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Predictors of chest wall toxicity after stereotactic ablative radiotherapy using real-time tumor tracking for lung tumors

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ABSTRACT

Background: To evaluate the incidence of chest wall toxicity after lung stereotactic ablative radiotherapy (SABR) and identify risk factors for the development of rib fracture.

Methods: Thirty-nine patients with 49 lesions underwent SABR for primary or metastatic lung tumors using Cyberknife® with tumor tracking systems. Patient characteristics, treatment factors and variables obtained from dose-volume histograms (DVHs) were analyzed to find the association with chest wall toxicity. Four-dimensional (4D) dose calculations were done to investigate the effect of respiratory motion on dose to the ribs.

Results: After follow-up of median 26.7 months (range: 8.4 – 80.0), 8 patients (20.5%) experienced rib fractures and among these patients, three (37.5%) had chest wall pain at 2–3 months after SABR. Median time to rib fracture was 13.4 months (range: 8.0 – 38.5) and the 2-year actuarial risk of rib fracture was 12.2%. Dose to the 4.6 cc of the ribs (D4.6cc) and rib volume received 160 Gy or more (V160) were significant predictor for rib fracture. No significant differences between three-dimensional (3D) and 4D dose calculations were found.

Conclusions: Parameters from DVH are useful in predicting the risk of chest wall toxicity after SABR for lung tumors. Efforts should be made to reduce the risk of the rib fracture after lung SABR.

No MeSH data available.


Related in: MedlinePlus

Cumulative incidence of rib fracture after SABR
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Fig1: Cumulative incidence of rib fracture after SABR

Mentions: Rib fractures were identified in 8 patients and actuarial incidence of rib fracture was 12.2% at 2 years and 16.6% at 3 years (Fig. 1). Five patients had Grade 1 rib fractures, one had Grade 2 and two had Grade 3. Time interval from SABR to the rib fracture was median 13.4 months (range, 8.0 – 38.5 months). Three patients complained of Grade 1 chest wall pain at 2–3 months after SABR without any evidence of rib fracture at that time. One patient need non-opioid analgesics and the other two did not need any analgesics. All these patients eventually developed Grade 3 rib fractures after longer follow-up, but the statistically significant associations were not found between chest wall pain and Grade of rib fractures. There was no patient who had chest wall pain alone without rib fractures. Therefore, we analyzed the risk factor for rib fractures in subsequent analysis.Fig. 1


Predictors of chest wall toxicity after stereotactic ablative radiotherapy using real-time tumor tracking for lung tumors
Cumulative incidence of rib fracture after SABR
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC5382431&req=5

Fig1: Cumulative incidence of rib fracture after SABR
Mentions: Rib fractures were identified in 8 patients and actuarial incidence of rib fracture was 12.2% at 2 years and 16.6% at 3 years (Fig. 1). Five patients had Grade 1 rib fractures, one had Grade 2 and two had Grade 3. Time interval from SABR to the rib fracture was median 13.4 months (range, 8.0 – 38.5 months). Three patients complained of Grade 1 chest wall pain at 2–3 months after SABR without any evidence of rib fracture at that time. One patient need non-opioid analgesics and the other two did not need any analgesics. All these patients eventually developed Grade 3 rib fractures after longer follow-up, but the statistically significant associations were not found between chest wall pain and Grade of rib fractures. There was no patient who had chest wall pain alone without rib fractures. Therefore, we analyzed the risk factor for rib fractures in subsequent analysis.Fig. 1

View Article: PubMed Central - PubMed

ABSTRACT

Background: To evaluate the incidence of chest wall toxicity after lung stereotactic ablative radiotherapy (SABR) and identify risk factors for the development of rib fracture.

Methods: Thirty-nine patients with 49 lesions underwent SABR for primary or metastatic lung tumors using Cyberknife® with tumor tracking systems. Patient characteristics, treatment factors and variables obtained from dose-volume histograms (DVHs) were analyzed to find the association with chest wall toxicity. Four-dimensional (4D) dose calculations were done to investigate the effect of respiratory motion on dose to the ribs.

Results: After follow-up of median 26.7 months (range: 8.4 – 80.0), 8 patients (20.5%) experienced rib fractures and among these patients, three (37.5%) had chest wall pain at 2–3 months after SABR. Median time to rib fracture was 13.4 months (range: 8.0 – 38.5) and the 2-year actuarial risk of rib fracture was 12.2%. Dose to the 4.6 cc of the ribs (D4.6cc) and rib volume received 160 Gy or more (V160) were significant predictor for rib fracture. No significant differences between three-dimensional (3D) and 4D dose calculations were found.

Conclusions: Parameters from DVH are useful in predicting the risk of chest wall toxicity after SABR for lung tumors. Efforts should be made to reduce the risk of the rib fracture after lung SABR.

No MeSH data available.


Related in: MedlinePlus