Estimation of the alpha/beta ratio of non-small cell lung cancer treated with stereotactic body radiotherapy

Klement, Rainer J.; Sonke, Jan-Jakob; Allgaeuer, Michael; Andratschke, Nicolaus; Appold, Steffen; Belderbos, Jose; Belka, Claus; Dieckmann, Karin; Eich, Hans T.; Flentje, Michael; Grills, Inga; Eble, Michael; Hope, Andrew; Grosu, Anca L.; Semrau, Sabine; Sweeney, Reinhart A.; Hoerner-Rieber, Juliane; Werner-Wasik, Maria; Engenhart-Cabillic, Rita; Ye, Hong und Guckenberger, Matthias (2020): Estimation of the alpha/beta ratio of non-small cell lung cancer treated with stereotactic body radiotherapy. In: Radiotherapy and Oncology, Bd. 142: S. 210-216

Abstract

Background: High-dose hypofractionated radiotherapy should theoretically result in a deviation from the typical linear-quadratic shape of the cell survival curve beyond a certain threshold dose, yet no evidence for this hypothesis has so far been found in clinical data of stereotactic body radiotherapy treatment (SBRT) for early-stage non-small cell lung cancer (NSCLC). A pragmatic explanation is a larger alpha/beta ratio than the conventionally assumed 10 Gy. We here attempted an estimation of the alpha/beta ratio for NSCLC treated with SBRT using individual patient data. Materials and methods: We combined two large retrospective datasets, yielding 1294 SBRTs (<= 10 fractions) of early stage NSCLC. Cox proportional hazards regression, a logistic tumor control probability model and a biologically motivated Bayesian cure rate model were used to estimate the alpha/beta ratio based on the observed number of local recurrences and accounting for tumor size. Results: A total of 109 local progressions were observed after a median of 17.7 months (range 0.60-76.3 months). Cox regression, logistic regression of 3 year tumor control probability and the cure rate model yielded best-fit estimates of alpha/beta = 12.8 Gy, 14.9 Gy and 12-16 Gy (depending on the prior for alpha/beta), respectively, although with large uncertainties that did not rule out the conventional alpha/beta = 10 Gy. Conclusions: Clinicians can continue to use the simple LQ formalism to compare different SBRT treatment schedules for NSCLC. While alpha/beta = 10 Gy is not ruled out by our data, larger values in the range 12-16 Gy are more probable, consistent with recent meta-regression analyses.

• Dokumententyp: Zeitschriftenartikel
• Fakultät: Medizin
• Themengebiete: 600 Technik, Medizin, angewandte Wissenschaften > 610 Medizin und Gesundheit
• ISSN: 0167-8140
• Sprache: Englisch