Results of a phase I dose-escalation study using three-dimensional conformal radiotherapy in the treatment of inoperable nonsmall cell lung carcinoma

Stereotactic ablative radiotherapy for locally advanced non-small cell lung cancer: A systematic review and meta-analysis

INTRODUCTION

To evaluate the feasibility, efficacy and safety of stereotactic ablative radiotherapy (SABR) to the primary tumor and lymph nodes in patients with locally advanced non-small cell lung cancer (LA-NSCLC) who are ineligible for or refused concomitant chemoradiation.

MATERIALS AND METHODS

In accordance with the PRISMA and MOOSE guidelines, a systematic review with meta-analysis was conducted. The study included reports that assessed the outcomes of SABR treatment in patients with LA-NSCLC. Studies evaluating SBRT as a boost following primary radiotherapy were excluded. The primary outcomes measured were local control (LC) and overall survival (OS). The secondary endpoint was the incidence of severe toxicity (grades 3-5). A meta-regression analysis was performed to explore the relationship between LC, OS, and severe toxicity. The Biologically Effective Dose (BED) was analyzed as a continuous variable. Statistical significance was defined as a p-value < 0.05.

RESULTS

A total of seven studies (3 prospective and 4 retrospective studies) involving 268 patients (SBRT to primary and lymph nodes) were included in the analysis. The pooled 1-year LC rate was 80 % (95 % CI: 63-94 %), and the factors significantly associated with LC were BEDGy10 (p = 0.005) and neoadjuvant chemotherapy (p = 0.005). The 1-year and 2-year OS rates were 74 % (95 % CI: 58-90 %) and 55 % (95 % CI: 34-76 %), respectively. Meta-regression analysis indicated a linear relationship between OS and LC, with a 0.7 % increase in OS for each 1 % improvement in LC (p = 0.005). The pooled rate of grade 3 acute toxicity was 5 % (95 % CI: 1-10 %), and the rate of grade 5 toxicity was 1.7 % (95 % CI: 0-3 %).

CONCLUSION

Promising results (LC and OS) with limited toxicity (feasibility) using SABR in LA-NSCLC warrant further research, emphasizing the need for larger, well-designed trials for further validation of the approach.

Cost-effectiveness of stereotactic body radiotherapy versus conventional fractionated radiotherapy for medically inoperable, early-stage non-small cell lung cancer

BACKGROUND

Stereotactic body radiotherapy (SBRT) is a novel radio-therapeutic technique that has recently emerged as standard-of-care treatment for medically inoperable, early-stage non-small cell lung cancer (NSCLC). In this study, we compared the cost-effectiveness of SBRT with that of conventional fractionated radiotherapy (CFRT) in patients with medically inoperable, early-stage NSCLC from the perspective of the Chinese health system.

METHODS

A Markov model was developed to describe health states of patients after treatment with SBRT and CFRT. The recurrence risks, treatment toxicities, and utilities inputs were obtained from the literature. The costs were based on listed prices and real-world evidence. A simulation was conducted to determine the post-treatment lifetime years. For each treatment, the total costs, quality-adjusted life-years (QALYs), and incremental cost-effectiveness ratios (ICERs) per QALY were calculated. Deterministic and probabilistic sensitivity analyses were performed to assess the uncertainty of the model parameters.

RESULTS

In the base case analysis, SBRT was associated with a mean cost of USD16,933 and 2.05 QALYs, whereas CFRT was associated with a mean cost of USD17,726 and 1.61 QALYs. SBRT is a more cost-effective strategy compared with CFRT for medically inoperable, early-stage NSCLC, with USD 1802 is saved for every incremental QALY. This result was validated by DSA and PSA, in which SBRT remained the most cost-effective option.

CONCLUSIONS

The findings suggested that, compared to CFRT, SBRT may be considered a more cost-effective strategy for medically inoperable, early-stage NSCLC.

Dosimetric benefits of adaptive radiation therapy for patients with stage III non-small cell lung cancer

BACKGROUND

Daily adaptive radiation therapy (ART) of patients with non-small cell lung cancer (NSCLC) lowers organs at risk exposure while maintaining the planning target volume (PTV) coverage. Thus, ART allows an isotoxic approach with increased doses to the PTV that could improve local tumor control. Herein we evaluate daily online ART strategies regarding their impact on relevant dose-volume metrics.

METHODS

Daily cone-beam CTs (1 × n = 28, 1 × n = 29, 11 × n = 30) of 13 stage III NSCLC patients were converted into synthetic CTs (sCTs). Treatment plans (TPs) were created retrospectively on the first-fraction sCTs (sCT₁) and subsequently transferred unaltered to the sCTs of the remaining fractions of each patient (sCT_2-n) (IGRT scenario). Two additional TPs were generated on sCT_2-n: one minimizing the lung-dose while preserving the D_95%(PTV) (isoeffective scenario), the other escalating the D_95%(PTV) with a constant V_20Gy(lung_ipsilateral) (isotoxic scenario).

RESULTS

Compared to the original TPs predicted dose, the median D_95%(PTV) in the IGRT scenario decreased by 1.6 Gy ± 4.2 Gy while the V_20Gy(lung_ipsilateral) increased in median by 1.1% ± 4.4%. The isoeffective scenario preserved the PTV coverage and reduced the median V_20Gy(lung_ipsilateral) by 3.1% ± 3.6%. Furthermore, the median V_5%(heart) decreased by 2.9% ± 6.4%. With an isotoxic prescription, a median dose-escalation to the gross target volume of 10.0 Gy ± 8.1 Gy without increasing the V_20Gy(lung_ipsilateral) and V_5%(heart) was feasible.

CONCLUSIONS

We demonstrated that even without reducing safety margins, ART can reduce lung-doses, while still reaching adequate target coverage or escalate target doses without increasing ipsilateral lung exposure. Clinical benefits by means of toxicity and local control of both strategies should be evaluated in prospective clinical trials.

[What dose escalation in the treatment of locally advanced non-small cell lung cancer?]

Despite significant therapeutic advances in the treatment of locally advanced inoperable non-small cell lung cancer (NSCLC), notably through adjuvant immunotherapy, the rate of therapeutic failure remains high. The use of positron emission tomography with fluorodeoxyglucose (FDG-PET), respiratory motion and intensity modulated radiotherapy (IMRT) have led to therapeutic improvements with reduced toxicity and better local control. The optimal dose to be delivered remains unknown due to discordant results of studies for almost 20 years and the way to define the area to benefit from a dose increase (whole volume, subvolume defined by pre- or per-radiotherapy PET).

Predicting personalised and progressive adaptive dose escalation to gross tumour volume using knowledge-based planning models for inoperable advanced-stage non-small cell lung cancer patients treated with volumetric modulated arc therapy

OBJECTIVES

Increased radiation doses could improve local control and overall survival of lung cancer patients, however, this could be challenging without exceeding organs at risk (OAR) dose constraints especially for patients with advanced-stage disease. Increasing OAR doses could reduce the therapeutic ratio and quality of life. It is therefore important to investigate methods to increase the dose to target volume without exceeding OAR dose constraints.

METHODS

Gross tumour volume (GTV) was contoured on synthetic computerised tomography (sCT) datasets produced using the Velocity adaptive radiotherapy software for eleven patients. The fractions where GTV volume decreased compared to that prior to radiotherapy (reference plan) were considered for personalised progressive dose escalation. The dose to the adapted GTV (GTVAdaptive) was increased until OAR doses were affected (as compared to the original clinical plan). Planning target volume (PTV) coverage was maintained for all plans. Doses were also escalated to the reference plan (GTVClinical) using the same method. Adapted, dose-escalated, plans were combined to estimate accumulated dose, D99 (dose to 99%) of GTVAdapted, PTV D99 and OAR doses and compared with those in the original clinical plans. Knowledge-based planning (KBP) model was developed to predict D99 of the adapted GTV with OAR doses and PTV coverage kept similar to the original clinical plans; prediction accuracy and model verification were performed using further data sets.

RESULTS

Compared to the original clinical plan, dose to GTV was significantly increased without exceeding OAR doses. Adaptive dose-escalation increased the average D99 to GTVAdaptive by 15.1Gy and 8.7Gy compared to the clinical plans. The KBP models were verified and demonstrated prediction accuracy of 0.4% and 0.7% respectively.

CONCLUSION

Progressive adaptive dose escalation can significantly increase the dose to GTV without increasing OAR doses or compromising dose to microscopic disease. This may increase overall survival without increasing toxicities.

Radiation Therapy in Non-Small-Cell Lung Cancer

The management of non-small-cell lung cancer (NSCLC) varies according to stage. Surgical resection is reserved for operable patients with early-stage NSCLC, while high-dose target radiation-stereotactic body radiation therapy (SBRT)-is reserved for patients whose comorbidities prohibit them from a major surgical procedure. The treatment of locally advanced NSCLC (LA-NSCLC) is stratified according to resectability. Those with resectable disease may require additional treatments such as chemotherapy and radiation, while patients with unresectable disease will require definitive chemoradiation therapy with adjuvant durvalumab. Patients with limited metastatic disease benefit from the combination of SBRT and systemic therapy.

Dose and fractionation schedules in radiotherapy for non-small cell lung cancer

In the field of radiotherapy (RT), the issues of total dose, fractionation, and overall treatment time for non-small cell lung cancer (NSCLC) have been extensively investigated. There is some evidence to suggest that higher treatment intensity of RT, when given alone or sequentially with chemotherapy (CHT), is associated with improved survival. However, there is no evidence that the outcome is improved by RT at a higher dose and/or higher intensity when it is used concurrently with CHT. Moreover, some reports on the combination of full dose CHT with a higher biological dose of RT warn of the significant risk posed by such intensification. Stereotactic body radiotherapy (SBRT) provides a high rate of local control in the management of early-stage NSCLC through the use of high ablative doses. However, in centrally located tumors the use of SBRT may carry a risk of serious damage to the great vessels, bronchi, and esophagus, owing to the high ablative doses needed for optimal tumor control. There is a similar problem with moderate hypofractionation in radical RT for locally advanced NSCLC, and more evidence needs to be gathered regarding the safety of such schedules, especially when used in combination with CHT. In this article, we review the current evidence and questions related to RT dose/fractionation in NSCLC.

Dosimetric evaluation of MRI-guided multi-leaf collimator tracking and trailing for lung stereotactic body radiation therapy

PURPOSE

The treatment margins for lung stereotactic body radiotherapy (SBRT) are often large to cover the tumor excursions resulting from respiration, such that underdosage of the tumor can be avoided. Magnetic resonance imaging (MRI)-guided multi-leaf collimator (MLC) tracking can potentially reduce the influence of respiration to allow for smaller treatment margins. However, tracking is accompanied by system latency that may induce residual tracking errors. Alternatively, a simpler mid-position delivery combined with trailing can be used. Trailing reduces influences of respiration by compensating for baseline motion, to potentially improve target coverage. In this study, we aim to show the feasibility of MRI-guided tracking and trailing to reduce influences of respiration during lung SBRT.

METHODS

We implemented MRI-guided tracking on the MR-linac using an Elekta research tracking interface to track tumor motion during intensity modulated radiotherapy (IMRT). A Quasar MRI 4 D phantom was used to generate Lujan motion ( cos 4 , 4 s period, 20 mm peak-to-peak amplitude) with and without 1.0 mm/min cranial drift. Phantom tumor positions were estimated from sagittal 2D cine-MRI (4 or 8 Hz) using cross-correlation-based template matching. To compensate the anticipated system latency, a linear ridge regression predictor was optimized for online MRI by comparing two predictor training approaches: training on multiple traces and training on a single trace. We created 15-beam clinical-grade lung SBRT plans for central targets (8 × 7.5 Gy) and peripheral targets (3 × 18 Gy) with different PTV margins for mid-position based motion management (3-5 mm) and for MLC tracking (3 mm). We used a film insert with a 3 cm spherical target to measure the spatial distribution and quantity of the delivered dose. A 1%/1 mm local gamma-analysis quantified dose differences between motion management strategies and reference cases. Additionally, a dose area histogram (DAH) revealed the target coverage relative to the reference scenario.

RESULTS

The prediction filter gain was on average 25% when trained on multiple traces and 44% when trained on a single trace. The filter reduced system latency from 313 ± 2 ms to 0 ± 5 ms for 4 Hz imaging and from 215 ± 3 ms to 3 ± 3 ms for 8 Hz. The local gamma analysis for the central delivery showed that tracking improved the gamma pass-rate from 23% to 96% for periodic motion and from 14% to 93% when baseline drift was applied. For the peripheral delivery during periodic motion, delivery pass-rates improved from 22% to 93%. Comparing mid-position delivery to trailing for periodic+drift motion increased the local gamma pass rate from 15% to 98% for a central delivery and from 8% to 98% for a peripheral delivery. Furthermore, the DAHs revealed a relative D 98 % GTV coverage of 101% and 97% compared to the reference scenario for, respectively, central and peripheral tracking of periodic+drift motion. For trailing, a relative D 98 % of 99% for central and 98% for peripheral trailing was found.

CONCLUSIONS

We provided a first experimental demonstration of the technical feasibility of MRI-guided MLC tracking and trailing for central and peripheral lung SBRT. Tracking maximizes the sparing of healthy tissue, while trailing is highly effective in mitigating baseline motion.

Robust treatment planning with 4D intensity modulated carbon ion therapy for multiple targets in stage IV non-small cell lung cancer

Intensity modulated particle therapy (IMPT) with carbon ions can generate highly conformal treatment plans; however, IMPT is limited in robustness against range and positioning uncertainty. This is particularly true for moving targets, even though all motion states of a 4DCT are considered in 4D-IMPT. Here, we expand 4D-IMPT to include robust non-linear RBE-weighted optimization to explore its potential in improving plan robustness and sparing critical organs. In this study, robust 4D-optimization-based on worst-case optimization on 9 scenarios-was compared to conventional 4D-optimization with PTV margins using 4D dose calculation and robustness analysis for 21 uncertainty scenarios. Slice-by-slice rescanning was used for motion mitigation. Both 4D-optimization strategies were tested on a cohort of 8 multi-lesion lung cancer patients with the goal of prioritizing OAR sparing in a hypofractionated treatment plan. Planning objectives were to keep the OAR volume doses below corresponding limits while simultaneously achieve CTV coverage with D95% ≥ 95 %. For the conventional plans, average D95% was at 98.7% which fulfilled the target objective in 83.2% of scenarios. For the robust plans, average D95% was reduced to 97.6% which still fulfilled the target objective in 80.7% of cases, but led to significantly improved overall OAR sparing: Volume doses were below the limits in 96.2% of cases for the conventional and 99.5% for the robust plans. When considering the particularly critical smaller airways only, fulfillment rates could be increased from 76.2% to 96% for the robust plans. This study has shown that plan robustness of 4D-IMPT could be improved by using robust 4D-optimization, offering greater control over uncertainties in the actual delivered dose. In some cases, this required sacrificing target coverage for the benefit of better OAR sparing.

A meta-analysis comparing stereotactic body radiotherapy vs conventional radiotherapy in inoperable stage I non-small cell lung cancer

BACKGROUND

Stereotactic body radiotherapy (SBRT) superseded conventional radiotherapy (CRT) for the treatment of patients with inoperable early stage non-small cell lung cancer (NSCLC) over a decade ago. However, the direct comparisons of the outcomes of SBRT and CRT remain controversial. This meta-analysis was performed to compare the survival and safety of SBRT and CRT in patients with inoperable stage I NSCLC.

METHODS

We systematically searched the Cochrane Library, Embase, PubMed, Web of Science, Ovid MEDLINE, ScienceDirect, Scopus and Google Scholar for relevant articles. Overall survival (OS), progression-free survival (PFS), lung cancer-specific survival (LCSS), local control rate (LCR) and adverse effects (AEs) were the primary outcomes.

RESULTS

We identified 11,110 articles, 17 of which were eventually included in this study; these 17 articles had 17,973 patients (SBRT: 7395; CRT: 10,578). Compared to CRT for the treatment of inoperable stage I NSCLC, SBRT had superior survival in terms of OS (hazard ratio [HR]: 0.66, 95% confidence interval [CI]: 0.62-0.70, P < .00001), LCSS (HR: 0.42 [0.35-0.50], P < .00001), and PFS (HR: 0.34 [0.25-0.48], P < .00001). The 4-year OS rate (OSR); 4-year LCSS rate (LCSSR); 3-year local control rate (LCR); 5-year PFS rate (PFSR) with SBRT were all higher than those with CRT. With regard to all-grade AEs, the SBRT group had a significantly lower rate of dyspnea, esophagitis and radiation pneumonitis; no significant difference was found in grade 3-5 AEs (risk ratio [RR]: 0.68 [0.30-1.53], P = .35).

CONCLUSIONS

With better survival and a lower rate of dyspnea, esophagitis and radiation pneumonitis than CRT, SBRT appears to be more suitable for patients with inoperable stage I NSCLC.

Efficacy and safety of CT-guided 125I brachytherapy in elderly patients with non-small cell lung cancer

Non-small cell lung cancer (NSCLC) has become the most common cancer type and the leading cause of cancer-associated mortality worldwide. The aim of the present retrospective study was to evaluate the efficacy and safety of computed tomography (CT)-guided ¹²⁵I brachytherapy alone in elderly patients with NSCLC. A total of 26 elderly patients with NSCLC stage I–III who had an inoperable lesion or progressive disease following radio-chemotherapy were treated with CT-guided ¹²⁵I seed implantation for lung lesions and included in the present study. The prescribed dose of ¹²⁵I brachytherapy was 80–140 Gy, and dosimetric verification was performed immediately after the procedure. The response rate (RR) and local control rate (LCR) were analyzed according to the Response Evaluation Criteria in Solid Tumors (version 1.1). Survival was estimated using the Kaplan-Meier method. Safety and complications were also documented. All patients were aged 65–85 years (median age, 77 years) and successfully completed the procedure, and the median follow-up time was 9.4 months (range, 3–31 months). After a 6-month follow-up, for pulmonary lesions, complete response (CR) was achieved in 11 (42.3%) cases, partial response in 9 (34.6%) cases, stable disease in 4 (15.4%) cases and progressive disease in 2 (7.7%) cases. The 6-month RR and LCR were 76.9 (20/26) and 92.3% (24/26), respectively. The mean overall survival (OS) time was 11.7±7.6 months and the 0.5- and 1-year OS rates were 90.1 and 73.3%, respectively. Tumor-related symptoms in patients were significantly alleviated following the procedure. No severe complications occurred during and after the procedure of ¹²⁵I seed implantation. In conclusion, CT-guided ¹²⁵I brachytherapy is a feasible, effective and safe therapy and may be considered as an alternative option to surgery and radiotherapy for elderly patients with NSCLC.

Chemoradiotherapy of locally-advanced non-small cell lung cancer: Analysis of radiation dose-response, chemotherapy and survival-limiting toxicity effects indicates a low α/β ratio

PURPOSE

To analyse changes in 2-year overall survival (OS_2yr) with radiotherapy (RT) dose, dose-per-fraction, treatment duration and chemotherapy use, in data compiled from prospective trials of RT and chemo-RT (CRT) for locally-advanced non-small cell lung cancer (LA-NSCLC).

MATERIAL AND METHODS

OS_2yr data was analysed for 6957 patients treated on 68 trial arms (21 RT-only, 27 sequential CRT, 20 concurrent CRT) delivering doses-per-fraction ≤4.0 Gy. An initial model considering dose, dose-per-fraction and RT duration was fitted using maximum-likelihood techniques. Model extensions describing chemotherapy effects and survival-limiting toxicity at high doses were assessed using likelihood-ratio testing, the Akaike Information Criterion (AIC) and cross-validation.

RESULTS

A model including chemotherapy effects and survival-limiting toxicity described the data significantly better than simpler models (p < 10^-14), and had better AIC and cross-validation scores. The fitted α/β ratio for LA-NSCLC was 4.0 Gy (95%CI: 2.8-6.0 Gy), repopulation negated 0.38 (95%CI: 0.31-0.47) Gy EQD2/day beyond day 12 of RT, and concurrent CRT increased the effective tumour EQD2 by 23% (95%CI: 16-31%). For schedules delivered in 2 Gy fractions over 40 days, maximum modelled OS_2yr for RT was 52% and 38% for stages IIIA and IIIB NSCLC respectively, rising to 59% and 42% for CRT. These survival rates required 80 and 87 Gy (RT or sequential CRT) and 67 and 73 Gy (concurrent CRT). Modelled OS_2yr rates fell at higher doses.

CONCLUSIONS

Fitted dose-response curves indicate that gains of ~10% in OS_2yr can be made by escalating RT and sequential CRT beyond 64 Gy, with smaller gains for concurrent CRT. Schedule acceleration achieved via hypofractionation potentially offers an additional 5-10% improvement in OS_2yr. Further 10-20% OS_2yr gains might be made, according to the model fit, if critical normal structures in which survival-limiting toxicities arise can be identified and selectively spared.

Accelerated hypofractionated radiotherapy plus chemotherapy for inoperable locally advanced non-small-cell lung cancer: final results of a prospective phase-II trial with a long-term follow-up

BACKGROUND

Concurrent chemotherapy and radiation using conventional fractionation is the standard treatment for inoperable, locally advanced non-small-cell lung cancer (NSCLC). We tested accelerated hypofractionated radiotherapy (AHR) and chemotherapy for the treatment of locally advanced NSCLC.

METHODS

Eligible patients with locally advanced NSCLC were treated with induction chemotherapy (cisplatin and docetaxel), followed by AHR using tomotherapy and consolidation chemotherapy. The prescribed doses were 30 Gy/5 daily fractions at the reference isodose (60-70%) to the tumor, and 25 Gy/5 daily fractions to the clinically involved lymph nodes. The primary end-point was response rate (RR); the secondary end-points were acute and late side-effects, local progression-free survival (PFS), metastasis-free survival (MFS) and overall survival (OS). This trial closed before the first planned interim analysis due to poor accrual.

RESULTS

From January 2009 to January 2012, 17 of the 23 enrolled patients were evaluable. Treatment yielded an overall RR of 82%. Median follow-up was 87 months (range: 6-87), local PFS was 19.8 months (95% CI 9.7 - not reached), MFS was 9.7 months (95% CI 5.8-46.0) and OS was 23 months (95% CI 8.4-48.4). 70% of patients experienced acute G4 neutropenia, 24% G4 leukopenia, 24% G3 paresthesia, 4% G3 cardiac arrythmia, 4% underwent death after chemotherapy. Late toxicity was represented by 24% dyspnea G3.

CONCLUSIONS

AHR combined with chemotherapy is feasible with no severe side-effects, and it appears highly acceptable by patients.

TRIAL REGISTRATION

This study is registered with the EudractCT registration 2008-006525-14 . Registered on 9 December 2008.

ICORG 06-35: a prospective evaluation of PET-CT scan in patients with non-operable or non-resectable non-small cell lung cancer treated by radical 3-dimensional conformal radiation therapy: a phase II study

BACKGROUND

Radiotherapy (RT) is a key treatment modality in the curative treatment of patients with non-small cell lung cancer (NSCLC). Incorrect definition of the gross, or clinical, target volume is a common source of error which can lead to a reduced probability of tumour control.

OBJECTIVE

This was a pilot and a phase II study. The pilot evaluated the technical feasibility of integrating positron emission tomography-computed tomography (PET-CT) fusion. The primary outcome of the phase II study was to evaluate the safety of PET-CT scan-based RT by evaluating the rate of loco-regional recurrence outside the PET-CT planning target volume (PTV) but within conventional 3-D PTV.

METHODS

Patients underwent standard post-treatment follow-up, including repeated three monthly CT scans of the thorax. In case of loco-regional recurrence, three categories were considered, with only extra-PET scan PTV and intra-CT scan PTV recurrences considered as a failure. Our hypothesis was that the rate of these events would be < 10%.

RESULTS

Twelve patients were recruited; the study closed early due to poor recruitment. The primary endpoint of the pilot was met; it was feasible to deliver a PET-CT-based plan to ≥ 60% of patients. Two patients had intra-PET scan PTV recurrences, six had extra-PET scan PTV and extra-CT, and three patients had both. Another patient had extra-PET scan PTV and extra-CT as well as extra-PET scan PTV and intra-CT scan PTV recurrence.

CONCLUSION/ADVANCES IN KNOWLEDGE

PET-based planning has the potential to reduce radiation treatment volumes because of the avoidance of mediastinal lymph nodes that are PET negative.

Phase II study of compensator-based non-coplanar intensity-modulated radiotherapy for Stage I non-small-cell lung cancer

We conducted a Phase II study to evaluate the usefulness of compensator-based non-coplanar intensity-modulated radiotherapy (ncIMRT) for patients with surgically inaccessible Stage I non-small-cell lung cancer (NSCLC). Patients with pathologically proven or clinically diagnosed surgically inaccessible Stage I NSCLC were enrolled in this study from May 2011 to April 2014. These patients underwent ncIMRT of 75 Gy in 30 fractions regardless of the tumor location. The primary end point was 3-year overall survival, and the secondary end points were local control rate and treatment-related toxicities. A total of 48 patients (50 tumors) were enrolled in this study. Of the 50 tumors, the Stage T1 to T2 ratio was 31 to 19, and the ratio of tumors located in the central to peripheral areas was 11 to 39. During the median follow-up time of 35.9 months, the 3-year actuarial local progression-free and overall survival rates were 82.6% and 87.1%, respectively. No patients experienced toxicities of Grade 3 or greater. Standard-fractionated ncIMRT was effective and safe for patients with surgically inaccessible stage I NSCLC, regardless of the tumor location.

Stereotactic body radiation therapy (SBRT) improves local control and overall survival compared to conventionally fractionated radiation for stage I non-small cell lung cancer (NSCLC)

BACKGROUND

Stereotactic body radiotherapy (SBRT) has been adopted as the standard of care for inoperable early-stage non-small cell lung cancer (NSCLC), with local control rates consistently >90%. However, data directly comparing the outcomes of SBRT with those of conventionally fractionated radiotherapy (CONV) is lacking.

MATERIAL AND METHODS

Between 1990 and 2013, 497 patients (525 lesions) with early-stage NSCLC (T1-T2N0M0) were treated with CONV (n = 127) or SBRT (n = 398). In this retrospective analysis, five endpoints were compared, with and without adjusting for clinical and dosimetric factors. Competing risks analysis was performed to estimate and compare the cumulative incidence of local failure (LF), nodal failure (NF), distant failure (DF) and disease progression. Overall survival (OS) was estimated by the Kaplan-Meier method and compared by the Cox regression model. Propensity score (PS) matched analysis was performed based on seven patient and clinical variables: age, gender, Karnofsky performance status (KPS), histology, T stage, biologically equivalent dose (BED), and history of smoking.

RESULTS

The median dose delivered for CONV was 75.6 Gy in 1.8-2.0 Gy fractions (range 60-90 Gy; median BED = 89.20 Gy) and for SBRT 48 Gy in four fractions (45-60 Gy in three to five fractions; median BED = 105.60 Gy). Median follow-up was 24.4 months, and 3-year LF rates were 34.1% with CONV and 13.6% with SBRT (p < .001). Three-year OS rates were 38.9 and 53.1%, respectively (p = .018). PS matching showed a significant improvement of OS (p = .0497) for SBRT. T stage was the only variable correlating with all five endpoints.

CONCLUSION

SBRT compared to CONV is associated with improved LF rates and OS. Our data supports the continued use and expansion of SBRT as the standard of care treatment for inoperable early-stage NSCLC.

Implications for high-precision dose radiation therapy planning or limited surgical resection after percutaneous computed tomography-guided lung nodule biopsy using a tract sealant

Purpose

Precision radiation therapy such as stereotactic body radiation therapy and limited resection are being used more frequently to treat intrathoracic malignancies. Effective local control requires precise radiation target delineation or complete resection. Lung biopsy tracts (LBT) on computed tomography (CT) scans after the use of tract sealants can mimic malignant tract seeding (MTS) and it is unclear whether these LBTs should be included in the calculated tumor volume or resected. This study evaluates the incidence, appearance, evolution, and malignant seeding of LBTs.

Methods and materials

A total of 406 lung biopsies were performed in oncology patients using a tract sealant over 19 months. Of these patients, 326 had follow-up CT scans and were included in the study group. Four thoracic radiologists retrospectively analyzed the imaging, and a pathologist examined 10 resected LBTs.

Results

A total of 234 of 326 biopsies (72%, including primary lung cancer [n = 98]; metastases [n = 81]; benign [n = 50]; and nondiagnostic [n = 5]) showed an LBT on CT. LBTs were identified on imaging 0 to 3 months after biopsy. LBTs were typically straight or serpiginous with a thickness of 2 to 5 mm. Most LBTs were unchanged (92%) or decreased (6.3%) over time. An increase in LBT thickness/nodularity that was suspicious for MTS occurred in 4 of 234 biopsies (1.7%). MTS only occurred after biopsy of metastases from extrathoracic malignancies, and none occurred in patients with lung cancer.

Conclusions

LBTs are common on CT after lung biopsy using a tract sealant. MTS is uncommon and only occurred in patients with extrathoracic malignancies. No MTS was found in patients with primary lung cancer. Accordingly, potential alteration in planned therapy should be considered only in patients with LBTs and extrathoracic malignancies being considered for stereotactic body radiation therapy or wedge resection.

Lung Cancer: Posttreatment Imaging: Radiation Therapy and Imaging Findings

Over the last few decades, advances in radiation therapy technology have markedly improved radiation delivery. Advancements in treatment planning with the development of image-guided radiotherapy and techniques such as proton therapy, allow precise delivery of high doses of radiation conformed to the tumor. These advancements result in improved locoregional control while reducing radiation dose to surrounding normal tissue. The radiologic manifestations of these techniques can differ from radiation induced lung disease seen with traditional radiation therapy. Awareness of these radiologic manifestations and correlation with radiation treatment plans are important to differentiate expected radiation induced lung injury from recurrence, infection and drug toxicity.

Lung Cancer: Posttreatment Imaging: Radiation Therapy and Imaging Findings

In this review, we discuss the different radiation delivery techniques available to treat non-small cell lung cancer, typical radiologic manifestations of conventional radiotherapy, and different patterns of lung injury and temporal evolution of the newer radiotherapy techniques. More sophisticated techniques include intensity-modulated radiotherapy, stereotactic body radiotherapy, proton therapy, and respiration-correlated computed tomography or 4-dimensional computed tomography for radiotherapy planning. Knowledge of the radiation treatment plan and technique, the completion date of radiotherapy, and the temporal evolution of radiation-induced lung injury is important to identify expected manifestations of radiation-induced lung injury and differentiate them from tumor recurrence or infection.

Imaging of Radiation Treatment of Lung Cancer

Radiation therapy is an important modality in the treatment of patients with lung cancer. Recent advances in delivering radiotherapy were designed to improve loco-regional tumor control by focusing higher doses on the tumor. More sophisticated techniques in treatment planning include 3-dimensional conformal radiation therapy, intensity-modulated radiotherapy, stereotactic body radiotherapy, and proton therapy. These methods may result in nontraditional patterns of radiation injury and various radiologic appearances that can be mistaken for recurrence, infection and other lung diseases. Knowledge of radiological manifestations, awareness of new radiation delivery techniques and correlation with radiation treatment plans are essential in order to correctly interpret imaging in these patients.

A Phase II Toxicity End Point Trial (ICORG 99-09) of Accelerated Dose-escalated Hypofractionated Radiation in Non-small Cell Lung Cancer

AIMS

The objective of this phase II clinical trial was to prospectively evaluate the safety and efficacy of accelerated hypofractionated three-dimensional conformal radiation therapy (3DCRT) in localised non-resectable/non-operable non-small cell lung cancer (NSCLC).

MATERIALS AND METHODS

Sixty patients with stage I-III NSCLC were enrolled in a prospective single-arm All Ireland Co-operative Oncology Research Group (ICORG 99-09) toxicity end point phase II trial. The protocol allocated patients between three radiation schedule dose levels (60, 66 or 72 Gy, in 20, 22 and 24 fractions, respectively, 3 Gy daily, five fractions per week) according to combined lung V_25Gy (V_25Gy ≤ 30%) with built-in early stopping toxicity rules. The primary end point was toxicity with evaluation of dose-limiting toxicity. The secondary objectives included radiological tumour response rate at 3 months after the completion of radiation therapy and the thoracic progression-free survival time.

RESULTS

Sixty patients were recruited from August 1999 to June 2009. Forty-nine patients were included in the primary per-protocol analysis. Eleven patients were not evaluable. In the first 30 evaluable patient cohort, severe oesophageal toxicity was reported in two patients (2/49; 4% experiencing grade 5 oesophageal late toxicity, related to the 97% oesophageal length). The trial was temporarily closed and was then reopened to validate an oesophageal dose volume constraint (DVC) of limiting the length of oesophagus fully encompassed by the 97% isodose to less than 1 cm (applied to 21 patients). The trial prospectively showed the safety of the oesophageal DVC, with no oesophageal toxicity above grade 3 thereafter. Thirty-nine per cent of patients had disease progression at 3-4 months after radiotherapy, 22% had stable disease, 20% had a complete response and 14% had a partial response. The median overall survival was 13.6 months (95% confidence interval 10.5-16.7) and overall survival at 1 and 3 years was 57% and 29%, respectively.

CONCLUSION

A strategy using accelerated hypofractionated 3DCRT is feasible and reasonably safe for patients with inoperable NSCLC. It is safe to deliver for centrally located tumours if DVCs are applied to the oesophagus, which is the primary dose-limiting toxicity. Further studies are required to assess the efficacy of hypofractionated regimens for centrally located tumours using an oesophageal DVC and monitoring for oesophageal toxicity.

Patterns and correlates of treatment failure in relation to isodose distribution in non-small cell lung cancer: An analysis of 1522 patients in the modern era

BACKGROUND AND PURPOSE

To examine the relationship between radiation dose and tumor control in limited stage non-small cell lung cancer (NSCLC).

MATERIALS AND METHODS

We searched a database of 1552 patients who received radiation therapy for non-metastatic NSCLC between 2000 and 2016. The primary endpoint was freedom from in-field failure.

RESULTS

Increasing BED correlated with decreasing estimated gross tumor volume-planning target volume expansion, and on multivariable analysis increasing BED was associated with an increased chance of field-edge failures (hazard ratio [HR] 1.032, 95% confidence interval [CI] 1.004-1.062, P = 0.027). Increasing BED also correlated with improved freedom from in-field failure on multivariable analysis (HR 0.978, 95% CI 0.964-0.993, P = 0.003), with the dose-response curve showing a sigmoidal relationship between increasing BED and freedom from in-field failure.

CONCLUSION

In this large study of patients treated in the modern era with varying dose fractionation regimens, higher BED was associated with improved freedom from in-field failure, and that this relationship appeared to be consistent with the classically described sigmoid shape. We also found that increased BED was associated with higher field-edge failures, implying that margin size may need to be further studied in patients receiving ablative regimens of radiation.

Prediction of Treatment Response for Combined Chemo- and Radiation Therapy for Non-Small Cell Lung Cancer Patients Using a Bio-Mathematical Model

The goal of this work was to develop a mathematical model to predict Kaplan-Meier survival curves for chemotherapy combined with radiation in Non-Small Cell Lung Cancer patients for use in clinical trial design. The Gompertz model was used to describe tumor growth, radiation effect was simulated by the linear-quadratic model with an α/β-ratio of 10, and chemotherapy effect was based on the log-cell kill model. To account for repopulation during treatment, we considered two independent methods: 1) kickoff-repopulation using exponential growth with a decreased volume doubling time, or 2) Gompertz-repopulation using the gradually accelerating growth rate with tumor shrinkage. The input parameters were independently estimated by fitting to the SEER database for untreated tumors, RTOG-8808 for radiation only, and RTOG-9410 for sequential chemo-radiation. Applying the model, the benefit from concurrent chemo-radiation comparing to sequential for stage III patients was predicted to be a 6.6% and 6.2% improvement in overall survival for 3 and 5-years respectively, comparing well to the 5.3% and 4.5% observed in RTOG-9410. In summary, a mathematical model was developed to model tumor growth over extended periods of time, and can be used for the optimization of combined chemo-radiation scheduling and sequencing.

Identifying the Optimal Radiation Dose in Locally Advanced Non-Small-cell Lung Cancer Treated With Definitive Radiotherapy Without Concurrent Chemotherapy

INTRODUCTION

The optimal radiation dose for locally advanced non-small-cell lung cancer (NSCLC) is not known for patients who receive sequential chemoradiation (CRT) or definitive radiotherapy (RT) only. Our objective was to determine whether a benefit exists for radiation dose escalation for these patients.

MATERIALS AND METHODS

The patients included in our retrospective analysis had undergone RT for NSCLC from 2004 to 2013, had not undergone surgery, and received a dose ≥ 50.0 Gy. Patients who received concurrent CRT were excluded from the analysis, leaving 336 patients for analysis. The primary outcomes were overall survival (OS), local failure (LF), and distant failure (DF).

RESULTS

On multivariate analysis, after adjusting for age, Karnofsky performance status, gross tumor volume, and treatment modality, patients treated with a radiation dose > 66 Gy had significantly improved OS compared with those treated with < 60 Gy (hazard ratio [HR], 0.58; 95% confidence interval [CI], 0.39-0.87; P = .008). After adjusting for smoking history and radiologic tumor size, patients treated with a radiation dose > 66 Gy had a significantly decreased risk of LF compared with those treated with < 60 Gy (HR, 0.59; 95% CI, 0.38-0.91; P = .02). The radiation dose was not an independent prognostic factor of DF on multivariate analysis.

CONCLUSION

When controlling for tumor volume and/or dimensions and other independent prognostic factors, patients with locally advanced NSCLC who were not candidates for concurrent CRT benefited from a radiation dose > 66 Gy versus < 60 Gy with improved OS and reduced LF. An increased radiation dose did not appear to affect the incidence of DF.

Geometric dose prediction model for hemithoracic intensity-modulated radiation therapy in mesothelioma patients with two intact lungs

The presence of two intact lungs makes it challenging to reach a tumoricidal dose with hemithoracic pleural intensity-modulated radiation therapy (IMRT) in patients with malignant pleural mesothelioma (MPM) who underwent pleurectomy/decortications or have unresectable disease. We developed an anatomy-based model to predict attainable prescription dose before starting optimization. Fifty-six clinically delivered IMRT plans were analyzed regarding correlation of prescription dose and individual and total lung volumes, planning target volume (PTV), ipsilateral normal lung volume and ratios: contralateral/ipsilateral lung (CIVR); contralateral lung/PTV (CPVR); ipsilateral lung /PTV (IPVR); ipsilateral normal lung /total lung (INTLVR); ipsilateral normal lung/PTV (INLPVR). Spearman's rank correlation and Fisher's exact test were used. Correlation between mean ipsilateral lung dose (MILD) and these volume ratios and between prescription dose and single lung mean doses were studied. The prediction models were validated in 23 subsequent MPM patients. CIVR showed the strongest correlation with dose (R=0.603,p<0.001) and accurately predicted prescription dose in the validation cases. INLPVR and MILD as well as MILD and prescription dose were significantly correlated (R=-0.784,p<0.001 and R=0.554,p<0.001, respectively) in the training and validation cases. Parameters obtainable directly from planning scan anatomy predict achievable prescription doses for hemithoracic IMRT treatment of MPM patients with two intact lungs. PACS number(s): 87.55.de, 87.55.dk.

Individual isotoxic radiation dose escalation based on V20 and advanced technologies benefits unresectable stage III non-small cell lung cancer patients treated with concurrent chemoradiotherapy: long term follow-up

Under the assumption that the highest therapeutic ratio could be achieved by increasing the total tumor dose (TTD) to the limits of normal tissues, the phase I trial was conducted in patients with unresectable stage III non-small cell lung cancer treated with concurrent chemoradiotherapy, to determine the feasibility and effects of individual isotoxic radiation dose escalation based on bilateral lung V20 and advanced technologies. Consecutive eligible patients were assigned to cohorts of eight. V20 of each cohort was increased from 27% to 30%, 33%, 35%, 37%, and so on. The criterion for cessation of dose escalation was defined as ≥ 2 patients in each cohort experienced dose limiting toxicity. Isotoxic dose escalation was based on V20, functional imaging was used to improve the accuracy of radiotherapy. To test the power of escalation dose, patients with TTD over 66 Gy were assigned to the higher dose group (HD), while the others to the standard dose one (SD). In result, the recommended value of V20 was 35%. For all patients, follow-up ranged from 1 to 112 months, median overall and progression free survivals were 25.0 and 13.0 months, respectively. The 1-, 3-, 5- and 8-year overall survival (OS) rates were 72.5%, 22.5%, 17.5%, and 10.0%, respectively. Especially, the OS and local recurrence-free survival of patients in HD group were significantly longer than those in SD one (P=0.035, P=0.007, respectively) without increasing severe toxicity. Thus, individual isotoxic dose escalation based on V20 with advanced technologies was feasible and effective.

The use of dose-escalated radiation for locally advanced non-small cell lung cancer in the U.S., 2004-2013

Purpose/Objectives

The clinical effects of radiation dose-intensification in locally advanced non-small cell lung (NSCLCa) and other cancers are challenging to predict and are ideally studied in randomized trials. The purpose of this study was to assess the use of dose-escalated radiation for locally advanced NSCLCa in the U.S., 2004–2013, a period in which there were no published level 1 studies on dose-escalation.

Materials/Methods

We performed analyses on two cancer registry databases with complementary strengths and weaknesses: the National Oncology Data Alliance (NODA) 2004–2013 and the National Cancer Database (NCDB) 2004–2012. We classified locally advanced patients according to the use of dose-escalation (>70 Gy). We used adjusted logistic regression to assess the association of year of treatment with dose-escalated radiation use in two periods representing time before and after the closure of a cooperative group trial (RTOG 0617) on dose-escalation: 2004–2010 and 2010–2013. To determine the year in which a significant change in dose could have been detected had dose been prospectively monitored within the NODA network, we compared the average annual radiation dose per year with the forecasted dose (average of the prior 3 years) adjusted for patient age and comorbidities.

Results

Within both the NODA and NCDB, use of dose-escalation increased from 2004 to 2010 (p < 0.0001) and decreased from 2010 to 2013 (p = 0.0018), even after controlling for potential confounders. Had the NODA network been monitoring radiation dose in this cohort, significant changes in average annual dose would have been detected at the end of 2008 and 2012.

Conclusions

Patterns of radiation dosing in locally advanced NSCLCa changed in the U.S. in the absence of level 1 evidence. Monitoring radiation dose is feasible using an existing national cancer registry data collection infrastructure.

Stereotactic ablative body radiosurgery (SABR) or Stereotactic body radiation therapy (SBRT)

While conventional treatment relies on protracted courses of therapy using relatively small dose-per-fraction sizes of 1.8-2Gy, there is substantial evidence gathered over decades that this may not be the optimal approach for all targetable disease. Stereotactic ablative body radiosurgery (SABR) or stereotactic body radiation therapy (SBRT) is a technique which uses precise targeting to deliver high doses of radiation capable of ablating tumors directly. In this review, we will discuss the justification for and techniques used to deliver ablative doses to improve treatment outcomes, interactions with biological and immunologic therapy, and special procedures to spare normal tissue, which have facilitated the expanding role for these techniques in the management of a wide range of malignant histologies and disease states.

A geometric atlas to predict lung tumor shrinkage for radiotherapy treatment planning

To develop a geometric atlas that can predict tumor shrinkage and guide treatment planning for non-small-cell lung cancer. To evaluate the impact of the shrinkage atlas on the ability of tumor dose escalation. The creation of a geometric atlas included twelve patients with lung cancer who underwent both planning CT and weekly CBCT for radiotherapy planning and delivery. The shrinkage pattern from the original pretreatment to the residual posttreatment tumor was modeled using a principal component analysis, and used for predicting the spatial distribution of the residual tumor. A predictive map was generated by unifying predictions from each individual patient in the atlas, followed by correction for the tumor's surrounding tissue distribution. Sensitivity, specificity, and accuracy of the predictive model for classifying voxels inside the original gross tumor volume were evaluated. In addition, a retrospective study of predictive treatment planning (PTP) escalated dose to the predicted residual tumor while maintaining the same level of predicted complication rates for a clinical plan delivering uniform dose to the entire tumor. The effect of uncertainty on the predictive model's ability to escalate dose was also evaluated. The sensitivity, specificity and accuracy of the predictive model were 0.73, 0.76, and 0.74, respectively. The area under the receiver operating characteristic curve for voxel classification was 0.87. The Dice coefficient and mean surface distance between the predicted and actual residual tumor averaged 0.75, and 1.6 mm, respectively. The PTP approach allowed elevation of PTV D95 and mean dose to the actual residual tumor by 6.5 Gy and 10.4 Gy, respectively, relative to the clinical uniform dose approach. A geometric atlas can provide useful information on the distribution of resistant tumors and effectively guide dose escalation to the tumor without compromising the organs at risk complications. The atlas can be further refined by using more patient data sets.

Concurrent Chemotherapy and Radiation Therapy for Inoperable Locally Advanced Non–Small-Cell Lung Cancer

The Oncology Grand Rounds series is designed to place original reports published in the Journal into clinical context. A case presentation is followed by a description of diagnostic and management challenges, a review of the relevant literature, and a summary of the authors’ suggested management approaches. The goal of this series is to help readers better understand how to apply the results of key studies, including those published in Journal of Clinical Oncology, to patients seen in their own clinical practice.

A 72-year-old man with a 40-pack-year tobacco history developed a cough and decreased exercise tolerance. A chest x-ray demonstrated a right-upper-lobe opacity. Chest computed tomography (CT) scan revealed a 2.5-cm mass in the right upper lobe with multiple mediastinal lymph node disease ( Fig 1 ). A positron emission tomography (PET) scan confirmed the lung lesion and the mediastinal lymphadenopathy without distant metastases. Brain magnetic resonance imaging results were negative. The biopsy specimen revealed adenocarcinoma with no actionable mutations present. Cervical mediastinoscopy was positive for carcinoma in level 2, 3, 4R, and 7 lymph nodes; level 4L was negative. The patient’s stage was T1bN2M0, stage IIIA. His medical history was significant for hyperlipidemia and hypothyroidism. He had smoked one pack a day for 40 years and had quit 15 years earlier. Physical examination was unrevealing, and the patient had an Eastern Cooperative Oncology Group performance status of 0. Because of the extent of lung cancer in the mediastinum, the patient’s cancer was deemed inoperable, and he was referred for consideration of concurrent chemotherapy and radiation.

Efficacy of stereotactic body radiotherapy for hepatocellular carcinoma with portal vein tumor thrombosis/inferior vena cava tumor thrombosis: evaluation by comparison with conventional three-dimensional conformal radiotherapy

This study aimed to evaluate the efficacy of stereotactic body radiotherapy (SBRT) compared with three-dimensional conformal radiotherapy (3DCRT). Forty-three patients with portal vein tumor thrombosis (PVTT)/inferior vena cava tumor thrombosis (IVCTT) treated with SBRT (27 with CyberKnife (CK) and 16 with TrueBeam (TB)) from April 2013 to December 2014, and 54 treated with 3DCRT from June 2008 to March 2013 were evaluated. Dosimetric parameters, response to radiotherapy (RT) and survival outcomes were compared in total SBRT vs. 3DCRT, CK vs. 3DCRT and TB vs. 3DCRT, respectively. The median biologically effective dose 10 (BED₁₀) values in total SBRT, CK, TB and 3DCRT were 73.4 Gy₁₀, 75.0 Gy₁₀, 60.5 Gy₁₀ and 58.5 Gy₁₀, respectively (P < 0.001 in total SBRT vs. 3DCRT, P < 0.001 in CK vs. 3DCRT, P = 0.004 in TB vs. 3DCRT). The tumor response rates were 67%, 70%, 62% and 46%, respectively (P = 0.04, P = 0.04, P = 0.25). The 1-year overall survival rates were 49.3%, 56.7%, 38.1% and 29.3%, respectively (P = 0.02, P = 0.02, P = 0.30), and the 1-year local progression rates were 20.4%, 21.9%, 18.8% and 43.6%, respectively (P = 0.01, P = 0.04, P = 0.10). The use of SBRT made it possible to achieve a higher BED₁₀ compared with the use of 3DCRT. Improvements in local control and survival were achieved in the CK group and the total SBRT group. Our results suggest that SBRT may have the potential to be the standard RT technique for the treatment of PVTT/IVCTT.

Radiosensitization by PARP Inhibition in DNA Repair Proficient and Deficient Tumor Cells: Proliferative Recovery in Senescent Cells

Radiotherapy continues to be a primary modality in the treatment of cancer. In addition to promoting apoptosis, radiation-induced DNA damage can promote autophagy and senescence, both of which can theoretically function to prolong tumor survival. In this work, we tested the hypothesis that autophagy and/or senescence could be permissive for DNA repair, thereby facilitating tumor cell recovery from radiation-induced growth arrest and/or cell death. In addition, studies were designed to elucidate the involvement of autophagy and senescence in radiosensitization by PARP inhibitors and the re-emergence of a proliferating tumor cell population. In the context of this work, the relationship between radiation-induced autophagy and senescence was also determined. Studies were performed using DNA repair-proficient HCT116 colon carcinoma cells and a repair-deficient ligase IV(-/-) isogenic cell line. Exposure to radiation promoted a parallel induction of autophagy and senescence that was strongly correlated with the extent of persistent H2AX phosphorylation in both cell lines, however, inhibition of autophagy failed to suppress senescence, indicating that the two responses were dissociable. Exposure to radiation resulted in a transient arrest in the HCT116 cells while arrest was prolonged in the ligase IV(-/-) cells, however, both cell lines ultimately recovered proliferative function, which may reflect maintenance of DNA repair capacity. The PARP inhibitors, olaparib and niraparib, increased the extent of persistent DNA damage induced by radiation exposure as well as the extent of both autophagy and senescence. Neither cell line underwent significant apoptosis by radiation exposure alone or in the presence of the PARP inhibitors. Inhibition of autophagy failed to attenuate radiosensitization, indicating that autophagy was not involved in the action of the PARP inhibitors. As with radiation alone, despite sensitization by PARP inhibition, proliferative recovery was evident within a period of 10-20 days. While inhibition of DNA repair via PARP inhibition may initially sensitize tumor cells to radiation via the promotion of senescence, this strategy does not appear to interfere with proliferative recovery, which could ultimately contribute to disease recurrence.

Long-term follow-up of patients with locally advanced non-small cell lung cancer receiving concurrent hypofractionated chemoradiotherapy with or without cetuximab

BACKGROUND AND PURPOSE

Radiation dose escalation using hypofractionation might improve overall survival (OS). We investigated OS in a phase II multicenter study in locally advanced non-small cell lung cancer (LA-NSCLC) patients treated with hypofractionated concurrent chemoradiotherapy.

MATERIALS AND METHODS

A 2-armed phase II, multi-center study (NTR2230) was performed with the aim to assess the effect of cetuximab to concurrent chemoradiotherapy in LA-NSCLC patients (stage II/IIIA/B). Arm A received high dose radiotherapy (24 × 2.75 Gy) and concurrent daily low-dose cisplatin (6 mg/m(2)). Arm B received an identical treatment regimen with additional weekly cetuximab. Kaplan-Meier survival curves and 1-, 2- and 5-year OS proportions were calculated.

RESULTS

Between February 2009 and May 2011, 102 patients were randomly allocated in two arms. Median OS was 31.5 months (range 12.8-52.3), not significantly different between arms A and B; 33.0 (range 17.0-57.0) and 30.0 (11.0-52.0) months. 1-, 2- and 5-year OS rates were 74.5%, 59.4% and 37.3%, respectively. In multivariate analyses, worse performance score, V35 of the esophagus and the existence of comorbidities were significantly (P-value<0.05) associated with a shorter OS.

DISCUSSION

In this phase II trial, the median OS for the entire group was remarkably high; 31.5 months. Furthermore, 5-year OS was still 37.3%. Hypofractionation might contribute to improved OS in LA-NSCLC patients.

Potential Use of (18)F-fluorodeoxyglucose Positron Emission Tomography-Based Quantitative Imaging Features for Guiding Dose Escalation in Stage III Non-Small Cell Lung Cancer

PURPOSE

To determine whether previously identified quantitative image features (QIFs) based on (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET) (co-occurrence matrix energy and solidity) are able to isolate subgroups of patients who would receive a benefit or detriment from dose escalation in terms of overall survival (OS) or progression-free survival (PFS).

METHODS AND MATERIALS

Subgroups of a previously analyzed 225 patient cohort were generated with the use of 5-percentile increment cutoff values of disease solidity and primary tumor co-occurrence matrix energy. The subgroups were analyzed with a log-rank test to determine whether there was a difference in OS and PFS between patients treated with 60 to 70 Gy and those receiving 74 Gy.

RESULTS

In the entire patient cohort, there was no statistical difference in terms of OS or PFS between patients receiving 74 Gy and those receiving 60 to 70 Gy. It was qualitatively observed that as disease solidity and primary co-occurrence matrix energy increased, patients receiving 74 Gy had an improved OS and PFS compared with those receiving 60 to 70 Gy. The opposite trend (detriment of receiving 74 Gy) was also observed regarding low values of disease solidity and primary co-occurrence matrix energy.

CONCLUSIONS

FDG-PET-based QIFs were found to be capable of isolating subgroups of patients who received a benefit or detriment from dose escalation.

Complications from Stereotactic Body Radiotherapy for Lung Cancer

Stereotactic body radiotherapy (SBRT) has become a standard treatment option for early stage, node negative non-small cell lung cancer (NSCLC) in patients who are either medically inoperable or refuse surgical resection. SBRT has high local control rates and a favorable toxicity profile relative to other surgical and non-surgical approaches. Given the excellent tumor control rates and increasing utilization of SBRT, recent efforts have focused on limiting toxicity while expanding treatment to increasingly complex patients. We review toxicities from SBRT for lung cancer, including central airway, esophageal, vascular (e.g., aorta), lung parenchyma (e.g., radiation pneumonitis), and chest wall toxicities, as well as radiation-induced neuropathies (e.g., brachial plexus, vagus nerve and recurrent laryngeal nerve). We summarize patient-related, tumor-related, dosimetric characteristics of these toxicities, review published dose constraints, and propose strategies to reduce such complications.

Is intermediate radiation dose escalation with concurrent chemotherapy for stage III non-small-cell lung cancer beneficial? A multi-institutional propensity score matched analysis

PURPOSE

The clinical benefits and risks of dose escalation (DE) for stage III non-small-cell lung cancer (NSCLC) remain uncertain despite the results from Radiation Therapy Oncology Group (RTOG) protocol 0617. There is significant heterogeneity of practice, with many clinicians prescribing intermediate dose levels between the 0617 study arms of 60 and 74 Gy. This study investigated whether this strategy is associated with any survival benefits/risks by analyzing a large multi-institutional database.

METHODS AND MATERIALS

An individual patient database of stage III NSCLC patients treated with radical intent concurrent chemoradiation therapy was created (13 institutions, n=1274 patients). Patients were divided into 2 groups based on tumor Biological Effective Dose at 10 Gy (BED 10): those receiving standard dose (SD; n=552), consisting of 72Gy ≤ BED 10 ≤ 76.8 Gy (eg 60-64 Gy/30-32 fractions [fr]), and those receiving intermediate dose (ID; n=497), consisting of 76.8Gy < BED 10 < 100.8 Gy (eg >64 Gy/32 fr and <74 Gy/37 fr), with lower-dose patients (n=225) excluded from consideration. Patients were then matched using propensity scores, leading to 2 matched groups of 196 patients. Outcomes were compared using various statistics including interquartile range (IQR), Kaplan-Meier curves, and adjusted Cox regression analysis.

RESULTS

Matched groups were found to be balanced except for N stage (more N3 disease in SD), median treatment year (SD in 2003; ID in 2007), platinum and taxane chemotherapy (SD in 28%; ID in 39%), and median follow-up (SD were 89 months; ID were 40 months). Median dose fractionation was 60 Gy/30 fr in SD (BED 10 IQR: 72.0-75.5 Gy) and 66 Gy/33 fr (BED 10 IQR: 78.6-79.2 Gy) in ID. Survival curves for SD and ID matched cohorts were statistically similar (P=.27); however, a nonstatistically significant trend toward better survival for ID was observed after 15 months (median survival SD: 19.3 months; ID: 21.0 months). There was an increase in grades III to V lung toxicity associated with ID (13.0% vs 4.9%, respectively).

CONCLUSIONS

No significant overall survival benefits were found with intermediate DE; however, more grade III or greater lung toxicity was observed. The separation of survival curves after 15 months of follow-up suggests that a small overall survival improvement associated with intermediate DE cannot be excluded.

Long-term outcomes after proton therapy, with concurrent chemotherapy, for stage II-III inoperable non-small cell lung cancer

PURPOSE

We report long-term disease control, survival, and toxicity for patients with locally advanced non-small cell lung cancer prospectively treated with concurrent proton therapy and chemotherapy on a nonrandomized case-only observational study.

METHODS

All patients received passive-scatter proton therapy, planned with 4D-CT-based simulation; all received proton therapy concurrent with weekly chemotherapy. Endpoints were local and distant control, disease-free survival (DFS), and overall survival (OS).

RESULTS

The 134 patients (21 stage II, 113 stage III; median age 69 years) had a median gross tumor volume (GTV) of 70 cm(3) (range, 5-753 cm(3)); 77 patients (57%) received 74 Gy(RBE), and 57 (42%) received 60-72 Gy(RBE) (range, 60-74.1 Gy(RBE)). At a median follow-up time of 4.7 years, median OS times were 40.4 months (stage II) and 30.4 months (stage III). Five-year DFS rates were 17.3% (stage II) and 18.0% (stage III). OS, DFS, and local and distant control rates at 5 years did not differ by disease stage. Age and GTV were related to OS and DFS. Toxicity was tolerable, with 1 grade 4 esophagitis and 16 grade 3 events (2 pneumonitis, 6 esophagitis, 8 dermatitis).

CONCLUSION

This report of outcomes after proton therapy for 134 patients indicated that this regimen produced excellent OS with tolerable toxicity.

Stereotactic body radiotherapy for early-stage non-small cell lung cancer: clinical outcomes from a National Patient Registry

Objectives

Stereotactic body radiotherapy (SBRT) is a definitive local treatment option for patients with stage I non-small cell lung cancer (NSCLC) who are not surgical candidates and patients who refuse surgery. The purpose of this study was to assess the impact of SBRT on T1–T2 NSCLC from a national registry, reflecting practices and outcomes in a real-world setting.

Methods

The RSSearch® Patient Registry was screened for T1–T2N0M0 NSCLC patients treated from May 2004 to May 2013 with SBRT. Descriptive analyses were used for patient, tumor, and treatment characteristics. Overall survival (OS) and local control (LC) were calculated using the Kaplan-Meier method.

Results

In total, 723 patients with 517 T1 and 224 T2 lesions were treated with SBRT. Median follow-up was 12 months (1–87 months) with a median age of 76 years. Median SBRT dose was 54 Gy (range 10–80 Gy) delivered in a median of 3 fractions (range 1–5), and median biological equivalent dose (BED₁₀) was 151.2 Gy (range 20–240 Gy). Median OS was 30 and 26 months for T1 and T2 tumors, respectively (p = 0.019). LC was associated with higher BED₁₀ for T2 tumors, but not in T1 tumors at a median follow-up of 17 months. Seventeen-month LC for T2 tumors treated with BED₁₀ < 105 Gy, BED₁₀ 105-149, and BED₁₀ ≥ 150 Gy was 43, 74, and 95 %, respectively (p = 0.011). Local failure rates for T2 tumors treated with BED₁₀ < 105 Gy, 105–149 Gy, and ≥150 Gy were 32, 21, and 8 % (p = 0.029), respectively. Median OS for patients with T2 tumors treated with BED₁₀ < 105 Gy was 17 vs. 32 months for T2 tumors treated with BED₁₀ 105–149 Gy (p = 0.062).

Conclusion

SBRT for T1–T2 NSCLC is feasible and effective in the community setting. OS was greater for patients with T1 lesions compared to T2 lesions. An improvement in LC was observed in patients with T2 lesions treated with BED₁₀ > 105 Gy.

Definitive dose thoracic radiation therapy in oligometastatic non-small cell lung cancer: A hypothesis-generating study

PURPOSE

A subset of patients with minimal extrathoracic disease may benefit from aggressive primary tumor treatment. We report comparative outcomes in oligometastatic non-small cell lung cancer (NSCLC) treated with and without definitive, conventionally fractionated thoracic radiation therapy.

METHODS AND MATERIALS

We identified consecutive patients with stage IV NSCLC who had an Eastern Cooperative Oncology Group performance status ≤2 and ≤4 total sites of metastatic disease and who had been prescribed ≥50 Gy of thoracic radiation.

RESULTS

Twenty-nine patients with oligometastatic NSCLC were identified between January 2004 and August 2010. Median survival was 22 months from diagnosis. Four patients (14%) experienced pneumonitis greater than or equal to grade 3; 6 (21%) had esophagitis greater than or equal to grade 3. Local control was associated with improved survival (P = .02). In matched subset analysis, median survival was 9 months (P < .01) in patients who received chemotherapy alone. Median time to local failure was 18 versus 6 months (P = .01). On multivariable analysis, radiation (P < .01; odds ratio [OR], 0.33), fewer metastases (P < .01; OR, 2.14), and female sex (P < .01; OR, 0.41) were associated with improved survival.

CONCLUSIONS

Definitive dose radiation therapy may improve survival in a select subset of patients with minimal extrathoracic disease in whom local progression is of primary concern. Prospective trials are needed to further evaluate the role of local control in oligometastatic NSCLC.

Definitive radiotherapy in locally advanced non-small cell lung cancer: dose and fractionation

Definitive radiotherapy plays a major role in the treatment of locally advanced non-small cell lung cancer (LA NSCLC). After the impact of RT dose for lung cancer was established, a number of trials were structured with the aim of better local control and overall survival by either dose escalation or shortening the total treatment time through conventional/altered fractionation, even in combination with chemotherapy (CT) and other targeted agents. In spite of the increased number of these studies, the optimal dose or fractionation still remains to be determined. Another aspect questioned is the incorporation of these higher doses and shorter treatment times with chemotherapy or targeted agents. This review summarises the results of significant trials on dose and altered fractionation in the treatment of LA-NSCLC with an emphasis on possible future perspectives.

Outcome and toxicity profiles in the treatment of locally advanced lung cancer with volumetric modulated arc therapy

PURPOSE

To report about the outcome of radiation treatment of advanced lung cancer patients with volumetric modulated arcs [RapidArc (RA)].

PATIENTS AND METHODS

Seventy-five consecutive patients (all stages IIIA and IIIB) were treated with RA. Among them 71 % were men; 25.4 % presented unspecified non-small cell lung cancer, 41.3% adenocarcinoma and 33.3 % squamous cell carcinoma. Of them, 54.7 % received sequential chemotherapy while 45.3% were treated with concomitant regimen. Dose prescription ranged from 54 to 72 Gy. Analysis included survival, local control (LC) and toxicity profiles.

RESULTS

Median follow-up was 21.2 months (range 6-75). One- two- and five-year actuarial LC was 91.9 ± 3.2, 79.5 ± 5.7 and 67.4 ± 9.5 %, respectively. Median survival was 19.0 ± 1.1 months. Actuarial survival at 1-2-5 years was 80.0 ± 4.6, 38.5 ± 5.9 and 15.2 ± 4.9 %, respectively. Acute toxicity of G2 was reported in 24, 25.3 and 4.0 % of patients for lung, esophageal and hematological profiles. A total of 2.7 % of patients reported G3 toxicity in the esophagus and 5.3 % of the patients experienced G3-G4 hematological toxicity. Significant differences were observed in all cases between concomitant and sequential chemotherapy regiments. Only 1.3 % (1 patient) showed G2 lung late toxicity. No significant correlation was found between toxicity and organ's irradiation levels.

CONCLUSION

RA proved to be a safe and advantageous treatment modality for advanced lung cancer with results in line with expectations from earlier literature.

A new plan quality index for dose painting radiotherapy

Dose painting radiotherapy is considered a promising radiotherapy technology that enables more targeted dose delivery to tumor rich regions while saving critical normal tissues. Obviously, dose painting planning would be more complicated and hard to be evaluated with current plan quality index systems that were developed under the paradigm of uniform dose prescription. In this study, we introduce a new plan quality index, named “index of achievement (IOA)” that assesses how close the planned dose distribution is to the prescribed one in a dose painting radiotherapy plan. By using voxel‐based comparison between planned and prescribed dose distributions in its formulation, the index allows for a single‐value evaluation regardless of the number of prescribed dose levels, which cannot be achieved with the conventional indices such as conventional homogeneity index. Benchmark calculations using patient data demonstrated feasibility of the index not only for contour‐based dose painting plans, but also for dose painting by numbers plans. Also, it was shown that there is strong correlation between the new index and conventional indices, which indicates a potential of the new index as an alternative to conventional ones in general radiotherapy plan evaluation.

PACS number: 87.55.D‐