Stereotactic Body Radiotherapy for T3N0 Lung Cancer With Chest Wall Invasion

Stereotactic Body Radiation Therapy for Stage IIA to IIIA Inoperable Non-Small Cell Lung Cancer: A Phase 1 Dose-Escalation Trial

PURPOSE

Larger tumors are underrepresented in most prospective trials on stereotactic body radiation therapy (SBRT) for inoperable non-small cell lung cancer (NSCLC). We performed this phase 1 trial to specifically study the maximum tolerated dose (MTD) of SBRT for NSCLC >3 cm.

METHODS AND MATERIALS

A 3 + 3 dose-escalation design (cohort A) with an expansion cohort at the MTD (cohort B) was used. Patients with inoperable NSCLC >3 cm (T2-4) were eligible. Select ipsilateral hilar and single-station mediastinal nodes were permitted. The initial SBRT dose was 40 Gy in 5 fractions, with planned escalation to 50 and 60 Gy in 5 fractions. Adjuvant chemotherapy was mandatory for cohort A and optional for cohort B, but no patients in cohort B received chemotherapy. The primary endpoint was SBRT-related acute grade (G) 4+ or persistent G3 toxicities (Common Terminology Criteria for Adverse Events version 4.03). Secondary endpoints included local failure (LF), distant metastases, disease progression, and overall survival.

RESULTS

The median age was 80 years; tumor size was >3 cm and ≤5 cm in 20 (59%) and >5 cm in 14 patients (41%). In cohort A (n = 9), 3 patients treated to 50 Gy experienced G3 radiation pneumonitis (RP), thus defining the MTD. In the larger dose-expansion cohort B (n = 25), no radiation therapy-related G4+ toxicities and no G3 RP occurred; only 2 patients experienced G2 RP. The 2-year cumulative incidence of LF was 20.2%, distant failure was 34.7%, and disease progression was 54.4%. Two-year overall survival was 53%. A biologically effective dose (BED) <100 Gy was associated with higher LF (P = .006); advanced stage and higher neutrophil/lymphocyte ratio were associated with greater disease progression (both P = .004).

CONCLUSIONS

Fifty Gy in 5 fractions is the MTD for SBRT to tumors >3 cm. A higher BED is associated with fewer LFs even in larger tumors. Cohort B appears to have had less toxicity, possibly due to the omission of chemotherapy.

Advances and controversies in the management of early stage non-small cell lung cancer

Complete resection continues to be the gold standard for the treatment of early-stage lung cancer. The landmark Lung Cancer Study Group trial in 1995 established lobectomy as the minimum intervention necessary for the management of early-stage non-small cell lung cancer, as it was associated with lower recurrence and metastasis rates than sublobar resection and lower postoperative morbidity and mortality than pneumonectomy. There is a growing tendency to perform sublobar resection in selected cases, as, depending on factors such as tumor size, histologic subtype, lymph node involvement, and resection margins, it can produce similar oncological results to lobectomy. Alternative treatments such as stereotactic body radiotherapy and radiofrequency ablation can also produce good outcomes in inoperable patients or patients who refuse surgery.

Can reducing planning safety margins broaden the inclusion criteria for lung stereotactic ablative body radiotherapy?

INTRODUCTION

Stereotactic ablative body radiotherapy (SABR) is currently indicated for inoperable, early-stage non-small cell lung carcinoma (NSCLC). Advancements in image-guidance technology continue to improve treatment precision and enable reductions in planning safety margins. We investigated the dosimetric benefits of margin reduction, its potential to extend SABR to more NSCLC patients and the factors influencing plan acceptability.

METHODS

This retrospective analysis included 61 patients (stage IA-IIIA) treated with conventional radiotherapy. Patients were ineligible for SABR due to tumour size or proximity to organs at risk (OAR). Using Pinnacle auto-planning, three SABR plans were generated for each patient: a regular planning target volume margin plan, a reduced margin plan (gross tumour volume GTV+3 mm) and a non-margin plan. Targets were planned to 48Gy/4 or 50Gy/5 fractions depending on location. Plans were compared in terms of target coverage, OAR doses and dosimetric acceptability based on local guidelines. Predictors of acceptability were investigated using logistic regression analysis.

RESULTS

Compared to regular margin plans, both reduced margin and non-margin plans resulted in significant reductions to almost all dose constraints. Dose conformity was significantly worse in non-margin plans (P < 0.05) and strongly correlated with targets' surface area/volume ratio (R2  = 0.9, P < 0.05). 26% of reduced margin plans were acceptable, compared to 54% of non-margin plans. GTV overlap with OARs significantly affected plan acceptability (OR 0.008, 95% CI 0.001-0.073).

CONCLUSION

Margin reduction significantly reduced OAR doses enabling acceptable plans to be achieved for patients previously excluded from SABR. Indications for lung SABR may broaden as treatment accuracy continues to improve; further work is needed to identify patients most likely to benefit.

Stereotactic body radiation therapy with higher biologically effective dose is associated with improved survival in stage II non-small cell lung cancer

OBJECTIVES

The role of stereotactic body radiation therapy (SBRT) in treating stage II non-small cell lung cancer (NSCLC) remains unclear. This study evaluates SBRT dose prescription patterns and survival outcomes in Stage II NSCLC using the National Cancer Database (NCDB).

MATERIALS AND METHODS

Patients diagnosed with Stage II NSCLC and treated with SBRT between 2004-2013 were identified in NCDB. The biologically effective dose with α/β = 10 Gy (BED₁₀) was calculated. Overall survival (OS) was analyzed using the Kaplan-Meier method and Cox regression models.

RESULTS

Of 56,543 patients with Stage II NSCLC, 451 (0.8%) received SBRT. There were 360 patients (79.8%) with node-negative and 91 patients (20.2%) with node-positive disease. The most common prescriptions were 10 Gy x 5 (35.9%) and 12 Gy x 4 (19.3%). The mean and median BED₁₀ were 114.9 Gy and 105.6 Gy, respectively. With median follow-up of 19.3 months, overall median survival was 23.7 months. Median survival was 22.4 months for those treated with BED₁₀ < 114.9 Gy versus 31.5 months for BED₁₀ ≥ 114.9 Gy (p = 0.036). On multivariate analysis, BED₁₀ as a continuous variable (hazard ratio [HR] 0.991, p = 0.009) and ≥ 114.9 Gy (HR 0.63, p = 0.015) were associated with improved survival in node-negative patients. BED₁₀ as a continuous variable (HR 0.997, p = 0.465) and ≥ 114.9 Gy (HR 0.81, p = 0.546) were not significant factors for predicting survival in node-positive patients.

CONCLUSION

SBRT is infrequently utilized to treat Stage II NSCLC in the United States. Treatment with higher BED₁₀ was associated with improved survival, and the benefit was limited to patients with node-negative disease.

Treatment of T3N0 non-small cell lung cancer with chest wall invasion using stereotactic body radiotherapy

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The role of SBRT for T3N0 lung cancer invading the chest wall is unknown.

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We treated 12 patients with T3N0 chest wall-invading lung cancer with SBRT.

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Local control was excellent and no grade 3+ toxicity was observed.

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Pre-treatment chest wall pain was relieved after SBRT in most patients.

Objectives

Chest wall invasion (CWI) is observed in 5% of localized non-small cell lung cancer (NSCLC). The role of stereotactic body radiotherapy (SBRT) in these patients is unknown. We investigate the safety and efficacy of SBRT in patients with T3N0 NSCLC due to CWI.

Methods

Patients with T3N0 NSCLC due to CWI were identified using a prospective registry. CWI was defined as radiographic evidence of soft tissue invasion or bony destruction. We excluded patients with recurrent or metastatic disease. All patients were treated with definitive SBRT. Prescribed dose was 50 Gy in 5 fractions for most patients. Kaplan-Meier analysis was used to estimate survival outcomes.

Results

We identified 12 patients treated between 2006 and 2017. Median age was 70 (range, 58–85). Median tumor diameter was 3.0 cm (range, 0.9–7.2). Median survival was 12.0 months (range, 2.4–63). At a median follow-up of 8.9 months (range, 2.1–63), 1-year primary tumor control was 89%, involved lobar control was 89%, local–regional control was 82%, distant control was 91%, and survival was 63%. Of the 4 patients with pre-treatment chest wall pain, 3 reported improvement after SBRT. Two patients reported new grade 1–2 chest wall pain. No grade 3+ toxicity was reported, with 1 patient experiencing grade 1 skin toxicity and 3 patients experiencing grade 1–2 radiation pneumonitis.

Conclusions

SBRT for CWI NSCLC is safe, with high early tumor control and low treatment-related toxicity. Most patients with pre-treatment chest wall pain experienced relief after SBRT, with no grade 3+ toxicity observed.

Definitive treatment patterns and survival in stage II non-small cell lung cancer

OBJECTIVES

This study delineated definitive treatment patterns for Stage II non-small cell lung cancer (NSCLC) in the United States and evaluated survival by treatment approach.

MATERIALS AND METHODS

Patients with clinically-staged Stage II NSCLC treated with surgery-based therapy, chemoradiation, conventionally-fractionated radiation (CFR), or stereotactic body radiotherapy (SBRT) were identified using the National Cancer Database (NCDB). Median survival was estimated using Kaplan-Meier analysis. Crude and adjusted hazard ratios (HR) and 95% confidence intervals were computed using Cox regression modeling.

RESULTS

Between 2004-2012, 19,749 patients met study criteria: 13,382 (67.8%) underwent surgery-based treatment, 4,310 (21.8%) received chemoradiation, 1,606 (8.1%) received CFR, and 451 (2.3%) received SBRT. Surgery and SBRT utilization increased over time while CFR and chemoradiation decreased (all p ≤ 0.002). Patients receiving radiation-based treatments were older, with more comorbidities, and higher T/N stage (all p < 0.0001). With median follow-up of 25.2 months, median survival was 51.6, 23.3, 15.4, and 23.7 months for surgery-based treatment, chemoradiation, CFR, and SBRT, respectively (p < 0.0001). On multivariate analysis, chemoradiation (HR 1.67 [1.59-1.75], p < 0.0001), CFR (HR 2.38 [2.22-2.55], p < 0.0001), and SBRT (HR 1.76 [1.53-2.01], p < 0.0001) were associated with decreased survival versus surgery-based treatment. CFR was associated with decreased survival versus chemoradiation (HR 1.52 [1.41-1.63], p < 0.0001) and SBRT (HR 1.39 [1.19-1.61], p < 0.0001). SBRT was associated with similar survival versus chemoradiation (HR 1.10 [0.95-1.27], p = 0.212).

CONCLUSION

NCDB data demonstrate increasing use of surgery-based treatments and SBRT for Stage II NSCLC over time. Radiation-based therapies were associated with decreased survival compared to surgery. CFR was associated with decreased survival compared to chemoradiation and SBRT.

Clinical Outcomes of 130 Patients with Primary and Secondary Lung Tumors treated with Cyberknife Robotic Stereotactic Body Radiotherapy

Background

Authors report clinical outcomes of patients treated with robotic stereotactic body radiotherapy (SBRT) for primary, recurrent and metastatic lung lesions.

Patients and methods

130 patients with 160 lesions were treated with Cyberknife SBRT, including T1-3 primary lung cancers (54%), recurrent tumors (22%) and pulmonary metastases (24%). The mean biologically equivalent dose (BED_10Gy) was 151 Gy (72–180 Gy). Median prescribed dose for peripheral and central lesions was 3×20 Gy and 3×15 Gy, respectively. Local control (LC), overall survival (OS), and cause-specific survival (CSS) rates, early and late toxicities are reported. Statistical analysis was performed to identify factors influencing local tumor control.

Results

Median follow-up time was 21 months. In univariate analysis, higher dose was associated with better LC and a cut-off value was detected at BED_10Gy ≤ 112.5 Gy, resulting in 1-, 2-, and 3-year actuarial LC rates of 93%, vs 73%, 80% vs 61%, and 63% vs 54%, for the high and low dose groups, respectively (p = 0.0061, HR = 0.384). In multivariate analysis, metastatic origin, histological confirmation and larger Planning Target Volume (PTV) were associated with higher risk of local failure. Actuarial OS and CSS rates at 1, 2, and 3 years were 85%, 74% and 62%, and 93%, 89% and 80%, respectively. Acute and late toxicities ≥ Gr 3 were observed in 3 (2%) and 6 patients (5%), respectively.

Conclusions

Our favorable LC and survival rates after robotic SBRT, with low rates of severe toxicities, are coherent with the literature data in this mixed, non-selected study population.