Late complications of high-dose (>/=66 Gy) thoracic conformal radiation therapy in combined modality trials in unresectable stage III non-small cell lung cancer

Preclinical models of radiation-induced cardiac toxicity: Potential mechanisms and biomarkers

Radiation therapy (RT) is an important modality in cancer treatment with >50% of cancer patients undergoing RT for curative or palliative intent. In patients with breast, lung, and esophageal cancer, as well as mediastinal malignancies, incidental RT dose to heart or vascular structures has been linked to the development of Radiation-Induced Heart Disease (RIHD) which manifests as ischemic heart disease, cardiomyopathy, cardiac dysfunction, and heart failure. Despite the remarkable progress in the delivery of radiotherapy treatment, off-target cardiac toxicities are unavoidable. One of the best-studied pathological consequences of incidental exposure of the heart to RT is collagen deposition and fibrosis, leading to the development of radiation-induced myocardial fibrosis (RIMF). However, the pathogenesis of RIMF is still largely unknown. Moreover, there are no available clinical approaches to reverse RIMF once it occurs and it continues to impair the quality of life of long-term cancer survivors. Hence, there is an increasing need for more clinically relevant preclinical models to elucidate the molecular and cellular mechanisms involved in the development of RIMF. This review offers an insight into the existing preclinical models to study RIHD and the suggested mechanisms of RIMF, as well as available multi-modality treatments and outcomes. Moreover, we summarize the valuable detection methods of RIHD/RIMF, and the clinical use of sensitive radiographic and circulating biomarkers.

Medical consequences of radiation exposure of the bronchi-what can we learn from high-dose precision radiation therapy?

The bronchial tolerance to high doses of radiation is not fully understood. However, in the event of a radiological accident with unintended exposure of the central airways to high doses of radiation it would be important to be able to anticipate the clinical consequences given the magnitude of the absorbed dose to different parts of the bronchial tree. Stereotactic body radiation therapy (SBRT) is a radiation treatment technique involving a few large fractions of photon external-beam radiation delivered to a well-defined target in the body. Despite generally favourable results, with high local tumour control and low-toxicity profile, its utility for tumours located close to central thoracic structures has been questioned, considering reports of severe toxic symptoms such as haemoptysis (bleedings from the airways), bronchial necrosis, bronchial stenosis, fistulas and pneumonitis. In conjunction with patient- and tumour-related risk factors, recent studies have analysed the absorbed radiation dose to different thoracic structures of normal tissue to better understand their tolerance to these high doses per fraction. Although the specific mechanisms behind the toxicity are still partly unknown, dose to the proximal bronchial tree has been shown to correlate with high-grade radiation side effects. Still, there is no clear consensus on the tolerance dose of the different bronchial structures. Recent data indicate that a too high dose to a main bronchus may result in more severe clinical side effects as compared to a smaller sized bronchus. This review analyses the current knowledge on the clinical consequences of bronchial exposure to high dose hypofractionated radiation delivered with the SBRT technique, and the tolerance doses of the bronchi. It presents the current literature regarding types of high-grade clinical side effects, data on dose response and comments on other risk factors for high-grade toxic effects.

Central Airway Toxicity After High Dose Radiation: A Combined Analysis of Prospective Clinical Trials for Non-Small Cell Lung Cancer

PURPOSE

To study the dosimetric risk factors for radiation-induced proximal bronchial tree (PBT) toxicity in patients treated with radiation therapy for non-small cell lung cancer (NSCLC).

METHODS AND MATERIALS

Patients with medically inoperable or unresectable NSCLC treated with conventionally fractionated 3-dimensional conformal radiation therapy (3DCRT) in prospective clinical trials were eligible for this study. Proximal bronchial tree (PBT) and PBT wall were contoured consistently per RTOG 1106 OAR-Atlas. The dose-volume histograms (DVHs) of physical prescription dose (DVHp) and biological effective dose (α/β = 2.5; DVH2.5) were generated, respectively. The primary endpoint was PBT toxicities, defined by CTCAE 4.0 under the terminology of bronchial stricture/atelectasis.

RESULTS

Of 100 patients enrolled, with a median follow-up of 64 months (95% confidence interval [CI], 50-78), 73% received 70 Gy or greater and 17% developed PBT toxicity (grade 1, 8%; grade 2, 6%; grade 3, 0%; and grade 4, 3%). The median time interval between RT initiation and onset of PBT toxicity was 8.4 months (95% CI, 4.7-44.1). The combined DVHs showed that no patient with a PBT maximum physical dose <65 Gy developed any PBT toxicity. Cox proportional hazards analysis and receiver operating characteristic analysis demonstrated that V75 of PBT was the most significant dosimetric parameter for both grade 1+ (P = .035) and grade 2+ (P = .037) PBT toxicities. The dosimetric thresholds for V75 of PBT were 6.8% and 11.9% for grade 1+ and grade 2+ PBT toxicity, respectively.

CONCLUSIONS

V75 of PBT appeared be the most significant dosimetric parameter for PBT toxicity after conventionally fractionated thoracic 3DCRT. Constraining V75 of PBT can limit clinically significant PBT toxicity.

The evolving role of radiotherapy in non-small cell lung cancer

Lung cancer is the most commonly diagnosed cancer and biggest cause of cancer mortality worldwide with non-small cell lung cancer (NSCLC) accounting for most cases. Radiotherapy (RT) plays a key role in its management and is used at least once in over half of patients in both curative and palliative treatments. This narrative review will demonstrate how the evolution of RT for NSCLC has been underpinned by improvements in RT technology. These improvements have facilitated geometric individualization, increasingly accurate treatment and now offer the ability to deliver truly individualized RT. In this review, we summarize and discuss recent developments in the field of advanced RT in early stage, locally advanced and metastatic NSCLC. We highlight limitations in current approaches and discuss future potential treatment strategies for patients with NSCLC.

A current review of dose-escalated radiotherapy in locally advanced non-small cell lung cancer

Background The mainstay therapy for locally advanced non-small cell lung cancer is concurrent chemoradiotherapy. Loco-regional recurrence constitutes the predominant failure patterns. Previous studies confirmed the relationship between increased biological equivalent doses and improved overall survival. However, the large randomized phase III study, RTOG 0617, failed to demonstrate the benefit of dose-escalation to 74 Gy compared with 60 Gy by simply increasing fraction numbers. Conclusions Though effective dose-escalation methods have been explored, including altered fractionation, adapting individualized increments for different patients, and adopting new technologies and new equipment such as new radiation therapy, no consensus has been achieved yet.

Concurrent chemo-radiotherapy for unresectable non-small cell lung cancer invading adjacent great vessels on radiologic findings: is it safe?

We performed a retrospective analysis to evaluate treatment outcomes and the risk of fatal hemorrhage by tumor regression when definitive concurrent chemo-radiotherapy (CCRT) was delivered to patients with non-small cell lung cancer (NSCLC) invading adjacent great vessels on radiological findings. We selected 37 unresectable NSCLC patients with adjacent great vessel invasion (GVI) by carefully reviewing each patient's images. The criteria of definite GVI were as follows: irregular indentation at the tumor-vessel contact border, slit-like narrowing of adjacent great vessels by the tumor, presence of intra-luminal mass formation, tumors contacting >5 cm of adjacent great vessel and obliteration of the intervening fat plane between tumor and adjacent great vessel, and/or tumors contacting more than half of the circumference of the aortic wall. All of the patients completed the CCRT, of which the median dose was 66.0 Gy (range, 59.4-72.0 Gy) with 1.8 or 2.0 Gy per fraction. The 2-year overall survival (OS) rate for total patients was 48.2%. Early nodal staging (P = 0.006) and good performance status (P = 0.044) were identified as independent prognostic factors associated with better OS. There was no fatal complication related to the GVI, such as a sudden death or massive hemoptysis due to vascular rupture after CCRT. We concluded that definitive CCRT for NSCLC patients with GVI on radiological findings has a low risk of fatal complication and it can benefit long-term survival when treated with CCRT in patients with early nodal staging or good performance status.

The acute and late toxicity results of a randomized phase II dose-escalation trial in non-small cell lung cancer (PET-boost trial)

BACKGROUND AND PURPOSE

The PET-boost randomized phase II trial (NCT01024829) investigated dose-escalation to the entire primary tumour or redistributed to regions of high pre-treatment FDG-uptake in inoperable non-small cell lung cancer (NSCLC) patients. We present a toxicity analysis of the 107 patients randomized in the study.

MATERIALS AND METHODS

Patients with stage II-III NSCLC were treated with an isotoxic integrated boost of ≥72 Gy in 24 fractions, with/without chemotherapy and strict dose limits. Toxicity was scored until death according to the CTCAEv3.0.

RESULTS

77 (72%) patients were treated with concurrent chemoradiotherapy. Acute and late ≥G3 occurred in 41% and 25%. For concurrent (C) and sequential or radiotherapy alone (S), the most common acute ≥G3 toxicities were: dysphagia in 14.3% (C) and 3.3% (S), dyspnoea in 2.6% (C) and 6.7% (S), pneumonitis in 0% (C) and 6.7% (S), cardiac toxicity in 6.5% (C) and 3.3% (S). Seventeen patients died of which in 13 patients a possible relation to treatment could not be excluded. In 10 of these 13 patients progressive disease was scored. Fatal pulmonary haemorrhages and oesophageal fistulae were observed in 9 patients.

CONCLUSION

Personalized dose-escalation in inoperable NSCLC patients results in higher acute and late toxicity compared to conventional chemoradiotherapy. The toxicity, however, was within the boundaries of the pre-defined stopping rules.

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.

Cardiac Toxicity After Radiotherapy for Stage III Non-Small-Cell Lung Cancer: Pooled Analysis of Dose-Escalation Trials Delivering 70 to 90 Gy

Purpose The significance of radiotherapy (RT) -associated cardiac injury for stage III non-small-cell lung cancer (NSCLC) is unclear, but higher heart doses were associated with worse overall survival in the Radiation Therapy Oncology Group (RTOG) 0617 study. We assessed the impact of heart dose in patients treated at our institution on several prospective dose-escalation trials. Patients and Methods From 1996 to 2009, 127 patients with stage III NSCLC (Eastern Cooperative Oncology Group performance status, 0 to 1) received dose-escalated RT to 70 to 90 Gy (median, 74 Gy) in six trials. RT plans and cardiac doses were reviewed. Records were reviewed for the primary end point: symptomatic cardiac events (symptomatic pericardial effusion, acute coronary syndrome, pericarditis, significant arrhythmia, and heart failure). Cardiac risk was assessed by noting baseline coronary artery disease and calculating the WHO/International Society of Hypertension score. Competing risks analysis was used. Results In all, 112 patients were analyzed. Median follow-up for surviving patients was 8.8 years. Twenty-six patients (23%) had one or more events at a median of 26 months to first event (effusion [n = 7], myocardial infarction [n = 5], unstable angina [n = 3], pericarditis [n = 2], arrhythmia [n = 12], and heart failure [n = 1]). Heart doses (eg, heart mean dose; hazard ratio, 1.03/Gy; P = .002,), coronary artery disease ( P < .001), and WHO/International Society of Hypertension score ( P = .04) were associated with events on univariable analysis. Heart doses remained significant on multivariable analysis that accounted for baseline risk. Two-year competing risk-adjusted event rates for patients with heart mean dose < 10 Gy, 10 to 20 Gy, or ≥ 20 Gy were 4%, 7%, and 21%, respectively. Heart doses were not associated with overall survival. Conclusion Cardiac events were relatively common after high-dose thoracic RT and were independently associated with both heart dose and baseline cardiac risk. RT-associated cardiac toxicity after treatment of stage III NSCLC may occur earlier than historically understood, and heart doses should be minimized.

Role of surgery in N2 NSCLC: pros

The optimal management of clinical N2 Stage IIIA non-small cell lung cancer is still controversial. For a cure of locally advanced IIIA/N2 non-small cell lung cancer, the control of both local regions and possible distant micrometastases is crucial. Chemotherapy is generally expected to prevent distant recurrence. For local tumor control, radiotherapy or surgery has been adopted singly or in combination. If a complete resection can be safely performed, surgery remains the strongest modality for 'eradicating' local disease. Many retrospective studies have reported a possible survival benefit of induction treatment followed by surgery in selected patients with IIIA/N2 non-small cell lung cancer; however, randomized Phase III trials have failed to demonstrate the superiority of induction treatment followed by surgery over chemoradiotherapy, mainly because of the heterogeneity of the N2 status. IIIA/N2 non-small cell lung cancer consists of a heterogeneous group of disease ranging from microscopically single station to radiologically bulky ipsilateral multi-station mediastinal lymph node involvement. A recent definition proposed by the American College of Chest Physicians classified non-small cell lung cancer based on the N2 status, such as discrete or infiltrative type, and recommendations were made according to this N2 status, with definitive chemoradiotherapy recommended for infiltrative clinical N2 and definitive chemoradiotherapy or induction treatment followed by surgery recommended for other cases. Thus, the introduction of a multimodality treatment strategy seems to be necessary for the improved prognosis of non-small cell lung cancer patients with IIIA/N2 disease. In this review, we discuss the role of surgery and the optimal surgical management for patients with IIIA/N2 non-small cell lung cancer.

Normal tissue considerations and dose-volume constraints in the moderately hypofractionated treatment of non-small cell lung cancer

Hypofractionated radiation therapy (RT) regimes in non-small cell lung cancer (NSCLC) have become increasingly popular with a number of international trials currently underway. The majority of the dose-volume-constraints (DVCs) published in the literature refer to conventional 2Gy per fraction deliveries. Here relevant organs-at-risk (OARs) are identified and available dose-volume constraint data discussed and summarised for moderately hypofractionated NSCLC regimes. The OARs examined include lung, brachial plexus, heart, oesophagus, airway and spinal cord. Where available the toxicity rates are also reported with all data summarised tabulated to aid its use in the clinic.

Tracheo-parenchymal fistula following concurrent chemo-radiation for stage III NSCLC

Non-Small Cell Cancer (NSCLC) are frequently diagnosed at a later stage [1]. Treatment involves chemotherapy and radiation, either sequentially or concurrently [2]. Concurrent therapy is more efficacious but also associated with more complications [4–6]. We present a rare care of trachea-pulmonary fistula formation after concurrent chemo and radiation in a patient with Squamous Cell Cancer (SCC).

Which radiation therapy schedule in combination with chemotherapy for locally advanced NSCLC?

Concurrent chemoradiotherapy is the standard of care in the management of locally advanced NSCLC, with disappointing results in terms of local tumor control and overall survival. Hystorically, it has been demonstrated a strict dose–response relationship in thoracic radiotherapy for lung cancer and, therefore, dose escalation was tested in many prospective trials. In this paper, we briefly review the most relevant publications focusing on dose management in terms of dose escalation with both conventional and altered fractionation schedules.

Integrating stereotactic body radiation therapy in stage II/III non-small cell lung cancer: is local control important?

Local control for advanced non-small cell lung cancer (NSCLC) remains a significant problem with chemoradiation local failure rates in the chest of 30-50%. Despite attempts at dose escalation with conventional radiation therapy techniques, toxicities limit the amount of radiation that can be delivered. For stage I NSCLC, mounting evidence supports the use of hypofractionated radiation therapy (SBRT) to gain high local control rates with acceptable toxicity. For healthy patients with stage II/III NSCLC, the National Comprehensive Cancer Network guidelines suggest surgery is the preferred standard of care for patients with <N2 nodes or T3 tumors. In select patients who are surgical candidates or have more extensive disease, guidelines may include pre-operative chemoradiation followed by surgery, although this remains controversial and is the subject of a current national clinical trial (RTOG 0839). Dose escalation through conventional radiation therapy planning suggests that we can improve outcomes in stage III patients, but toxicity remains problematic. It follows that with improvements in imaging and delivery of radiotherapy, dose escalation with SBRT incorporation may improve local control in stage II/III NSCLC for medically inoperable patients. The rationale for dose escalation and some of the considerations for incorporation of SBRT dose escalation in stage III lung cancer are reviewed here.

Hypofractionated three-dimensional conformal radiation therapy alone for centrally located cT1-3N0 non-small-cell lung cancer

PURPOSE

We retrospectively analyzed the treatment outcomes and toxicities by hypofractionated three-dimensional conformal radiation therapy (RT) alone in the patients with centrally located cT1-3N0 non-small-cell lung cancer (NSCLC).

METHODS

Sixty patients with centrally located cT1-3N0 NSCLC received definitive RT alone at 3.0 Gy per fraction for either medical comorbidity or refusal of surgery, between January 2001 and December 2010. The central tumor was defined as being within 2 cm around the proximal bronchial tree. The median total dose was 60 (39-60) Gy.

RESULTS

The local control (LC), overall survival (OS), and cause-specific survival rates at 2 and 5 years were 57.9%, 59.6%, 61.7%, and 50.1%, 33.5%, and 40.5%, respectively. Multivariate analyses showed that high cT stage (p = 0.007) and histology with NSCLC-not otherwise specified (p = 0.008) were the significantly unfavorable prognostic factors for OS, and that high cT stage (p = 0.031) and poor performance state (p = 0.007) were for LC. The LC rate at 2 years was 100% for cT1 tumor, 56.5% for cT2 tumor, and 28.6% for cT3 tumor, respectively. No patients experienced grade 3 or higher esophagitis, and three experienced grade 3 or higher pneumonitis.

CONCLUSION

Hypofractionated RT regimen for centrally located cT1-3N0 NSCLC proved safe with minimal toxicity, and, based on the excellent clinical outcomes in cT1 tumors, might serve as an alternative option for the patients who might not tolerate stereotactic body radiation therapy. As the clinical outcomes in cT2-3 tumors were still unsatisfactory, further dose intensifying regimen coupled with the use of concurrent systemic chemotherapy might be warranted.

Management of normal tissue toxicity associated with chemoradiation (primary skin, esophagus, and lung)

Nearly one quarter of patients with lung cancer present with locally advanced disease where concurrent chemoradiotherapy is the current standard of care for patients with good performance status. Cisplatin-based concurrent chemoradiotherapy consistently showed an improvement in survival compared with sequential chemoradiotherapy, at the expense of an increase in the toxicity profile. Over the past decades, several encouraging biomarkers such as transforming growth factor-beta and radioprotective agents such as amifostine were studied but without reaching approval for patient care. We reviewed the prevalence and risk factors for different adverse effects associated with the combined chemoradiotherapy modality, especially dermatitis, mucositis, esophagitis, and pneumonitis. These adverse effects can further be divided into acute, subacute, and chronic. Dermatitis is usually rare and responds well to topical steroids and usual skin care. Acute esophagitis occurs in 30% of patients and is treated with proton pump inhibitors, promotility agents, local anesthetic, and dietary changes. Radiation pneumonitis is a subacute complication seen in 15% of patients and is usually managed with steroids. Chronic adverse effects such as radiation fibrosis and esophageal stricture occur approximately 6 months after completion of radiation therapy and are usually permanent. In this review, complications of chemoradiotherapy for patients with locally advanced lung cancer are delineated, and approaches to their management are described. Given that treatment interruption is associated with a worse outcome, patients are aggressively treated with a curative intent. Therefore, planning for treatment adverse effects improves patient tolerance, compliance, and outcome.

Fluoroscopically guided balloon dilation for benign bronchial stricture occurring after radiotherapy in patients with lung cancer

PURPOSE

To evaluate the safety and clinical effectiveness of fluoroscopically guided balloon dilation in patients with benign bronchial stricture occurring after radiotherapy (RT).

METHODS

From March 2002 to January 2013, ten patients with benign bronchial stricture occurring after RT underwent fluoroscopically guided balloon dilation as their initial treatment. Technical success, primary and secondary clinical success, improvement in respiratory status, and complications were evaluated. The symptomatic improvement period was calculated.

RESULTS

A total of 15 balloon dilation sessions were performed in ten patients, with a range of 1-4 sessions per patient (mean 1.5 sessions). Technical success was achieved in 100 %. Six of the ten patients exhibited no symptom recurrence and required no further treatment until the end of follow-up (range 4-105 months). Four patients (40 %) experienced recurrent symptom, and two of four patients underwent repeat balloon dilations. The remaining two patients underwent cutting balloon dilation and temporary stent placement, respectively, and they exhibited symptom improvement after adjuvant treatment until the end of our study. Finally, primary clinical success was achieved in six of ten patients (60 %) and secondary clinical success was achieved in eight of ten patients (80 %). The mean symptom improvement period was 61.9 ± 16 months (95 % confidence interval 30.6-93.3).

CONCLUSION

Fluoroscopically guided balloon dilation seems to be safe and clinically effective for the treatment of RT-induced benign bronchial stricture. Temporary stent placement or cutting balloon dilation could be considered in patients with benign bronchial strictures resistant to fluoroscopically guided balloon dilation.

Dose-limiting toxicity after hypofractionated dose-escalated radiotherapy in non-small-cell lung cancer

PURPOSE

Local failure rates after radiation therapy (RT) for locally advanced non-small-cell lung cancer (NSCLC) remain high. Consequently, RT dose intensification strategies continue to be explored, including hypofractionation, which allows for RT acceleration that could potentially improve outcomes. The maximum-tolerated dose (MTD) with dose-escalated hypofractionation has not been adequately defined.

PATIENTS AND METHODS

Seventy-nine patients with NSCLC were enrolled on a prospective single-institution phase I trial of dose-escalated hypofractionated RT without concurrent chemotherapy. Escalation of dose per fraction was performed according to patients' stratified risk for radiation pneumonitis with total RT doses ranging from 57 to 85.5 Gy in 25 daily fractions over 5 weeks using intensity-modulated radiotherapy. The MTD was defined as the maximum dose with ≤ 20% risk of severe toxicity.

RESULTS

No grade 3 pneumonitis was observed and an MTD for acute toxicity was not identified during patient accrual. However, with a longer follow-up period, grade 4 to 5 toxicity occurred in six patients and was correlated with total dose (P = .004). An MTD was identified at 63.25 Gy in 25 fractions. Late grade 4 to 5 toxicities were attributable to damage to central and perihilar structures and correlated with dose to the proximal bronchial tree.

CONCLUSION

Although this dose-escalation model limited the rates of clinically significant pneumonitis, dose-limiting toxicity occurred and was dominated by late radiation toxicity involving central and perihilar structures. The identified dose-response for damage to the proximal bronchial tree warrants caution in future dose-intensification protocols, especially when using hypofractionation.

Conference Scene: Notable trial results in radiation therapy for lung cancer at the ASCO 2013 Annual Meeting

The theme of the American Society of Clinical Oncology 2013 Annual Meeting was ‘building bridges to conquer cancer’. With its diverse attendees and collaborative nature, this meeting provided an excellent forum to define the optimal use of radiation therapy for lung cancer in today’s multimodality environment. Research presented at the meeting touched on core issues including: the optimal dose of radiation for locally advanced lung cancer patients, the efficacy and safety of stereotactic body radiation therapy for early-stage operable lung cancer patients, and the interpretation of surveillance imaging findings in patients treated with radiation therapy. These presentations are recapped and discussed.

Radiation therapy in locally advanced non-small-cell lung cancer: an overview of dose/fractionation strategies to improve outcomes

SUMMARY Local disease control and survival rates of locally advanced non-small-cell lung cancer patients are still poor, even with the best combination of chemotherapy and radiotherapy. Radiotherapy dose is believed to play a major role in controlling local disease, due a steep dose–response relationship for lung cancer, and therefore there is a strong biological rationale to escalate/accelerate the dose. In previous years, several prospective trials explored this option and obtained contrasting results, and recent technical advances in radiotherapy raise the issue of which approach should be considered the most appropriate for future studies. In this article, we briefly review selected prospective Phase I–III trials testing escalation/altered fractionation and focus on future perspectives in this field.

Multimodal hypoxia imaging and intensity modulated radiation therapy for unresectable non-small-cell lung cancer: the HIL trial

Background

Radiotherapy, preferably combined with chemotherapy, is the treatment standard for locally advanced, unresectable non-small cell lung cancer (NSCLC). The tumor response to different therapy protocols is variable, with hypoxia known to be a major factor that negatively influences treatment effectiveness. Visualisation of tumor hypoxia prior to the use of modern radiation therapy strategies, such as intensity modulated radiation therapy (IMRT), might allow optimized dose applications to the target volume, leading to improvement of therapy outcome. ¹⁸ F-fluoromisonidazole dynamic positron emission tomography and computed tomography (¹⁸ F-FMISO dPET-CT) and functional magnetic resonance imaging (functional MRI) are attractive options for imaging tumor hypoxia.

Methods/design

The HIL trial is a single centre study combining multimodal hypoxia imaging with ¹⁸ F-FMISO dPET-CT and functional MRI, with intensity modulated radiation therapy (IMRT) in patients with inoperable stage III NSCLC. 15 patients will be recruited in the study. All patients undergo initial FDG PET-CT and serial ¹⁸ F-FMISO dPET-CT and functional MRI before treatment, at week 5 of radiotherapy and 6 weeks post treatment. Radiation therapy is performed as inversely planned IMRT based on 4D-CT.

Discussion

Primary objectives of the trial are to characterize the correlation of ¹⁸ F-FMISO dPET-CT and functional MRI for tumor hypoxia imaging in NSCLC and evaluate possible effects of radiation therapy on tumor re-oxygenation. Further objectives include the generation of data regarding the prognostic value of ¹⁸ F-FMISO dPET-CT and functional MRI for locoregional control, progression free survival and overall survival of NSCLC treated with IMRT, which will form the basis for larger clinical trials focusing on possible interactions between tumor oxygenation and radiotherapy outcome.

Trial registration

The ClinicalTrials.gov protocol ID is NCT01617980

Emerging developments of chemoradiotherapy in stage III NSCLC

Over the past decade, concomitant chemotherapy and radiotherapy has become the established treatment for patients with stage III non-small-cell lung cancer (NSCLC). Unfortunately, many patients with NSCLC are too old or have multiple comorbidities to withstand such aggressive treatments. Attempts to improve outcomes have included studies of radiotherapy dose escalation and new chemotherapy combinations, as well as adding biological agents and cancer vaccines to existing regimens. Technical radiotherapy modifications, including intensity-modulated radiotherapy and particle beam therapy, have also been investigated. Given the number of potential advances to current models of treatment development, phase III trials of any single new treatment can take years to complete, which is inadequate. To advance research within shorter timescales to improve patient outcomes, we need methods of improving clinical trial accrual, which might require changes in models of research governance, cooperative group activity, trial design and patient consent.

Radiation Dose Escalation in Stage III Non-Small-Cell Lung Cancer

For patients with stage III non-small-cell lung cancer with unresectable or inoperable tumors, definitive chemoradiotherapy is often utilized. Historically, local control and overall survival rates have been poor. In an effort to improve local control, new chemotherapeutic agents in combination with higher doses of radiotherapy have been investigated. Early dose escalation trials date back to the 1980s, and the feasibility and efficacy of dose escalation for patients with inoperable stage III lung cancer continue to be topics of investigation. Herein, we review the evolution of chemotherapy as it relates to treatment of unresectable stage III lung cancer, and we outline the early and the more recent dose escalation studies. While dose escalation appears to provide a modest benefit in terms of preventing local failure and improving overall survival, advances in diagnostic imaging and radiotherapy treatment have possibly resulted in selection of a more favorable patient population. These variables make statements regarding the benefit of dose escalation challenging.

Clinical perspectives on dose escalation for non-small-cell lung cancer

Lung cancer remains the leading cause of cancer death in the United States. The standard of care for patients with locally advanced non-small-cell lung cancer is radiation plus chemotherapy. The nationally accepted standard radiation prescription dose has remained at 60-63 Gy for more than 30 years, with local failure rates reaching 85% and median survival rates of approximately 17 months. With smaller treatment volumes and the increased conformality of radiation delivery, the administration of higher radiation doses to the target while minimizing dose to critical structures is feasible. Clinical outcome is improved while minimizing toxicity. Recent prospective trials escalating doses to 74 Gy with concurrent chemotherapy have demonstrated promise with improved survival rates and acceptable toxicity rates.

Long-term disease-free survival of patients with primary cardiac lymphoma treated with systemic chemotherapy and radiotherapy

Primary cardiac lymphoma (PCL) is a rare disease entity with only a few reported cases in Korea. In this paper, we report a case of PCL in a 59-year-old man presenting with chest pain. Diffuse large B-cell lymphoma was diagnosed through a cardiac catheterization-assisted percutaneous endomyocardial biopsy, and there was no evidence of extracardiac involvement of the lymphoma.The patient had a complete clinical response after systemic chemotherapy with a rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisolone (R-CHOP) regimen and additional post-chemotherapeutic radiation therapy. The patient experienced a long-term disease-free survival of over 4 years. However, he received coronary artery bypass graft surgery due to an acute myocardial infarction that occurred 3 years after the completion of the radiation therapy. Although the addition of radiation therapy to the treatment is thought to decrease the risk of relapse in patients with PCL, a careful and thorough consideration of the potential complications of radiation therapy, particularly with respect to cardiac complications, should be considered.

Effect of image-guidance frequency on geometric accuracy and setup margins in radiotherapy for locally advanced lung cancer

PURPOSE

To assess the relative effectiveness of five image-guidance (IG) frequencies on reducing patient positioning inaccuracies and setup margins for locally advanced lung cancer patients.

METHODS AND MATERIALS

Daily cone-beam computed tomography data for 100 patients (4,237 scans) were analyzed. Subsequently, four less-than-daily IG protocols were simulated using these data (no IG, first 5-day IG, weekly IG, and alternate-day IG). The frequency and magnitude of residual setup error were determined. The less-than-daily IG protocols were compared against the daily IG, the assumed reference standard. Finally, the population-based setup margins were calculated.

RESULTS

With the less-than-daily IG protocols, 20-43% of fractions incurred residual setup errors ≥ 5 mm; daily IG reduced this to 6%. With the exception of the first 5-day IG, reductions in systematic error (∑) occurred as the imaging frequency increased and only daily IG provided notable random error (σ) reductions (∑ = 1.5-2.2 mm, σ = 2.5-3.7 mm; ∑ = 1.8-2.6 mm, σ = 2.5-3.7 mm; and ∑ = 0.7-1.0 mm, σ = 1.7-2.0 mm for no IG, first 5-day IG, and daily IG, respectively. An overall significant difference in the mean setup error was present between the first 5-day IG and daily IG (p < .0001). The derived setup margins were 5-9 mm for less-than-daily IG and were 3-4 mm with daily IG.

CONCLUSION

Daily cone-beam computed tomography substantially reduced the setup error and could permit setup margin reduction and lead to a reduction in normal tissue toxicity for patients undergoing conventionally fractionated lung radiotherapy. Using first 5-day cone-beam computed tomography was suboptimal for lung patients, given the inability to reduce the random error and the potential for the systematic error to increase throughout the treatment course.

Primary analysis of the phase II component of a phase I/II dose intensification study using three-dimensional conformal radiation therapy and concurrent chemotherapy for patients with inoperable non-small-cell lung cancer: RTOG 0117

PURPOSE

Phase I of Radiation Therapy Oncology Group (RTOG) 0117 determined that 74 Gy was the maximum-tolerated dose with concurrent weekly carboplatin/paclitaxel chemotherapy for inoperable non-small-cell lung cancer (NSCLC). Phase II results are reported here. PATIENTS AND METHODS Patients with unresectable stages I-III NSCLC were eligible. Chemotherapy consisted of weekly paclitaxel at 50 mg/m(2) and carboplatin at area under the curve 2 mg/m(2). The radiation dose was 74 Gy given in 37 fractions. Radiation therapy volumes included those of the gross tumor and involved nodes. The volume of lung at or exceeding 20 Gy (V20) was mandated to be

RESULTS

Of the combined phase I/II enrollment, a total of 55 patients received 74 Gy, of whom 53 were evaluable. The median follow-up was 19.3 months (range, 0.9 to 57.9 months) for all patients and 25.4 months (range, 13.1 to 57.9 months) for those still alive. The median survival for all patients was 25.9 months. The percentage surviving at least 12 months was 75.5% (95% CI, 65.7% to 85.2%). The median overall survival (OS) and progression-free survival (PFS) times for stage III patients (n = 44) were 21.6 months and 10.8 months, respectively. OS and PFS rates at 12 months were 72.7% and 50.0%, respectively. Twelve patients experienced grade >or= 3 lung toxicity (two patients had grade 5 lung toxicity).

CONCLUSION

The median survival time and OS rate at 12 months for this regimen are encouraging. These results serve as projection expectations for the high-dose radiation arms of the current RTOG 0617 phase III intergroup trial.

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MESH Headings

• Adult
• Aged
• Aged, 80 and over
• Antineoplastic Combined Chemotherapy Protocols/adverse effects
• Antineoplastic Combined Chemotherapy Protocols/therapeutic use
• Carboplatin/administration & dosage
• Carcinoma, Non-Small-Cell Lung/drug therapy
• Carcinoma, Non-Small-Cell Lung/mortality
• Carcinoma, Non-Small-Cell Lung/pathology
• Carcinoma, Non-Small-Cell Lung/radiotherapy
• Chemotherapy, Adjuvant
• Chi-Square Distribution
• Disease-Free Survival
• Dose Fractionation, Radiation
• Female
• Humans
• Kaplan-Meier Estimate
• Lung Neoplasms/drug therapy
• Lung Neoplasms/mortality
• Lung Neoplasms/pathology
• Lung Neoplasms/radiotherapy
• Male
• Middle Aged
• Neoplasm Staging
• Paclitaxel/administration & dosage
• Radiotherapy, Adjuvant
• Radiotherapy, Conformal/adverse effects
• Time Factors
• Treatment Outcome

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Grants

• U24 CA081647 NCI NIH HHS
• U10 CA21661 NCI NIH HHS
• U10 CA37422 NCI NIH HHS
• U10 CA037422 NCI NIH HHS
• U10 CA021661 NCI NIH HHS

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Affiliation(s)

Jeffrey D Bradley Department of Radiation Oncology, Washington University School of Medicine, Alvin J Siteman Comprehensive Cancer Center, 4921 Parkview Place, St Louis, MO, USA.
Kyounghwa Bae
Mary V Graham
Roger Byhardt
Ramaswamy Govindan
Jack Fowler
James A Purdy
Jeff M Michalski
Elizabeth Gore
Hak Choy

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Systemic review of the patterns of failure following stereotactic body radiation therapy in early-stage non-small-cell lung cancer: clinical implications

PURPOSE

To analyze the patterns of failure, the toxicity profile, and the factors influencing efficacy of stereotactic body radiation (SBRT) for early-stage non-small-cell lung cancer (NSCLC).

METHODS AND MATERIALS

A search was based on PubMed electronic databases. All searches were conducted in May, 2009.

RESULTS

The local control ranged from 80% to 100% in most studies with adequate isocentric or peripheral biologically effective dose (BED). Recurrences were associated with increased tumor size. The main pattern of failure after SBRT was distant metastasis. Grades 3-5 toxicity occurred mostly in centrally located tumors, and adjuvant chemotherapy may further decrease all recurrences; possibly translating to a survival benefit in large or centrally located tumors where high BED cannot be safely reached.

CONCLUSION

SBRT is an excellent treatment option for early-stage, and mostly medically inoperable, NSCLC. BED at both the isocenter and the tumor periphery is very important for optimal tumor control; higher doses are required for large (T2) lesions; SBRT for centrally located tumors can be feasible with a much less aggressive dose regimen than 60-66Gy/3 fractions and adjacent critical structures excluded from the target volume; chemotherapy may optimize the clinical outcome in large or centrally located lesions.