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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 radiation induced rib fracture after SABR
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Fig3: Cumulative incidence of radiation induced rib fracture after SABR

Mentions: A representative case of dose distribution and rib fracture on CT image is shown in Fig. 2. The results of univariate and multivariate analysis are summarized in Table 2. On univariate analysis, no clinical factors showed significant association with RIRF but rib-tumor distance, D4.6cc and V160 were significant risk factors (p = 0.035, p = 0.001 and p = 0.000, respectively). Three factors, rib-tumor distance, D4.6cc and V160 were significantly associated to each other, therefore, to avoid multicollinearity, only D4.6cc was included on multivariate analysis. On multivariate analysis, D4.6cc was confirmed as a significant risk factor for RIRF (p = 0.009). Cumulative incidence of RIRF according to the D4.6cc is shown in Fig. 3.Fig. 2


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

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

Fig3: Cumulative incidence of radiation induced rib fracture after SABR
Mentions: A representative case of dose distribution and rib fracture on CT image is shown in Fig. 2. The results of univariate and multivariate analysis are summarized in Table 2. On univariate analysis, no clinical factors showed significant association with RIRF but rib-tumor distance, D4.6cc and V160 were significant risk factors (p = 0.035, p = 0.001 and p = 0.000, respectively). Three factors, rib-tumor distance, D4.6cc and V160 were significantly associated to each other, therefore, to avoid multicollinearity, only D4.6cc was included on multivariate analysis. On multivariate analysis, D4.6cc was confirmed as a significant risk factor for RIRF (p = 0.009). Cumulative incidence of RIRF according to the D4.6cc is shown in Fig. 3.Fig. 2

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