title: Incidental radiation to axilla in early breast cancer treated with intensity modulated tangents and comparison with conventional and 3D conformal tangents.
abstract: OBJECTIVE
  To analyze incidental radiation doses to minimally dissected axilla with Intensity modulated radiotherapy (IMRT), 3D conformal radiotherapy (3DCRT) and standard tangents (ST).
  
  
  METHODS
  We prospectively evaluated incidental radiation to axilla in fifty cases of early breast cancer treated with breast conservation surgery with sentinel node biopsy alone followed by whole breast irradiation with IMRT. Three plans were devised for each CT dataset, comprising ST, 3DCRT and IMRT tangents. Doses to axillary nodal levels I, II and III were evaluated for mean dose, V95, V90, V80 and V50. Comparisons were made using ANOVA.
  
  
  RESULTS
  The mean doses delivered to axilla by the three techniques (IMRT, 3DCRT, ST) were: 78% (range 67-90, SD ± 5.2%), 80% (63-95, ±7.5%) and 87% (73-98, ±4.8%) for level I (IMRT vs ST; p = 0.037); 70% (46-89, ±12.4%), 72% (34-93, ±15.5%) and 65% (29-87, ±11.8%) for level II; and 51% (28-76, ±11.1%), 53% (19-86, ±13.7%) and 41% (6-72, ±10.6%) for level III, respectively. V90 values (volume receiving 90% of dose) for the three techniques were 49% (43-53, ±2.7%), 57% (51-65, ±3.1%) and 73% (65-80, ±3.4%) for level I (IMRT vs. ST; p = 0.029); 35% (26-42, ±4.7%), 41% (33-50, ±4.2%) and 25% (17-36, ±4.5%) for level II (IMRT vs ST; p = 0.068); and 15% (9-22, ±3.4%), 16% (10-24, ±3.7%) and 8 (5-12, ±3.1%) for level III (IMRT vs ST; p = 0.039), respectively.
  
  
  CONCLUSIONS
  Axillary levels I and II (lower axilla) receive substantial amount of incidental radiation doses with all the three techniques; however, conformal techniques (IMRT, 3DCRT) deliver significantly lesser incidental radiation to lower axilla than ST technique.
authors.affiliation: Radiation Oncology, Medanta - The Medicity, Gurgaon, Haryana, India. Electronic address: teji1960@gmail.com.
authors.forename: Tejinder
authors.initials: T
authors.lastname: Kataria
authors.forename: Shyam Singh
authors.initials: SS
authors.lastname: Bisht
authors.forename: Deepak
authors.initials: D
authors.lastname: Gupta
authors.forename: Shikha
authors.initials: S
authors.lastname: Goyal
authors.forename: Kannan
authors.initials: K
authors.lastname: Jassal
authors.forename: Ashu
authors.initials: A
authors.lastname: Abhishek
authors.forename: Kuldeep
authors.initials: K
authors.lastname: Sharma
authors.forename: Puneet
authors.initials: P
authors.lastname: Pareek
authors.forename: Vikash
authors.initials: V
authors.lastname: Kumar
authors.forename: Sandeep
authors.initials: S
authors.lastname: Jain
authors.forename: Manoj
authors.initials: M
authors.lastname: Tayal
authors.forename: N
authors.initials: N
authors.lastname: Karthikeyan
mesh_terms: D000328:Adult; D000368:Aged; D001365:Axilla; D001943:Breast Neoplasms / Q000532:radiotherapy* / Q000601:surgery; D018270:Carcinoma, Ductal, Breast / Q000532:radiotherapy* / Q000601:surgery; D005260:Female; D006801:Humans; D008198:Lymph Nodes; D015412:Mastectomy, Segmental; D008875:Middle Aged; D011446:Prospective Studies; D011879:Radiotherapy Dosage; D020266:Radiotherapy, Conformal; D050397:Radiotherapy, Intensity-Modulated; D021701:Sentinel Lymph Node Biopsy
keywords: Axilla; Breast cancer; Incidental dose