Volumetric tumor burden and its effect on brachial plexus dosimetry in head and neck intensity-modulated radiotherapy.
To determine the effect of gross tumor volume of the primary (GTV-P) and nodal (GTV-N) disease on planned radiation dose to the brachial plexus (BP) in head and neck intensity-modulated radiotherapy (IMRT). Overall, 75 patients underwent definitive IMRT to a median total dose of 69.96Gy in 33 fractions. The right BP and left BP were prospectively contoured as separate organs at risk. The GTV was related to BP dose using the unpaired t-test. Receiver operating characteristics curves were constructed to determine optimized volumetric thresholds of GTV-P and GTV-N corresponding to a maximum BP dose cutoff of > 66Gy. Multivariate analyses were performed to account for factors associated with a higher maximal BP dose. A higher maximum BP dose (> 66 vs ≤ 66Gy) correlated with a greater mean GTV-P (79.5 vs 30.8cc; p = 0.001) and ipsilateral GTV-N (60.6 vs 19.8cc; p = 0.014). When dichotomized by the optimized nodal volume, patients with an ipsilateral GTV-N ≥ 4.9 vs < 4.9cc had a significant difference in maximum BP dose (64.2 vs 59.4Gy; p = 0.001). Multivariate analysis confirmed that an ipsilateral GTV-N ≥ 4.9cc was an independent predictor for the BP to receive a maximal dose of > 66Gy when adjusted individually for BP volume, GTV-P, the use of a low anterior neck field technique, total planned radiation dose, and tumor category. Although both the primary and the nodal tumor volumes affected the BP maximal dose, the ipsilateral nodal tumor volume (GTV-N ≥ 4.9cc) was an independent predictor for high maximal BP dose constraints in head and neck IMRT.
Department of Radiation Oncology, Boston Medical Center, Boston University School of Medicine, Boston, MA.
Paul B
PB
Romesser
Department of Radiation Oncology, Boston Medical Center, Boston University School of Medicine, Boston, MA.
Muhammad M
MM
Qureshi
Department of Radiation Oncology, Boston Medical Center, Boston University School of Medicine, Boston, MA.
Nataliya
N
Kovalchuk
Department of Radiation Oncology, Boston Medical Center, Boston University School of Medicine, Boston, MA. Electronic address: mitruong@bu.edu.
Minh Tam
MT
Truong
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001917:Brachial Plexus; D006258:Head and Neck Neoplasms / Q000532:radiotherapy*; D006801:Humans; D008875:Middle Aged; D015999:Multivariate Analysis; D012372:ROC Curve; D011829:Radiation Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D012189:Retrospective Studies; D016896:Treatment Outcome
Brachial plexus; Dose-volume histogram; Gross tumor volume; Head and neck cancer