Treatment optimization using computed tomography-delineated targets should be used for supraclavicular irradiation for breast cancer.
BACKGROUND
The purpose of this study was to determine whether the use of optimized CT treatment planning offered better coverage of axillary level III (LIII)/supraclavicular (SC) targets than the empirically derived dose prescription that are commonly used.


METHODS
Thirty-two consecutive breast cancer patients who underwent CT treatment planning of a SC field were evaluated. Each patient was categorized according to body mass index (BMI) classes: normal, overweight, or obese. The SC and LIII nodal beds were contoured, and four treatment plans for each patient were generated. Three of the plans used empiric dose prescriptions, and these were compared with a CT-optimized plan. Each plan was evaluated by two criteria: whether 98% of target volume receive >90% of prescribed dose and whether < 5% of the irradiated volume received 105% of prescribed dose.


RESULTS
The mean depth of SC and LIII were 3.2 cm (range, 1.4-6.7 cm) and 3.1 (range, 1.7-5.8 cm). The depth of these targets varied according across BMI classes (p = 0.01). Among the four sets of plans, the CT-optimized plans were the most successful at achieving both of the dosimetry objectives for every BMI class (normal BMI, p = .003; overweight BMI, p < .0001; obese BMI, p < .001).


CONCLUSIONS
Across all BMI classes, routine radiation prescriptions did not optimally cover intended targets for every patient. Optimized CT-based treatment planning generated the most successful plans; therefore, we recommend the use of routine CT simulation and treatment planning of SC fields in breast cancer.
Liengsawangwong
Raweewan
R
Department of Radiation Oncology, University of Texas M. D. Anderson Cancer Center, Houston, TX 77030, USA.
Yu
Tse-Kuan
TK
Sun
Tzouh-Liang
TL
Erasmus
Jeremy J
JJ
Perkins
George H
GH
Tereffe
Welela
W
Oh
Julia L
JL
Woodward
Wendy A
WA
Strom
Eric A
EA
Salephour
Mohammad
M
Buchholz
Thomas A
TA
D001365:Axilla; D015992:Body Mass Index; D001943:Breast Neoplasms / Q000145:classification / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D002968:Clavicle; D005260:Female; D006801:Humans; D015182:Lymphatic Irradiation / Q000379:methods*; D009765:Obesity / Q000145:classification; D050177:Overweight / Q000145:classification; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D014057:Tomography, X-Ray Computed