Chest wall toxicity after hypofractionated proton beam therapy for liver malignancies

Publication date: Available online 24 December 2017
Source:Practical Radiation Oncology
Author(s): Rosanna Yeung, Stephen R. Bowen, Tobias R. Chapman, Grayden T. MacLennan, Smith Apisarnthanarax
PurposeNormal liver-sparing with proton beam therapy (PBT) allows for dose escalation in the treatment of liver malignancies, but may result in high doses to the chest wall (CW). CW toxicity (CWT) data after PBT for liver malignancies are limited, with most published reports describing toxicity after a combination of hypofractionated proton and photon radiotherapy. We examined the incidence and associated factors for CWT after hypofractionated PBT for liver malignancies.Methods and MaterialsWe retrospectively reviewed the charts of 37 consecutive patients with liver malignancies (30 hepatocellular carcinoma, 6 intrahepatic cholangiocarcinoma and 1 metastasis) treated with hypofractionated PBT. CWT was scored using CTCAEv4. Receiver-operating characteristic (ROC) curves were used to identify patient and dosimetric factors associated with CWT and to determine optimal DVH parameters/cut-offs. Cox regression univariate analysis was used to associate factors to time-dependent onset of CWT.ResultsThirty-nine liver lesions were treated with a median dose of 60 GyE (range, 35–67.5 GyE) in 15 fractions (range, 13–20 fractions). Median follow-up was 11months (range, 2–44months). Grade≥2 and 3 CW pain occurred in 7 (19%) and 4 (11%) patients, respectively. Median time to onset of pain was 6months (range, 1–14months). No patients had radiographic rib fracture. On univariate analysis, CW EQD2α/β=3V57>20cm³ (HR 2.7, p=0.004), V63>17cm³ (HR 2.7, p=0.003), and V78>8cm³ (HR 2.6, p=0.003) had the strongest association with grade≥2 CW pain as did tumor dose of >75Gy EQD2α/β=10 (HR 8.7, p=0.03). No other patient factors were associated with CWT.ConclusionsCWT after hypofractionated PBT for liver malignancies is clinically relevant. For a 15-fraction regimen, V47>20cm³, V50>17cm³, and V58>8cm³ were associated with higher rates of CWT. Further investigation of PBT techniques to reduce CW dose are warranted.



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