Modeling Local Control After Hypofractionated Stereotactic Body Radiation Therapy for Stage I Non-Small Cell Lung Cancer: A Report From the Elekta Collaborative Lung Research Group

Journal Article · Thu Nov 01 04:00:00 EDT 2012 · International Journal of Radiation Oncology, Biology and Physics

DOI:https://doi.org/10.1016/J.IJROBP.2012.04.040· OSTI ID:22149598

Ohri, Nitin ^[1]; Werner-Wasik, Maria ^[1]; Grills, Inga S. ^[2]; Belderbos, Jose ^[3]; Hope, Andrew ^[4]; Di, Yan; Kestin, Larry L. ^[2]; Guckenberger, Matthias ^[5]; Sonke, Jan-Jakob ^[3]; Bissonnette, Jean-Pierre ^[4]; Xiao, Ying ^[1]

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1. Department of Radiation Oncology, Jefferson Medical College of Thomas Jefferson University, Philadelphia, Pennsylvania (United States)
2. Department of Radiation Oncology, William Beaumont Hospital, Royal Oak, Michigan (United States)
3. Department of Radiation Oncology, The Netherlands Cancer Institute, Amsterdam (Netherlands)
4. Department of Radiation Oncology, Princess Margaret Hospital and University of Toronto, Toronto, ON (Canada)
5. Department of Radiation Oncology, University of Wuerzburg, Wuerzburg (Germany)

Purpose: Hypofractionated stereotactic body radiation therapy (SBRT) has emerged as an effective treatment option for early-stage non-small cell lung cancer (NSCLC). Using data collected by the Elekta Lung Research Group, we generated a tumor control probability (TCP) model that predicts 2-year local control after SBRT as a function of biologically effective dose (BED) and tumor size. Methods and Materials: We formulated our TCP model as follows: TCP = e{sup [BED10-c Asterisk-Operator L-TCD50]/k} Division-Sign (1 + e{sup [BED10-c Asterisk-Operator L-TCD50]/k}), where BED10 is the biologically effective SBRT dose, c is a constant, L is the maximal tumor diameter, and TCD50 and k are parameters that define the shape of the TCP curve. Least-squares optimization with a bootstrap resampling approach was used to identify the values of c, TCD50, and k that provided the best fit with observed actuarial 2-year local control rates. Results: Data from 504 NSCLC tumors treated with a variety of SBRT schedules were available. The mean follow-up time was 18.4 months, and 26 local recurrences were observed. The optimal values for c, TCD50, and k were 10 Gy/cm, 0 Gy, and 31 Gy, respectively. Thus, size-adjusted BED (sBED) may be defined as BED minus 10 times the tumor diameter (in centimeters). Our TCP model indicates that sBED values of 44 Gy, 69 Gy, and 93 Gy provide 80%, 90%, and 95% chances of tumor control at 2 years, respectively. When patients were grouped by sBED, the model accurately characterized the relationship between sBED and actuarial 2-year local control (r=0.847, P=.008). Conclusion: We have developed a TCP model that predicts 2-year local control rate after hypofractionated SBRT for early-stage NSCLC as a function of biologically effective dose and tumor diameter. Further testing of this model with additional datasets is warranted.

• OSTI ID: 22149598
• Journal Information: International Journal of Radiation Oncology, Biology and Physics, Journal Name: International Journal of Radiation Oncology, Biology and Physics Journal Issue: 3 Vol. 84; ISSN IOBPD3; ISSN 0360-3016
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
CONTROL
DATASETS
LEAST SQUARE FIT
LUNGS
NEOPLASMS
OPTIMIZATION
PATIENTS
RADIATION DOSES
RADIOTHERAPY
SIMULATION
TESTING