Clinical results of stereotactic body radiotherapy for Stage I small-cell lung cancer: a single institutional experience

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.

Progress in radiotherapy for small-cell lung cancer

Small-cell lung cancer (SCLC) is a highly aggressive neuroendocrine tumor that is prone to spread extensively. Compared to non-small-cell lung cancer (NSCLC), SCLC treatment progresses slowly. Although SCLC is highly sensitive to chemotherapy during the initial treatment, most patients still experience resistance and recurrence after receiving chemotherapy. A meta-analysis demonstrated that thoracic radiotherapy (TRT) improves overall survival in SCLC. The results of the CALGB and CONVERT trials provide evidence for the efficacy of once-daily high-dose TRT. TRT at 60 Gy administered twice daily significantly improved survival without increasing toxicity. The long-standing debate over the optimal timing of radiotherapy has not been fully resolved. SBRT has excellent local control rates and is a safe and effective treatment option for patients with stage I or II SCLC. Prophylactic cranial irradiation (PCI) is used to reduce treatment-related neurotoxicity to the extent that there has been a recent discussion on whether magnetic resonance imaging (MRI) monitoring can replace PCI. Radiotherapy combined with immunotherapy significantly improves the survival rate of patients with NSCLC; however, its clinical effectiveness has not been systematically explored in patients with SCLC. Therefore, we summarize the evolving therapeutic strategies, (TRT for limited stage-SCLC and consolidative TRT for extensive stage-SCLC) and improved radiotherapy techniques (role of SBRT in stage I or II node-negative SCLC, progress of PCI, and stereotactic radiosurgery), and discuss the possibilities and prospects of radiotherapy combined with immunotherapy for SCLC.

Comparison of long-term outcomes of stereotactic body radiotherapy (SBRT) via Helical tomotherapy for early-stage lung cancer with or without pathological proof

BACKGROUND

Stereotactic body radio therapy (SBRT) has emerged as a standard treatment option for nonsurgical candidates with early-stage non-small cell lung cancer (NSCLC). Pathological proof is sometimes difficult to obtain in patients with solitary pulmonary nodules (SPNs). We aimed to compare the clinical outcomes of stereotactic body radiotherapy via helical tomotherapy (HT-SBRT) for early-stage lung cancer patients with or without a pathological diagnosis.

METHODS

Between June 2011 and December 2016, we treated 119 lung cancer patients with HT-SBRT, including 55 with a clinical diagnosis and 64 with a pathological diagnosis. Survival outcomes, including local control (LC), progression-free survival (PFS), cancer-specific survival (CSS), and overall survival (OS), were compared between two cohorts with and without a pathological diagnosis.

RESULTS

The median follow-up for the whole group was 69 months. Patients with a clinical diagnosis were significantly older (p = 0.002). No significant differences were observed between the clinical and pathological diagnosis cohorts in terms of the long-term outcome, with 5-year LC, PFS, CSS, and OS of 87% versus 83% (p = 0.58), 48% versus 45% (p = 0.82), 87% versus 84% (p = 0.65), and 60% versus 63% (p = 0.79), respectively. Recurrence patterns and toxicity were also similar.

CONCLUSIONS

Empiric SBRT appears to be a safe and effective treatment option in a multidisciplinary setting when patients with SPNs highly suggestive of malignancy are unable/refuse to obtain a definitive pathological diagnosis.

Stereotactic Body Radiotherapy (SBRT) in Very Limited-Stage Small Cell Lung Cancer (VLS-SCLC)

Small cell lung cancer (SCLC) is an aggressive neuroendocrine tumour with metastatic propensity. Stereotactic body radiation therapy (SBRT) is an emerging therapeutic option for SCLC, despite limited supporting evidence. By evaluating the use of SBRT in very limited stage (VLS) SCLC at our institution, we aimed to contribute to the existing knowledge in this area while establishing a basis for further research. We performed a retrospective review of all cases of VLS-SCLC treated with SBRT between 2013 and 2020. Baseline demographics, diagnostic, and treatment information were collected. The primary outcome was overall survival (OS). We identified 46 patients with pathologically confirmed VLS-SCLC; 25 were treated with SBRT, and the remainder received either surgery, conventional radiation therapy, chemotherapy, or palliative-intent therapy. After a median follow-up of 23.7 months, 44% of the patients had died; the median OS was of 24.4 months for the SBRT cohort and 67.0 months for the curative intent non-SBRT cohort. The difference in disease recurrence and survival between cohorts was underpowered and not statistically significant. Higher baseline ECOG and comorbidity was noted in the SBRT cohort.

Limited-Stage Small-Cell Lung Cancer: Current Progress and the Next Frontier

Limited-stage (LS) small-cell lung cancer (SCLC) is defined as disease confined to a tolerable radiation portal without extrathoracic metastases. Despite clinical research over two decades, the prognosis of LS-SCLC patients remains poor. The current standard of care for LS-SCLC patients is concurrent platinum-based chemotherapy with thoracic radiotherapy (RT). Widespread heterogeneity on the optimal radiation dose and fractionation regimen among physicians highlights the logistical challenges of administering BID regimens. Prophylactic cranial irradiation (PCI) is recommended to patients following a good initial response to chemoradiation due to improved overall survival from historical trials and the propensity for LS-SCLC to recur with brain metastases. However, PCI utilization is being debated due to the greater availability of magnetic resonance imaging (MRI) and data in extensive-stage SCLC regarding close MRI surveillance in lieu of PCI while spurring novel RT techniques, such as hippocampal-avoidance PCI. Additionally, novel treatment combinations incorporating targeted small molecule therapies and immunotherapies with or following radiation for LS-SCLC have seen recent interest and some concepts are being investigated in clinical trials. Here, we review the landscape of progress, limitations, and challenges for LS-SCLC including current standard of care, novel radiation techniques, and the integration of novel therapeutic strategies for LS-SCLC.

Stereotactic ablative radiotherapy in T1-2N0M0 small cell lung cancer: A systematic review and meta-analysis

OBJECTIVES

Stereotactic ablative radiotherapy (SABR) is used to treat inoperable early-stage, node-negative small cell lung cancer (SCLC). We performed a systematic review and meta-analysis of the literature on SABR for T1-2N0M0 SCLC to summarize outcomes including local control (LC), overall survival (OS), recurrence rates, and toxicity.

MATERIALS AND METHODS

This study was conducted in accordance with PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) and MOOSE (Meta-analysis of Observational Studies in Epidemiology) guidelines. A systematic review of PubMed and EMBASE (inception to April 2021) was conducted. Two authors independently reviewed articles for inclusion and extracted study-level data. Random-effects meta-analysis was conducted using R (version 3.6.2) at a significance threshold of 0.05.

RESULTS

Eleven studies were identified in the systematic review and seven (399 patients) were selected for meta-analysis. Inoperability was noted as the indication for SABR in 94% (75-100%) of patients. Median follow-up and tumor size were 19.5 months (11.9-32) and 24 mm (19-29), respectively. Chemotherapy and PCI use rates were 44.1% (95% confidence interval [CI], 27.0-61.9%) and 13.8% (95% CI, 0.4-41.2%), respectively. Local control was 97.3% (95% CI, 92.3-99.8%) at 1 year and 95.7% (95% CI, 74.2-100.0%) at 2 years. Overall survival was 86.3% (95% CI, 74.4-94.9%) at 1 year and 63.7% (95% CI, 45.7-79.9%) at 2 years. Nodal and distant recurrence rates were 17.8% (95% CI, 7.5-31.2%) and 26.9% (95% CI, 7.4-53.0%), respectively. The rates of grade 1, grade 2, and grade 3 toxicity (CTCAE) were 12.6% (95% CI, 6.7-19.9%), 6.7% (95% CI, 3.3-11.2%), and 1.4% (95% CI, 0.0-5.3%), respectively. No grade 4 or 5 events were observed across the studies.

CONCLUSION

SABR for inoperable early-stage, node-negative SCLC is locally effective with limited toxicity. Prospective studies are required to further evaluate the role of SABR for patients at higher risk of toxicity with surgery or combined chemoradiation.

Large-scale dosimetric assessment of Monte Carlo recalculated doses for lung robotic stereotactic body radiation therapy

Owing to its short computation time and simplicity, the Ray-Tracing algorithm (RAT) has long been used to calculate dose distributions for the CyberKnife system. However, it is known that RAT fails to fully account for tissue heterogeneity and is therefore inaccurate in the lung. The aim of this study is to make a dosimetric assessment of 219 non-small cell lung cancer CyberKnife plans by recalculating their dose distributions using an independent Monte Carlo (MC) method. For plans initially calculated by RAT without heterogeneity corrections, target coverage was found to be significantly compromised when considering MC doses. Only 35.4% of plans were found to comply to their prescription doses. If the normal tissue dose limits were respected in the treatment planning dose, the MC recalculated dose did not exceed these limits in over 97% of the plans. Comparison of RAT and recalculated-MC doses confirmed the overestimation of RAT doses observed in previous studies. An inverse correlation between the RAT/MC dose ratio and the target size was also found to be statistically significant (p<10^-4), consistent with other studies. In addition, the inaccuracy and variability in target coverage incurred from dose calculations using RAT without heterogeneity corrections was demonstrated. On average, no clinically relevant differences were observed between MC-calculated dose-to-water and dose-to-medium for all tissues investigated (⩽1%). Patients receiving a dose D_95% larger than 119 Gy in EQD2₁₀ (or ≈52 Gy in 3 fractions) as recalculated by MC were observed to have significantly superior loco-regional progression-free survival rates (p=0.02) with a hazard ratio of 3.45 (95%CI: 1.14-10.5).

Stereotactic body radiotherapy versus conventional radiotherapy for early-stage small cell lung cancer

Purpose

This study was designed to compare survival outcomes for non-surgically managed T1-T2N0M0 small cell lung cancer (SCLC) who received either stereotactic body radiation therapy (SBRT) or conventionally fractionated radiotherapy (CFRT) using the National Cancer Data Base (NCDB).

Methods

The was queried between 2004-2015 for patients with T1-T2N0M0 SCLC. Patients must have been treated with curative intent SBRT or CFRT (delivered daily or twice daily, 45-70 Gy) with or without chemotherapy. The primary outcome was overall survival (OS). A subset analysis of patient receiving chemotherapy was also performed. A propensity score matched (PSM) analysis was performed to compare OS among patients who received chemotherapy.

Results

We evaluated 1378 patients in the general cohort. Multivariable Cox regression analysis(MVA) in the general cohort revealed that SBRT was significantly associated with improved survival (HR 0.68, p<0.001) along with receipt of chemotherapy (HR 0.63, p <0.001). SBRT patients were less likely to receive chemotherapy compared to CFRT patients (p<0.01). In the chemotherapy subset, of 1096 patients, on MVA, there was a trend in favor of the SBRT group (HR 0.73; p=0.06). A 3:1 PSM analysis on the chemotherapy subset found similar results on MVA with a trend in favor of SBRT (p=0.06).

Conclusion

Patients with T1-2N0M0 SCLC treated with SBRT regimens incorporating chemotherapy had comparable outcomes to concurrent chemoradiotherapy using standard fractionation. Treatment paradigms for T1-2N0M0 SCLC incorporating SBRT warrant further exploration and should incorporate chemotherapy.

Clinical Outcomes of Stereotactic Body Radiotherapy for Patients With Stage I Small-Cell Lung Cancer: Analysis of a Subset of the Japanese Radiological Society Multi-Institutional SBRT Study Group Database

Stereotactic body radiotherapy (SBRT) is widely used as a curative treatment option for stage I non-small-cell lung cancer, but for patients with stage I small-cell lung cancer, the role of stereotactic body radiotherapy is unclear. In this study, we retrospectively analyzed the outcomes of a subset of patients with stage I small-cell lung cancer treated with stereotactic body radiotherapy in the database of the Japanese Radiological Society-Multi-Institutional stereotactic body radiotherapy Study Group. The 43 patients treated with stereotactic body radiotherapy for stage I small-cell lung cancer between 2004 and 2012 at 11 Japanese institutions were studied: median age = 77 years; 32 (74%) males and 11 females; and 80% were medically inoperable. The clinical stage was IA in 31 and IB in 12. In all patients, the lung tumors were pathologically proven as small-cell lung cancer. A total dose of 48 to 60 Gy was administered in 4 to 8 fractions. The median biologically effective dose (α/β = 10 Gy) was 105.6 Gy. Chemotherapy and prophylactic cranial irradiation were administered in only 8 patients, respectively. The median follow-up time was 23.2 months. The 2-year overall survival, progression-free survival, and distant metastasis-free survival rates were 72.3%, 44.6%, and 47.2%, respectively. The 2-year local control was 80.2%. Regarding the patterns of failure, distant metastasis, lymph node metastasis, and local recurrence were observed in 47%, 28%, and 16% of patients, respectively. No ≥grade 3 stereotactic body radiotherapy-related toxicities were observed. Although stereotactic body radiotherapy was thus revealed to be effective for the local control of stage I small-cell lung cancer, the incidence of distant metastases was high. Further investigations of larger cohorts are needed, including analyses of the effects of combined chemotherapy.

The optimal treatment approaches for stage I small cell lung cancer

Although small cell lung cancer (SCLC) represents less than one-sixth of all lung cancer cases, it is an aggressive disease with a high metastatic potential to various sites including the brain. Most landmark trials assessing individual therapy benefits for SCLC dichotomized patients as having either limited or extensive disease. Over the last decade, however, there has been a clear shift towards categorizing and analyzing survival patterns using a more thorough staging system that accounts for tumor size and the degree of nodal or metastatic disease burden. For the 5% of patients who present with clinical stage I (cT1-2aN0M0) SCLC, extrapolating treatment recommendations from a rather heterogeneous population that constitutes limited disease SCLC remains controversial and has led to numerous investigations of alternative therapies such as stereotactic body radiation therapy (SBRT) for the management of this highly select group of patients. Given the changing landscape of multimodal therapy, this review will summarize relevant data pertaining to and outline optimal treatment algorithms for stage I SCLC, with a particular focus on SBRT as a primary mode of local therapy.

Outcomes of Stereotactic Body Radiotherapy for T1-T2N0 Small Cell Carcinoma According to Addition of Chemotherapy and Prophylactic Cranial Irradiation: A Multicenter Analysis

BACKGROUND

Although T1-T2N0 non-small cell lung cancer can be managed with stereotactic body radiotherapy (SBRT) alone, this management has often been extrapolated to T1-T2N0 small cell lung cancer (SCLC). This secondary analysis of a multi-institutional cohort study investigated whether the addition of chemotherapy and prophylactic cranial irradiation (PCI) improved the outcomes for these patients.

MATERIALS AND METHODS

All cases of histologically confirmed T1-T2N0M0 SCLC were obtained from 24 institutions' prospectively collected SBRT databases. The clinical and treatment characteristics, toxicities, outcomes, and patterns of failure were assessed. We used Kaplan-Meier analysis to evaluate the survival outcomes. Univariate and multivariate analyses identified the predictors of outcomes.

RESULTS

From 24 institutions, 76 lesions were treated in 74 patients (median follow-up, 18 months). Chemotherapy and PCI were delivered in 56% and 23% of cases, respectively. The median SBRT dose per fraction was 50 Gy/5 fractions. Patients receiving chemotherapy experienced increased median disease-free survival (61.3 vs. 9.0 months; P = .02) and overall survival (31.4 vs. 14.3 months; P = .02). Chemotherapy independently predicted for better outcomes for disease-free survival and overall survival on multivariate analysis (P = .01). Toxicities were uncommon; 5.2% experienced grade ≥ 2 pneumonitis. Post-treatment failures were most commonly distant (45.8% of recurrences), followed by nodal (25.0%), and elsewhere in the lung (20.8%). The median time to each was 5 to 7 months.

CONCLUSION

Patients undergoing primary SBRT for T1-T2N0 SCLC should also undergo additional chemotherapy. No established role was found for PCI in this population.

Stage-I small cell lung cancer: A new potential option for stereotactic ablative radiation therapy? A review of literature

Small cell lung cancer (SCLC) is relative rare histology in lung cancer patients. The standard treatment, in patients with an intra-thoracic disease, is represented by the use of concurrent chemo-radiotherapy; while patients with early SCLC stage, surgical resection could be recommended. Stereotactic body radiotherapy (SBRT) is a recently introduced technique allowing the delivery of very high radiation doses to limited target volumes and it is considered the standard approach in the treatment of not operable stage I Non Small-Cell Lung Cancer (NSCLC). The successful role option of SBRT in early NSCLC in terms of local control and toxicity profile opened the issue in the use of this approach in early stage small cell lung cancer (SCLC). Aim of this review is to discuss the current literature in the safety and efficacy of SBRT in the treatment of patients with stage I SCLC.

Multi-Institutional Experience of Stereotactic Ablative Radiation Therapy for Stage I Small Cell Lung Cancer

PURPOSE

For inoperable stage I (T1-T2N0) small cell lung cancer (SCLC), national guidelines recommend chemotherapy with or without conventionally fractionated radiation therapy. The present multi-institutional cohort study investigated the role of stereotactic ablative radiation therapy (SABR) for this population.

METHODS AND MATERIALS

The clinical and treatment characteristics, toxicities, outcomes, and patterns of failure were assessed in patients with histologically confirmed stage T1-T2N0M0 SCLC. Kaplan-Meier analysis was used to evaluate the survival outcomes. Univariate and multivariate analyses identified predictors of outcomes.

RESULTS

From 24 institutions, 76 lesions were treated in 74 patients (median follow-up 18 months). The median age and tumor size was 72 years and 2.5 cm, respectively. Chemotherapy and prophylactic cranial irradiation were delivered in 56% and 23% of cases, respectively. The median SABR dose and fractionation was 50 Gy and 5 fractions. The 1- and 3-year local control rate was 97.4% and 96.1%, respectively. The median disease-free survival (DFS) duration was 49.7 months. The DFS rate was 58.3% and 53.2% at 1 and 3 years, respectively. The median, 1-year, and 3-year disease-specific survival was 52.3 months, 84.5%, and 64.4%, respectively. The median, 1-year, and 3-year overall survival (OS) was 17.8 months, 69.9%, and 34.0% respectively. Patients receiving chemotherapy experienced an increased median DFS (61.3 vs 9.0 months; P=.02) and OS (31.4 vs 14.3 months; P=.02). The receipt of chemotherapy independently predicted better outcomes for DFS/OS on multivariate analysis (P=.01). Toxicities were uncommon; 5.2% experienced grade ≥2 pneumonitis. Post-treatment failure was most commonly distant (45.8% of recurrence), followed by nodal (25.0%) and "elsewhere lung" (20.8%). The median time to each was 5 to 7 months.

CONCLUSIONS

From the findings of the largest report of SABR for stage T1-T2N0 SCLC to date, SABR (≥50 Gy) with chemotherapy should be considered a standard option.

Trends in stereotactic body radiation therapy for stage I small cell lung cancer

OBJECTIVES

We aimed to report trends in stereotactic body radiation therapy (SBRT) utilization, dose prescriptions, and chemotherapy administration for stage I small cell lung cancer (SCLC) in the United States.

MATERIALS AND METHODS

The National Cancer Data Base (NCDB) was used to identify patients with cT1-2 N0 SCLC treated with SBRT between 2004 and 2013. Trends in SBRT use and dose prescription were analyzed over time. Multivariable logistic regression was used to determine factors associated with the administration of chemotherapy with SBRT. The Kaplan-Meier method was used to estimate overall survival.

RESULTS

Of 9265 patients with clinical stage I SCLC who were examined for initial treatment allocation, 285 were treated with SBRT and represented the subject of the primary analysis. SBRT utilization increased from 2004 (0.4% of all stage I patients diagnosed that year) to 2013 (6.4%). During this same time period, definitive surgical management also increased from 14.9% of all patients in 2004 to 28.5% in 2013. The median SBRT biologically effective dose (BED₁₀) was 112.5Gy (range, 72-290) and only 33 out of 285 (11.6%) received a BED₁₀<100Gy. Nearly half of all patients (130/285, 45.6%) received chemotherapy, with 42.7% of those patients receiving their chemotherapy prior to SBRT. On multivariable logistic regression, only age<75 (the median) vs. ≥75years (OR 4.97, 95% CI 2.96-8.35, p<0.001) and year of diagnosis 2004-2008 vs. 2009-2013 (OR 2.58, 95% CI 1.27-5.26, p=0.009) were predictive of chemotherapy use with SBRT. After median follow up of 45 months, the median survival was 23.5 months.

CONCLUSIONS

Our findings suggest that SBRT utilization for stage I SCLC has increased between 2004 and 2013, highlighting the need for additional research to validate the feasibility of this management approach for inoperable patients.

Stereotactic body radiation therapy for the treatment of a post-chemotherapy remnant lung mass in extensive-stage small-cell lung cancer: A case report

Stereotactic body radiation therapy (SBRT) can significantly improve the treatment outcomes of patients with inoperable stage I non-small-cell lung cancer. Similarly, a few case studies have reported the effectiveness of SBRT for stage I small-cell lung cancer (SCLC). However, no study has investigated the use of SBRT for extensive-stage SCLC (ES-SCLC). Compared with conventional RT, SBRT is able to deliver a higher radiation dose precisely and safely to small targets in short-duration treatments. The present study reports the outcome of a patient with ES-SCLC who responded favorably to initial chemotherapy and received SBRT for a residual mass in the peripheral lung. A 62-year-old female presented with pathologically determined SCLC at clinical stage T4N3M0-T4 as separate tumor nodules were present in different ipsilateral lobes. The patient received 6 cycles of standard chemotherapy with cisplatin and etoposide. The response of the patient to chemotherapy was evaluated using contrast-enhanced chest computed tomography and 18F-fluorodeoxyglucose positron emission tomography-computed tomography. The only suspected residual viable tumor was a 1.5-cm mass in the right upper lobe. Targeting this mass, intensity-modulated SBRT was performed with 48 Gy in 4 fractions and 6 MV photons. In addition, prophylactic cranial irradiation was conducted with 25 Gy in 10 fractions. The patient is alive with no evidence of disease 4 years after treatment. SBRT toxicity was limited to radiation pneumonitis or fibrosis without pulmonary symptoms. This case report suggests the efficacy of SBRT in select ES-SCLC patients with small residual lung disease following chemotherapy.

The Role of Radiotherapy in Small Cell Lung Cancer: a Revisit

Small cell lung cancer is staged as either limited (potentially curable) or extensive (incurable), based on the extent of disease in the chest. Limited stage disease is treated with concurrent chemotherapy and thoracic radiotherapy followed by prophylactic cranial irradiation (PCI). The conventional approach to extensive disease is chemotherapy only, with radiotherapy reserved for site-specific palliation. Recent reports suggest increasing applications for radiotherapy. The administration of PCI to extensive stage patients demonstrating response to chemotherapy is now recommended due to local control and overall survival benefits. Likewise, the role of consolidation chest radiotherapy after chemotherapy for advanced disease patients has seen a resurgence of interest in light of a recent publication suggesting improved local benefits which may influence survival. Recent technical advances in radiotherapy such as stereotactic body treatment and intensity-modulated therapy may also provide new indications for radiation, to enhance delivery and minimize toxicities.

Stereotactic Radiotherapy for Stage I Small Cell Lung Cancer

Although the use of stereotactic ablative radiotherapy (SABR) for stage I small cell lung cancer is in its infancy, there are many reasons to believe that with more time and experience, it could emerge as the standard of care in inoperable patients, and perhaps even have equipoise with surgery for operable patients. Reporting of modeling studies and as much clinical data as possible are very much needed.

SBRT Treatment of Metachronous Small-Cell and Non-Small-Cell Lung Carcinomas in a Patient with Severe COPD

Stereotactic body radiotherapy (SBRT) has not been widely employed in the treatment of limited-stage (LS) small-cell lung cancer (SCLC), although SBRT finds particular utility in patients medically unfit to undergo surgical resection or radiotherapy with conventional fields. The authors present the case of a 61-year-old female smoker with severe chronic obstructive pulmonary disease (COPD), diagnosed incidentally with LS-SCLC. Concurrent chemoradiotherapy was contraindicated by her poor pulmonary function, and she was treated radically with four cycles of cisplatin and etoposide chemotherapy. This was followed by prophylactic cranial irradiation and consolidative SBRT (48 Gy in 4 fractions) to the residual tumour, which achieved a complete clinical response. Fifteen months following the patient’s initial diagnosis, a metachronous Stage IA contralateral non-small cell lung cancer (NSCLC) was incidentally diagnosed and was treated with SBRT (48 Gy in 4 fractions). Although studies have established that the incidence of a second lung cancer is higher in patients with previous SCLC, this case is unique in that both primaries were treated with SBRT.

Development of a small animal model to simulate clinical stereotactic body radiotherapy-induced central and peripheral lung injuries

Given the tremendous potential of stereotactic body radiotherapy (SBRT), investigations of the underlying radiobiology associated with SBRT-induced normal tissue injury are of paramount importance. This study was designed to develop an animal model that simulates centrally and peripherally located clinical SBRT-induced lung injuries. A 90-Gy irradiation dose was focally delivered to the central and peripheral areas of the left mouse lung with an image-guided small-animal irradiation system. At 1, 2 and 4 weeks after irradiation, micro-computed tomography (micro-CT) images of the lung were taken. Lung function measurements were performed with the Flexivent® system (SCIREQ©, Montreal, Canada). For the histopathological analysis, the lungs were fixed by perfusing with formalin, and paraffin sections were stained with hematoxylin and eosin and Masson's Trichrome. Gross inspection clearly indicated local lung injury confined to the central and peripheral areas of the left lung. Typical histopathological alterations corresponding to clinical manifestations were observed. The micro-CT analysis results appeared to correlate with the histopathological findings. Mouse lung tissue damping increased dramatically at central settings, compared with that at the control or peripheral settings. An animal model to simulate clinical SBRT-induced central and peripheral lung injuries was developed and validated with histopathological, radiological and functional analyses. This model increases our understanding of SBRT-induced central and peripheral lung injuries and will help to improve radiation therapy in the future.

Clinical outcome of hypofractionated breath-hold image-guided SABR of primary lung tumors and lung metastases

Background

Stereotactic Ablative RadioTherapy (SABR) of lung tumors/metastases has been shown to be an effective treatment modality with low toxicity. Outcome and toxicity were retrospectively evaluated in a unique single-institution cohort treated with intensity-modulated image-guided breath-hold SABR (igSABR) without external immobilization. The dose–response relationship is analyzed based on Biologically Equivalent Dose (BED).

Patients and methods

50 lesions in 43 patients with primary NSCLC (n = 27) or lung-metastases of various primaries (n = 16) were consecutively treated with igSABR with Active-Breathing-Coordinator (ABC®) and repeat-breath-hold cone-beam-CT. After an initial dose-finding/-escalation period, 5x12 Gy for peripheral lesions and single doses of 5 Gy to varying dose levels for central lesions were applied. Overall-survival (OS), progression-free-survival (PFS), progression pattern, local control (LC) and toxicity were analyzed.

Results

The median BED2 was 83 Gy. 12 lesions were treated with a BED2 of <80 Gy, and 38 lesions with a BED2 of >80 Gy. Median follow-up was 15 months. Actuarial 1- and 2-year OS were 67% and 43%; respectively. Cause of death was non-disease-related in 27%. Actuarial 1- and 2-year PFS was 42% and 28%. Progression site was predominantly distant. Actuarial 1- and 2 year LC was 90% and 85%. LC showed a trend for a correlation to BED2 (p = 0.1167). Pneumonitis requiring conservative treatment occurred in 23%.

Conclusion

Intensity-modulated breath-hold igSABR results in high LC-rates and low toxicity in this unfavorable patient cohort with inoperable lung tumors or metastases. A BED2 of <80 Gy was associated with reduced local control.

Percutaneous fiducial marker placement under CT fluoroscopic guidance for stereotactic body radiotherapy of the lung: an initial experience

The aim of this study is to describe our initial experience with the VISICOIL, which is the first percutaneous fiducial marker approved for stereotactic body radiotherapy in Japan, and to evaluate its technical and clinical efficacy, and safety. Eight patients underwent this procedure under CT fluoroscopic guidance. One patient had two tumors, so the total number of procedures was nine. We evaluated the technical and clinical success rates of the procedure and the frequencies of complications. Technical success was defined as when the fiducial marker could be placed at the target site, and clinical success was defined as when stereotactic body radiotherapy could be performed without the marker dropping out of position. The technical success rate was 78% (7/9). In one of the two failed cases, we aimed to place the marker inside the tumor, but misplaced it beside the tumor. In the other failed case, we successfully placed the marker beside the tumor as planned; however, the marker migrated to near the pleura after the patient stopped holding their breath. None of the markers dropped out of place, so the clinical success rate was 100% (9/9). The complication rates were as follows: pneumothorax: 56% (5/9), pneumothorax necessitating chest tube placement: 44% (4/9), focal intrapulmonary hemorrhaging: 67% (6/9), hemoptysis: 11% (1/9), mild hemothorax 11% (1/9), air embolism 0% (0/9), and death 0% (0/9). In conclusion, this new percutaneous fiducial marker appears to be useful for stereotactic body radiotherapy due to its good stability.