Clinical outcomes of stage I and IIA non-small cell lung cancer patients treated with stereotactic body radiotherapy using a real-time tumor-tracking radiotherapy system

Abstract

PurposeTo investigate the clinical outcomes of stage I and IIA non-small cell lung cancer (NSCLC) patients treated with stereotactic body radiotherapy (SBRT) using a real-time tumor-tracking radiotherapy (RTRT) system.Materials and methodsPatterns-of-care in SBRT using RTRT for histologically proven, peripherally located, stage I and IIA NSCLC was retrospectively investigated in four institutions by an identical clinical report format. Patterns-of-outcomes was also investigated in the same manner.ResultsFrom September 2000 to April 2012, 283 patients with 286 tumors were identified. The median age was 78 years (52–90) and the maximum tumor diameters were 9 to 65 mm with a median of 24 mm. The calculated biologically effective dose (10) at the isocenter using the linear-quadratic model was from 66 Gy to 126 Gy with a median of 106 Gy. With a median follow-up period of 28 months (range 0–127), the overall survival rate for the entire group, for stage IA, and for stage IB + IIA was 75%, 79%, and 65% at 2 years, and 64%, 70%, and 50% at 3 years, respectively. In the multivariate analysis, the favorable predictive factor was female for overall survival. There were no differences between the clinical outcomes at the four institutions. Grade 2, 3, 4, and 5 radiation pneumonitis was experienced by 29 (10.2%), 9 (3.2%), 0, and 0 patients. The subgroup analyses revealed that compared to margins from gross tumor volume (GTV) to planning target volume (PTV) ≥ 10 mm, margins < 10 mm did not worsen the overall survival and local control rates, while reducing the risk of radiation pneumonitis.ConclusionsThis multi-institutional retrospective study showed that the results were consistent with the recent patterns-of-care and patterns-of-outcome analysis of SBRT. A prospective study will be required to evaluate SBRT using a RTRT system with margins from GTV to PTV < 10mm.Electronic supplementary materialThe online version of this article (doi:10.1186/s13014-016-0742-3) contains supplementary material, which is available to authorized users.

Clinical Results of Mean GTV Dose Optimized Robotic-Guided Stereotactic Body Radiation Therapy for Lung Tumors

“…Concerning radiation-induced toxicities, we found only mild acute radiation pneumonitis grade 1–2 in 4.8 and 0.5% chronic grade 2 rip fractures while grade 3 side effects were not observed. Our toxicity profiles compare very favorably with published reports as they range at the lowest spectrum of reported side effects ( 5 , 7 – 9 , 21 – 24 , 48 , 49 , 51 – 54 , 58 ). This importantly confirms our previously reported strategy of reducing the PTV prescription dose when necessary (e.g., for chest wall or for large lesions) while maintaining high mean GTV doses for high LC ( 38 , 39 ).…”

“…In the present joined evaluation that included direct and non-direct tumor tracking, we now found excellent agreement with previous large multi-institutional dose modeling studies for 90% local tumor control cutoff maximum doses of 181 Gy 10 for primary lung tumors [compared to 176 Gy 10 ( 13 )] and 149 Gy 10 [compared to 160 Gy 10 ( 13 )] for lung metastases. Those results also confirm the minimally higher necessary maximum doses for primary vs. secondary lung tumors and the demand for in-homogeneous dose in the PTV as compared to a homogeneous dose prescription approach ( 53 , 58 ). Yet still, distinct description and reporting of the dose distribution ( 50 ) and benchmark trials ( 17 ) are necessary for multi-institutional multi-technology comparison or pooled evaluation of SBRT for lung tumors.…”

“…On the other hand, there has been increasing evidence that the central dose to the GTV significantly matters for LC ( 13 , 37 – 39 , 55 , 56 ). As further prove, our LC rates were substantially higher compared to those studies using more homogeneous dose prescription ( 53 , 58 ). This significantly substantiates the German Society for Radiation Oncology (DEGRO) guidelines on lung SBRT which prefer lower prescription dose in combination with in-homogeneous dose distribution in the PTV ( 6 , 17 ).…”

Moving targets in 4D-CTs versus MIP and AIP: comparison of patients data to phantom data

“…The large deviations using MIP for tumors bordering soft tissues could be also observer dependent, in particular as a visual approach was followed instead of automatic contouring. Since extreme movement of tumors bordering soft tissue impedes definition of an ITV, other treatment options like robotic radio surgery or breath hold techniques should be taken into consideration, in these situations [ 22 , 23 ].…”

Stereotactic hypofractionated radiotherapy for clinical stage I-IIA lung cancer. Predictors for efficacy and toxicity

“…С учетом подводимых экстремально высоких биологически эффективных доз одну из основных проблем представляет угроза тяжелой лучевой токсичности после СРТ, как правило, у больных с исходно низкими соматическими показателями. Потенциальный риск используемых для СРТ высоких доз в недавнем исследовании продемонстрирован зависимостью между размером облучаемого объема и уровнем легочной токсичности при подведении BED ≥90 Гр, тогда как при превышении пороговых BED для риска возникновения тяжелого пульмонита уже теряют значимость параметры объема облучения [12]. При использовании режима фракционирования 18 Гр за 3 фракции (BED 150 Гр) тяжелая легочная токсичность 3-й, 4-й степени возникла у 16% больных с периферическими формами рака легкого после СРТ в исследовании II фазы RTOG 0236, но симптомы токсичности в большей степени связаны с первично низкими функциональными параметрами легких [13].…”