Early Stage Peripheral Non-small Cell Research Articles

Effect of MU-weighted multi-leaf collimator position error on dose distribution of SBRT radiotherapy in peripheral non-small cell lung cancer.

PurposePosition accuracy of the multi‐leaf collimator (MLC) is essential in stereotactic body radiotherapy (SBRT). This study is aimed to investigate the dosimetric impacts of the MU‐weighted MLC positioning uncertainties of SBRT for patients with early stage peripheral non‐small cell lung cancer (NSCLC).MethodsThree types of MLC position error were simulated: Type 1, random error; Type 2, system shift, in which both MLC banks shifted to the left or right direction; and Type 3, in which both MLC banks moved with same magnitudes in the opposite directions. Two baseline plans were generated: an automatic plan (AP) and a manually optimized plan (MP). Multi‐leaf collimator position errors were introduced to generate simulated plans with the preset MLC leaf position errors, which were then reimported into the Pinnacle system to generate simulated plans, respectively. The dosimetric parameters (CI, nCI, GI, etc.) and gEUD values of PTV and OARs were calculated. Linear regression between MU‐weighted/unweighted MLC position error and gEUD was performed to obtain dose sensitivity.ResultsThe dose sensitivities of the PTVs were −4.93, −38.94, −41.70, −55.55, and 30.33 Gy/mm for random, left shift, right shift, system close, and system open MLC errors, respectively. There were significant differences between the MU‐weighted and the unweighted dose sensitivity, which was −38.94 Gy/mm vs −3.42 Gy/mm (left shift), −41.70 Gy/mm vs −3.56 Gy/mm (right shift), −55.55 Gy/mm vs −4.84 Gy/mm (system close), and 30.33 vs 2.64 Gy/mm (system open). For the system open/close MLC errors, as the PTV volume became larger, the dose sensitivity decreased. APs provided smaller dose sensitivity for the system shift and system close MLC errors compared to the conventional MPs.ConclusionsThere was significant difference in dose sensitivity between MU‐weighted and unweighted MLC position error of SBRT radiotherapy in peripheral NSCLC. MU is suggested to be included in the dosimetric evaluation of the MLC misalignments, since it is much closer to clinical radiotherapy.

Single Fraction SBRT for Stage I Non–Small Cell Lung Cancer: Treatment Outcomes and Effect of Tumor Location on Chest Wall Toxicity

Two randomized Phase II trials with primary endpoints of toxicity showed single fraction SBRT for early stage peripheral non-small cell lung cancer in medically inoperable patients (pts) to be the optimal schedule after meeting pre-specified criteria for both toxicity and efficacy compared to fractionated schedules. These trials did not stratify by distance of tumor to chest wall (CW). Therefore, we sought to determine CW toxicity (CWT) rates for single fraction SBRT by location in pts treated with 30 Gy or 34 Gy. An IRB-approved prospective SBRT registry was used to identify pts treated with 30 Gy or 34 Gy in one fraction, on or off relevant protocols. Tumors were ≤ 5 cm, node-negative, and ≥ 2 cm from the proximal tracheo-bronchial tree. GTV was measured as abutting, ≤ 1 cm, or > 1 cm from the CW. CWT and pneumonitis were graded according to CTCAE 3.0 criteria. Chi-square test or unpaired t-test was used to assess differences in pt and disease characteristics between the two dose groups. Overall survival (OS) was calculated using the Kaplan Meier method and compared using the log-rank test. Rates of disease failure and toxicity were calculated using the cumulative incidence method and compared using Gray’s test. This study included 140 pts treated with single fraction SBRT to 147 lesions. 81 lesions (55.1%) were treated to 30 Gy and 66 lesions (44.9%) to 34 Gy. Median follow-up was 23.7 months (30.2 months for living pts). Pt and tumor factors were balanced between groups, except for more active smokers (34.8% vs. 19.8%; p=0.04), higher median body mass index (26.9 vs. 24.5; p= 0.01), and shorter follow up (19.2 months vs. 27.0 months) in the 34 Gy cohort. The rate of pneumonitis (any grade, 6.2% vs. 8.9%; p= 0.74) and CWT (any grade, 7.5% vs. 15.6%; p=0.17) at 2 years was not significantly different between 30 Gy and 34 Gy. CWT was 30.6% for lesions abutting the CW, 6.0% for lesions ≤ 1 cm from the CW, and 3.3% for lesions > 1 cm from the CW. Abutment was significantly associated with CWT (p <0.0001) on UVA. Grade ≥ 3 CWT was modest for the entire cohort (1.4%). For the 30 Gy and 34 Gy subsets, rates of local failure (7.6% vs. 12.8%; p= 0.55), distant metastasis (16.2% vs. 20.4%; p= 0.54), and OS (64.6% vs. 65.8%; p= 0.40) at 2 years were not significantly different, respectively. With single fraction lung SBRT, rates of local control, CWT, and pneumonitis do not significantly vary with prescription dose. The rate of CWT is associated with distance from the CW. The overall rate of CWT for single fraction SBRT appears similar to that reported for fractionated SBRT in randomized trials. Even when considering only lesions adjacent to the CW, the rate of CWT in this series (30.6%) does not appear to exceed the rates in the published fractionated SBRT literature (20-33%). Our results suggest location adjacent to the CW should not be a contraindication to single fraction SBRT.

Computed tomography-guided percutaneous microwave ablation of patients 75 years of age and older with early-stage nonsmall cell lung cancer.

We aimed to assess the clinical outcome of computed tomography (CT)-guided percutaneous microwave ablation (MWA) in patients 75 years of age and older with early stage peripheral nonsmall cell lung cancer (NSCLC). Twenty-eight patients, aged ≥ 75 years, with Stage I and lymph node-negative IIa peripheral NSCLC underwent CT-guided percutaneous MWA in our hospital between July 2007 and March 2015. The overall 1-, 2-, 3-, and 4-year survival rates were estimated using Kaplan-Meier analysis. Adverse events were recorded. The median follow-up time was 22.5 months. The overall median survival time (MST) was 35 months (95% confidence interval [CI] 22.3-47.7 months), and the cancer-specific MST was 41.9 months (95% CI 38.8-49.9 months). The 1-, 2-, 3-, and 4-year overall survival rates were 91.7%, 76.5%, 47.9%, and 47.9%, while the cancer-specific survival rates were 94.7%, 73.9%, 64.7%, and 64.7%, respectively. Median time to local progression was 28.0 months (95% CI 17.7-38.3 months). Major complications were included pneumothorax (21.4%, requiring drainage), pleural effusions (3.6%, requiring drainage), and pulmonary infection (3.6%). CT-guided percutaneous MWA is safe and effective for the treatment of patients 75 years of age and older with medically inoperable early stage peripheral NSCLC.

Stereotactic body radiotherapy for peripheral non-small cell lung cancer

Stereotactic body radiotherapy (SBRT) can treat the lesions in a surgical manner and inhibit tumor cell proliferation.Furthermore,it has a character of non-invasive,which shortens the duration of treatment.Although surgery and radiotherapy are the major means for early stage peripheral non-small cell lung cancer,some studies in recent years show that SBRT has certain advantages in local control ratio and adverse reaction compared with radiotherapy,and acquires the similar curative effect with surgery. Key words: Carcinoma, non-small-cell lung; Radiosurgery; Treatment outcome

No Clinically Significant Changes in Pulmonary Function Following Stereotactic Body Radiation Therapy (SBRT) Among Medically Inoperable Patients With Early Stage Peripheral Non-small Cell Lung Cancer: An Analysis of RTOG 0236

To investigate pulmonary function (PF) and arterial blood gas changes following SBRT and to see whether baseline PF correlates with lung toxicity and overall survival among medically inoperable patients receiving SBRT for early stage, peripheral, non-small cell lung cancer (NSCLC).

Stereotactic ablative radiotherapy for stage I NSCLC: Recent advances and controversies.

Stereotactic ablative radiotherapy (SABR) is a technique that has rapidly entered routine care for early-stage peripheral non-small cell lung cancer in many countries in the last decade. The adoption of SABR was partly stimulated by advances in the so-called 'image guided' radiotherapy delivery. In the last 2 years, a growing body of publications has reported on clinical outcomes, acute and late radiological changes after SABR, and sub-acute and late toxicity. The local control rates in many publications have exceeded 90% when tumors of up to 5 cm have been treated, with corresponding regional nodal failure rates of approximately 10%. However, these results are not universal: lower control rates reported by some authors serve to emphasize the importance of quality assurance in all steps of SABR treatment planning and delivery. High-grade toxicity is uncommon when so-called 'risk-adapted' fractionation schemes are applied; an approach which involves the use of lower daily doses and more fractions when critical normal organs are in the proximity of the tumor volume. This review will address the new data available on a number of controversial topics such as the treatment of patients without a tissue diagnosis of malignancy, data on SABR outcomes in patients with severe chronic obstructive airways disease, use of a classification system for late radiological changes post-SABR, late treatment-related toxicity, and the evidence to support a need for expert multi-disciplinary teams in the follow-up of such patients.

Comparative Analysis of Coplanar vs. Noncoplanar Planning Approaches in Extra-cranial Stereotactic Radiotherapy (SBRT) of Early Stage Peripheral Non-Small Cell Lung Cancer (NSCLC)

Varying opinions exist regarding the optimal planning approach for lung SBRT. In order to quantify differences, we analyzed the dosimetric parameters achieved with coplanar versus noncoplanar treatments for twenty patients previously treated with lung SBRT.