Stereotactic MR-guided online adaptive radiation therapy (SMART) for ultracentral thorax malignancies

Results of a phase 1 trial

Lauren E. Henke, Jeffrey R. Olsen, Jessika A. Contreras, Austen Curcuru, Todd DeWees, Olga L. Green, Jeff Michalski, Sasa Mutic, Michael C. Roach, Jeffrey D. Bradley, Parag J. Parikh, Rojano Kashani, Clifford G. Robinson

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

Purpose: Stereotactic body radiation therapy (SBRT) is an effective treatment for oligometastatic or unresectable primary malignancies, although target proximity to organs at risk (OARs) within the ultracentral thorax (UCT) limits safe delivery of an ablative dose. Stereotactic magnetic resonance (MR)–guided online adaptive radiation therapy (SMART) may improve the therapeutic ratio using reoptimization to account for daily variation in target and OAR anatomy. This study assessed the feasibility of UCT SMART and characterized dosimetric and clinical outcomes in patients treated for UCT lesions on a prospective phase 1 trial. Methods and Materials: Five patients with oligometastatic (n = 4) or unresectable primary (n = 1) UCT malignancies underwent SMART. Initial plans prescribed 50 Gy in 5 fractions with goal 95% planning target volume (PTV) coverage by 95% of prescription, subject to strict OAR constraints. Daily real-time online adaptive plans were created as needed to preserve hard OAR constraints, escalate PTV dose, or both, based on daily setup MR image set anatomy. Treatment times, patient outcomes, and dosimetric comparisons were prospectively recorded. Results: All initial and daily adaptive plans met strict OAR constraints based on simulation and daily setup MR imaging anatomy, respectively. Four of the 5 patients received ≥1 adapted fraction. Ten of the 25 total delivered fractions were adapted. A total of 30% of plan adaptations were performed to improve PTV coverage; 70% were for reversal of ≥1 OAR violation. Local control by Response Evaluation Criteria in Solid Tumors was 100% at 3 and 6 months. No grade ≥3 acute (within 6 months of radiation completion) treatment-related toxicities were identified. Conclusions: SMART may allow PTV coverage improvement and/or OAR sparing compared with nonadaptive SBRT and may widen the therapeutic index of UCT SBRT. In this small prospective cohort, we found that SMART was clinically deliverable to 100% of patients, although treatment delivery times surpassed our predefined, timing-based feasibility endpoint. This technique is well tolerated, offering excellent local control with no identified acute grade ≥3 toxicity.

Original languageEnglish (US)
JournalAdvances in Radiation Oncology
DOIs
StateAccepted/In press - Jan 1 2018

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Organs at Risk
Magnetic Resonance Spectroscopy
Radiotherapy
Thorax
Neoplasms
Anatomy
Therapeutics
Feasibility Studies
Prescriptions
Magnetic Resonance Imaging
Radiation

ASJC Scopus subject areas

  • Oncology
  • Radiology Nuclear Medicine and imaging

Cite this

Stereotactic MR-guided online adaptive radiation therapy (SMART) for ultracentral thorax malignancies : Results of a phase 1 trial. / Henke, Lauren E.; Olsen, Jeffrey R.; Contreras, Jessika A.; Curcuru, Austen; DeWees, Todd; Green, Olga L.; Michalski, Jeff; Mutic, Sasa; Roach, Michael C.; Bradley, Jeffrey D.; Parikh, Parag J.; Kashani, Rojano; Robinson, Clifford G.

In: Advances in Radiation Oncology, 01.01.2018.

Research output: Contribution to journalArticle

Henke, LE, Olsen, JR, Contreras, JA, Curcuru, A, DeWees, T, Green, OL, Michalski, J, Mutic, S, Roach, MC, Bradley, JD, Parikh, PJ, Kashani, R & Robinson, CG 2018, 'Stereotactic MR-guided online adaptive radiation therapy (SMART) for ultracentral thorax malignancies: Results of a phase 1 trial', Advances in Radiation Oncology. https://doi.org/10.1016/j.adro.2018.10.003
Henke, Lauren E. ; Olsen, Jeffrey R. ; Contreras, Jessika A. ; Curcuru, Austen ; DeWees, Todd ; Green, Olga L. ; Michalski, Jeff ; Mutic, Sasa ; Roach, Michael C. ; Bradley, Jeffrey D. ; Parikh, Parag J. ; Kashani, Rojano ; Robinson, Clifford G. / Stereotactic MR-guided online adaptive radiation therapy (SMART) for ultracentral thorax malignancies : Results of a phase 1 trial. In: Advances in Radiation Oncology. 2018.
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abstract = "Purpose: Stereotactic body radiation therapy (SBRT) is an effective treatment for oligometastatic or unresectable primary malignancies, although target proximity to organs at risk (OARs) within the ultracentral thorax (UCT) limits safe delivery of an ablative dose. Stereotactic magnetic resonance (MR)–guided online adaptive radiation therapy (SMART) may improve the therapeutic ratio using reoptimization to account for daily variation in target and OAR anatomy. This study assessed the feasibility of UCT SMART and characterized dosimetric and clinical outcomes in patients treated for UCT lesions on a prospective phase 1 trial. Methods and Materials: Five patients with oligometastatic (n = 4) or unresectable primary (n = 1) UCT malignancies underwent SMART. Initial plans prescribed 50 Gy in 5 fractions with goal 95{\%} planning target volume (PTV) coverage by 95{\%} of prescription, subject to strict OAR constraints. Daily real-time online adaptive plans were created as needed to preserve hard OAR constraints, escalate PTV dose, or both, based on daily setup MR image set anatomy. Treatment times, patient outcomes, and dosimetric comparisons were prospectively recorded. Results: All initial and daily adaptive plans met strict OAR constraints based on simulation and daily setup MR imaging anatomy, respectively. Four of the 5 patients received ≥1 adapted fraction. Ten of the 25 total delivered fractions were adapted. A total of 30{\%} of plan adaptations were performed to improve PTV coverage; 70{\%} were for reversal of ≥1 OAR violation. Local control by Response Evaluation Criteria in Solid Tumors was 100{\%} at 3 and 6 months. No grade ≥3 acute (within 6 months of radiation completion) treatment-related toxicities were identified. Conclusions: SMART may allow PTV coverage improvement and/or OAR sparing compared with nonadaptive SBRT and may widen the therapeutic index of UCT SBRT. In this small prospective cohort, we found that SMART was clinically deliverable to 100{\%} of patients, although treatment delivery times surpassed our predefined, timing-based feasibility endpoint. This technique is well tolerated, offering excellent local control with no identified acute grade ≥3 toxicity.",
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T2 - Results of a phase 1 trial

AU - Henke, Lauren E.

AU - Olsen, Jeffrey R.

AU - Contreras, Jessika A.

AU - Curcuru, Austen

AU - DeWees, Todd

AU - Green, Olga L.

AU - Michalski, Jeff

AU - Mutic, Sasa

AU - Roach, Michael C.

AU - Bradley, Jeffrey D.

AU - Parikh, Parag J.

AU - Kashani, Rojano

AU - Robinson, Clifford G.

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N2 - Purpose: Stereotactic body radiation therapy (SBRT) is an effective treatment for oligometastatic or unresectable primary malignancies, although target proximity to organs at risk (OARs) within the ultracentral thorax (UCT) limits safe delivery of an ablative dose. Stereotactic magnetic resonance (MR)–guided online adaptive radiation therapy (SMART) may improve the therapeutic ratio using reoptimization to account for daily variation in target and OAR anatomy. This study assessed the feasibility of UCT SMART and characterized dosimetric and clinical outcomes in patients treated for UCT lesions on a prospective phase 1 trial. Methods and Materials: Five patients with oligometastatic (n = 4) or unresectable primary (n = 1) UCT malignancies underwent SMART. Initial plans prescribed 50 Gy in 5 fractions with goal 95% planning target volume (PTV) coverage by 95% of prescription, subject to strict OAR constraints. Daily real-time online adaptive plans were created as needed to preserve hard OAR constraints, escalate PTV dose, or both, based on daily setup MR image set anatomy. Treatment times, patient outcomes, and dosimetric comparisons were prospectively recorded. Results: All initial and daily adaptive plans met strict OAR constraints based on simulation and daily setup MR imaging anatomy, respectively. Four of the 5 patients received ≥1 adapted fraction. Ten of the 25 total delivered fractions were adapted. A total of 30% of plan adaptations were performed to improve PTV coverage; 70% were for reversal of ≥1 OAR violation. Local control by Response Evaluation Criteria in Solid Tumors was 100% at 3 and 6 months. No grade ≥3 acute (within 6 months of radiation completion) treatment-related toxicities were identified. Conclusions: SMART may allow PTV coverage improvement and/or OAR sparing compared with nonadaptive SBRT and may widen the therapeutic index of UCT SBRT. In this small prospective cohort, we found that SMART was clinically deliverable to 100% of patients, although treatment delivery times surpassed our predefined, timing-based feasibility endpoint. This technique is well tolerated, offering excellent local control with no identified acute grade ≥3 toxicity.

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