Stereotactic Ablative Radiotherapy Patients Research Articles

Late radiologic changes after stereotactic ablative radiotherapy for early stage lung cancer: A comparison of fixed-beam versus arc delivery techniques

Background and purposeTo characterize the radiologic changes occurring following arc stereotactic ablative radiotherapy (SABR) for early-stage non-small cell lung cancer relative to those following fixed-beam SABR. MethodsTwenty-nine patients treated with arc SABR without local recurrence and more than two years follow-up were retrospectively evaluated using a published scoring system. The late morphologic patterns, timing and severity of radiologic change were assessed and compared to 54 patients treated with fixed-beam SABR that we previously assessed using the same system. ResultsThe baseline characteristics and follow-up of both cohorts were well matched and SABR technique was not associated with morphologic differences before 6months (p=0.23). Thereafter the predicted probabilities of a modified-conventional pattern following arc and fixed-beam SABR were 96.3% vs. 68.9%, respectively (OR 11.7, 95% CI 3.38–40.8, p<0.001). In addition, at 1year follow-up the predicted probabilities of arc and fixed-beam SABR patients having expected or pronounced radiologic changes were 64.9% and 22.1%, respectively (OR=6.56, 95% CI: 3.13–13,7, p<0.001). ConclusionsPost-SABR radiologic changes differ with delivery technique, which has important implications during follow-up. Confirmation in larger studies is required and etiologic factors remain to be determined.

Stage I–II non-small-cell lung cancer treated using either stereotactic ablative radiotherapy (SABR) or lobectomy by video-assisted thoracoscopic surgery (VATS): outcomes of a propensity score-matched analysis

BackgroundVideo-assisted thoracoscopic surgery (VATS) lobectomy and stereotactic ablative radiotherapy (SABR) are both used for early-stage non-small-cell lung cancer. We carried out a propensity score-matched analysis to compare locoregional control (LRC). Patients and methodsVATS lobectomy data from six hospitals were retrospectively accessed; SABR data were obtained from a single institution database. Patients were matched using propensity scores based on cTNM stage, age, gender, Charlson comorbidity score, lung function and performance score. Eighty-six VATS and 527 SABR patients were matched blinded to outcome (1:1 ratio, caliper distance 0.025). Locoregional failure was defined as recurrence in/adjacent to the planning target volume/surgical margins, ipsilateral hilum or mediastinum. Recurrences were either biopsy-confirmed or had to be PET-positive and reviewed by a tumor board. ResultsThe matched cohort consisted of 64 SABR and 64 VATS patients with the median follow-up of 30 and 16 months, respectively. Post-SABR LRC rates were superior at 1 and 3 years (96.8% and 93.3% versus 86.9% and 82.6%, respectively, P = 0.04). Distant recurrences and overall survival (OS) were not significantly different. ConclusionThis retrospective analysis found a superior LRC after SABR compared with VATS lobectomy, but OS did not differ. Our findings support the need to compare both treatments in a randomized, controlled trial.

Stages I-II non-small cell lung cancer treated using either lobectomy by video-assisted thoracoscopic surgery (VATS) or stereotactic ablative radiotherapy (SABR): Outcomes of a propensity score-matched analysis.

7009 Background: VATS procedures are increasingly used in early-stage NSCLC. As high local control rates are also seen with stereotactic ablative radiotherapy (SABR), we performed a propensity score-matched analysistocompare loco-regional control (LRC) after both treatments. Methods: Patients with stage I-II NSCLC treated at 6 hospitals (1 university and 5 regional hospitals) with VATS lobectomy were eligible. Details of SABR patients were obtained from a single-institutional database. All VATS-lobectomies were performed in accordance with ESTS guidelines. Patients were matched using propensity scores based on cTNM, age, gender, Charlson comorbidity score, lung function and performance score. Matching was performed blinded to all outcomes. Excluded were: synchronous lung tumors, COPD GOLD class 4 or history of prior lung cancer. A total of 86 VATS- and 527 SABR patients were eligible for matching (1:1 ratio, caliper distance of 0.025 without replacement). Loco-regional failure was defined as recurrence in/adjacent to the radiation planning target volume or surgical margins, the ipsilateral hilum or mediastinum. Recurrences were either biopsy-confirmed or PET-positive and reviewed by a tumor board. Patients upstaged during VATS and those developing recurrence were treated in accordance with national guidelines. Results: The matched cohort consisted of 128 patients with cT1-3N0 NSCLC following SABR (n=64) or VATS-lobectomy (n=64). Median follow-up was 30 and 16 months, respectively. The groups were well matched on baseline variables. SABR patients had better LRC rates at 1- and 3-years (96.8% and 93.3% vs. 86.9% and 82.6%, respectively, p= .03). Three-year progression-free survival (PFS) did not significantly differ after SABR (79.3% versus 63.2%, p = .09). Distant recurrence rates and overall survival (OS) did not significantly differ. Conclusions: Although loco-regional control was superior after SABR compared to VATS-lobectomy, PFS and OS did not differ at this time-point. Our findings support the current randomized controlled trial evaluating both treatments (ACOSOG Z4099).

Outcomes of Stereotactic Ablative Radiotherapy for Centrally Located Early-Stage Lung Cancer

The use of stereotactic ablative radiotherapy (SABR) in centrally located early-stage lung tumors has been associated with increased toxicity. We studied outcomes after delivery of risk-adapted SABR of central tumors. SABR was delivered in eight fractions of 7.5 Gy to 63 such patients between 2003 and 2009. Of these, 37 patients had a tumor at a central hilar location, whereas 26 patients had tumors abutting the pericardium or mediastinal structures. Survival outcomes were compared with patients with peripheral tumors treated during the same time period using fewer fractions of SABR. Median follow-up was 35 months. Late grade III toxicity was limited to chest wall pain (n = 2) and increased dyspnoea (n = 2). No grade IV/V toxicity was observed, but grade V toxicity could not be excluded with certainty in nine patients who died of cardiopulmonary causes. Distant metastases were the predominant cause of death; cardiovascular deaths were not associated with a paracardial tumor location. No significant differences in outcomes were observed between these 63 patients and 445 other SABR patients treated for peripheral early-stage lung tumors. Three-year local control rates were 92.6% and 90.2% (p = 0.9). Three-year overall survival rates were 64.3% and 51.1% with median survival rates of 47 and 36 months, in favor of the group of patients with central tumors (p = 0.09). Use of risk-adapted SABR delivered in eight fractions of 7.5 Gy did not result in excess toxicity for centrally located early-stage lung tumors, and clinical outcomes were comparable with those seen for peripheral lesions.

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Stereotactic Ablative Radiotherapy (SABR) has recently emerged as a favourable treatment option for prostate cancer patients. With higher doses delivered over fewer fractions, motion adaptation is a requirement for accurate delivery of SABR. This study compared the efficacy of multileaf collimator (MLC) tracking vs. gating as a real-time motion adaptation strategy for prostate SABR patients enrolled in a clinical trial.Forty-four prostate cancer patients treated over five fractions in the TROG 15.01 SPARK trial were analysed in this study. Forty-nine fractions were treated using MLC tracking and 166 fractions were treated using beam gating and couch shifts. A time-resolved motion-encoded dose reconstruction method was used to evaluate the dose delivered using each motion adaptation strategy and compared to an estimation of what would have been delivered with no motion adaptation strategy implemented.MLC tracking and gating both delivered doses closer to the plan compared to when no motion adaptation strategy was used. Differences between MLC tracking and gating were small with differences in the mean discrepancy from the plan of −0.3% (CTV D98%), 1.4% (CTV D2%), 0.4% (PTV D95%), 0.2% (rectum V30Gy) and 0.0% (bladder V30Gy). On average, 0.5 couch shifts were required per gated fractions with a mean interruption duration of 1.8 ± 2.6 min per fraction treated using gating.Both MLC tracking and gating were effective strategies at improving the accuracy of the dose delivered to the target and organs at risk. While dosimetric performance was comparable, gating resulted in interruptions to treatment.Clinical trial registration number: NCT02397317.