title: Detection of a numeric value predictive of increased dose to left anterior descending coronary artery (LAD) in radiotherapy of breast cancer.
abstract: OBJECTIVE
  We have evaluated thoracic conformation of patients in order to derive a numeric value predictive of an increased dose to left anterior descending coronary artery (LAD), critical structure for the development of late radio induced cardiac morbidity.
  
  
  METHODS
  We have evaluated 91 patients (36-88 years) affected by breast cancer stage I-II (Tis-T1-2 N0-1), undergoing adjuvant radiotherapy with conventional fractionation. For each patient on CT images was measured the distance between the back face of the sternum (manubrium) and the anterior face of body of the corresponding vertebra (a), and the distance measured on the line at 45° between the vertebral body of the same vertebra and the back face of the rib corresponding (b). The a/b ratio showed values between 0.626 and 1.123. We used the median value (0.821) as cut-off to divide the patients in two groups. We calculated in both groups: Volume (Vol) heart, Vol LAD with an expansion of 0.6 mm; Dmean LAD (Gy); Dmax LAD (Gy); V10-V20-V30 (%) LAD and we correlated these values with parametric and non-parametric tests.
  
  
  RESULTS
  The Pearson test has showed a statistically significant correlation between Vol breast and V10, V20, V30 with borderline significance (p = 0.006; p = 0.02; p = 0.05). The data were confirmed by testing non-parametric Kendall (tau = 0.004; tau = 0.015; tau = 0.016) and Spearman (rho = 0.003; rho = 0.016; rho = 0.015). We conducted categorizing into quartiles of breast volume and evaluated the correlation with a/b. We have found a significative correlation (p = 0.01) between small Vol breast (≤660.23 cc) and a/b < 0.0821 and greater Vol breast (>660.23 cc) with a/b > 0.0821. From the evaluation of the distribution of V10 in the two groups taking account of the Dmean ≤5 or >5 significance was found with a/b; Chi square 0.009 (0.01). Values ≤5 were observed in women with a/b < 0.0821. Values >5 in women with a/b > 0.0821.
  
  
  CONCLUSIONS
  The geometric conformity of chest thorax considering a/b and the value of 0.0821 can reveals an important parameter in the selection of patients suitable for radiation therapy on left breast in order to evaluate the risk of late cardiac events. This consideration during treatment planning can change the technique or the set-up allowing the development of a customized plan.
authors.affiliation: UOC Radiation Oncology, Istituto Nazionale per lo studio e la cura dei tumori "Fondazione Giovanni Pascale" - IRCCS, Via Mariano Semmola, 80131 Naples, Italy.
authors.forename: R
authors.initials: R
authors.lastname: Di Franco
authors.affiliation: UOC Radiation Oncology, Istituto Nazionale per lo studio e la cura dei tumori "Fondazione Giovanni Pascale" - IRCCS, Via Mariano Semmola, 80131 Naples, Italy.
authors.forename: V
authors.initials: V
authors.lastname: Ravo
authors.affiliation: UOC Radiation Oncology, Istituto Nazionale per lo studio e la cura dei tumori "Fondazione Giovanni Pascale" - IRCCS, Via Mariano Semmola, 80131 Naples, Italy.
authors.forename: V
authors.initials: V
authors.lastname: Nieddu
authors.affiliation: Division of Epidemiology, Istituto Nazionale per lo studio e la cura dei tumori "Fondazione Giovanni Pascale" - IRCCS, Via Mariano Semmola, 80131 Naples, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Crispo
authors.affiliation: UOC Radiation Oncology, Istituto Nazionale per lo studio e la cura dei tumori "Fondazione Giovanni Pascale" - IRCCS, Via Mariano Semmola, 80131 Naples, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Falivene
authors.affiliation: UOC Radiation Oncology, Istituto Nazionale per lo studio e la cura dei tumori "Fondazione Giovanni Pascale" - IRCCS, Via Mariano Semmola, 80131 Naples, Italy.
authors.forename: F M
authors.initials: FM
authors.lastname: Giugliano
authors.affiliation: UOC Radiation Oncology, Istituto Nazionale per lo studio e la cura dei tumori "Fondazione Giovanni Pascale" - IRCCS, Via Mariano Semmola, 80131 Naples, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Argenone
authors.affiliation: UOC Radiation Oncology, Istituto Nazionale per lo studio e la cura dei tumori "Fondazione Giovanni Pascale" - IRCCS, Via Mariano Semmola, 80131 Naples, Italy.
authors.forename: V
authors.initials: V
authors.lastname: Borzillo
authors.affiliation: UOC Radiation Oncology, Istituto Nazionale per lo studio e la cura dei tumori "Fondazione Giovanni Pascale" - IRCCS, Via Mariano Semmola, 80131 Naples, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Cammarota
authors.affiliation: UOC Radiation Oncology, Istituto Nazionale per lo studio e la cura dei tumori "Fondazione Giovanni Pascale" - IRCCS, Via Mariano Semmola, 80131 Naples, Italy.
authors.forename: P
authors.initials: P
authors.lastname: Muto
keywords: Breast cancer; Chest thorax; Coronary arteries; Heart; Radiotherapy