Dose escalation in non-small-cell lung cancer using three-dimensional conformal radiation therapy: update of a phase I trial

Novel Harmonization Method for Multi-Centric Radiomic Studies in Non-Small Cell Lung Cancer

The purpose of this multi-centric work was to investigate the relationship between radiomic features extracted from pre-treatment computed tomography (CT), positron emission tomography (PET) imaging, and clinical outcomes for stereotactic body radiation therapy (SBRT) in early-stage non-small cell lung cancer (NSCLC). One-hundred and seventeen patients who received SBRT for early-stage NSCLC were retrospectively identified from seven Italian centers. The tumor was identified on pre-treatment free-breathing CT and PET images, from which we extracted 3004 quantitative radiomic features. The primary outcome was 24-month progression-free-survival (PFS) based on cancer recurrence (local/non-local) following SBRT. A harmonization technique was proposed for CT features considering lesion and contralateral healthy lung tissues using the LASSO algorithm as a feature selector. Models with harmonized CT features (B models) demonstrated better performances compared to the ones using only original CT features (C models). A linear support vector machine (SVM) with harmonized CT and PET features (A1 model) showed an area under the curve (AUC) of 0.77 (0.63–0.85) for predicting the primary outcome in an external validation cohort. The addition of clinical features did not enhance the model performance. This study provided the basis for validating our novel CT data harmonization strategy, involving delta radiomics. The harmonized radiomic models demonstrated the capability to properly predict patient prognosis.

Stereotactic Body Radiation Therapy for the Treatment of Locally Recurrent and Oligoprogressive Non-Small Cell Lung Cancer: A Single Institution Experience

Objectives

To investigate the efficacy and safety of lung stereotactic body radiation therapy (SBRT) for non-small cell lung cancer (NSCLC) including oligorecurrent and oligoprogressive disease.

Methods

Single-institution retrospective analysis of 60 NSCLC patients with 62 discrete lesions treated with SBRT between 2008 and 2017. Patients were stratified into three groups, including early stage, locally recurrent, and oligoprogressive disease. Group 1 included early stage local disease with no prior local therapy. Group 2 included locally recurrent disease after local treatment of a primary lesion, and group 3 included regional or well-controlled distant metastatic disease receiving SBRT for a treatment naive lung lesion (oligoprogressive disease). Patient/tumor characteristics and adverse effects were recorded. Local failure free survival (LFFS), progression free survival (PFS), and overall survival (OS) were estimated using the Kaplan Meier method.

Results

At median follow-up of 34 months, 67% of the study population remained alive. The estimated 3-year LFFS for group 1, group 2, and group 3 patients was 95% (95% CI: 86%-100%), 82%(62% - 100%), and 83% (58-100%), respectively. The estimated 3-year PFS was 59% (42-83%), 40% (21%-78%), and 33% (12%-95%), and the estimated 3-year OS was 58% (41-82%), 60% (37-96%), and 58% (31-100%)), respectively for each group. When adjusted for age and size of lesion, no significant difference in OS, LFFS, and PFS emerged between groups (p > 0.05). No patients experienced grade 3 to 5 toxicity. Eighteen patients (29%) experienced grade 1 to 2 toxicity. The most common toxicities reported were cough and fatigue.

Conclusions

Our data demonstrates control rates in group 1 patients comparable to historical controls. Our study also reveals comparable clinical results for SBRT in the treatment of NSCLC by demonstrating similar rates of LFFS and OS in group 2 and group 3 patients with locally recurrent and treatment naïve lung lesion with well-controlled distant metastatic disease.

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

PURPOSE

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

METHODS AND MATERIALS

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

RESULTS

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

CONCLUSIONS

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

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.

Collision-Free Path Planning and Delivery Sequence Optimization in Noncoplanar Radiation Therapy

Radiation therapy is among the top three cancer treatments in current medical services. The novel noncoplanar radiation therapy which claimed the best characteristics in almost all dosimetric properties encountered the challenges of the potential collision and the long time delivering. In this paper, we proposed a brand new scheme which uses a combined method of the collision avoidance path planning based on an improved probability roadmap method (PRM) and the delivery sequence optimization based on a modified genetic algorithm (GA) to solve the problems in noncoplanar radiation therapy. A uniform sampling strategy, an improved connection strategy, and an efficient local planner are introduced to optimize the roadmap result and accelerate the roadmap construction. The GA is improved by the elitist selection, the local search strategy, and the similar substitution strategy to achieve a better performance both in convergence rate and optimal solution. Experiments are carried out on the simulation platform with typical therapy system models. The results show that our proposed methods work well with the radiation therapy system in a compact working area. Collision is avoided and time consumption is reduced. We believe that our proposed algorithms could solve the problems in current radiation therapy and promote their clinic applications.

Radiotherapy in Italy for Non-Small Cell Lung Cancer: Patterns of Care Survey

Aims and Background

Surveys in clinical practice are useful to find how current clinical approaches follow recommendations from evidence-based medicine, to stimulate discussion in a multidisciplinary team, and to hypothesize collaborative multi-centric trials. To assess management strategies for the use of radiotherapy in the treatment of lung cancer in Italy, in 2009, the Italian Society of Radiation Oncology Lung Cancer Study Group proposed the survey to all Italian radiation oncology institutions. Results were compared with literature data and international reports.

Study Design

Questionnaires on patterns of care of non-small cell lung cancer were sent to radiation oncology centers active at June 2009 and evaluated data recorded in 2008.

Results

A total of 65 of 143 Italian centers responded to the questionnaire. The responding centers reflect the distribution of radiotherapy centers throughout the country. Of the treated patients, 55.2% were stage III, and most cases had a good performance status. FDG-PET was routinely used by 51% of centers for diagnostic and contouring phases. Postoperative radiotherapy was prescribed to pN1 and pN2 patients in 42.2% and 98.5%, respectively. The possible use of neo-adjuvant concomitant chemoradiation was declared by 70% of responders. A sequential chemoradiation approach was actually used in 43.6% of cases, induction chemotherapy followed by concomitant radiochemotherapy in 42.4%, and upfront concomitant radiochemotherapy in only 14%. In 53% of the institutions, patients have a clinical examination by a radiation oncologist only after the beginning of chemotherapy and in 82.4% of cases they have already received 2–4 cycles of chemotherapy. Most of the institutions exclude elective nodal irradiation from routine application. Total dose and fractionation in adjuvant, neoadjuvant, curative and palliative settings confirm literature data. There were significant differences in treatment planning constraints applied for lung, esophageal and cardiac tissues. Of the responding centers, 41% had stereotactic therapy for primary inoperable lung cancer and for metastatic lesions.

Conclusions

In Italy, daily practice differs in some ways from the evidence supported by the results of meta-analyses/clinical trials as regards concurrent chemoradiation approaches. It could be postulated that there is an urgent need for groups that collaborate with the other societies involved in the treatment of non-small cell lung cancer in order to offer the best therapy to our patients.

Normal lung sparing Tomotherapy technique in stage III lung cancer

PURPOSE

Radiation pneumonitis (RP) has been a challenging obstacle in treating stage III lung cancer patients. Beam angle optimization (BAO) technique for Tomotherapy was developed to reduce the normal lung dose for stage III non-small cell lung cancer (NSCLC). Comparative analyses on plan quality by 3 different Intensity-modulated radiation therapy (IMRT) methods with BAO were done.

MATERIALS AND METHODS

Ten consecutive stage IIIB NSCLC patients receiving linac-based static IMRT (L-IMRT) with total 66 Gy in 33 fractions to the PTV were selected. Two additional Tomotherapy-based IMRT plans (helical beam (TH-IMRT) and static beam (TD-IMRT)) were generated on each patient. To reduce the normal lung dose, Beam angles were optimized by using complete and directional block functions in Tomotherapy based on knowledge based statistical analysis. Plan quality was compared with target coverage, normal organ sparing capability, and normal tissue complication probability (NTCP). Actual beam delivery times and risk of RP related with planning target volume (PTV) were also evaluated.

RESULTS

The best PTV coverage measured by conformity index and homogeneity index was achievable by TH-IMRT (0.82 and 1.06), followed by TD-IMRT (0.81 and 1.07) and L-IMRT (0.75 and 1.08). Mean lung dose was the lowest in TH-IMRT plan followed by TD-IMRT and L-IMRT, all of which were ≤20 Gy. TH-IMRT plan could significantly lower the lung volumes receiving low to medium dose levels: V5~30 when compared to L-IMRT plan; and V5~20 when compared to TD-IMRT plan, respectively. TD-IMRT plan was significantly better than L-IMRT with respects to V20 and V30 and there was no significant difference with respect to V40 among three plans. The NTCP of the lung was the lowest in TH-IMRT plan, followed by TD-IMRT and L-IMRT (6.42% vs. 6.53% vs. 8.11%). Beam delivery time was the shortest in TD-IMRT plan followed by L-IMRT. As PTV length increased, NTCP and Mean lung dose proportionally increased significantly in all three plans.

CONCLUSION

Advantageous profiles by TH-IMRT could be achieved by BAO by complete and directional block functions. Current observation could help radiation oncologists to make wise selection of IMRT method for stage IIIB NSCLC.

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.

Priority-driven plan optimization in locally advanced lung patients based on perfusion SPECT imaging

Purpose

Limits on mean lung dose (MLD) allow for individualization of radiation doses at safe levels for patients with lung tumors. However, MLD does not account for individual differences in the extent or spatial distribution of pulmonary dysfunction among patients, which leads to toxicity variability at the same MLD. We investigated dose rearrangement to minimize the radiation dose to the functional lung as assessed by perfusion single photon emission computed tomography (SPECT) and maximize the target coverage to maintain conventional normal tissue limits.

Methods and materials

Retrospective plans were optimized for 15 patients with locally advanced non-small cell lung cancer who were enrolled in a prospective imaging trial. A staged, priority-based optimization system was used. The baseline priorities were to meet physical MLD and other dose constraints for organs at risk, and to maximize the target generalized equivalent uniform dose (gEUD). To determine the benefit of dose rearrangement with perfusion SPECT, plans were reoptimized to minimize the generalized equivalent uniform functional dose (gEUfD) to the lung as the subsequent priority.

Results

When only physical MLD is minimized, lung gEUfD was 12.6 ± 4.9 Gy (6.3-21.7 Gy). When the dose is rearranged to minimize gEUfD directly in the optimization objective function, 10 of 15 cases showed a decrease in lung gEUfD of >20% (lung gEUfD mean 9.9 ± 4.3 Gy, range 2.1-16.2 Gy) while maintaining equivalent planning target volume coverage. Although all dose-limiting constraints remained unviolated, the dose rearrangement resulted in slight gEUD increases to the cord (5.4 ± 3.9 Gy), esophagus (3.0 ± 3.7 Gy), and heart (2.3 ± 2.6 Gy).

Conclusions

Priority-driven optimization in conjunction with perfusion SPECT permits image guided spatial dose redistribution within the lung and allows for a reduced dose to the functional lung without compromising target coverage or exceeding conventional limits for organs at risk.

Comparison of dose-volume histograms between proton beam and X-ray conformal radiotherapy for locally advanced non-small-cell lung cancer

The purpose of this study was to compare the parameters of the dose-volume histogram (DVH) between proton beam therapy (PBT) and X-ray conformal radiotherapy (XCRT) for locally advanced non-small-cell lung cancer (NSCLC), according to the tumor conditions. A total of 35 patients having NSCLC treated with PBT were enrolled in this analysis. The numbers of TNM stage and lymph node status were IIB (n = 3), IIIA (n = 15) and IIIB (n = 17), and N0 (n = 2), N1 (n = 4), N2 (n = 17) and N3 (n = 12), respectively. Plans for XCRT were simulated based on the same CT, and the same clinical target volume (CTV) was used based on the actual PBT plan. The treatment dose was 74 Gy-equivalent dose (GyE) for the primary site and 66 GyE for positive lymph nodes. The parameters were then calculated according to the normal lung dose, and the irradiation volumes of the doses (Vx) were compared. We also evaluated the feasibility of both plans according to criteria: V5 ≥ 42%, V20 ≥ 25%, mean lung dose ≥ 20 Gy. The mean normal lung dose and V5 to V50 were significantly lower in PBT than in XCRT. The differences were greater with the more advanced nodal status and with the larger CTV. Furthermore, 45.7% of the X-ray plans were classified as inadequate according to the criteria, whereas 17.1% of the proton plans were considered unsuitable. The number of inadequate X-ray plans increased in cases with advanced nodal stage. This study indicated that some patients who cannot receive photon radiotherapy may be able to be treated using PBT.

Lung cancer: a 6-field technique using lateral beams in conformal radiotherapy for bilateral supraclavicular lymph node metastases

A 6-field technique using lateral beams in conformal radiotherapy was developed for patients with bilateral supraclavicular lymph node metastasis of lung cancer. The possibility of using this technique in practice was evaluated. Six fields with the same isocenter point (IP) were arranged. Two fields using anterior-posterior opposed beams involved all of the planning target volume (PTV). The next 2 fields using off-cord oblique beams involved the PTV inferior to the IP. The remaining 2 fields using lateral opposed beams, that shielded the spinal cord, involved the PTV superior to the IP. The oblique 2 fields and lateral 2 fields were connected using a half-beam technique. In 6 patients with non-small-cell lung cancer (NSCLC, n = 4) or small-cell lung cancer (SCLC, n = 2), treatment re-planning based on this technique was performed. This technique was applicable in 4 patients with NSCLC, in whom the general criteria of radiotherapy for lung cancer were met. In 2 patients with SCLC, the cumulative volume of lung that received more than 20 Gy exceeded 37% of the total lung volume. This technique was usable in 67% of the patients and was not necessarily contraindicated in the other 33%.

High-dose concurrent chemo-proton therapy for Stage III NSCLC: preliminary results of a Phase II study

The aim of this report is to present the preliminary results of a Phase II study of high-dose (74 Gy RBE) proton beam therapy (PBT) with concurrent chemotherapy for unresectable locally advanced non-small-cell lung cancer (NSCLC). Patients were treated with PBT and chemotherapy with monthly cisplatin (on Day 1) and vinorelbine (on Days 1 and 8). The treatment doses were 74 Gy RBE for the primary site and 66 Gy RBE for the lymph nodes without elective lymph nodes. Adapted planning was made during the treatment. A total of 15 patients with Stage III NSCLC (IIIA: 4, IIIB: 11) were evaluated in this study. The median follow-up period was 21.7 months. None of the patients experienced Grade 4 or 5 non-hematologic toxicities. Acute pneumonitis was observed in three patients (Grade 1 in one, and Grade 3 in two), but Grade 3 pneumonitis was considered to be non-proton-related. Grade 3 acute esophagitis and dermatitis were observed in one and two patients, respectively. Severe ( ≥ Grade 3) leukocytopenia, neutropenia and thrombocytopenia were observed in 10 patients, seven patients and one patient, respectively. Late radiation Grades 2 and 3 pneumonitis was observed in one patient each. Six patients (40%) experienced local recurrence at the primary site and were treated with 74 Gy RBE. Disease progression was observed in 11 patients. The mean survival time was 26.7 months. We concluded that high-dose PBT with concurrent chemotherapy is safe to use in the treatment of unresectable Stage III NSCLC.

Improving radiotherapy planning, delivery accuracy, and normal tissue sparing using cutting edge technologies

In the United States, more than half of all new invasive cancers diagnosed are non-small cell lung cancer, with a significant number of these cases presenting at locally advanced stages, resulting in about one-third of all cancer deaths. While the advent of stereotactic ablative radiation therapy (SABR, also known as stereotactic body radiotherapy, or SBRT) for early-staged patients has improved local tumor control to >90%, survival results for locally advanced stage lung cancer remain grim. Significant challenges exist in lung cancer radiation therapy including tumor motion, accurate dose calculation in low density media, limiting dose to nearby organs at risk, and changing anatomy over the treatment course. However, many recent technological advancements have been introduced that can meet these challenges, including four-dimensional computed tomography (4DCT) and volumetric cone-beam computed tomography (CBCT) to enable more accurate target definition and precise tumor localization during radiation, respectively. In addition, advances in dose calculation algorithms have allowed for more accurate dosimetry in heterogeneous media, and intensity modulated and arc delivery techniques can help spare organs at risk. New delivery approaches, such as tumor tracking and gating, offer additional potential for further reducing target margins. Image-guided adaptive radiation therapy (IGART) introduces the potential for individualized plan adaptation based on imaging feedback, including bulky residual disease, tumor progression, and physiological changes that occur during the treatment course. This review provides an overview of the current state of the art technology for lung cancer volume definition, treatment planning, localization, and treatment plan adaptation.

Patterns of locoregional failure in stage III non-small cell lung cancer treated with definitive chemoradiation therapy

PURPOSE

Chemoradiation therapy (CRT) is the core treatment of locally advanced non-small cell lung cancer (LA-NSCLC), but potential toxicities limit radiation therapy dose. These toxicities, plus the advent of increasingly conformal radiation therapy, have prioritized target definition and the use of involved-field radiation therapy (IFRT). Published data largely focus on regional rather than local failure patterns. We report our pattern-of-failure experience treating patients with LA-NSCLC with definitive CRT, focusing on both local and regional recurrences with detailed dosimetric analyses of failure location.

METHODS AND MATERIALS

Patients treated between December 2004-2010 were included. Imaging scans from date of failure were fused with the RT-planning CT scan, and recurrent nodes were contoured to determine if the recurrence was in a previously irradiated region, defined as involved nodal recurrence (INR) versus elective nodal recurrence (ENR). Local failures were contoured and identified as in-field, marginal, or out-of-field based on dose received. Actuarial overall survival (OS) and progression-free survival (PFS) were calculated, and the cumulative incidences of local, regional, locoregional, and distant recurrence (CILR, CIRR, CILRR, CIDR) were determined with death as a competing risk.

RESULTS

One hundred five patients were included with a median survival of 21.8 months. The 3-year OS and PFS were 36% and 22%, respectively. The 3 year CILRR, CILR, CIRR, CIDR were 41%, 38%, 40%, and 58%, respectively. Thirty patients failed regionally, but only 7 patients developed an ENR with no concurrent local failure or INR, and only 1 of these patients did not develop distant metastases within 1 month of recurrence. A total of 21 patients (20%) developed an ENR with or without other areas of recurrence.

CONCLUSIONS

Elective regional recurrences rarely occurred as the sole site of failure, despite the use of IFRT. Moreover, the pattern of local failure was entirely in-field. These data strongly support field design focusing on gross nodal and primary disease.

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

Background

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

Patients and methods

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

Results

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

Conclusion

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

Lung

The lungs are particularly sensitive to RT, and are often the primary dose-limiting structure during thoracic therapy.

The alveolar/capillary units and pneumocytes within the alveoli appear to be particularly sensitive to RT.

Hypoxia may be important in the underlying physiology of RT-associated lung injury.

The cytokine transforming growth factor-beta (TGF-β), plays an important role in the development of RT-induced fibrosis.

The histopathological changes observed in the lung after RT are broadly characterized as diffuse alveolar damage.

The interaction between pre-treatment PFTs and the risk of symptomatic lung injury is complex. Similarly, the link between changes in PFTs and the development of symptoms is uncertain.

The incidence of symptomatic lung injury increases with increase in most dosimetric parameters. The mean lung dose (MLD) and V20 have been the most-often considered parameters. MLD might be a preferable metric since it considers the entire 3D dose distribution.

Radiation to the lower lobes appears to be more often associated with clinical symptoms than is radiation to the upper lobes. This might be related to incidental cardiac irradiation. In pre-clinical models, there appears to be a complex interaction between lung and heart irradiation.

TGF-β has been suggested in several studies to predict for RT-induced lung injury, but the data are still somewhat inconsistent.

Oral prednisone (Salinas and Winterbauer 1995), typically 40–60 mg daily for 1–2 weeks with a slow taper, is usually effective in treating pneumonitis. There are no widely accepted treatments for fibrosis.

A number of chemotherapeutic agents have been suggested to be associated with a range of pulmonary toxicities.

Evidence based radiation oncology with existing technology

AIM

To assess the real contribution of modern radiation therapy (RT) technology in the more common tumoral types in Central America, Caribbean and South America.

BACKGROUND

RT is an essential tool in the management of cancer. RT can be either palliative or of curative intent. In general, for palliative radiotherapy, major technologies are not needed.

MATERIALS AND METHODS

We analyzed the contribution of RT technology based on published evidence for breast, lung, gastric, gallbladder, colorectal, prostate and cervix cancer in terms of disease control, survival or toxicity with especial focus on Latin America.

RESULTS

Findings indicate that three dimensional conformal radiation therapy (3D RT) is the gold standard in most common type of cancer in the studied regions. Prostate cancer is probably the pathology that has more benefits when using new RT technology such as intensity modulated radiation therapy (IMRT) versus 3DRT in terms of toxicity and biochemical progression-free survival.

CONCLUSIONS

In light of the changes in technology, the ever-increasing access of developing countries to such technology, and its current coverage in Latin America, any efforts in this area should be aimed at improving the quality of the radiotherapy departments and centers that are already in place.

The use of proton-beam therapy in the treatment of non-small-cell lung cancer

Lung cancer is the most common cause of cancer death worldwide. Surgical resection has played a major role in the treatment of non-small-cell lung cancer (NSCLC); however, the disease is often detected in a progressive and inoperable form. Surgical resection may also be impossible for early-stage NSCLC due to medical conditions, such as pulmonary or cardiovascular disease and old age. Radiotherapy plays an important role for these patients. Proton-beam therapy is a particle radiotherapy with an excellent dose localization that permits treatment of lung cancer by administering a high dose to the tumor while minimizing damage to the surrounding normal tissues. Thus, proton beams are increasingly being used for lung cancer. In this context, the authors review the current knowledge on proton-beam therapy for the treatment of NSCLC.

ACR appropriateness criteria nonsurgical treatment for non-small-cell lung cancer: poor performance status or palliative intent

Radiation therapy plays a potential curative role in the treatment of patients with non-small-cell lung cancer with locoregional disease who are not surgical candidates and a palliative role for patients with metastatic disease. Stereotactic body radiation therapy is a relatively new technique in patients with early-stage non-small-cell lung cancer. A trial from RTOG(®) reported >97% local control at 3 years. For patients with locally advanced disease, thoracic radiation to a dose of 60 Gy remains the standard of care. Sequential chemotherapy or radiation alone can be used for patients with poor performance status who cannot tolerate more aggressive approaches. Chemotherapy should be used for patients with metastatic disease. Radiation therapy is useful for palliation of symptomatic tumors, and a dose of approximately 30 Gy is commonly used. Endobronchial brachytherapy is useful for patients with symptomatic endobronchial tumors. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every 2 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

Involved-field radiotherapy versus elective nodal irradiation in combination with concurrent chemotherapy for locally advanced non-small cell lung cancer: a prospective randomized study

This prospective randomized study is to evaluate the locoregional failure and its impact on survival by comparing involved field radiotherapy (IFRT) with elective nodal irradiation (ENI) in combination with concurrent chemotherapy for locally advanced non-small cell lung cancer. It appears that higher dose could be delivered in IFRT arm than that in ENI arm, and IFRT did not increase the risk of initially uninvolved or isolated nodal failures. Both a tendency of improved locoregional progression-free survival and a significant increased overall survival rate are in favor of IFRT arm in this study.

Patterns of regional failure in stage III non-small cell lung cancer treated with neoadjuvant chemoradiation therapy and resection

PURPOSE

Treatment of locally advanced non-small cell lung cancer (LA-NSCLC) involves definitive chemoradiation therapy (CRT) or neoadjuvant CRT and resection, but radiation treatment volumes remain in question. With CRT, involved-field radiation therapy (IFRT) is replacing elective nodal irradiation, reducing toxicity, and allowing dose escalation. However, prior reports of IFRT describe failures only after radical CRT; with improved local control after resection, IFRT may lead to more regional recurrences. Our objective is to evaluate pattern-of-failure in patients with LA-NSCLC treated with split-course IFRT, chemotherapy, and subsequent surgery.

METHODS AND MATERIALS

Patients treated between December 2004 and 2010 were included. Imaging scans demonstrating failure were fused into the radiation therapy planning computed tomography, and recurrent nodes were contoured to determine pattern-of-failure (involved versus elective nodal failure [INF vs ENF]). Locoregional progression-free survival and distant metastasis-free survival were calculated using Kaplan-Meier methodology. The cumulative incidence of regional recurrence (CIRR) was determined with death as a competing risk.

RESULTS

Forty-five patients met inclusion criteria, and patients with RR had a lower rate of pN0 than those without RR (20% vs 60%, P = .02). With a median follow-up of 2.9 years, median survival was not reached, and 3-year locoregional progression-free survival and distant metastasis-free survival were 53% and 35%, respectively. Two and 3-year CIRR were 25% and 33%, respectively. There were no local failures. Thirteen (29%) patients had RR, 8 with INF only and 5 with ENF alone or both, totaling 27 recurrences. Only 2 (4%) ENF occurred without INF, both with distant metastasis, and no elective node was the first and only site of failure.

CONCLUSIONS

Our data suggest that IFRT does not compromise regional control in the neoadjuvant management of LA-NSCLC. Tailoring nodal volumes may improve treatment-related morbidity and allow for dose intensification of involved nodes. Further research is necessary to improve regional and distant control.

Dosimetric Feasibility of Dose Escalation Using SBRT Boost for Stage III Non-Small Cell Lung Cancer

PURPOSE

Standard chemoradiation therapy for stage III non-small cell lung cancer (NSCLCa) results in suboptimal outcomes with a high rate of local failure and poor overall survival. We hypothesize that dose escalation using stereotactic body radiotherapy (SBRT) boost could improve upon these results. We present here a study evaluating the dosimetric feasibility of such an approach.

METHODS

Anonymized CT data sets from five randomly selected patients with stage III NSCLCa undergoing definitive chemoradiation therapy in our department with disease volumes appropriate for SBRT boost were selected. Three-dimensional conformal radiation therapy (3D-CRT) plans to 50.4 Gy in 28 fractions were generated follow by SBRT plans to two dose levels, 16 Gy in two fractions and 28 Gy in two fractions. SBRT plans and total composite (3D-CRT and SBRT) were optimized and evaluated for target coverage and dose to critical structures; lung, esophagus, cord, and heart.

RESULTS

All five plans met predetermined target coverage and normal tissue dose constraints. PTV V95 was equal to or greater than 95% in all cases. The cumulative lung V20 and V5 of the combined 3D-CRT and SBRT plans were less than or equal to 30 and 55%, respectively. The 5 cc esophageal dose was less than 12 Gy for all low and high dose SBRT plans. The cumulative dose to the esophagus was also acceptable with less than 10% of the esophagus receiving doses in excess of 50 Gy. The cumulative spinal cord dose was less than 33 Gy and heart V25 was less than 5%.

CONCLUSION

The combination of chemoradiation to 50.4 Gy followed by SBRT boost to gross disease at the primary tumor and involved regional lymph nodes is feasible with respect to normal tissue dose constraints in this dosimetric pilot study. A phase I/II trial to evaluate the clinical safety and efficacy of this approach is being undertaken.

Superiority of conventional intensity-modulated radiotherapy over helical tomotherapy in locally advanced non-small cell lung cancer. A comparative plan analysis

PURPOSE

To compare helical tomotherapy (HT) and conventional intensity-modulated radiotherapy (IMRT) using a variety of dosimetric and radiobiologic indexes in patients with locally advanced non-small cell lung cancer (LA-NSCLC).

PATIENTS AND METHODS

A total of 20 patients with LA-NSCLC were enrolled. IMRT plans with 4-6 coplanar beams and HT plans were generated for each patient. Dose distributions and dosimetric indexes for the tumors and critical structures were computed for both plans and compared.

RESULTS

Both modalities created highly conformal plans. They did not differ in the volumes of lung exposed to > 20 Gy of radiation. The average mean lung dose, volume receiving ≥ 30 Gy, and volume receiving ≥ 10 Gy in HT planning were 18.3 Gy, 18.5%, and 57.1%, respectively, compared to 19.4 Gy, 25.4%, and 48.9%, respectively, with IMRT (p = 0.004, p < 0.001, and p < 0.001). The differences between HT and IMRT in lung volume receiving ≥ 10-20 Gy increased significantly as the planning target volume (PTV) increased. For 6 patients who had PTV greater than 700 cm(3), IMRT was superior to HT for 5 patients in terms of lung volume receiving ≥ 5-20 Gy. The integral dose to the entire thorax in HT plans was significantly higher than in IMRT plans.

CONCLUSION

HT gave significantly better control of mean lung dose and volume receiving ≥ 30-40 Gy, whereas IMRT provided better control of the lung volume receiving ≥ 5-15 Gy and the integral dose to entire thorax. In most patients with PTV greater than 700 cm(3), IMRT was superior to HT in terms of lung volume receiving ≥ 5-20 Gy. It is therefore advised that caution should be exercised when planning LA-NSCLC using HT.

Pattern of failure after high-dose thoracic radiation for non-small cell lung cancer: the University of Michigan experience

PURPOSE

Our main purpose is to study the pattern of local failure for patients with non-small cell lung cancer treated with conformal therapy.

METHODS

This study included patients who failed locally and a matched group without failures after 3D conformal radiation per a radiation dose-escalation trial. Radiation doses ranged from 65.1 to 102.9 Gy in 2.1 Gy fractions, originally computed using an equivalent path length algorithm. The recurrent gross target volumes (RGTV) were contoured. The original and recurrent planning target volume (PTV and RPTV) were generated by 1 cm uniform expansion from GTV. DVHs and generalized equivalent uniform doses (EUD={Σ _i (d_i ) ^a }^1/a ) were computed. Marginal failures were defined for RGTVs covered by the original 10 to 90 % isodose surfaces.

RESULTS

There were no significant differences between the failed and control groups with regard to average original GTV volumes, GTV and PTV doses, and minimum PTV doses. Of the 18 RGTVs, four had marginal failure, 12 failed mostly within, and two failed outside of the original PTV. The mean EUDs were 57.1 Gy (95 % confidence interval (CI) 43.9-70.6) and 47.5 Gy (95 % CI 33.7-61.2), for the RGTVs and RPTVs, respectively, significantly below the prescribed doses (p=0.03). EUDs were less than 60 Gy for 39 % of the RGTVs and 56 % of the RPTVs.

CONCLUSIONS

Recurrent tumors had significantly lower doses than the prescribed dose suggesting that some of these failures could have been avoided with modern technology such as 4D CT simulation and image-guided radiation therapy.

Randomized phase II study of palifermin for reducing dysphagia in patients receiving concurrent chemoradiotherapy for locally advanced unresectable non-small cell lung cancer

INTRODUCTION

Dysphagia is a common, dose-limiting toxicity of combined chemoradiotherapy (CT/RT) in patients with locally advanced non-small cell lung cancer (NSCLC). This study assessed the efficacy and safety of palifermin in reducing dysphagia from CT/RT followed by consolidation chemotherapy (CT).

METHODS

This randomized, double-blind, phase II trial enrolled adults with unresectable stage III NSCLC. Subjects received weekly paclitaxel (50 mg/m2) and carboplatin (AUC 2.0) with concurrent daily radiation (RT) of 6000 to 6600 cGy, followed by consolidation CT. Palifermin (n = 49) or placebo (n = 46) was administered before starting concurrent CT/RT and once weekly for 6 weeks. The primary end points were the incidence of grade ≥ 2 dysphagia and safety.

RESULTS

The incidence of grade ≥ 2 and ≥ 3 dysphagia was numerically lower in palifermin subjects versus placebo subjects (61% versus 70%; p = 0.36; 22% versus 28%, p = 0.50, respectively). Mean duration of dysphagia (grade ≥ 2) was 25 days for palifermin subjects and 32 days for placebo subjects (p = 0.32). The incidence of adverse events was similar in the two treatment groups, and median overall survival and progression-free survival were not adversely affected by palifermin treatment (overall survival: 513 versus 319 days; progression-free survival: 262 versus 235 days for palifermin versus placebo arms, respectively). The palifermin arm received more doses of CT per study design and significantly more patients received RT doses ≥ 6000 cGy (84% versus 61%, p = 0.01).

CONCLUSIONS

The results of this exploratory trial suggest that additional larger studies may be warranted to further evaluate the effect of palifermin on dysphagia, exposure to CT/RT, and long-term survival.

Stereotactic body radiation therapy and 3-dimensional conformal radiotherapy for stage I non-small cell lung cancer: A pooled analysis of biological equivalent dose and local control

PURPOSE

To determine the relationship between tumor control probability (TCP) and biological effective dose (BED) for radiation therapy in medically inoperable stage I non-small cell lung cancer (NSCLC).

METHODS AND MATERIALS

Forty-two studies on 3-dimensional conformal radiation therapy (3D-CRT) and SBRT for stage I NSCLC were reviewed for tumor control (TC), defined as crude local control ≥ 2 years, as a function of BED. For each dose-fractionation schedule, BED was calculated at isocenter using the linear quadratic (LQ) and universal survival curve (USC) models. A scatter plot of TC versus BED was generated and fitted to the standard TCP equation for both models.

RESULTS

A total of 2696 patients were included in this study (SBRT: 1640; 3D-CRT: 1056). Daily fraction size was 1.2-4 Gy (total dose: 48-102.9) with 3D-CRT and 6-26 (total dose: 20-66) with SBRT. Median BED was 118.6 Gy (range, 68.5-320.3) and 95.6 Gy (range, 46.1-178.1) for the LQ and USC models, respectively. According to the LQ model, BED to achieve 50% TC (TCD50) was 61 Gy (95% confidence interval, 50.2-71.1). TCP as a function of BED was sigmoidal, with TCP ≥ 90% achieved with BED ≥ 159 Gy and 124 Gy for the LQ and USC models, respectively.

CONCLUSIONS

Dose-escalation beyond a BED 159 by LQ model likely translates into clinically insignificant gain in TCP but may result in clinically significant toxicity. When delivered with SBRT, BED of 159 Gy corresponds to a total dose of 53 Gy in 3 fractions at the isocenter.

Stereotactic body radiation therapy in non-small-cell lung cancer: linking radiobiological modeling and clinical outcome

For patients with peripheral, early-stage non-small-cell lung cancer, it has been found feasible to deliver 5 or fewer fractions of large doses through stereotactic body radiation therapy (SBRT) without causing severe early or late injury and with impressive tumor control. In this review, we employ radiobiological modeling with the linear quadratic formulation to explore the adequacy of various dose schedules used for tumor control in the lung as supported by clinical evidence, the influence of dose distribution and delivery time on local control, and how to decrease the likelihood of severe toxicity following SBRT. Furthermore, the validity of the linear quadratic formalism in the high dose range of SBRT for lung cancer is explored.

Functional and molecular image guidance in radiotherapy treatment planning optimization

Functional and molecular imaging techniques are increasingly being developed and used to quantitatively map the spatial distribution of parameters, such as metabolism, proliferation, hypoxia, perfusion, and ventilation, onto anatomically imaged normal organs and tumor. In radiotherapy optimization, these imaging modalities offer the promise of increased dose sparing to high-functioning subregions of normal organs or dose escalation to selected subregions of the tumor as well as the potential to adapt radiotherapy to functional changes that occur during the course of treatment. The practical use of functional/molecular imaging in radiotherapy optimization must take into cautious consideration several factors whose influences are still not clearly quantified or well understood including patient positioning differences between the planning computed tomography and functional/molecular imaging sessions, image reconstruction parameters and techniques, image registration, target/normal organ functional segmentation, the relationship governing the dose escalation/sparing warranted by the functional/molecular image intensity map, and radiotherapy-induced changes in the image intensity map over the course of treatment. The clinical benefit of functional/molecular image guidance in the form of improved local control or decreased normal organ toxicity has yet to be shown and awaits prospective clinical trials addressing this issue.

Proton therapy in clinical practice

Radiation dose escalation and acceleration improves local control but also increases toxicity. Proton radiation is an emerging therapy for localized cancers that is being sought with increasing frequency by patients. Compared with photon therapy, proton therapy spares more critical structures due to its unique physics. The physical properties of a proton beam make it ideal for clinical applications. By modulating the Bragg peak of protons in energy and time, a conformal radiation dose with or without intensity modulation can be delivered to the target while sparing the surrounding normal tissues. Thus, proton therapy is ideal when organ preservation is a priority. However, protons are more sensitive to organ motion and anatomy changes compared with photons. In this article, we review practical issues of proton therapy, describe its image-guided treatment planning and delivery, discuss clinical outcome for cancer patients, and suggest challenges and the future development of proton therapy.

Individualized higher dose of 70-75 Gy using five-fraction robotic stereotactic radiotherapy for non-small-cell lung cancer: a feasibility study

OBJECTIVE

To determine whether robotic stereotactic radiotherapy of 70-75 Gy delivered in five fractions results in an improved therapeutic ratio, compared with three fractions, in the treatment of peripheral non-small-cell lung cancer (NSCLC), in which case doses of up to 85 Gy in five fractions may be feasible.

MATERIALS AND METHODS

Between December 2006 and May 2010, 20 patients (9 female, 11 male, aged 65 to 88) were treated using the CyberKnife® Robotic Radiosurgery System for NSCLC with doses ranging from 67 Gy to 75 Gy based on location, histopathological type, grade of histopathological differentiation, tumor diameter/volume, and normal tissue constraints, with the doses being delivered in five fractions over 5 to 8 days. Tumor diameters ranged from 1.5 cm to 3.4 cm (median: 2.5 cm). Patients with Stage I to IV NSCLC were treated, and the results and observations were analyzed for clinical characteristics and outcomes including toxicity. All patients, except one who had refused surgery, had co-morbid conditions that precluded a lobectomy.

RESULTS

Twenty patients were followed every three months by positron emission tomography/computed tomography (PET/CT). Mean follow-up was 23 months (range: four to 58 months). Local control was achieved in all treated tumors. Three patients expired, and three developed new regional metastases, none of which was within the planning target volume (PTV). The remainder of the patients demonstrated no evidence of recurrence or continued growth detectable by PET/CT. There was no toxicity above Grade 1.

CONCLUSIONS

It is feasible to treat peripheral NSCLC with individualized maximal tolerable doses ranging from 67 Gy to 75 Gy in five fractions chosen on the basis of location, histopathological type, grade of histopathological differentiation, tumor diameter/volume, and normal tissue constraints.

Multiple breath-hold CBCT for online image guided radiotherapy of lung tumors: simulation with a dynamic phantom and first patient data

BACKGROUND AND PURPOSE

Computer controlled breath-hold effectively reduces organ motion for image-guided precision radiotherapy of lung tumors. However, the acquisition time of 3D cone-beam-CT (CBCT) exceeds maximum breath-hold times. We have developed an approach enabling online verification using CBCT image acquisition with ABC®-based breath-hold.

METHODS

Patient CBCT images were acquired with ABC®-based repeat breath-hold. The clinical situation was also simulated with a Motion Phantom. Reconstruction of patient and phantom images with selection of free-breathing and breath-hold projections only was performed.

RESULTS

CBCT-imaging in repeat breath-hold resulted in a precisely spherical appearance of a tumor-mimicking structure in the phantom. A faint "ghost" structure (free-breathing phases) can be clearly discriminated. Mean percentage of patient breath-hold time was 66%. Reconstruction based on free-breathing-only shows blurring of both tumor and diaphragm, reconstruction based on breath-hold projections only resulted in sharp contours of the same structures. From the phantom experiments, a maximal repositioning error of 1mm in each direction can be estimated.

DISCUSSION AND CONCLUSION

CBCT during repetitive breath hold provides reliable soft-tissue-based positioning. Fast 3D-imaging during one breath-hold is currently under development and has the potential to accelerate clinical linac-based volume imaging.

The effect of an inconsistent breathing amplitude on the relationship between an external marker and internal lung deformation in a porcine model

PURPOSE

Investigate the relationship between the motion of the Varian Real-time Position Management (RPM) device and the internal motion of a pig during induced inconsistencies in the amplitude of breathing.

METHODS

Twelve studies were performed on four ventilated female Landrace cross pigs using a GE Healthcare, Discovery CT 750 HD scanner. In each study, a 4.0 cm section (64 slices) of the pig's lungs was repeatedly scanned 20 times using cine mode, each time lasting more than one breathing cycle. During these cine scans, a Varian RPM device was used to collect respiratory amplitudes and the ventilator air return tube was periodically crimped to induce inconsistent breathing amplitudes. Each breathing cycle and its associated cine scan were categorized as either consistent or inconsistent, based on thresholds of the minimum expiration and maximum inspiration amplitudes. From the group of consistent amplitude cine scans in a study, a reference scan was chosen. The effect of inconsistent breathing amplitudes on the relationship between the motion of the RPM marker and the motion within three regions of interest (in each lung and the chest wall) was investigated with two methods: (1) A 4D-CT sorting algorithm based on RPM amplitude was used to sort volumes into 4D-CT phase bins. Within each phase bin, the nonlinear deformation of volumes collected during consistent and inconsistent breathing amplitude was calculated with respect to the reference volume. The magnitude of the deformations (in mm) were compared to determine if inconsistent breathing amplitude caused greater deformations. (2) Nonlinear deformations between each CT volume from a cine scan and the maximum expiration volume of the reference scan were calculated. Regression analyses between the nonlinear deformations within three regions of interest (in each lung and the chest wall) and the RPM amplitudes were performed to test the effect of inconsistent breathing amplitudes on the linearity of the relationship between the 3D motion of internal anatomy and the 1D motion of the RPM external marker.

RESULTS

(1) Inconsistent versus consistent breathing amplitudes caused a significant increase in deformation relative to the reference scan within the left lung (1.40 +/- 0.42 versus 1.29 +/- 0.36 mm, p < 0.05). (2) One-to-one correspondences between motions of internal anatomies and motion of the RPM external marker did not exist. The regression lines between the two types of motions did not yield an identity relationship (unity slope and zero intercept). Inconsistent breathing produced significantly different regression lines than consistent breathing in ten of the 12 studies within a left lung region of interest.

CONCLUSIONS

The results of these two studies indicate that inconsistency in the amplitude of breathing disrupted the correspondence between the motion of the external marker and internal anatomies. As a consequence, radiation therapy of tumors embedded in lung tissue may be prone to significant errors if inconsistent breathing amplitudes occur during treatment.

European Organisation for Research and Treatment of Cancer Recommendations for Planning and Delivery of High-Dose, High-Precision Radiotherapy for Lung Cancer

Purpose

To derive recommendations for routine practice and clinical trials for techniques used in high-dose, high-precision thoracic radiotherapy for lung cancer.

Methods

A literature search was performed to identify published articles considered both clinically relevant and practical to use. Recommendations were categorized under the following headings: patient selection, patient positioning and immobilization, tumor motion, computed tomography and [18F]fluorodeoxyglucose–positron emission technology scanning, generating target volumes, radiotherapy treatment planning, treatment delivery, and scoring of response and toxicity. The American College of Chest Physicians grading of recommendations was used.

Results

Recommendations were identified for each of the recommendation categories. Although most of the recommended techniques have not been evaluated in multicenter clinical trials, their use in high-precision thoracic radiotherapy and stereotactic body radiotherapy (SBRT) appears to be justified on the basis of available evidence.

Conclusion

Recommendations to facilitate the clinical implementation of high-precision conformal radiotherapy and SBRT for lung tumors were identified from the literature. Some techniques that are considered investigational at present were also highlighted.

Exploring the feasibility of dose escalation positron emission tomography-positive disease with intensity-modulated radiation therapy and the effects on normal tissue structures for thoracic malignancies

The pattern of failure is one of the major causes of mortality among thoracic patients. Studies have shown a correlation between local control and dose. Intensity-modulated radiation therapy (IMRT) has resulted in conformal dose distributions while limiting dose to normal tissue. However, thoracic malignancies treated with IMRT to highly conformal doses up to 70 Gy still have been found to fail. Thus, the need for dose escalation through simultaneous integrated boost (SIB) may prove effective in minimizing reoccurrences. For our study, 28 thoracic IMRT plans were reoptimized via dose escalation to the gross tumor volume (GTV) and planning target volume (PTV) of 79.2 Gy and 68.4 Gy, respectively. Reoccurrences in surrounding regions of microscopic disease are rare therefore, dose-escalating regional nodes (outside GTV) were not included. Hence, the need to edit GTV margins was acceptable for our retrospective study. A median dose escalation of approximately 15 Gy (64.8-79.2 Gy) via IMRT using SIB was deemed achievable with minimal percent differences received by critical structures compared with the original treatment plan. The target's mean doses were significantly increased based on p-value analysis, while the normal tissue structures were not significantly changed.

Large volume unresectable locally advanced non-small cell lung cancer: acute toxicity and initial outcome results with rapid arc

BACKGROUND

To report acute toxicity, initial outcome results and planning therapeutic parameters in radiation treatment of advanced lung cancer (stage III) with volumetric modulated arcs using RapidArc (RA).

METHODS

Twenty-four consecutive patients were treated with RA. All showed locally advanced non-small cell lung cancer with stage IIIA-IIIB and with large volumes (GTV:299 ± 175 cm3, PTV:818 ± 206 cm3). Dose prescription was 66Gy in 33 fractions to mean PTV. Delivery was performed with two partial arcs with a 6 MV photon beam.

RESULTS

From a dosimetric point of view, RA allowed us to respect most planning objectives on target volumes and organs at risk. In particular: for GTV D1% = 105.6 ± 1.7%, D99% = 96.7 ± 1.8%, D5%-D95% = 6.3 ± 1.4%; contra-lateral lung mean dose resulted in 13.7 ± 3.9Gy, for spinal cord D1% = 39.5 ± 4.0Gy, for heart V45Gy = 9.0 ± 7.0Gy, for esophagus D1% = 67.4 ± 2.2Gy. Delivery time was 133 ± 7s. At three months partial remission > 50% was observed in 56% of patients. Acute toxicities at 3 months showed 91% with grade 1 and 9% with grade 2 esophageal toxicity; 18% presented grade 1 and 9% with grade 2 pneumonia; no grade 3 acute toxicity was observed. The short follow-up does not allow assessment of local control and progression free survival.

CONCLUSIONS

RA proved to be a safe and advantageous treatment modality for NSCLC with large volumes. Long term observation of patients is needed to assess outcome and late toxicity.

High-dose conformal radiotherapy for patients with stage III non-small-cell lung carcinoma

PURPOSE

To determine the effectiveness of high-dose conformal radiotherapy to the involved field for patients with Stage III non-small-cell lung cancer (NSCLC).

METHODS AND MATERIALS

Between May 1999 and April 2006, a total of 100 consecutive patients with inoperable Stage IIIA or IIIB NSCLC with a performance score of 0 to 2 and treatment by radical radiotherapy combined with chemotherapy were included. Up to August 2002, 33 patients underwent conventional radiotherapy of 56 Gy to 66 Gy using anteroposterior opposite ports to the primary tumor and elective lymph nodes (conventional group). After September 2002, the remaining 67 patients underwent high-dose radiotherapy of 66 Gy to 84 Gy to the involved volume with three-dimensional (3-D) conformal radiotherapy (conformal group).

RESULTS

The median survival was 13.2 months (95% confidence interval [CI], 7.5-18.5 months) in the conventional group and 17.3 months (95% CI, 10.7- 24.0 months) in the conformal group. The overall survival at 3 years were 9.1% (95% CI, -0.7-18.9%) in the conventional group and 31.0% (95% CI, 18.9-43.1%) in the conformal group; the conformal group had a significantly better overall survival (p < 0.05). The radiotherapy method (hazard ratio = 0.55, p < 0.05) and performance status (hazard ratio = 1.48, p < 0.05) were shown to be statistically significant independent prognostic factors.

CONCLUSIONS

Based on the practical experience reported here, 3-D conformal radiotherapy allowed dose escalation without excessive toxicity, and may improve overall survival rates for patients with Stage III NSCLC.

Effect of radiotherapy planning complexity on survival of elderly patients with unresected localized lung cancer

PURPOSE

To evaluate whether complex radiotherapy (RT) planning was associated with improved outcomes in a cohort of elderly patients with unresected Stage I-II non-small-cell lung cancer (NSCLC).

METHODS AND MATERIALS

Using the Surveillance, Epidemiology, and End Results registry linked to Medicare claims, we identified 1998 patients aged >65 years with histologically confirmed, unresected stage I-II NSCLC. Patients were classified into an intermediate or complex RT planning group using Medicare physician codes. To address potential selection bias, we used propensity score modeling. Survival of patients who received intermediate and complex simulation was compared using Cox regression models adjusting for propensity scores and in a stratified and matched analysis according to propensity scores.

RESULTS

Overall, 25% of patients received complex RT planning. Complex RT planning was associated with better overall (hazard ratio 0.84; 95% confidence interval, 0.75-0.95) and lung cancer-specific (hazard ratio 0.81; 95% confidence interval, 0.71-0.93) survival after controlling for propensity scores. Similarly, stratified and matched analyses showed better overall and lung cancer-specific survival of patients treated with complex RT planning.

CONCLUSIONS

The use of complex RT planning is associated with improved survival among elderly patients with unresected Stage I-II NSCLC. These findings should be validated in prospective randomized controlled trials.