Promising clinical outcome of stereotactic body radiation therapy for patients with inoperable Stage I/II non–small-cell lung cancer

Radioresistant Pulmonary Oligometastatic and Oligoprogressive Lesions From Nonlung Primaries: Impact of Histology and Dose-Fractionation on Local Control After Radiation Therapy

Purpose

We investigated whether pulmonary metastases from historically considered radioresistant primaries would have inferior local control after radiation therapy than those from nonradioresistant nonlung primaries, and whether higher biologically effective dose assuming alpha/beta=10 (BED10) would be associated with superior local control.

Methods and Materials

We identified patients treated with radiation therapy for oligometastatic or oligoprogressive pulmonary disease to 1 to 5 lung metastases from nonlung primaries in 2013 to 2020 at a single health care system. Radioresistant primary cancers included colorectal carcinoma, endometrial carcinoma, renal cell carcinoma, melanoma, and sarcoma. Nonradioresistant primary cancers included breast, bladder, esophageal, pancreas, and head and neck carcinomas. The Kaplan-Meier estimator, log-rank test, and multivariable Cox proportional hazards regression were used to compare local recurrence-free survival (LRFS), new metastasis-free survival, progression-free survival, and overall survival.

Results

Among 114 patients, 73 had radioresistant primary cancers. The median total dose was 50 Gy (IQR, 50-54 Gy) and the median number of fractions was 5 (IQR, 3-5). Median follow-up time was 59.6 months. One of 41 (2.4%) patients with a nonradioresistant metastasis experienced local failure compared with 18 of 73 (24.7%) patients with radioresistant metastasis (log-rank P = .004). Among radioresistant metastases, 12 of 41 (29.2%) patients with colorectal carcinoma experienced local failure compared with 6 of 32 (18.8%) with other primaries (log-rank P = .018). BED10 ≥100 Gy was associated with decreased risk of local recurrence. On univariable analysis, BED10 ≥100 Gy (hazard ratio [HR], 0.263; 95% CI, 0.105-0.656; P = .004) was associated with higher LRFS, and colorectal primary (HR, 3.060; 95% CI, 1.204-7.777; P = .019) was associated with lower LRFS, though these were not statistically significant on multivariable analysis. Among colorectal primary patients, BED10 ≥100 Gy was associated with higher LRFS (HR, 0.266; 95% CI, 0.072-0.985; P = .047) on multivariable analysis.

Conclusions

Local control after radiation therapy was encouraging for pulmonary metastases from most nonlung primaries, even for many of those classically considered to be radioresistant. Those from colorectal primaries may benefit from testing additional strategies, such as resection or systemic treatment concurrent with radiation.

Hyperfractionated Accelerated Radiotherapy Versus Stereotactic Body Radiotherapy in the Treatment of Limited-Stage Small Cell Lung Cancer: A Matched-Pair Analysis

BACKGROUND

Concurrent chemoradiotherapy based on hyperfractionated accelerated radiotherapy (HART) is the first-line recommended regimen for the treatment of small-cell lung cancer (SCLC). However, Stereotactic Body Radiotherapy (SBRT) is also regarded as an effective treatment for limited-stage (LS) SCLC, and the efficacy and safety of HART versus SBRT stay controversial.

METHODS

In this study, 188 LS-SCLC patients were retrospectively divided into two groups receiving chemotherapy combined with either HART or SBRT. In HART group, patients received 4500 cGy in 30 fractions, administered twice daily for 3 weeks. Whereas in the SBRT group, a total radiation dose of 4000-4500 cGy was delivered in 10 fractions over 2 weeks. Thirty-three pairs of patients were finally included for next analysis.

RESULTS

The estimated objective response rates were 63.6 % (21/33) and 78.8 % (26/33) in HART group and SBRT group, respectively (P = 0.269). Furthermore, there was no significant difference between HART and SBRT groups in overall survival (26 months vs. 29 months, P = 0.362) and progression free survival (11 months vs. 15 months, P = 0.223). As for the adverse events, toxicity of both groups is similar and slight that no grade 4 event was observed. Grade 3 pneumonitis cases were all occurred in the HART group (9.1%, 3/33, P = 0.238), and grade 3 esophagitis cases were all occurred in the SBRT group (6.1%, 2/33, P = 0.492).

CONCLUSION

Compared with HART, SBRT could be another effective treatment with satisfactory safety for the concurrent chemoradiotherapy in patients with LS-SCLC.

Dosimetry and treatment efficiency of SBRT using TaiChiB radiotherapy system for two-lung lesions with one overlapping organs at risk

Purpose

This study aims to assess the dosimetry and treatment efficiency of TaiChiB-based Stereotactic Body Radiotherapy (SBRT) plans applying to treat two-lung lesions with one overlapping organs at risk.

Methods

For four retrospective patients diagnosed with two-lung lesions each patient, four treatment plans were designed including Plan Edge, TaiChiB linac-based, RGS-based, and a linac-RGS hybrid (Plan TCLinac, Plan TCRGS, and Plan TCHybrid). Dosimetric metrics and beam-on time were employed to evaluate and compare the TaiChiB-based plans against Plan Edge.

Results

For Conformity Index (CI), Plan TCRGS outperformed all other plans with an average CI of 1.06, as opposed to Plan Edge's 1.33. Similarly, for R50 %, Plan TCRGS was superior with an average R50 % of 3.79, better than Plan Edge's 4.28. In terms of D2 cm, Plan TCRGS also led with an average of 48.48%, compared to Plan Edge's 56.25%. For organ at risk (OAR) sparing, Plan TCRGS often displayed the lowest dosimetric values, notably for the spinal cord (Dmax 5.92 Gy) and lungs (D1500cc 1.00 Gy, D1000cc 2.61 Gy, V10 Gy 15.14%). However, its high Dmax values for the heart and great vessels sometimes exceeded safety thresholds. Plan TCHybrid presented a balanced approach, showing doses comparable to or better than Plan Edge without crossing safety limits. In terms of beam-on time, Plan TCLinac emerged as the most efficient treatment option in three out of four cases, followed closely by Plan Edge in one case. Plan TCRGS, despite its dosimetric advantages, was the least efficient, recording notably longer beam-on times, with a peak at 33.28 minutes in Case 2.

Conclusion

For patients with two-lung lesions treated by SBRT whose one lesion overlaps with OARs, the Plan TCHybrid delivered by TaiChiB digital radiotherapy system can be recommended as a clinical option.

A novel X-Ray and γ-Ray combination strategy for potential dose escalation in patients with locally advanced pancreatic cancer

BACKGROUND

Treatment of locally advanced pancreatic cancer (LAPC) has long been calling for advances in technology of radiotherapy. Patients who received radiotherapy still had high risks of local recurrence, while suffering from gastrointestinal side effects. Based on the inherent characteristics of the x-ray and γ-Ray radiation techniques, here we proposed and investigated an unexplored radiation therapy.

PURPOSE

To investigate the potential clinical benefit of a novel x-ray and γ-Ray combination radiation technique in patients with LAPC.

METHODS

Retrospective intensity-modulated radiotherapy (IMRT) treatment plans of 10 LAPC patients were randomly selected to compare with dual-modality plans. The prescribed dose to PGTV was 60.2 Gy. The PGTV dose was further escalated in dual-modality plan while maintaining clinically tolerable dose to organs at risk (OARs). Dosimetric comparisons were made and analyzed for three treatment plans (tomotherapy, standard dual-modality plan, escalated dual-modality plan) to assess the ability to increase dose to target volume while minimizing dose in adjacent OARs. Finally, radiobiological models were utilized for comparison.

RESULTS

All strategies resulted in dosimetrically acceptable plans. Dual-modality plans were present with similar conformity index (CI) and significantly lower gradient index (GI) compared with tomotherapy (3.64 ± 0.37 vs. 4.14 ± 0.61, p = 0.002; 3.64 ± 0.42 vs. 4.14 ± 0.61, p = 0.003). D_mean of PGTV (65.46 ± 3.13 vs. 61.56 ± 1.00, p = 0.009; 77.98 ± 5.86 vs. 61.56 ± 1.00, p < 0.001) and PCTV (55.04 ± 2.14 vs. 53.93 ± 1.67, p = 0.016; 58.24 ± 3.24 vs. 53.93 ± 1.67, p = 0.001) were significantly higher, while D_mean of the stomach was reduced in both dual-modality plans (17.98 ± 10.23 vs. 19.34 ± 9.75, p = 0.024; 17.62 ± 9.92 vs. 19.34 ± 9.75, p = 0.040). The lower V_30Gy in the liver (4.83 ± 5.87 vs. 6.23 ± 6.68, p = 0.015; 4.90 ± 5.93 vs. 6.23 ± 6.68, p = 0.016) and lower V_45Gy of the small intestine (3.35 ± 3.30 vs. 4.06 ± 3.87, p = 0.052) were found in dual-modality plans. Meanwhile, radiobiological models demonstrated higher probability of tumor control (29.27% ± 9.61% vs. 18.34% ± 4.70%, p < 0.001; 44.67% ± 18.16% vs. 18.34% ± 4.70%, p = 0.001) and lower probability of small intestine complication (2.16% ± 2.30% vs. 1.25% ± 2.72%, p = 0.048) in favor of dual-modality strategy.

CONCLUSIONS

A novel dual-modality strategy of x-ray and γ-Ray combination radiation appears reliable for target dose escalation and normal tissue dose reduction. This strategy might be beneficial for local tumor control and the protection of normal organs in patients with LAPC.

Utilization and Survival Impact of Hypofractionated Radiotherapy in Stage I Non-small Cell Lung Cancer

OBJECTIVES

The optimal fractionation schedule in unresected stage I non-small cell lung cancer (NSCLC) unsuitable for stereotactic body radiation therapy is unclear. Given the lack of comparative data regarding nonstereotactic body radiation therapy schemas, we compared overall survival (OS) with hypofractionated radiotherapy (HFRT) versus conventionally fractionated radiotherapy (CFRT) and examined the OS impact of different HFRT doses.

MATERIALS AND METHODS

This retrospective analysis included 2159 patients from the National Cancer Database diagnosed with stage I (cT1-2aN0M0) NSCLC between 2008 and 2016. Patients underwent CFRT (70≤BED10 [biologically effective dose] <100 Gy10 in ≥30 fractions), low-dose HFRT (LD-HFRT; 70≤BED10 [assuming α/β=10] <100 Gy10 in 11 to 24 fractions), or high-dose HFRT (HD-HFRT; 100≤BED10 ≤120 Gy10 in 6 to 10 fractions). Patients who received surgery, chemotherapy, or immunotherapy were excluded. We compared CFRT versus all HFRT, and separately CFRT versus LD-HFRT and CFRT versus HD-HFRT. OS was evaluated with the Kaplan-Meier estimator, log-rank test, and Cox regression.

RESULTS

A total of 63.2% of patients underwent CFRT, 23.5% LD-HFRT, and 13.3% HD-HFRT. OS was significantly longer with HFRT versus CFRT on univariable (28.2 mo [95% CI, 25.6-31.7] vs 26.4 mo [25.0-27.9]; log-rank=0.0025) but not multivariable analysis (MVA; hazard ratio [HR] 0.90; P=0.062). MVA yielded no significant difference in OS between CFRT and LD-HFRT (HR 0.96, P=0.53). OS was significantly longer with HD-HFRT versus CFRT on MVA (HR, 0.75; P=0.003). However, on sensitivity analysis using different multivariable modeling techniques, this did not retain statistical significance (HR, 0.83; P=0.12).

CONCLUSIONS

For stage I NSCLC, HFRT does not show a robust OS benefit compared with CFRT but may be preferred given the convenience and lower costs.

Adaptive hypofractionted and stereotactic body radiotherapy for lung tumors with real-time MRI guidance

The treatment of central and ultracentral lung tumors with radiotherapy remains an ongoing clinical challenge. The risk of Grade 5 toxicity with ablative radiotherapy doses to these high-risk regions is significant as shown in recent prospective studies. Magnetic resonance (MR) image-guided adaptive radiotherapy (MRgART) is a new technology and may allow the delivery of ablative radiotherapy to these high-risk regions safely. MRgART is able to achieve this by utilizing small treatment margins, real-time gating/tracking and on-table plan adaptation to maintain dose to the tumor but limit dose to critical structures. The process of MRgART is complex and has nuances and challenges for the treatment of lung tumors. We outline the critical steps needed for appropriate delivery of MRgART for lung tumors safely and effectively.

Promising clinical outcome after body gamma knife radiotherapy for mediastinal follicular dendritic cell sarcoma with thoracic spine invasion and iliac metastasis: A case report and literature review

Background

Follicular dendritic cell sarcoma (FDCS) is a rare type of intermediate grade tumor. Mediastinal FDCS with spinal invasion has not been well described. The treatment options include surgical resection and radiation therapy. The body gamma knife is a stereotactic body radiotherapy (SBRT) technology that is widely used in China. The pathological evaluation of a bone lesion after a body gamma knife procedure has not been reported. Here, we report a case of a patient with FDCS with thoracic spine invasion and iliac metastasis treated with surgery and body gamma knife.

Case summary

A 36-year-old male patient was hospitalized at Zhongshan Hospital, Fudan University, due to a gradually aggravated pain on the lateral side of the left scapula for 6 months. Imaging examination showed neoplastic lesions on the left side of C7-T2 invading the vertebral body of T1, T2, and caput costae of the second rib and suspected metastasis in the left ilium. FDCS was diagnosed after performing a computed tomography (CT)-guided core needle biopsy, and the thoracic lesion was surgically resected. The body gamma knife was used as an adjuvant radiotherapy for the thoracic lesion and a primary therapy for the left ilium lesion. Iliac bone lesion resection was performed at Zhongshan Hospital, Fudan University, 10 weeks after RT. Compared with the biopsy report, the body gamma knife treatment resulted in a pathological complete response (PCR). The magnetic resonance imaging (MRI) examinations showed stable disease of the thoracic lesion after body gamma knife radiosurgery.

Conclusion

This case report describes the treatment of mediastinal FDCS with thoracic spinal invasion and iliac metastasis. The promising outcome suggests that separation surgery is an effective treatment option for mediastinal FDCS with spinal column invasion. It also demonstrates the application prospects of the body gamma knife treatment in malignant lesions of the axial bones.

Development of Radiographic Radiation Pneumonitis (RP) in Non-small Cell Lung Cancer Patients Treated With Stereotactic Body Radiation Therapy (SBRT) May Be Protective Against Further Disease Progression

Objectives: Radiation pneumonitis (RP) is a local inflammatory response, and we hypothesize that RP serves as an immune stimulator and is a protective factor against disease progression. 

Methods: We analyzed patients with early-stage non-small cell lung cancer (NSCLC) treated with stereotactic body radiation therapy (SBRT) at two institutions. Radiographic RP (RRP) was evaluated and maximal axial dimensions were measured at three-, six-, and twelve-month timepoints with surveillance CT. RRP was measured using radiographic markers such as ground-glass opacities and airspace consolidation. Disease recurrence was evaluated and categorized as local, regional, and distant. 

Results: Seventy-seven unique patient records were randomly selected from the database, 72 patients (93.5%) had RRP and five patients (6.5%) did not. The median follow-up was 24.3 months (IQR: 12.0 - 41.9). Disease failure occurred in 28.6% of patients with 6.5% local only, 2.6% regional only, 7.8% distant only, and 11.7% with multiple recurrences. Patients with RRP demonstrated a lower rate of disease failure with 25.0% of those with RRP experiencing disease failure and 80% of those without RRP experiencing disease failure (p=0.02). Patients with RRP had a 71% reduced risk of disease recurrence, compared to patients with no RRP, after adjusting for maximum tumor dimension (HR 0.29, p = 0.05). Among patients with RRP, there was no significant difference in recurrence based on extent of RRP (maximal area of RRP on CT). RRP did not correlate with overall survival. 

Discussion: Most patients who received SBRT had RRP, and this study suggests that it may be protective of cancer recurrence. These results are hypothesis-generating and will need to be validated in larger and independent datasets. 

Optimal and actual rates of Stereotactic Ablative Body Radiotherapy (SABR) utilisation for primary lung cancer in Australia

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Stereotactic Ablative Body Radiotherapy (SABR) plays a major role in the management of early-stage non-small cell lung cancer (NSCLC).

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An evidence-based model is developed to estimate optimal rates of lung SABR utilisation within the Australian population.

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Optimal utilisation rates are compared against actual utilisation rates to evaluate service provision.

Background and purpose

Radiotherapy utilisation rates considerably vary across different countries and service providers, highlighting the need to establish reliable benchmarks against which utilisation rates can be assessed. Here, optimal utilisation rates of Stereotactic Ablative Body Radiotherapy (SABR) for lung cancer are estimated and compared against actual utilisation rates to identify potential shortfalls in service provision.

Materials and Methods

An evidence-based optimal utilisation model was constructed after reviewing practice guidelines and identifying indications for lung SABR based on the best available evidence. The proportions of patients likely to develop each indication were obtained, whenever possible, from Australian population-based studies. Sensitivity analysis was performed to account for variations in epidemiological data. Practice pattern studies were reviewed to obtain actual utilisation rates.

Results

A total of 6% of all lung cancer patients were estimated to optimally require SABR at least once during the course of their illness (95% CI: 4–6%). Optimal utilisation rates were estimated to be 32% for stage I and 10% for stage II NSCLC. Actual utilisation rates for stage I NSCLC varied between 6 and 20%. For patients with inoperable stage I, 27–74% received SABR compared to the estimated optimal rate of 82%.

Conclusion

The estimated optimal SABR utilisation rates for lung cancer can serve as useful benchmarks to highlight gaps in service delivery and help plan for more adequate and efficient provision of care. The model can be easily modified to determine optimal utilisation rates in other populations or updated to reflect any changes in practice guidelines or epidemiological data.

Efficacy and Safety of Local Radiotherapy to All Oligometastatic Sites in Elderly Patients with Metachronous Oligometastatic Cancers After Initial Treatment for the Primary Tumor

Background and Purpose

This study aimed to investigate the efficacy and safety of maintenance therapy combined with local radiotherapy at all oligometastatic sites (LRTOS) in elderly patients with metachronous oligometastatic cancers (MOC).

Patients and Methods

A total of 242 elderly patients with MOC (≤5 metastases) and primary tumor well controlled after definitive treatment was retrospectively analyzed between August 2014 and February 2020 at Beijing Geriatric Hospital and Air Force General Hospital. Patients were divided into maintenance therapy group (maintenance therapy alone) and local radiotherapy group (maintenance therapy combined with LRTOS).

Results

There were 86 patients in the local radiotherapy group and 156 patients in the maintenance therapy group. The median length of follow-up was 36 months (range, 8.0–62 months). Median overall survival (mOS) was 25 months (95% CI: 21.1–28.9) in the local radiotherapy group and 16 months (95% CI: 14.5–17.6) in the maintenance therapy group (p < 0.001). Multivariate analyses demonstrated that LRTOS (hazard ratio (HR) = 0.49, 95% confidence interval (CI): 0.35–0.67, p < 0.001), good Eastern Cooperative Oncology Group Performance Status (ECOG PS, HR = 0.69, 95% CI: 0.49–0.97, p = 0.032), longer duration between diagnosis of primary tumor and occurrence of progression (HR = 0.87, 95% CI: 0.78–0.97, p = 0.015), and subsequent systemic treatment (HR = 0.52, 95% CI: 0.38–0.72, p < 0.001) were independent predictors of good OS. In patients who did not receive subsequent systemic treatment, their mOS was 21 months (95% CI: 12.8–29.2) for those treated with LRTOS and 14 months (95% CI: 11.4–16.6) for those who did not receive local radiotherapy (p = 0.001). Further multivariate analysis showed that LRTOS was the only independent factor for predicting good OS (HR = 0.47, 95% CI: 0.26–0.83, p = 0.010). Patients with metachronous oligometastatic lung cancer, colorectal cancer, prostate cancer, and breast cancer had higher survival benefits following LRTOS. Most patients suffered from grade 1–2 toxicities, but no treatment-related death was recorded.

Conclusion

This retrospective study shows that elderly patients with MOC treated with LRTOS may have better survival outcomes.

MVCT versus kV-CBCT for targets subject to respiratory motion: A phantom study

The use of kilovoltage cone-beam computed tomography (kV-CBCT) or megavoltage computed tomography (MVCT) for image guidance prior to lung stereotactic body radiation therapy (SBRT) is common clinical practice. We demonstrate that under equivalent respiratory conditions, image guidance using both kV-CBCT and MVCT may result in the inadequate estimation of the range of target motion under free-breathing (FB) conditions when standard low-density window and levels are used. Two spherical targets within a respiratory motion phantom were imaged using both long-exhale (LE) and sinusoidal respiratory traces. MVCT and kV-CBCT images were acquired and evaluated for peak-to-peak amplitudes of 10 or 20 mm in the cranial-caudal direction, and with 2, 4 or 5 s periods. All images were visually inspected for artifacts and conformity to the ITV for each amplitude, period, trace-type, and target size. All LE respiratory traces required a lower threshold HU window for MVCT and kV-CBCT compared to sinusoidal traces to obtain 100% volume conformity compared with the theoretical ITV (ITVT ). Excess volume was less than 2% for all kV-CBCT contours regardless of trace-type, breathing period, or amplitude, while the maximum excess volume for MVCT was 48%. Adjusting window and level to maximize conformity with the ITVT is necessary to reduce registration uncertainty to less than 5 mm. To fully capture target motion with either MVCT or kV-CBCT, substantial changes in HU levels up to -600 HU are required which may not be feasible clinically depending on the target's location and surrounding tissue contrast. This registration method, utilizing a substantially decreased window and level compared to standard low-density settings, was retrospectively compared to the automated registration algorithm for five lung SBRT patients exposed to pre-treatment kV-CBCT image guidance. Differences in registrations in the super-inferior (SI) direction greater than the commonly used ITV to PTV margin of 5 mm were encountered for several cases. In conclusion, pre-treatment image guidance for lung SBRT targets using MVCT or kV-CBCT is unlikely to capture the full extent of target motion as defined by the ITVT and additional caution is warranted to avoid registration errors for small targets and patients with LE respiratory traces.

Local Control After Stereotactic Body Radiation Therapy for Stage I Non-Small Cell Lung Cancer

PURPOSE

Numerous dose and fractionation schedules have been used to treat medically inoperable stage I non-small cell lung cancer (NSCLC) with stereotactic body radiation therapy (SBRT) or stereotactic ablative radiation therapy. We evaluated published experiences with SBRT to determine local control (LC) rates as a function of SBRT dose.

METHODS AND MATERIALS

One hundred sixty published articles reporting LC rates after SBRT for stage I NSCLC were identified. Quality of the series was assessed by evaluating the number of patients in the study, homogeneity of the dose regimen, length of follow-up time, and reporting of LC. Clinical data including 1, 2, 3, and 5-year tumor control probabilities for stages T1, T2, and combined T1 and T2 as a function of the biological effective dose were fitted to the linear quadratic, universal survival curve, and regrowth models.

RESULTS

Forty-six studies met inclusion criteria. As measured by the goodness of fit χ2/ndf, with ndf as the number of degrees of freedom, none of the models were ideal fits for the data. Of the 3 models, the regrowth model provides the best fit to the clinical data. For the regrowth model, the fitting yielded an α-to-β ratio of approximately 25 Gy for T1 tumors, 19 Gy for T2 tumors, and 21 Gy for T1 and T2 combined. To achieve the maximal LC rate, the predicted physical dose schemes when prescribed at the periphery of the planning target volume are 43 ± 1 Gy in 3 fractions, 47 ± 1 Gy in 4 fractions, and 50 ± 1 Gy in 5 fractions for combined T1 and T2 tumors.

CONCLUSIONS

Early-stage NSCLC is radioresponsive when treated with SBRT or stereotactic ablative radiation therapy. A steep dose-response relationship exists with high rates of durable LC when physical doses of 43-50 Gy are delivered in 3 to 5 fractions.

Stereotactic radiotherapy for early stage non-small cell lung cancer: current standards and ongoing research

Stereotactic body radiation therapy (SBRT) allows for the non-invasive and precise delivery of ablative radiation dose. The use and availability of SBRT has increased rapidly over the past decades. SBRT has been proven to be a safe, effective and efficient treatment for early stage non-small cell lung cancer (NSCLC) and is presently considered the standard of care in the treatment of medically or functionally inoperable patients. Evidence from prospective randomized trials on the optimal treatment of patients deemed medically operable remains owing, as three trials comparing SBRT to surgery in this cohort were terminated prematurely due to poor accrual. Yet, SBRT in early stage NSCLC is associated with favorable toxicity profiles and excellent rates of local control, prompting discussion in regard of the treatment of medically operable patients, where the standard of care currently remains surgical resection. Although local control in early stage NSCLC after SBRT is high, distant failure remains an issue, prompting research interest to the combination of SBRT and systemic treatment. Evolving advances in SBRT technology further facilitate the safe treatment of patients with medically or anatomically challenging situations. In this review article, we discuss international guidelines and the current standard of care, ongoing clinical challenges and future directions from the clinical and technical point of view.

New method for measurement of chest surface motion in lung cancer patients: Quantification using a technique of deformable image registration

The purpose of this study was to measure the motion of the chest surface during breath-holding treatment for lung cancer using deformable image registration (DIR). Forty non-small-cell lung cancer patients treated with breath-holding stereotactic body radiation therapy were retrospectively examined. First, intensity-based DIR between 2 breath-holding computed tomography (CT) images was performed. Subsequently, deformation vector field (DVF) for all dimensions (left-right, anterior-posterior, and superior-inferior) was calculated from the result. For the analysis of chest surface, the DVF value of the only chest surface area was extracted after the chest surface was divided into 12 regions of interest (ROI) based on anatomy. Additionally, for the analysis of the correlation with the internal tumor motion, the median value of DVF for each surface ROI and the motion of the center of gravity of the tumor volume were used. It was possible to calculate the motion of chest surface without any outliers for all patients. For the average of 12 surface ROIs, the motion of 3D chest surface was within 2 mm (30 cases), 3 mm (8 cases), and 4 mm (2 cases). There was no correlation between the motion of the chest surface and that of the tumor for all 12 surface ROIs. We proposed a technique to evaluate the surface motion using DIR between multiple CT images. It could be a useful tool to calculate the motion of chest surface.

Ultra-central Thoracic Re-irradiation Using 10-fraction Stereotactic Body Radiotherapy for Recurrent Non-small-cell Lung Cancer Tumors: Preliminary Toxicity and Efficacy Outcomes

BACKGROUND

We report our clinical outcomes of patients with recurrent non-small-cell lung cancer (NSCLC) tumors with ultra-central (UC) location treated with hypofractionated 10-fraction stereotactic body radiotherapy (hSBRT) in the context of thoracic re-irradiation.

PATIENTS AND METHODS

This study was conducted from 2009 to 2017 on 20 patients with recurrent NSCLC from previous thoracic radiation treatment who underwent hSBRT to 21 total UC located recurrent tumors. The planning target volumes (PTVs) that overlapped with previous treatment fields (within the 50% isodose line) were included in this analysis with endpoints of overall survival, tumor control, and toxicity.

RESULTS

The median follow-up time was 17.8 months. The median total dose of hSBRT and total biologically effective dose (BED₁₀) were 65 Gy and 107.25 Gy, respectively. The median time from previous treatment was 14.6 months. The 1-year overall survival, progression-free survival, and local control rates were 68%, 35%, and 83%, respectively. The median time to local progression was 13.3 months. The most common toxicity was grade 2 or above pneumonitis (35%). One patient, whose tumor was abutting the esophagus, experienced grade 3 esophagitis. Two (10%) patients died from "unlikely" treatment-related hemorrhage from local tumor progression at 10 and 24 months after hSBRT. Bronchoscopic evaluation of 1 patient suggested endobronchial tumor progression, and clear radiographic evidence of treated hilar tumor progression was documented in the second patient's case.

CONCLUSION

Despite having a high-risk population with recurrent ultra-central NSCLC tumors in the setting of re-irradiation, our results demonstrate that ablative doses of hSBRT may serve as a feasible option for these challenging cases and concur with current reported literature.

Outcomes of Hypofractional Tomotherapy in Patients with Stage III Nonsmall Cell Lung Cancer Who Are Not Eligible for Surgery or Concurrent Chemoradiation

Purpose

We assessed the clinical outcomes and toxicities following hypofractionation with helical tomographic intensity-modulated radiotherapy technology (tomotherapy) in patients with stage III non-small cell lung cancer (NSCLC) who were not candidates for surgery or concurrent chemoradiation.

Methods

Forty-three patients with stage III NSCLC who were treated between 2011 and 2017 were enrolled. The prescription doses for gross target volume and clinical target volume were 70 Gy and 60 Gy (respectively) delivered in 15–25 fractions over 3–5 weeks.

Results

The median overall survival (OS) time was 34.23 (range 11.33–99.33) months. The estimated 1-, 2-, and 3-year OS rates were 97.7%, 74.4%, and 55.9%, respectively; the corresponding progression-free survival (PFS) rates were 79.1%, 53.5%, and 36.1%, respectively. The local disease recurrence, regional disease recurrence, and distant metastasis rates at 3 years were 4.7%, 11.62%, and 55.81%, respectively. On multivariate analysis, dose regimen (<19 f vs. ≥19 f) was an independent prognostic factor affecting OS, PFS, and DM (p < 0.05). Seven patients developed grade 1-2 acute radiation pneumonia (RP), 5 patients developed grade 1-2 late RP, while 3 patients developed grade 3 late RP. None of the patients developed grade 4-5 radiation lung injury.

Conclusion

Tomotherapy may be an effective treatment option for patients with stage III NSCLC. It may be a viable alternative to surgery with lower incidence of side effects.

Non-invasive stereotactic ablative boost in patients with locally advanced cervical cancer

INTRODUCTION

The current literature is insufficient to guide care for patients with cervical cancer ineligible for brachytherapy. Stereotactic ablative radiotherapy boost is a clinical necessity for these patients, but highly debated among radiation oncologists.

OBJECTIVE

To report toxicity and survival outcomes in a large cohort of patients with locally advanced cervical cancer treated with a non-invasive stereotactic ablative radiotherapy boost instead of brachytherapy METHODS: Patients with locally advanced cervical cancer were entered, between January 2008 and December 2018, who were recommended definitive intent external boost after pelvic radiotherapy to 45-50.4 Gy concurrent with weekly cisplatin and simultaneous/sequential nodal boost up to 55-66 Gy. Simulation CT was facilitated using radio-opaque fiducials, empty rectum, dedicated bladder filling, and whole body vaculoplastic immobilization. Kaplan-Meier survival estimates were used to report local/regional recurrences, distant metastases, cancer-specific survival, and overall survival.

RESULTS

A total of 25 patients were analyzed. Median follow-up was 25 months (range 6-54). Patients received stereotactic ablative radiotherapy due to refusal of brachytherapy (9/25, 36%), medical co-morbidities limiting implantation (9/25, 36%), or technical infeasibility (7/25, 28%). Typical fractionation was 24-30 Gy in 4-5 fractions (24/25, 96%). The most common long-term toxicity was grade 1-2 vaginal dryness, discomfort, stenosis, and/or dyspareunia (4/25, 16%). One patient had new post-treatment grade 4 fistula in an area of previous tumor erosion (1/25, 4%). Overall survival, cancer specific survival, loco-regional control, and distant control were 95.5%, 100%, 95.5%, and 89.1%, respectively, at 2 years.

CONCLUSION

Further study of stereotactic ablative radiotherapy boost for cervical cancer is needed; a brachytherapy-similar approach portends clinical success with 95.5% overall survival and loco-regional control at 2 years.

Oncologic Outcomes of Surgery Versus SBRT for Non-Small-Cell Lung Carcinoma: A Systematic Review and Meta-analysis

BACKGROUND

The optimal treatment of stage I non-small-cell lung carcinoma is subject to debate. The aim of this study was to compare overall survival and oncologic outcomes of lobar resection (LR), sublobar resection (SR), and stereotactic body radiotherapy (SBRT).

METHODS

A systematic review and meta-analysis of oncologic outcomes of propensity matched comparative and noncomparative cohort studies was performed. Outcomes of interest were overall survival and disease-free survival. The inverse variance method and the random-effects method for meta-analysis were utilized to assess the pooled estimates.

RESULTS

A total of 100 studies with patients treated for clinical stage I non-small-cell lung carcinoma were included. Long-term overall and disease-free survival after LR was superior over SBRT in all comparisons, and for most comparisons, SR was superior to SBRT. Noncomparative studies showed superior long-term overall and disease-free survival for both LR and SR over SBRT. Although the papers were heterogeneous and of low quality, results remained essentially the same throughout a large number of stratifications and sensitivity analyses.

CONCLUSION

Results of this systematic review and meta-analysis showed that LR has superior outcomes compared to SBRT for cI non-small-cell lung carcinoma. New trials are underway evaluating long-term results of SBRT in potentially operable patients.

Stereotactic body radiotherapy feasibility for patients with peripheral stage I lung cancer and poor pulmonary function

The aim of the present study was to evaluate the toxicity and investigate the prognostic factors of stereotactic body radiotherapy (SBRT) for peripheral stage I lung cancer in patients with poor pulmonary function. Data from 95 patients with stage I lung cancer with poor pulmonary function treated using SBRT at Osaka Rosai Hospital were retrospectively analyzed. Poor pulmonary function was defined as the forced expiratory volume %/sec (FEV1/FVC) <70% or percentage of vital capacity (%VC) <80% during pretreatment spirometry testing. The median FEV1/FVC and %VC of the patients were 59.1 and 78.8%, respectively. The most commonly prescribed dose of SBRT was 50 Gy in four fractions (68 patients, 72%). The median follow-up period was 34 months. Four patients developed adverse effects of grade ≥3, one patient developed grade 5 radiation pneumonitis, one grade 5 hemoptysis, one grade 3 radiation pneumonitis and one grade 3 chest wall pain. The 3-year local control and overall survival (OS) rates were 78.8 and 59.9%, respectively. Univariate analysis revealed that Karnofsky performance status (KPS) significantly predicted OS (P=0.037). Thus, SBRT in patients with stage I lung cancer with poor pulmonary function may be effective with acceptable toxicity. A KPS score ≥80 indicated good prognosis.

Salvage Therapy for Locoregional Recurrence After Stereotactic Ablative Radiotherapy for Early-Stage NSCLC

Although isolated local (LRs) and regional recurrences (RRs) constitute a minority of post-stereotactic ablative radiotherapy (SABR) relapses, their management is becoming increasingly important as the use of SABR continues to expand. However, few evidence-based strategies are available to guide treatment of these potentially curable recurrences. On behalf of the Advanced Radiation Technology Committee of the International Association for the Study of Lung Cancer, this article was written to address management of recurrent disease. Topics discussed include diagnosis and workup, including the roles of volumetric and functional imaging as well as histopathologic methods; clinical outcomes after salvage therapy; patterns of recurrence after salvage therapy; and management options. Our main conclusions are that survival for patients with adequately salvaged LRs is similar to that for patients after primary SABR without recurrence, and survival for those with salvaged RRs (regardless of nodal burden or location) is similar to that of patients with de novo stage III disease. Although more than half of patients who undergo salvage do not develop a second relapse, the predominant pattern of second failure is distant, especially for RRs. Management requires rigorous multidisciplinary coordination. Isolated LRs can be managed with resection and nodal dissection, repeat SABR, thermal ablation, or systemic therapies. RRs can be treated with combined chemoradiotherapy, radiation or chemotherapy alone, or supportive services. Finally, regular and structured follow-up is recommended after post-SABR salvage therapy.

[Stereotactic radiotherapy of stage I non-small cell lung cancer. State of the art in 2019 and recommendations: Stereotaxy as an alternative to surgery?]

Stereotactic radiotherapy (or Stereotactic body radiotherapy [SBRT]) is a technique currently well established in the therapeutic arsenal for the management of bronchial cancers. It represents the standard treatment for inoperable patients or who refuses surgery. It is well tolerated, especially in elderly and frail patients, and the current issue is to define its indications in operated patients, based on retrospective and randomized trials comparing stereotactic radiotherapy and surgery, with results equivalents. This work analyzes in detail the different aspects of pulmonary stereotactic radiotherapy and suggests arguments that help in the therapeutic choice between surgery and stereotaxic irradiation. In all cases, the therapeutic decision must be discussed in a multidisciplinary consultation meeting, while informing the patient of the possible therapeutic options.

Hypofractionated radiotherapy as a salvage treatment for recurrent hepatocellular carcinoma with inferior vena cava/right atrium tumor thrombus: a multi-center analysis

Background

Recurrent hepatocellular carcinoma (HCC) with a tumor thrombus (TT) extending into the inferior vena cava (IVC)/right atrium (RA) is generally regarded as a terminal-stage condition and there is no worldwide consensus on the proper management of this situation. In the present study, we report the efficacy of hypofractionated radiotherapy (HFRT) as a salvage treatment for recurrent HCC with IVC/RA TT.

Methods

We retrospectively reviewed 75 HCC patients with an IVC/RA TT who were referred for HFRT at three institutions between 2008 and 2016. 57 cases had a TT located in the IVC (IVC group), and 18 cases had a TT located in the IVC and RA (IVC + RA group). HFRT was designed to focus on the TT with or without the primary intrahepatic tumors.

Results

In all cases, the TT completely disappeared (CR) in 17 patients (22.7%), 55 patients (73.3%) had a partial response (PR), and 3 patients (4.0%) had a stable disease (SD). There were no cases of progressive disease (PD). The 1-, 2-, and 3-year overall survival rates of the 75 patients were 38.7% (29/75), 13.3% (10/75) and 5.3% (4/75), respectively. The overall median survival time was 10 months. The mean survival times for the IVC group and IVC+ RA group were 13.8 ± 1.1 and 11.6 ± 2.5 months, respectively. There was no significant difference in survival between the two groups (p = 0.205). Log-rank test revealed that factors predicting poor survival were Child-Pugh B liver function classification, AFP ≥ 400 μg/L, intrahepatic multiple tumors, distant metastases, only the TT as the target, a biological effective dose (BED) < 55 Gy and no chance of further radiotherapy.

Conclusions

HFRT appears to be an effective and reasonable treatment option for recurrent HCC patients with IVC/RA TT. The location of the tumor thrombus, either in IVC or in IVC and RA, is not the factor that influences the efficacy of radiotherapy or survival.

Calculating the individualized fraction regime in stereotactic body radiotherapy for non-small cell lung cancer based on uncomplicated tumor control probability function

BACKGROUND

To calculate the individualized fraction regime (IFR) in stereotactic body radiotherapy (SBRT) for non-small cell lung cancer (NSCLC) patients using the uncomplicated tumor control probability (UTCP, P⁺) function.

METHODS

Thirty-three patients with peripheral lung cancer or lung metastases who had undergone SBRT were analyzed. Treatment planning was performed using the dose regime of 48 Gy in 4 fractions. Dose volume histogram (DVH) data for the gross tumor volume (GTV), lung, chest wall (CW) and rib were exported and the dose bin was multiplied by a certain percentage of the dose in that bin which ranged from 1 to 200% in steps of 1%. For each dose fraction, P⁺ values were calculated by considering the tumor control probability (TCP), radiation-induced pneumonitis (RIP), chest wall pain (CWP) and radiation-induced rib fracture (RIRF). UTCP values as a function of physical dose were plotted and the maximum P⁺ values corresponded to the optimal therapeutic gain. The IFR in 3 fractions was also calculated with the same method by converting the dose using the linear quadratic (LQ) model.

RESULTS

Thirty-three patients attained an IFR using the introduced methods. All the patients achieved a TCP value higher than 92.0%. The IFR ranged from 3 × 10.8 Gy to 3 × 12.5 Gy for 3 fraction regimes and from 4 × 9.2 Gy to 4 × 10.7 Gy for 4 fraction regimes. Four patients with typical tumor characteristics demonstrated that the IFR was patient-specific and could maximize the therapeutic gain. Patients with a large tumor had a lower TCP and UTCP and a smaller fractional dose than patients with a small tumor. Patients with a tumor adjacent to the organ at risk (OAR) or at a high risk of RIP had a lower UTCP and a smaller fractional dose compared with patients with a tumor located distant from the OAR.

CONCLUSIONS

The proposed method is capable of predicting the IFR for NSCLC patients undergoing SBRT. Further validation in clinical samples is required.

Stereotactic body radiotherapy in patients with chronic obstructive pulmonary disease and interstitial pneumonia: a review

Stereotactic body radiation therapy (SBRT) can yield excellent local tumor control, as well as survival benefit comparable to that of surgery for early-stage lung cancer. However, in terms of toxicity, SBRT might lead to fatal radiation pneumonitis. Lung diseases, such as chronic obstructive pulmonary disease (COPD) and interstitial lung disease (ILD), are major risk factors for lung cancer. However, these patients are typically not candidates for the gold-standard treatment option, lobectomy, because of the perioperative risks. In addition, patients with poor respiratory function can be excluded in prospective clinical trials. Thus, SBRT for patients with pulmonary diseases is still challenging, but there appears to be a clinical role for this modality as an alternative treatment. However, there are few well-documented review articles on SBRT for patients with pulmonary diseases. Therefore, we aimed to review SBRT in the context of important patient-related factors, including COPD and ILD. SBRT is an acceptable alternative treatment option for patients with lung cancer who also have COPD with an equivalent risk of radiation pneumonitis to normal lung. However, latent ILD should be detected prior to treatment. The indication for SBRT should be decided by carefully considering the risks and benefit for patients with ILD.

Is stereotactic body radiotherapy for ultra-central lung tumor a feasible option? A systemic review and meta-analysis

INTRODUCTION

Ultra-central (UC) tumors, which are generally defined as tumors directly abutting the proximal bronchial tree, are difficult to treat with stereotactic body radiotherapy (SBRT) owing to possible serious complications. This systemic review and meta-analysis analyzed the early experiences and evaluated the efficacy and feasibility of SBRT for UC tumors.

METHODS AND MATERIALS

The present study adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Systemic searches of the EMBASE, PubMed, MEDLINE, and Cochrane library electronic databases were performed. The primary endpoints were two-year local control (LC), overall survival (OS), and grade ≥3 complication rates. A random-effects model was used to determine the pooled rates of the primary endpoints. Grade 5 complications were descriptively assessed.

RESULTS

Nine studies involving 291 patients with UC tumors who underwent SBRT were included. The pooled two-year LC, two-year OS, and grade ≥3 complication rates were 96.7% (95% confidence interval [CI]: 91.0-98.9), 57.7% (95% CI: 32.0-79.8), and 23.2% (95% CI: 11.8-40.5), respectively. The incidence of grade 5 complication was 0-22% and was 0% in three of eight available studies. Hemorrhage (68.2%) was the commonest fatal complication. The risk factors for fatal hemoptysis included anticoagulant use, excessive maximum irradiation dose, endobronchial involvement, squamous histology, and bevacizumab exposure.

CONCLUSIONS

SBRT for UC tumors confers efficient LC, although the risk of complications was not negligible. Control of possible risk factors of hemorrhage and dose optimization through further studies are warranted.

Survival After Stereotactic Body Radiation Therapy for Clinically Diagnosed or Biopsy-Proven Early-Stage NSCLC: A Systematic Review and Meta-Analysis

INTRODUCTION

Stereotactic body radiation therapy (SBRT) is a promising curative treatment for early-stage NSCLC. It is unclear if survival outcomes for SBRT are influenced by a lack of pathological confirmation of malignancy and staging of disease in these patients. In this systematic review and meta-analysis, we assess survival outcomes after SBRT in studies with patients with clinically diagnosed versus biopsy-proven early-stage NSCLC.

METHODS

The main databases were searched for trials and cohort studies without restrictions to publication status or language. Two independent researchers performed the screening and selection of eligible studies. Outcomes were overall survival, cancer-specific survival, and disease-free survival. The inverse variance method and the random effects method for meta-analysis were used to assess pooled survival estimates.

RESULTS

A total of 11,195 nonduplicate records were identified by the original search strategy. After screening by title and abstract, 1051 potentially eligible records were identified. A total of 43 articles were included. The comparative studies showed lower 3-year overall survival and lower 2-year and 5-year cancer-specific survival for biopsy-proven disease compared to clinical disease. However, 5-year overall survival was the same for both groups. For the pooled estimates, 3-year disease-free survival and 2-year cancer-specific survival were lower for biopsied disease.

CONCLUSIONS

Results of this systematic review and meta-analysis show a discrepancy in oncological outcomes for patients undergoing SBRT for suspected early-stage NSCLC in whom there is pathologic conformation of malignancy and those who there is only a clinical diagnose of NSCLC. These results emphasize the importance of obtaining pathologic proof of malignancy.

Stereotactic body radiation therapy in early-stage NSCLC: historical review, contemporary evidence and future implications

Clinical use of stereotactic body radiation therapy (SBRT) has increased dramatically over the last 2 decades and is the current standard-of-care in cases of inoperable early stage non-small-cell lung cancer. While surgical resection remains the standard-of-care for operable patients, several ongoing clinical trials are investigating the role of SBRT in these operative candidates as well. Taking into consideration the expanding role and utility of SBRT, this paper will: review the historical basis of SBRT; examine landmark trials establishing the framework for the current body of evidence; discuss areas of active and future research; and identify epidemiological trends that are likely to further increase the use of SBRT.

Comparison of Three Radiobiological Models in Stereotactic Body Radiotherapy for Non-Small Cell Lung Cancer

Objective: The applicability of the linear quadratic (LQ) model to local control (LC) modeling after hypofractionated radiotherapy to treat lung cancer is highly debated. To date, the differences in predicted outcomes between the LQ model and other radiobiological models, which are characterized by additional dose modification beyond a certain transitional dose (d_T), have not been well established. This study aims to compare the outcomes predicted by the LQ model with those predicted by two other radiobiological models in stereotactic body radiotherapy (SBRT) for non-small cell lung cancer (NSCLC). Methods: Computer tomography (CT) simulation data sets for 20 patients diagnosed with stage Ⅰ primary NSCLC were included in this study. Three radiobiological models, including the LQ, the universal survival curve (USC) and the modified linear quadratic and linear (mLQL) model were employed to predict the tumor control probability (TCP) data. First, the d_T values for the USC and mLQL models were determined. Then, the biologically effective dose (BED) and the predicted TCP values from the LQ model were compared with those calculated from the USC and mLQL models. Results: The d_T values from the USC model were 29.6 Gy, 33.8 Gy and 44.5 Gy, whereas the values were 90.2 Gy, 84.0 Gy and 57.3 Gy for the mLQL model for 1-year, 2-year and 3-year TCP prediction. The remarkable higher d_T values obtained from the mLQL model revealed the same dose-response relationship as the LQ model in the low- and high-dose ranges. We also found that TCP prediction from the LQ and USC models differed by less than 3%, although the BED values for the two models were significantly different. Conclusion: Radiobiological analysis reveals small differences between the models and suggested that the LQ model is applicable for modeling LC using SBRT to treat lung cancer, even when an extremely high fractional dose is used.

Changes in quality of life after surgery or radiotherapy in early-stage lung cancer

BACKGROUND

Although surgical resection is considered the standard of care for early-stage non-small cell lung cancer, radiotherapy [stereotactic body radiation therapy (SBRT)] has been proposed as a minimally invasive treatment alternative. Studies have not examined differences in quality of life (QoL) between surgery and radiotherapy, despite important implications for patient and provider decision making.

METHODS

The Surveillance, Epidemiology, and End Results Medicare Health Outcomes Survey (1998-2014) was used to assess changes in physical QoL score [Physical Component Summary (PCS)] and mental health QoL score [Mental Component Summary (MCS)] from baseline (prior to cancer diagnosis) to follow-up after treatment with surgery only or radiotherapy only. QoL was measured using the 36-item Short Form Health Survey (SF-36) until 2006, when it was replaced by the Veterans RAND 12-Item Health Survey (VR-12).

RESULTS

Data from 184 patients (28 SBRT, 156 surgery) was included. There was a significant decline in PCS score from baseline to follow-up (surgery: -4.81; 95% CI: -6.31, -3.30; P<0.0001; SBRT: -5.6; 95% CI: -9.96, -1.24; P=0.0137). Similarly, MCS scores declined for both groups although the change was significant for surgery patients only (surgery: -2.96; 95% CI: -4.55, -1.37; P=0.0003; SBRT: -1.86; 95% CI: -5.4, 1.68; P=0.2902). Surgical patients had higher baseline PCS (P=0.0061) and MCS (P=0.0056) than SBRT patients. There was no significant difference in the change over time between the two treatment options for PCS or MCS.

CONCLUSIONS

Although both treatments negatively impact QoL, the impact of SBRT on QoL may be comparable to surgery and therefore SBRT should be given consideration as an alternative treatment, especially when surgery is not an option.

Promising Clinical Outcome With Long Term Follow-Up After Body Gamma Knife Stereotactic Radiosurgery for Patients With Early Stage Non-small Cell Lung Cancer

Introduction: Stereotactic ablative radiosurgery (SRS) or stereotactic ablative body radiotherapy (SABR) is the standard treatment for patients with inoperable early stage non-small cell lung cancer (NSCLC), the body gamma knife SRS (ɤ-SRS) is a special SABR technology developed in China. This study prospectively assessed the clinical outcome, toxicity and cost following body ɤ-SRS for early stage NSCLC. Methods: From 2007 to 2010, a total of 29 patients with early stage NSCLC were prospectively enrolled in this study. The prescription dose for Planning Target Volume (PTV), Clinical Target Volume (CTV), and Gross Target Volume (GTV) were 50, 60, and 70 gray (Gy) in 10 fractions. Isodose curves of 50, 60, and 70% covered at least 100% of PTV, 90% of CTV, and 80% of GTV, respectively. The body ɤ-SRS was delivered 5 days per week and completed in 2 weeks. Results: Median follow-up time was 62.0 (range 11.1-140.3) months. 1-, 3-, 5-year OS rates were 93.1%, 72.0%, 60.3%; PFS rates were 86.2, 64.2 and 48.8%; and LR, RR, and DM rates were 10.9%, 21.4%, 29.0%. The median cost of the body ɤ-SRS during treatment was 4,838 (range 4,615-4,923) dollars and the median cost through 5 years was 36,960 (range 9920-56,824) dollars. Conclusion: With existing clinical data, the body ɤ-SRS is an effective treatment option for patients with medically inoperable early stage NSCLC or patients who do not prefer operation, as they may benefit from the minimized toxicity. Due to excellent cost effectiveness, the availability of the body ɤ-SRS will expand, especially in developing nations, and underdeveloped countries.

Tumor Control and Toxicity after SBRT for Ultracentral, Central, and Paramediastinal Lung Tumors

PURPOSE

Increased rates of toxicity have been described after stereotactic body radiation therapy (SBRT) for central lung tumors within 2 cm of the proximal bronchial tree (PBT). Recent studies have defined a new class of ultracentral tumors. We report our experience treating ultracentral, central, and paramediastinal tumors with SBRT and compare toxicity, disease control, and survival rates.

METHODS AND MATERIALS

We reviewed the records of patients with central lung tumors treated with SBRT between September 2009 and July 2017. Tumors were classified as central if within 2 cm of the PBT, ultracentral if the planning target volume touched the PBT or esophagus, and paramediastinal if touching mediastinal pleura. Actuarial rates of grades 2+ and 3+ toxicity, local control (LC), and overall survival were assessed using the Kaplan-Meier method and compared using a log-rank test. Toxicity was scored with the Common Terminology Criteria for Adverse Events, version 4.03.

RESULTS

We identified 68 patients with 69 central lung tumors, including 14 ultracentral, 15 paramediastinal, and 39 central tumors. Fifty-three patients were treated for early stage lung cancer and 15 for lung metastases. The prescribed dose ranged from 40 Gy to 60 Gy over 3 to 8 fractions. Most patients were treated using 5 fractions (83%), followed by 8 fractions (10%). Median follow-up was 19.7 months (range, 3.3-78.3 months). The 2-year estimates of LC (89%, 85%, and 93%, respectively; P = .72) and overall survival (76%, 73%, and 72%, respectively; P = .75) for ultracentral, central, and paramediastinal tumors were similar. Ultracentral tumors had an increased risk of grade 2+ toxicity (57.6% vs 14.2% vs 7.1%; P = .007) at 2 years. One patient with an ultracentral tumor developed grade 5 respiratory failure.

CONCLUSIONS

The oncologic outcomes after SBRT for ultracentral, central, and paramediastinal lung tumors were similar, with LC exceeding 85% at 2 years using predominantly 5-fraction schedules. Ultracentral lung tumors were associated with an increased risk of toxicity in our patient cohort. Additional studies are needed to minimize toxicity for ultracentral tumors.

A hybrid planning strategy for stereotactic body radiation therapy of early stage non-small-cell lung cancer

Currently dynamic conformal arcs (DCA) and volumetric modulated arc therapy (VMAT) are two popular planning techniques to treat lung stereotactic body radiation therapy (SBRT) patients. Of the two, DCA has advantages in terms of multi-leaf collimator (MLC) motion, positioning error, and delivery efficiency. However, VMAT is often the choice when critical organ sparing becomes important. We developed a hybrid strategy to incorporate DCA component into VMAT planning, results were compared with DCA and VMAT plans. Four planning techniques were retrospectively simulated for 10 lung SBRT patients: DCA, Hybrid-DCA (2/3 of the doses from DCA beams), Hybrid-VMAT (2/3 of the doses from VMAT beams) and VMAT. Plan complexity was accessed by modulation complexity score (MCS). Conformity index (CI) for the planning target volume (PTV), V₂₀ and V₅ for the lung, V₃₀ for the chestwall, and maximum dose to all other critical organs were calculated. Plans were compared with regard to these metrics and measured agreement between the planned and delivered doses. DCA technique did not result in acceptable plan quality due to target location for five patients. Hybrid-DCA produced one unacceptable plan, and Hybrid-VMAT and VMAT produced no unacceptable plans. The CI improved with increasing VMAT usage, as did the dose sparing to critical structures. Compared to the VMAT technique, a total MU reduction of 14%, 25% and 37% were found for Hybrid-VMAT, Hybrid-DCA and DCA techniques for 54 Gy patient group, and 9%, 23% and 34% for 50 Gy patient group, suggesting improvement in delivery efficiency with increasing DCA usage. No significant variations of plan complexity were observed between Hybrid-DCA and Hybrid-VMAT (P = 0.46 from Mann-Whitney U-test), but significant differences were found among DCA, Hybrid and VMAT (P < 0.05). Better agreements between the planned and delivered doses were found with more DCA contributions. By adding DCA components to VMAT planning, hybrid technique offers comparable dosimetry to full VMAT, while increasing delivery efficiency and minimizing MLC complexity.

Stereotactic ablative radiotherapy (SABR) for early-stage central lung tumors: New insights and approaches

The use of stereotactic ablative radiotherapy (SABR) for central lung tumors is increasing. Centrally located lung tumors can be subdivided into two categories, namely the 'moderately central' tumors where the planning target volume is located within 2 cm of the proximal bronchial tree, and the 'ultracentral' tumors where a planning target volume (PTV) overlaps the trachea or main stem bronchi. The toxicity of SABR appears acceptable when 'moderately central' tumors are treated using techniques that comply with organs at risk tolerance doses used for prospective trials and in recent publications. A high toxicity is seen when ultracentral tumors are treated using SABR, and conventional radiotherapy appears more appropriate in such tumors as the true normal organ tolerance doses remain unknown. When ultracentral tumors are treated with non-SABR hypofractionated radiotherapy, a homogenous dose distribution in the planning target volume and limitation of both normal organ maximum point doses and volumes receiving high doses seems to be needed.

Stereotactic body radiotherapy (SBRT) for Stage I lung cancer

Stereotactic body radiation therapy (SBRT) is a newly developed technique currently in clinical use. SBRT originated from stereotactic radiosurgery (SRS) for intracranial tumors. Since the 1990s, SBRT has been widely used in clinical settings for the treatment of lung cancer. We review the history and current standard techniques. Previous clinical studies of lung cancer showed high local control rates with acceptable toxicities. Past and on-going clinical trials are also reviewed.

Comparison of the progressive resolution optimizer and photon optimizer in VMAT optimization for stereotactic treatments

The photon optimization (PO) algorithm was recently released by Varian Medical Systems to improve volumetric modulated arc therapy (VMAT) optimization within Eclipse (Version 13.5). The purpose of this study is to compare the PO algorithm with its predecessor, progressive resolution optimizer (PRO) for lung SBRT and brain SRS treatments. A total of 30 patients were selected retrospectively. Previously, all the plans were generated with the PRO algorithm within Eclipse Version 13.6. In the new version of PO algorithm (Version 15), dynamic conformal arcs (DCA) were first conformed to the target, then VMAT inverse planning was performed to achieve the desired dose distributions. PTV coverages were forced to be identical for the same patient for a fair comparison. SBRT plan quality was assessed based on selected dose-volume parameters, including the conformity index, V₂₀ for lung, V_30 Gy for chest wall, and D_0.035 cc for other critical organs. SRS plan quality was evaluated based on the conformity index and normal tissue volumes encompassed by the 12 and 6 Gy isodose lines (V₁₂ and V₆ ). The modulation complexity score (MCS) was used to compare plan complexity of two algorithms. No statistically significant differences between the PRO and PO algorithms were found for any of the dosimetric parameters studied, which indicates both algorithms produce comparable plan quality. Significant improvements in the gamma passing rate (increased from 97.0% to 99.2% for SBRT and 96.1% to 98.4% for SRS), MCS (average increase of 0.15 for SBRT and 0.10 for SRS), and delivery efficiency (MU reduction of 29.8% for SBRT and 28.3% for SRS) were found for the PO algorithm. MCS showed a strong correlation with the gamma passing rate, and an inverse correlation with total MUs used. The PO algorithm offers comparable plan quality to the PRO, while minimizing MLC complexity, thereby improving the delivery efficiency and accuracy.

Dosimetric comparison of helical tomotherapy and conventional Linac-based X-knife stereotactic body radiation therapy for primary lung cancer or pulmonary metastases

Background

To compare helical tomotherapy (HT) with X-knife stereotactic body radiation therapy (HT-SBRT/X-SBRT) for primary or metastatic lung cancer regarding planning target volume (PTV) coverage, such as homogeneity index (HI), conformity index (CI) and dose-volume histogram (DVH) of organs at risk (OARs).

Methods

We retrospectively analyzed 21 patients receiving definitive radiation treatment for non-small cell lung cancer (NSCLC) or pulmonary metastases at our institution between March 2015 and October 2016. Tumors were irradiated with 4-10 Gy per fraction in 5-15 fractions. Plans were compared according to PTV coverage and OARs sparing.

Results

Significant differences between HT and X-knife were observed for both HI (P=0.003) and CI (P<0.001). The V5 (P=0.001), V10 (P=0.009), V20 (P=0.001), the mean lung dose (P=0.005) of total lung and maximum dose of the spinal cord (P=0.010) were significantly lower in the X-SBRT group than the HT-SBRT group. There were no significant differences for the V30 (P=0.075) and the mean heart dose (P=0.584) between the two groups.

Conclusions

X-SBRT was dosimetrically superior to HT-SBRT, when applied in these tumors' maximum diameters <5 cm. As HT resulted in increased low-dose volume, it is essential to optimize the patient selection in order to avoid severe radiation pneumonitis in HT-SBRT.

Stereotactic body radiotherapy for centrally located stage I non-small cell lung cancer

Stereotactic body radiotherapy (SBRT) has become the standard of care for the treatment of early stage non-small cell lung cancer in high risk or medically inoperable patients. It is very well tolerated when given to peripherally located tumors and is associated with high rates of local control. Centrally located tumors represent a bigger challenge as they are closer to a number of critical structures, namely the major bronchi, esophagus, large vessels and brachial plexus, that can be damaged by the high ablative doses of SBRT needed for optimal tumor control. Thus, the fractionation schedule for centrally located tumors needs to balance the need for tumor control while minimizing the risk of significant radiotherapy toxicity. In this article, we review the current evidence, summarize the prospective and retrospective studies of SBRT for centrally located tumors, and highlight several practical considerations.

Approaches to stereotactic body radiation therapy for large (≥5 centimeter) non-small cell lung cancer

Although larger (≥5 cm) node-negative non-small cell lung cancer (NSCLC) lesions are altogether uncommon, their incidence may increase following the implementation of lung cancer screening. A rigorous assessment of stereotactic body radiation therapy (SBRT) for these challenging cases is imperative not only owing to concerns of increased risks when delivering ablative doses to large volumes, but also due to lack of prospective data, as these patients were excluded from seminal phase II SBRT trials. In addition to appraising the available institutional or multi-institutional experiences, multiple strategies to reduce toxicities are discussed. These include exploration of several different dose/fractionation schemes and regimens, as well as specialized techniques for SBRT treatment planning and delivery. Because these lesions have a higher rate of occult lymphatic or distant spread, the role of systemic therapies (including chemotherapy and immunotherapy) are also discussed. Altogether, the publication of several key reports, entirely over the last few years, has created a more solid foundation with which to utilize evidence-based management for this unique patient population.

Efficacy and safety of stereotactic radiosurgery for pulmonary metastases from osteosarcoma: Experience in 73 patients

Osteosarcoma pulmonary metastases are typically treated with resection and/or chemotherapy. We hypothesize that stereotactic radiosurgery (SRS) can be an alternative to surgery that can achieve high rates of local control with limited toxicity. From January 2005 to December 2013, 73 patients who developed pulmonary metastasis during period of adjuvant chemotherapy or follow-up were analyzed. 33 patients were treated by stereotactic radiosurgery using the body gamma-knife system. A total dose of 50 Gy was delivered at 5 Gy/fraction to the 50% isodose line covering the planning target volume, whereas a total dose of 70 Gy was delivered at 7 Gy/fraction to the gross target volume. The other 40 patients were treated by surgical resection. Four-year progression-free survival rate, four-year survival rate, median time of PRPFS (post-relapse progress-free survival) and PROS (post-relapse overall survival) in SRS group were parallel to that in surgical group. Patients tolerated gamma knife radiosurgery well. Our study demonstrates that SRS is well-tolerated with excellent local control and less complications. SRS should be considered as a potential option in patients with pulmonary metastases from osteosarcoma, especially in those who are medically inoperable, refuse surgery.

A modified formula for dose calculations of stereotactic ablative body radiotherapy for non-small cell lung cancer

To provide a modified formula consistent with the Monte Carlo (MC) algorithm for dose calculations during stereotactic ablative body radiotherapy for non-small cell lung cancer. Seventy CyberKnife treatment plans were calculated and analyzed by MC and ray-tracing (RT) algorithms, separately. Parameters of treatment plans were compared, and those associated with differences of dose distributions were analyzed to establish a modified formula. Gross tumor volume and tumor tracking volume (TTV) were defined as the evident disease on the sequences of the window width and level of the lung and the mediastinum. Additionally, the formula was validated by another 20 plans. The prescription dose of the 90 patients was 60 Gy/5f. The RT algorithm overestimated the planning target volume (PTV) D₉₅ by an average of 8.59 Gy and the gross tumor volume D₉₉ by an average of 5.84 Gy. The homogeneity index of PTV was underestimated by 0.11 on average, whereas the conformity index and new conformity index was underestimated by 0.05. The RT algorithm overestimated the dose distribution to the spinal cord by 2.23 Gy, the esophagus by 1.96 Gy, the trachea by 1.89 Gy, the left-sided bronchus by 1.77 Gy, the right-sided bronchus by 1.64 Gy, and the heart by 2.16 Gy. The average whole-lung dose volumes of lung tissues and dose volumes of V₅ were overestimated by 2.69 Gy and 7.52%, respectively. A power function distribution (R² = 0.8626) was confirmed between PTV D₉₅ and TTV volumes. PTV D₉₅ calculated by the MC algorithm could be computed easily with TTV and PTV D₉₅ calculated by the RT algorithm based on the formula. The modified equation was more consistent with MC algorithm than with other formula, which could be a reference to those not accessible to the MC algorithm.

No differences in radiological changes after 3D conformal vs VMAT-based stereotactic radiotherapy for early stage non-small cell lung cancer

OBJECTIVE

To compare patterns of acute and late radiological lung injury following either 3D conformal or image-guided volumetric modulated arc therapy stereotactic radiotherapy for Stage I non-small-cell lung cancer.

METHODS

We included 148 patients from a prospective mono-institutional stereotactic body radiation therapy (SBRT) series (time interval 2004-2014), treated with prescription BED_{10 Gy} (at 80%) in the range 100-120 Gy. The first 95 patients (2004-2010) were planned with 3D-CRT, with a stereotactic body frame. The second cohort (2010-2014) included 53 patients, planned with volumetric IMRT on a smaller planning target volume generated from a patient's specific internal target volume, with a frameless approach through cone-beam CT guidance. Acute and late radiological modifications were scored based on modified Kimura's and Koenig's classifications, respectively.

RESULTS

Median follow-up time was 20.5 months. The incidence of acute radiological changes was superimposable between the groups: increased density was observed in 68.4 and 64.2% of patients for 3D-CRT and VMAT, respectively, and patchy ground glass opacity in 23.7 and 24.5%, respectively; diffuse ground glass opacity was 2.6 vs 9.4%, respectively, and patchy consolidation 2.6 vs 1.9%, respectively. Late changes occurred in approximately 60% of patients: modified conventional pattern was the most frequent modification (25 vs 32.6%, respectively); other patterns were less common (mass-like 19.6 vs 17.4%, and scar-like 13 vs 10.9%, respectively).

CONCLUSION

Results of the present study indicate that the pattern of radiological lung changes following SBRT for peripheral early stage non-small-cell lung cancer is not influenced by the different techniques used for planning and delivery. Advances in knowledge: This comparative observational study shows that smaller margins, image guidance and most importantly dose distribution do not change the pattern of radiological injury after lung SBRT; the same scoring system can be used, and expected incidence is similar.

Carbon-ion radiotherapy for non-small cell lung cancer with interstitial lung disease: a retrospective analysis

Background

Lung cancer is frequently complicated by interstitial lung disease (ILD). Treatment protocols for lung cancer patients with ILD have not been established; surgery, chemotherapy, and radiotherapy can all cause acute exacerbation of ILD. This study evaluated the toxicity and efficacy of carbon ion radiotherapy (CIRT) in patients with non-small cell lung cancer (NSCLC) and ILD.

Methods

Between June 2004 and November 2014, 29 patients diagnosed with NSCLC and ILD were treated with CIRT. No patient was eligible for curative surgery or conventional radiotherapy secondary to ILD. Owing to prior symptomology, radiation pneumonitis (RP) and symptom progression pre- and post-treatment were evaluated. The relationships between RP and clinical factors were investigated.

Results

Twenty-eight men and one woman, aged 62 to 90 years old, were followed for 2.7–77.1 months (median: 22.8 months). Single-grade symptomatic progression (grade 2–3) was observed in 4 patients, while 1 patient experiencedtwo-grade progression. Two patients experienced radiation-induced acute exacerbation. Local control at 3 years was 63.3% (72.2% for stage I disease); survival at 3 years was 46.3% (57.2% for stage I disease). Eighteen patients had died by the time of this writing, 10 of lung cancer progression. Radiation pneumonitis post-treatment progression correlated with dosimetric factors of the lungs (V5, V10) and a low pre-treatment serum surfactant protein-D.

Conclusions

We found that CIRT may be useful as a low-risk, curative option for NSCLC patients with ILD, a population that is typically ineligible for conventional therapy. The DVH analysis showed that minimizing the low-dose region is important for reducing the risk of severe RP.

Trial registration

NIRS-9404. Registered 1 March 1994.

Stereotactic Body Radiotherapy for Early-stage Non-small-cell Lung Cancer in Patients 80 Years and Older: A Multi-center Analysis

BACKGROUND

Stereotactic body radiotherapy (SBRT) is the standard of care for medically inoperable early-stage non-small-cell lung cancer. Despite the limited number of octogenarians and nonagenarians on trials of SBRT, its use is increasingly being offered in these patients, given the aging cancer population, medical fragility, or patient preference. Our purpose was to investigate the efficacy, safety, and survival of patients ≥ 80 years old treated with definitive lung SBRT.

METHODS

Patients who underwent SBRT were reviewed from 2009 to 2015 at 4 academic centers. Patients diagnosed at ≥ 80 years old were included. Kaplan-Meier and multivariate logistic regression and Cox proportional hazard regression analyses were performed. Recursive partitioning analysis was done to determine a subgroup of patients most likely to benefit from therapy.

RESULTS

A total of 58 patients were included, with a median age of 84.9 years (range, 80.1-95.2 years), a median follow-up time of 19.9 months (range, 6.9-64.9 months), a median fraction size of 10.0 Gy (range, 7.0-20.0 Gy), and a median number of fractions of 5.0 (range, 3.0-8.0 fractions). On multivariate analysis, higher Karnofsky performance status (KPS) was associated with higher local recurrence-free survival (hazard ratio [HR], 0.92; P < .01), regional recurrence-free survival (HR, 0.94; P < .01), and overall survival (HR, 0.91; P < .01). On recursive partitioning analysis, patients with KPS ≥ 75 had improved 3-year cancer-specific and overall survival (99.4% and 91.9%, respectively) compared with patients with KPS < 75 (47.8% and 23.6%, respectively; P < .01).

CONCLUSION

Definitive lung SBRT for early-stage non-small-cell lung cancer was efficacious and safe in patients ≥ 80 years old. Patients with a KPS of ≥ 75 derived the most benefit from therapy.

Stereotactic Body Radiation Therapy for Early-Stage Lung Cancer

Stereotactic body radiation therapy (SBRT), also known as stereotactic ablative radiotherapy, is a technique of external beam radiation that delivers precisely targeted, ablative doses to extracranial sites. It has become an integral component of the management of early-stage non-small cell lung cancer (NSCLC). In this review, we discuss the technology and techniques used in treatment planning and delivery, the efficacy and toxicity of SBRT for medically inoperable early-stage NSCLC, and the preliminary investigations into the role of SBRT for operable early-stage NSCLC.

Stereotactic ablative radiotherapy in treatment of early-stage non-small cell lung cancer: Unsolved questions and frontiers ahead

Stereotactic ablative radiotherapy (SABR) has been recognized as a standard alternative treatment to surgery for inoperable early stage non-small cell lung cancer (NSCLC). Guaranteed local control rates over 90% makes oncologists wonder whether SABR is qualified enough to challenge surgery in operable patients. The role of SABR for centrally located lesions would be another question because of the increased risk of severe toxic effect. Plenty of studies suggest that optimization of dose regimen and appropriate case selection would be helpful. Additionally, the effect of adjuvant therapy following SABR in selected patients is worth looking forward, given that it significantly reduced risk of recurrence after complete resection. A consensus about salvage treatment after SABR also needs, given the current diversity of options. Finally, witnessing the emergence of proton therapy and immunotherapy, we believe that the future of SABR lay behind these novel forms of treatment.

Next-generation sequencing and clinical outcomes of patients with lung adenocarcinoma treated with stereotactic body radiotherapy

BACKGROUND

Genetic aberrations are well characterized in lung adenocarcinomas (LACs) and clinical outcomes have been influenced by targeted therapies in the advanced setting. Stereotactic body radiotherapy (SBRT) is the standard-of-care therapy for patients with nonoperable, early-stage LAC, but to the authors' knowledge, no information is available regarding the impact of genomic changes in these patients. The current study sought to determine the frequency and clinical impact of genetic aberrations in this population.

METHODS

Under an Institutional Review Board-approved protocol, the records of 242 consecutive patients with early-stage lung cancers were reviewed; inclusion criteria included LAC histology with an adequate tumor sample for the successful use of next-generation sequencing and fluorescence in situ hybridization testing. Univariate analysis was performed to identify factors associated with clinical outcomes.

RESULTS

LAC samples from 98 of the 242 patients were reviewed (40.5%), of whom 45 patients (46.0%) had genetic testing. The following mutations were noted: KRAS in 20.0% of samples, BRAF in 2.2% of samples, SMAD family member 4 (SMAD4) in 4.4% of samples, epidermal growth factor receptor (EGFR) in 15.6% of samples, STK1 in 2.2% of samples, tumor protein 53 (TP53) in 15.6% of samples, and phosphatase and tensin homolog (PTEN) in 2.2% of samples. The following gene rearrangements were observed: anaplastic lymphoma kinase (ALK) in 8.9% of samples, RET in 2.2% of samples, and MET amplification in 17.8% of samples. The median total delivered SBRT dose was 50 grays (range, 48-60 grays) over a median of 5 fractions (range, 3-8 fractions). The KRAS mutation was associated with worse local control (odds ratio [OR], 3.64; P<.05). MET amplification was associated with worse regional (OR, 4.64; P<.05) and distant (OR, 3.73; P<.05) disease control.

CONCLUSIONS

To the authors' knowledge, the current series is the first to quantify genetic mutations and their association with clinical outcomes in patients with early-stage LAC treated with SBRT. KRAS mutations were associated with worse local control and MET amplification was associated with worse regional and distant disease control, findings that need to be validated in a prospective setting. Cancer 2017;123:3681-3690. © 2017 American Cancer Society.