Optimized dose coverage of regional lymph nodes in breast cancer: the role of intensity-modulated radiotherapy.
OBJECTIVE
To determine whether the use of intensity-modulated radiotherapy (IMRT) would lead to improved dosimetry for the breast and regional nodes.


METHODS
Ten patients with left-sided breast cancer were selected. The clinical target volume included left breast and internal mammillary (IM), supraclavicular (SC), and axillary (AX) nodes. The critical structures included heart, right and left lungs, contralateral breast, esophagus, thyroid, and humeral head. Conventional and a series of IMRT plans were generated for comparison.


RESULTS
The average heart D(3) was reduced from 31.4 +/- 18.9 with three-dimensional conformal radiotherapy (3D-CRT) to 15 +/- 7.2 Gy with 9-field (9-FLD IMRT). The average left lung D(30) was also decreased from 27.9 +/- 11.5 Gy (3D-CRT) to 12.6 +/- 8.2 Gy (9-FLD IMRT). The average contralateral breast D(2) was reduced from 4.4 +/- 5.3 Gy (3D-CRT) to 1.8 +/- 1.2 Gy (4-FLD IMRT). Esophagus D(2) was increased from 9.3 +/- 8.1 Gy (3D-CRT) to 29.4 +/- 5.4 (9-FLD IMRT); thyroid D(50) was increased from 0.9 +/- 0.6 Gy (3D-CRT) to 11.9 +/- 6.6 (9-FLD IMRT); humeral head D(2) was increased from 36.1 +/- 13.1 Gy (3D-CRT) to 39.9 +/- 6.5 (9-FLD IMRT).


CONCLUSIONS
The use of IMRT improves breast and regional node coverage while decreasing doses to the lungs, heart, and contralateral breast when compared with 3D-CRT. Doses to esophagus, thyroid, and humeral head, however, were increased with IMRT.
Dogan
Nesrin
N
Department of Radiation Oncology, Virginia Commonwealth University Medical Center, 401 College Street, Richmond, VA 23298, USA. ndogan@mcvh-vcu.edu
Cuttino
Laurie
L
Lloyd
Rick
R
Bump
Edward A
EA
Arthur
Douglas W
DW
D001365:Axilla; D001940:Breast; D001943:Breast Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D004947:Esophagus; D005260:Female; D006321:Heart; D006801:Humans; D006811:Humerus; D008168:Lung; D015182:Lymphatic Irradiation / Q000379:methods*; D011879:Radiotherapy Dosage; D050397:Radiotherapy, Intensity-Modulated; D013961:Thyroid Gland; D047368:Tumor Burden