
authors.affiliation: Biostat International Inc, Tampa, Florida.
authors.forename: Alfred K
authors.initials: AK
authors.lastname: Mbah
authors.affiliation: Biostat International Inc, Tampa, Florida.
authors.forename: Maureen
authors.initials: M
authors.lastname: Lyden
authors.affiliation: Department of Surgery, Dallas Breast Center, Dallas, Texas.
authors.forename: Peter
authors.initials: P
authors.lastname: Beitsch
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D001918:Brachytherapy / Q000706:statistics & numerical data*; D001943:Breast Neoplasms / Q000175:diagnosis / Q000453:epidemiology* / Q000532:radiotherapy*; D019583:Dose Fractionation, Radiation; D005260:Female; D006801:Humans; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000175:diagnosis / Q000453:epidemiology* / Q000517:prevention & control*; D049451:Nomograms; D059351:Organ Sparing Treatments / Q000379:methods / Q000706:statistics & numerical data*; D017063:Outcome Assessment, Health Care / Q000379:methods; D011379:Prognosis; D015203:Reproducibility of Results; D018570:Risk Assessment / Q000379:methods; D012680:Sensitivity and Specificity; D014481:United States / Q000453:epidemiology