Simultaneous integrated boost in breast conserving treatment of breast cancer: a dosimetric comparison of helical tomotherapy and three-dimensional conformal radiotherapy.
OBJECTIVE
To evaluate the dosimetry of helical tomotherapy (HT) and three-dimensional conformal radiotherapy (3D-CRT) in breast cancer patients undergoing whole breast radiation with simultaneous integrated boost (SIB) of the tumor bed.


METHODS
Thirteen patients with breast cancer treated by lumpectomy and requiring whole breast radiotherapy with tumor bed boost were planned using both HT and 3D-CRT using the field-in-field technique. The whole breast and tumor bed were prescribed 50.68 Gy and 64.4 Gy, respectively, in 28 fractions. Dosimetries for both techniques were compared.


RESULTS
Coverage of the whole breast was adequate with both techniques (V(95%)=96.22% vs. 96.25%, with HT and 3D-CRT, respectively; p=0.64). Adequate tumor bed coverage was also achieved, although it was significantly lower with HT (V(95%)=97.18% vs. 99.72%; p<0.001). Overdose of the breast volume outside the tumor bed was significantly lower with HT (V(54.23 Gy)=12.47% vs. 30.83%; p<0.001). Ipsilateral lung V(20 Gy) (6.34% vs. 10.17%; p<0.001), V(5 Gy) (16.54% vs. 18.53%; p<0.05) and mean dose (4.05 Gy vs. 6.36 Gy; p<0.001) were significantly lower with HT. In patients with left-sided tumors, heart V(30 Gy) (0.03% vs. 1.14%; p<0.05) and mean dose (1.35 Gy vs. 2.22 Gy; p<0.01) were significantly lower with HT, but not V(5 Gy). Contralateral breast V(5 Gy) (0.27% vs. 0.00%; p<0.01) and maximum dose were significantly increased with HT.


CONCLUSIONS
In breast cancer treated with SIB, both HT and 3D-CRT provided adequate target volume coverage and low heart doses. Tumor bed coverage was slightly lower with HT, but HT avoided unnecessary breast overdosage while improving ipsilateral lung dosimetry.
Hijal
Tarek
T
Department of Radiation Oncology, Institut Curie, Paris, France. tarekhijal@hotmail.com
Fournier-Bidoz
Nathalie
N
Castro-Pena
Pablo
P
Kirova
Youlia M
YM
Zefkili
Sophia
S
Bollet
Marc A
MA
Dendale
Rémi
R
Campana
François
F
Fourquet
Alain
A
D001943:Breast Neoplasms / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D005260:Female; D006801:Humans; D015412:Mastectomy, Segmental; D011879:Radiotherapy Dosage; D020266:Radiotherapy, Conformal; D012189:Retrospective Studies; D036542:Tomography, Spiral Computed