Clinical outcomes of helical conformal versus non-conformal palliative radiotherapy for axial skeletal metastases

Publication date: Available online 9 April 2017
Source:Practical Radiation Oncology
Author(s): Kara D. Romano, Daniel M. Trifiletti, Kristine Bauer-Nilsen, Nolan A. Wages, William T. Watkins, Paul W. Read, Timothy N. Showalter
PurposePalliative radiotherapy (RT) for bone metastases has traditionally been delivered with conventional, non-conformal RT (NCRT). Conformal RT (CRT) is potentially more complex and expensive than NCRT, but may reduce normal tissue dose and subsequently toxicity. In this retrospective analysis, we compared CRT versus NCRT to investigate the association between conformality and toxicity.Methods/MaterialsA retrospective analysis of patients receiving palliative RT for axial skeletal bone metastases from 2012-2014 was conducted. Patient and treatment characteristics were obtained including dosimetric variables, acute toxicity, and subjective pain during treatment and in the acute post-treatment period (≤ 60 days after completion). Statistical analyses included t-tests, Chi-square tests, and multivariate logistic regression (MVA).Results179 patients and 254 bone metastases were identified (142 CRT, 112 NCRT). The CRT and NCRT groups were well matched for baseline characteristics (number of fractions, field size, treatment sites, and concurrent chemotherapy). In MVA models, technique (CRT vs. NCRT) was not associated with development of acute toxicity. Regarding toxicity, ECOG performance status and total dose were significantly associated with a higher rate of acute toxicity during radiotherapy (OR 0.649 and 1.129 and p = 0.027 and 0.044, respectively); and only a higher number of vertebral bodies in the treatment field was significantly associated with acute toxicity post-treatment (OR 1.219, p = 0.028). CRT was associated with improvement in bone pain during and post treatment (p = 0.049 and 0.045, respectively).ConclusionOur results demonstrate no difference in acute toxicity following palliative radiotherapy with CRT compared to NCRT for painful bone metastases; however, treatment volume did predict for increased toxicity. Larger studies may further elucidate the value of CRT including the impact of dose escalation for bone metastases and differences in patient reported outcomes between RT techniques.SummaryConformal radiotherapy (CRT) may provide improved sparing of normal tissues compared to non-conformal radiotherapy (NCRT), and thus reduce toxicity for patients receiving palliative radiotherapy for bone metastases. In this retrospective analysis, we observed no difference in acute toxicity between treatment techniques (CRT versus NCRT); however, larger treatment volumes were associated with increased toxicity. CRT was associated with improvement in bone pain control.



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