Radiation Dose–Volume Effects in the Spinal Cord

Single-fraction spine SBRT end-to-end testing on TomoTherapy, Vero, TrueBeam, and CyberKnife treatment platforms using a novel anthropomorphic phantom

Spine SBRT involves the delivery of very high doses of radiation to targets adjacent to the spinal cord and is most commonly delivered in a single fraction. Highly conformal planning and accurate delivery of such plans is imperative for successful treatment without catastrophic adverse effects. End-to-end testing is an important practice for evaluating the entire treatment process from simulation through treatment delivery. We performed end-to-end testing for a set of representative spine targets planned and delivered using four different treatment planning systems (TPSs) and delivery systems to evaluate the various capabilities of each. An anthropomorphic E2E SBRT phantom was simulated and treated on each system to evaluate agreement between measured and calculated doses. The phantom accepts ion chambers in the thoracic region and radiochromic film in the lumbar region. Four representative targets were developed within each region (thoracic and lumbar) to represent different presentations of spinal metastases and planned according to RTOG 0631 constraints. Plans were created using the TomoTherapy TPS for delivery using the Hi·Art system, the iPlan TPS for delivery using the Vero system, the Eclipse TPS for delivery using the TrueBeam system in both flattened and flattening filter free (FFF), and the MultiPlan TPS for delivery using the CyberKnife system. Delivered doses were measured using a 0.007 cm3 ion chamber in the thoracic region and EBT3 GAFCHROMIC film in the lumbar region. Films were scanned and analyzed using an Epson Expression 10000XL flatbed scanner in conjunction with FilmQAPro2013. All treatment platforms met all dose constraints required by RTOG 0631. Ion chamber measurements in the thoracic targets delivered an overall average difference of 1.5%. Specifically, measurements agreed with the TPS to within 2.2%, 3.2%, 1.4%, 3.1%, and 3.0% for all three measureable cases on TomoTherapy, Vero, TrueBeam (FFF), TrueBeam (flattened), and CyberKnife, respectively. Film measurements for the lumbar targets resulted in average global gamma index passing rates of 100% at 3%/3 mm, 96.9% at 2%/2mm, and 61.8% at 1%/1 mm, with a 10% minimum threshold for all plans on all platforms. Local gamma analysis was also performed with similar results. While gamma passing rates were consistently accurate across all platforms through 2%/2 mm, treatment beam-on delivery times varied greatly between each platform with TrueBeam FFF being shortest, averaging 4.4 min, TrueBeam using flattened beam at 9.5 min, TomoTherapy at 30.5 min, Vero at 19 min, and CyberKnife at 46.0 min. In spite of the complexity of the representative targets and their proximity to the spinal cord, all treatment platforms were able to create plans meeting all RTOG 0631 dose constraints and produced exceptional agreement between calculated and measured doses. However, there were differences in the plan characteristics and significant differences in the beam-on delivery time between platforms. Thus, clinical judgment is required for each particular case to determine most appropriate treatment planning/delivery platform.

A case report of long-term survival of metastatic extraskeletal myxoid chondrosarcoma treated with surgery and hypofractionated radiotherapy

We describe the case of a patient with a 10-year history of metastatic extraskeletal myxoid chondrosarcoma (EMC), who underwent repeated surgical excision and ten courses of hypofractionated radiotherapy to locally recurrent or metastatic disease. We review the literature on EMC’s and propose that surgery and radiotherapy can be used to control disease progression and palliate symptoms for extended periods of time with acceptable toxicity profiles.

Regorafenib-induced transverse myelopathy after stereotactic body radiation therapy

Stereotactic body radiation therapy (SBRT) delivers large doses of radiation with great accuracy, but is known to have deleterious effects on the vascular compartment of irradiated tissues. Combining SBRT with targeted anti-angiogenesis agents, while able to increase therapeutic efficacy, may unexpectedly precipitate vascular-based toxicities. In this report, we describe a patient with colon cancer who developed transverse myelopathy from regorafenib 2 years after receiving SBRT for three metastatic liver lesions. Regorafenib (Stivarga), formerly BAY 73-4506, (Bayer HealthCare Pharmaceuticals, Montville, NJ) is a multiple receptor tyrosine kinase inhibitor with anti-angiogenic effects used in metastatic colon cancer. Its most common side effects are fatigue, diarrhea and hypertension. However, severe neurologic toxicity has not been previously recognized. Here, we illustrate a case in which the patient developed hyperalgesia and radicular pain 2 weeks after starting regorafenib. Several studies report an increased neurological toxicity when angiogenesis inhibitors are given after radiation therapy, and we postulate that the angioinhibitory effects of regorafenib accelerated subclinical microvascular injury from SBRT. This unexpected toxicity may be clinically relevant when giving targeted angiogenesis inhibitors after SBRT.

Dosimetric impact of the 160 MLC on head and neck IMRT treatments

The purpose of this work is to investigate if the change in plan quality with the finer leaf resolution and lower leakage of the 160 MLC would be dosimetrically significant for head and neck intensity‐modulated radiation therapy (IMRT) treatment plans. The 160 MLC consisting of 80 leaves of 0.5 cm on each bank, a leaf span of 20 cm, and leakage of less than 0.37% without additional backup jaws was compared against the 120 Millennium MLC with 60 leaves of 0.5 and 1.0 cm, a leaf span of 14.5 cm, and leakage of 2.0%. CT image sets of 16 patients previously treated for stage III and IV head and neck carcinomas were replanned on Prowess 5.0 and Eclipse 11.0 using the 160 MLC and the 120 MLC. IMRT constraints for both sets of 6 MV plans were identical and based on RTOG 0522. Dose‐volume histograms (DVHs), minimum dose, mean dose, maximum dose, and dose to 1 cc to the organ at risks (OAR) and the planning target volume, as recommended by QUANTEC 2010, were compared. Both collimators were able to achieve the target dose to the PTVs. The dose to the organs at risk (brainstem, spinal cord, parotids, and larynx) were 1%–12% (i.e., 0.5–8 Gy for a 70 Gy prescription) lower with the 160 MLC compared to the 120 MLC, depending on the proximity of the organ to the target. The large field HN plans generated with the 160 MLC were dosimetrically advantageous for critical structures, especially those located further away from the central axis, without compromising the target volume.

PACS number: 87.55 D‐

Stereotactic radiosurgery results in three cases of intramedullary spinal cord arteriovenous malformations

BACKGROUND CONTEXT

Intramedullary spinal cord arteriovenous malformations (AVMs) are rare and have an unfavorable prognosis. We report our experience of treating three symptomatic patients with stereotactic radiosurgery (SRS). The standard treatment for these lesions are embolization or microsurgical resection. There are only a few reports of efficacy of radiosurgery in these cases.

PURPOSE

To study the efficacy of radiosurgery in intramedullary spinal cord AVM patients, who failed or refused conventional treatment.

STUDY SETTING

This study reports the results of SRS in 3 cases of intramedullary spinal cord AVMs.

PATIENT SAMPLE

Three symptomatic patients diagnosed with intramedullary spinal cord AVMs. Two patients underwent embolization previously and one was newly diagnosed.

OUTCOME MEASURES

The AVM obliteration was assessed by yearly high-resolution magnetic resonance imaging (MRI). Clinical examination was carried out every 6 months.

METHODS

Three symptomatic patients with intramedullary spinal cord AVMs were treated with SRS using the cyberknife system from January 2010 to May 2011. All the three patients presented with acute neurologic symptoms. Two patients were treated previously with embolization. As per protocol, patients underwent a plain computed tomography (CT), CT angiography, high-resolution MRI, and conventional spinal angiography for radiotherapy planning. The mean target volume was 4.05 cc. The prescribed dose was 21 Gy in three fractions on consecutive days. No special immobilization was done during treatment. Continuous image guidance of the treated area was done using the specialized spine tracking software. Follow-up was done by yearly clinical examination and high-resolution spine MRI after SRS.

RESULTS

Mean follow-up was 36 months. Follow-up MRI revealed absence of flow voids, suggesting complete obliteration of the AVM in two patients, with significant improvement in neurologic and functional symptoms. The third patient did not show any clinical improvement or deterioration. There was no incidence of hemorrhage after SRS in any patient and the treatment was well tolerated without any significant complications.

CONCLUSIONS

Stereotactic radiosurgery for intramedullary spinal AVMs appears to be well tolerated and effective in selected cases.

Stereotactic body radiotherapy as primary therapy for head and neck cancer in the elderly or patients with poor performance

OBJECTIVE

Stereotactic body radiotherapy (SBRT) is increasingly used to treat a variety of tumors, including head and neck squamous cell carcinoma (HNSCC) in the recurrent setting. While there are published data for re-irradiation using SBRT for HNSCC, there are limited data supporting its use as upfront treatment for locally advanced disease.

STUDY DESIGN/METHODS

Here, we describe three patients who received SBRT as the primary treatment for their HNSCC along with a review of the current literature and discussion of future pathways.

RESULTS

The three cases discussed tolerated treatment well with manageable acute toxicities and had either a clinical or radiographic complete response to therapy.

CONCLUSION

Head and neck squamous cell carcinoma presents a unique challenge in the elderly, where medical comorbidities make it difficult to tolerate conventional radiation, often given with a systemic sensitizer. For these individuals, providing a shortened course using SBRT may offer an effective alternative.

Dosimetric Evaluation of Volumetric-Modulated Arc Therapy (RapidArc) for Primary Leiomyosarcoma in the Spine

This study aims to investigate the suitability of volumetric-modulated arc therapy (VMAT) with RapidArc for primary leiomyosarcoma (LMS) in the spine, and present a new method to improve the target coverage and organs at risk (OAR) sparing. Five patients with LMS were retrospectively reviewed. The intensity-modulated radiotherapy (IMRT) with five coplanar beams (5b-IMRT) or seven coplanar beams (7b-IMRT), and VMAT using four quasi-quarter coplanar arcs (4q-VMAT) or two full coplanar arcs (2f-VMAT) were generated. Planning target volume (PTV) dose coverage, OAR dose sparing, conformity index (CI), and homogeneity index (HI) were evaluated. A hollow-cylinder model (HCM) was also used for feasible optimal beam arrangements. The mean doses to PTV were 95.2% ± 1.0%, 93.0% ± 1.0%, 97.9% ± 1.0% and 96.2% ± 1.5% for 4q-VMAT, 2f-VMAT, 5b-IMRT and 7b-IMRT respectively, while the mean maximum doses to spinal cord (SC) were 43.7 ± 0.9 Gy, 42.0 ± 0.8 Gy, 41.4 ± 1.2 Gy and 40.6 ± 1.4 Gy. Compared to 5b-IMRT, the mean doses delivered to kidneys decreased by about 35.1% (8.5 Gy), 2.5% (0.6 Gy) and 35.5% (8.6 Gy) for 4q-VMAT, 2f-VMAT, and 7b-IMRT, respectively. The CI proposed by Baltas et al. was twice as good with IMRT than with 4q-VMAT, and the numbers of monitor units were increased five- and threefold with 7b-IMRT and with 5b-IMRT compared to VMAT. The unexpected results we presented here show that VMAT technique can't achieve highly conformal treatment plans while maintaining SC sparing for LMS in the spine. An approach is proposed based on a hollow-cylinder model, but it is difficult to apply to clinical practice. In this case, VMAT is not superior to IMRT except for significant reduction in delivery time.

Clinical evaluation of X-ray voxel Monte Carlo versus pencil beam-based dose calculation in stereotactic body radiotherapy of lung cancer under normal and deep inspiration breath hold

The purpose of this study is to evaluate the differences between dose distributions calculated with the pencil beam (PB) and X-ray voxel Monte Carlo (MC) algorithms for patients with lung cancer using intensity-modulated radiotherapy (IMRT) or HybridArc techniques. The 2 algorithms were compared in terms of dose-volume histograms, under normal and deep inspiration breath hold, and in terms of the tumor control probability (TCP). The dependence of the differences in tumor volume and location was investigated. Dosimetric validation was performed using Gafchromic EBT3 (International Specialty Products, ISP, Wayne, NJ). Forty-five Computed Tomography (CT) data sets were used for this study; 40 Gy at 8 Gy/fraction was prescribed with 5 noncoplanar 6-MV IMRT beams or 3 to 4 dynamic conformal arcs with 3 to 5 IMRT beams distributed per arc. The plans were first calculated with PB and then recalculated with MC. The difference between the mean tumor doses was approximately 10% ± 4%; these differences were even larger under deep inspiration breath hold. Differences between the mean tumor dose correlated with tumor volume and path length of the beams. The TCP values changed from 99.87% ± 0.24% to 96.78% ± 4.81% for both PB- and MC-calculated plans (P = .009). When a fraction of hypoxic cells was considered, the mean TCP values changed from 76.01% ± 5.83% to 34.78% ± 18.06% for the differently calculated plans (P < .0001). When the plans were renormalized to the same mean dose at the tumor, the mean TCP for oxic cells was 99.05% ± 1.59% and for hypoxic cells was 60.20% ± 9.53%. This study confirms that the MC algorithm adequately accounts for inhomogeneities. The inclusion of the MC in the process of IMRT optimization could represent a further step in the complex problem of determining the optimal treatment plan.

Dosimetric and radiobiologic comparison of 3D conformal, IMRT, VMAT and proton therapy for the treatment of early-stage glottic cancer

BACKGROUND

This study aims to compare dosimetrically and radiobiologically 3D conformal, intensity modulated radiation therapy (IMRT), RapidArc (RA) volumetric modulated arc therapy and proton therapy techniques for early-stage glottic cancer.

METHODS

Ten patients were retrospectively selected. Photon treatment planning was performed using Eclipse External Beam Planning, and proton planning was performed using CMS Xio. The minimum, mean and maximum dose values for planning target volume (PTV), mean and maximum dose values for organ at risk, % of volume of PTV receiving at least 95% of the prescription dose, and D20, D50 and D90 of carotid arteries were compared. Biological response models of tumour control probabilities and normal tissue complication probabilities were calculated.

RESULTS

IMRT, RA and proton plans versus three-dimensional conformal radiotherapy (3D-CRT) plans consistently provided superior PTV coverage and decreased mean dose to the thyroid and carotid arteries.

CONCLUSION

All these three modalities showed superiority with less variation among themselves compared with 3D-CRT plans. Clinical investigation is warranted to determine if these treatment approaches will translate into a reduction in radiation therapy-induced toxicities.

[Stereotactic ablative irradiation for lung cancer]

Stereotactic radiotherapy for lung cancer is a technique that is now well established in the therapeutic arsenal. Protocols are effective, with very high local control rate and an acceptable rate of survival if one takes into account the patient's age and comorbidities. Complications are rare. This review of the literature analyses the whole process of the therapeutic indications and future prospects.

Recurrent and second primary squamous cell carcinoma of the head and neck: when and how to reirradiate

BACKGROUND

Local and/or regional recurrence and metachronous primary tumor arising in a previously irradiated area are rather frequent events in patients with head and neck squamous cell carcinoma (HNSCC). Re-treatment is associated with an increased risk of serious toxicity and impaired quality of life (QOL) with an uncertain survival advantage.

METHODS

We analyzed the literature on the efficacy and toxicity of photon/electron-based external beam reirradiation for previously irradiated patients with HNSCC of non-nasopharyngeal origin. Studies were grouped according to the radiotherapy technique used for reirradiation. Patient selection criteria, target volume identification method, tumor dose, fractionation schedule, systemic therapy administration, and toxicities were reviewed.

RESULTS

In addition to disease-related factors, current comorbidities and preexisting organ dysfunction must be considered when selecting patients for reirradiation. As morbidity from re-treatment may be considerable and differ depending on which mode of re-treatment is used, it is important to give patients information on potential morbidity outcomes so that an informed choice can be made within a shared decision-making context. With improved dose distribution and adequate imaging support, including positron emission tomography-CT, modern radiotherapy techniques may improve local control and reduce toxicity of reirradiation. A reirradiation dose of ≥60 Gy and a volume encompassing the gross tumor with up to a 5-mm margin are recommended. Concomitant administration of systemic therapeutics and reirradiation is likely to be of similar benefit as observed in large randomized studies of upfront therapy.

CONCLUSION

Reirradiation, administered either with or without concurrent systemic therapy, is feasible and tolerable in properly selected patients with recurrent or a new primary tumor in a previously irradiated area of the head and neck, offering a meaningful survival (in the range of 10% to 30% at 2 years). Whenever feasible, salvage surgery is the method of choice for curative intent; patients at high-risk for local recurrence should be advised that postoperative reirradiation is expected to increase locoregional control at the expense of higher toxicity and without survival advantage compared to salvage surgery without reirradiation. © 2014 Wiley Periodicals, Inc. Head Neck 37: 134-150, 2015.

Preventive sparing of spinal cord and brain stem in the initial irradiation of locally advanced head and neck cancers

Since reirradiation in recurrent head and neck patients is limited by previous treatment, a marked reduction of maximum doses to spinal cord and brain stem was investigated in the initial irradiation of stage III/IV head and neck cancers. Eighteen patients were planned by simultaneous integrated boost, prescribing 69.3 Gy to PTV1 and 56.1 Gy to PTV2. Nine 6 MV coplanar photon beams at equispaced gantry angles were chosen for each patient. Step‐and‐shoot IMRT was calculated by direct machine parameter optimization, with the maximum number of segments limited to 80. In the standard plan, optimization considered organs at risk (OAR), dose conformity, maximum dose <45 Gy to spinal cord and <50 Gy to brain stem. In the sparing plans, a marked reduction to spinal cord and brain stem were investigated, with/without changes in dose conformity. In the sparing plans, the maximum doses to spinal cord and brain stem were reduced from the initial values (43.5±2.2 Gy and 36.7±14.0 Gy), without significant changes on the other OARs. A marked difference (−15.9±1.9 Gy and −10.1±5.7 Gy) was obtained at the expense of a small difference (−1.3%±0.9%) from initial PTV195% coverage (96.6%±0.9%). Similar difference (−15.7±2.2 Gy and −10.2±6.1 Gy) was obtained compromising dose conformity, but unaffecting PTV195% and with negligible decrease in PTV295% (−0.3%±0.3% from the initial 98.3%±0.8%). A marked spinal cord and brain stem preventive sparing was feasible at the expense of a decrease in dose conformity or slightly compromising target coverage. A sparing should be recommended in highly recurrent tumors, to make potential reirradiation safer.

PACS number: 87.55.D

Gradual Recovery from Nonambulatory Quadriparesis Caused by Metastatic Epidural Cervical Cord Compression in an Octogenarian Gallbladder Carcinoma Patient Treated with Image-Guided Three-Dimensional Conformal Radiotherapy Alone Using a Field-in-Field Technique

Radiotherapy for acute metastatic epidural spinal cord compression (MESCC) involves conventional techniques and dose fractionation schemes, as it needs to be initiated quickly. However, even with rapid intervention, few paraplegic patients regain ambulation. Here, we describe the case of a mid-octogenarian who presented with severe pain and nonambulatory quadriparesis attributable to MESCC at the fifth cervical vertebra, which developed 10 months after the diagnosis of undifferentiated carcinoma of the gallbladder. Image-guided three-dimensional conformal radiotherapy (IG-3DCRT) was started with 25 Gy in 5 fractions followed by a boost of 12 Gy in 3 fractions, for which a field-in-field (FIF) technique was used to optimize the dose distribution. Despite the fact that steroids were not administered, the patient reported significant pain reduction and showed improved motor function 3 and 4 weeks after the IG-3DCRT, respectively. Over the following 4 months, her neurological function gradually improved, and she was consequently able to eat and change clothes without assistance and to walk slowly for 10–20 m using a walker. She succumbed to progression of abdominal disease 8.5 months after the IG-3DCRT. This case demonstrates that image-guided FIF radiotherapy with a dose-escalated hypofractionated regimen can potentially improve functional outcome and local control.

Stereotactic body radiotherapy: a critical review for nonradiation oncologists

Stereotactic body radiotherapy (SBRT) involves the treatment of extracranial primary tumors or metastases with a few, high doses of ionizing radiation. In SBRT, tumor kill is maximized and dose to surrounding tissue is minimized, by precise and accurate delivery of multiple radiation beams to the target. This is particularly challenging, because extracranial lesions often move with respiration and are irregular in shape, requiring careful treatment planning and continual management of this motion and patient position during irradiation. This review presents the rationale, process workflow, and technology for the safe and effective administration of SBRT, as well as the indications, outcome, and limitations for this technique in the treatment of lung cancer, liver cancer, and metastatic disease.

Re-irradiation of spinal column metastases by IMRT: impact of setup errors on the dose distribution

BACKGROUND

This study investigates the impact of an automated image guided patient setup correction on the dose distribution for ten patients with in-field IMRT re-irradiation of vertebral metastases.

METHODS

10 patients with spinal column metastases who had previously been treated with 3D-conformal radiotherapy (3D-CRT) were simulated to have an in-field recurrence. IMRT plans were generated for treatment of the vertebrae sparing the spinal cord. The dose distributions were compared for a patient setup based on skin marks only and a Cone Beam CT (CBCT) based setup with translational and rotational couch corrections using an automatic robotic image guided couch top (Elekta - HexaPOD™ IGuide® - system). The biological equivalent dose (BED) was calculated to evaluate and rank the effects of the automatic setup correction for the dose distribution of CTV and spinal cord.

RESULTS

The mean absolute value (± standard deviation) over all patients and fractions of the translational error is 6.1 mm (±4 mm) and 2.7° (±1.1 mm) for the rotational error. The dose coverage of the 95% isodose for the CTV is considerable decreased for the uncorrected table setup. This is associated with an increasing of the spinal cord dose above the tolerance dose.

CONCLUSIONS

An automatic image guided table correction ensures the delivery of accurate dose distribution and reduces the risk of radiation induced myelopathy.

A critical evaluation of the PTW 2D-ARRAY seven29 and OCTAVIUS II phantom for IMRT and VMAT verification

Quality assurance (QA) for intensity- and volumetric-modulated radiotherapy (IMRT and VMAT) has evolved substantially. In recent years, various commercial 2D and 3D ionization chamber or diode detector arrays have become available, allowing for absolute verification with near real time results, allowing for streamlined QA. However, detector arrays are limited by their resolution, giving rise to concerns about their sensitivity to errors. Understanding the limitations of these devices is therefore critical. In this study, the sensitivity and resolution of the PTW 2D-ARRAY seven29 and OCTAVIUS II phantom combination was comprehensively characterized for use in dynamic sliding window IMRT and RapidArc verification. Measurement comparisons were made between single acquisition and a multiple merged acquisition techniques to improve the effective resolution of the 2D-ARRAY, as well as comparisons against GAFCHROMIC EBT2 film and electronic portal imaging dosimetry (EPID). The sensitivity and resolution of the 2D-ARRAY was tested using two gantry angle 0° modulated test fields. Deliberate multileaf collimator (MLC) errors of 1, 2, and 5 mm and collimator rotation errors were inserted into IMRT and RapidArc plans for pelvis and head & neck sites, to test sensitivity to errors. The radiobiological impact of these errors was assessed to determine the gamma index passing criteria to be used with the 2D-ARRAY to detect clinically relevant errors. For gamma index distributions, it was found that the 2D-ARRAY in single acquisition mode was comparable to multiple acquisition modes, as well as film and EPID. It was found that the commonly used gamma index criteria of 3% dose difference or 3 mm distance to agreement may potentially mask clinically relevant errors. Gamma index criteria of 3%/2 mm with a passing threshold of 98%, or 2%/2 mm with a passing threshold of 95%, were found to be more sensitive. We suggest that the gamma index passing thresholds may be used for guidance, but also should be combined with a visual inspection of the gamma index distribution and calculation of the dose difference to assess whether there may be a clinical impact in failed regions.

Application of Helical Tomotherapy for the Treatment of a Right Atrium Angiosarcoma: A Case Report

We report the case of a 48-year-old woman affected by inoperable primary angiosarcoma of the right atrium who was treated with 4 cycles of induction chemotherapy and radical radiotherapy. We present the application and the result of helical tomotherapy for this patient. We also describe the technical aspects of the simulation, planning, setup and delivery of radiotherapy. At 16 months after the diagnosis the patient is still in good condition without any symptoms and with a partial response of the lesion. This case shows the feasibility of treatment with high doses of radiation for a primary unresectable cardiac sarcoma.

Concurrent palliative chemoradiation leads to survival and quality of life benefits in poor prognosis stage III non-small-cell lung cancer: a randomised trial by the Norwegian Lung Cancer Study Group

Background:

The palliative role of chemoradiation in the treatment of patients with locally advanced, inoperable non-small-cell lung cancer stage III and negative prognostic factors remains unresolved.

Methods:

Patients not eligible for curative radiotherapy were randomised to receive either chemoradiation or chemotherapy alone. Four courses of intravenous carboplatin on day 1 and oral vinorelbin on days 1 and 8 were given with 3-week intervals. Patients in the chemoradiation arm also received radiotherapy with fractionation 42 Gy/15, starting at the second chemotherapy course. The primary end point was overall survival; secondary end points were health-related quality of life (HRQOL) and toxicity.

Results:

Enrolment was terminated due to slow accrual after 191 patients from 25 Norwegian hospitals were randomised. Median age was 67 years and 21% had PS 2. In the chemotherapy versus the chemoradiation arm, the median overall survival was 9.7 and 12.6 months, respectively (P<0.01). One-year survival was 34.0% and 53.2% (P<0.01). Following a minor decline during treatment, HRQOL remained unchanged in the chemoradiation arm. The patients in the chemotherapy arm reported gradual deterioration during the subsequent months. In the chemoradiation arm, there were more hospital admissions related to side effects (P<0.05).

Conclusion:

Chemoradiation was superior to chemotherapy alone with respect to survival and HRQoL at the expense of more hospital admissions due to toxicity.

Assessing the uncertainty in QUANTEC's dose-response relation of lung and spinal cord with a bootstrap analysis

PURPOSE

To apply a statistical bootstrap analysis to assess the uncertainty in the dose-response relation for the endpoints pneumonitis and myelopathy reported in the QUANTEC review.

METHODS AND MATERIALS

The bootstrap method assesses the uncertainty of the estimated population-based dose-response relation due to sample variability, which reflects the uncertainty due to limited numbers of patients in the studies. A large number of bootstrap replicates of the original incidence data were produced by random sampling with replacement. The analysis requires only the dose, the number of patients, and the number of occurrences of the studied endpoint, for each study. Two dose-response models, a Poisson-based model and the Lyman model, were fitted to each bootstrap replicate using maximum likelihood.

RESULTS

The bootstrap analysis generates a family of curves representing the range of plausible dose-response relations, and the 95% bootstrap confidence intervals give an estimated upper and lower toxicity risk. The curve families for the 2 dose-response models overlap for doses included in the studies at hand but diverge beyond that, with the Lyman model suggesting a steeper slope. The resulting distributions of the model parameters indicate correlation and non-Gaussian distribution. For both data sets, the likelihood of the observed data was higher for the Lyman model in >90% of the bootstrap replicates.

CONCLUSIONS

The bootstrap method provides a statistical analysis of the uncertainty in the estimated dose-response relation for myelopathy and pneumonitis. It suggests likely values of model parameter values, their confidence intervals, and how they interrelate for each model. Finally, it can be used to evaluate to what extent data supports one model over another. For both data sets considered here, the Lyman model was preferred over the Poisson-based model.

The role of re-irradiation of secondary and recurrent head and neck carcinomas. Is it a potentially curative treatment? A practical approach

Despite aggressive efforts to cure head and neck cancer patients, including altered fractionation and the addition of chemotherapy to radiation, locoregional recurrence remains a serious issue to face in clinical practice. Indeed, recurrent and second primary tumors occurring in previously irradiated area are common clinical challenge. Whenever possible, patients are advised to undergo salvage surgery. Nevertheless, few patients are suitable candidates for curative resection. In such cases, chemotherapy alone has traditionally been considered, with a poor response rate. It has been questioned whether re-irradiation toxicity outweighs the potential benefits, considering that the median survival of re-irradiated patients marginally exceeds the benefits observed with chemotherapy alone. However, full-dose re-irradiation is a viable treatment option, offering long-term survival for selected patients. Moreover, several prognostic factors should be considered for patients undergoing re-irradiation, such as basic patient characteristics, performance status, the location and extension of recurrent disease, patient co-morbidities, current speech and swallowing function, the interval from the initial radiation therapy to recurrence, previously received doses by critical structures and prior treatment toxicity. Nevertheless, several questions remain unanswered. The purpose of this review is to evaluate the major issues in the field of re-irradiation regarding the current evidence. Therefore, the major selection criteria and new treatment strategies are discussed to define the ideal candidates to undergo re-irradiation and describe a practical approach to these patients. Given the limited evidence in this field, the optimal treatment of recurrent and second primary cancers remains to be defined. Future prospective study of this approach is warranted.

Intradural extramedullary benign spinal lesions radiosurgery. Medium- to long-term results from a single institution experience

BACKGROUND

Surgery represents the first-choice treatment for spinal intradural tumours. On the other hand, whether it is most appropriate in the setting of recurrences, residual or multiple lesions remains an open question. Moreover, some patients are less than ideal candidates for surgery. In this study we report about our own radiosurgery experience in the treatment of benign intradural extramedullary tumours of the spine.

METHODS

In our study we analyzed the outcomes for 18 patients (21 lesions) treated for benign intradural extramedullary lesions, with a minimum follow-up period of 32 months. The lesions included 11 meningiomas, 9 schwannomas and 1 neurofibroma.

RESULTS

The mean follow-up was 43 months (32-73 months). The median tumour volume was 2 cc (0.2-17.7 cc). Eleven lesions underwent single-fraction treatment (mean prescribed dose ranging from 10 to 13 Gy). The others received a multisession radiosurgery treatment (4-6 fractions) with a mean prescription dose ranging from 18.5 to 25 Gy. The maximum dose to the spinal cord ranged from 9.2 to 26 Gy. During the follow-up period, none of the lesions showed radiological evidence of progression. Neurological status was preserved or improved and no permanent sequelae were observed. Significant and durable pain relief was observed.

CONCLUSIONS

Although surgical excision remains the primary treatment option for most intradural tumours, radiosurgery offers a real alternative therapeutic modality, especially in case of recurrent and residual lesions or when surgery is contraindicated.

Comparative study of four advanced 3d-conformal radiation therapy treatment planning techniques for head and neck cancer

For the head-and-neck cancer bilateral irradiation, intensity-modulated radiation therapy (IMRT) is the most reported technique as it enables both target dose coverage and organ-at-risk (OAR) sparing. However, during the last 20 years, three-dimensional conformal radiotherapy (3DCRT) techniques have been introduced, which are tailored to improve the classic shrinking field technique, as regards both planning target volume (PTV) dose conformality and sparing of OAR’s, such as parotid glands and spinal cord. In this study, we tested experimentally in a sample of 13 patients, four of these advanced 3DCRT techniques, all using photon beams only and a unique isocentre, namely Bellinzona, Forward-Planned Multisegments (FPMS), ConPas, and field-in-field (FIF) techniques. Statistical analysis of the main dosimetric parameters of PTV and OAR’s DVH’s as well as of homogeneity and conformity indexes was carried out in order to compare the performance of each technique. The results show that the PTV dose coverage is adequate for all the techniques, with the FPMS techniques providing the highest value for D95%; on the other hand, the best sparing of parotid glands is achieved using the FIF and ConPas techniques, with a mean dose of 26 Gy to parotid glands for a PTV prescription dose of 54 Gy. After taking into account both PTV coverage and parotid sparing, the best global performance was achieved by the FIF technique with results comparable to that of IMRT plans. This technique can be proposed as a valid alternative when IMRT equipment is not available or patient is not suitable for IMRT treatment.

Re-irradiation of recurrent head and neck carcinomas: comparison of robust intensity modulated proton therapy treatment plans with helical tomotherapy

BACKGROUND

To test the hypothesis that the therapeutic ratio of intensity-modulated photon therapy using helical tomotherapy (HT) for retreatment of head and neck carcinomas can be improved by robust intensity-modulated proton therapy (IMPT).

METHODS

Comparative dose planning with robust IMPT was performed for 7 patients retreated with HT.

RESULTS

On average, HT yielded dose gradients steeper in a distance ≤ 7.5 mm outside the target (p<0.0001, F-test) and more conformal high dose regions down to the 50% isodose than IMPT. Both methods proved comparably robust against set-up errors of up to 2 mm, and normal tissue exposure was satisfactory. The mean body dose was smaller with IMPT.

CONCLUSIONS

IMPT was found not to be uniformly superior to HT and the steeper average dose fall-off around the target volume is an argument pro HT under the methodological implementations used. However, looking at single organs at risk, the normal tissue sparing of IMPT can surpass tomotherapy for an individual patient. Therefore, comparative dose planning is recommended, if both methods are available.

Developments in stereotactic ablative radiotherapy for the treatment of early-stage lung cancer

SUMMARY Stereotactic ablative radiotherapy (SABR), also known as stereotactic body radiation therapy, has emerged as an effective treatment for inoperable early-stage non-small-cell lung cancer. SABR differs from conventional radiotherapy by virtue of its tight spatial tolerances and use of oligofractionated radiation. The modern technique is characterized by management of tumor motion, image guidance before each fraction and specialized radiation delivery techniques. The result is a highly conformal target dose with a sharp gradient that spares normal tissues with great accuracy. This enables delivery of very potent (ablative) doses, causing more rapid and durable responses than traditional radiation therapy treatment regimens can achieve. The established techniques, new developments and ongoing questions related to SABR for early-stage non-small-cell lung cancer are reviewed herein.

Review of stereotactic radiosurgery for intramedullary spinal lesions

Stereotactic radiosurgery (SR) represents an increasingly utilized modality in the treatment of intracranial and extracranial pathologies. Stereotactic spine radiosurgery (SSR) uses an alternative strategy to increase the probability of local control by delivering large cumulative doses of radiation therapy (RT) in only a few fractions. SSR in the treatment of intramedullary lesions remains in its infancy-this review summarizes the current literature regarding the use of SSR for treating intramedullary spinal lesions. Several studies have suggested that SSR should be guided by the principles of intracranial radiosurgery with radiation doses placed no further than 1-2mm apart, thereby minimizing exposure to the surrounding spinal cord and allowing for delivery of higher radiation doses to target areas. Maximum dose-volume relationships and single-point doses with SSR for the spinal cord are currently under debate. Prior reports of SR for intramedullary metastases, arteriovenous malformations, ependymomas, and hemangioblastomas demonstrated favorable outcomes. In the management of intrame-dullary spinal lesions, SSR appears to provide an effective and safe treatment compared to conventional RT. SSR should likely be utilized for select patient-scenarios given the potential for radiation-induced myelopathy, though high-quality literature on SSR for intramedullary lesions remains limited.

A spinal cord window chamber model for in vivo longitudinal multimodal optical and acoustic imaging in a murine model

In vivo and direct imaging of the murine spinal cord and its vasculature using multimodal (optical and acoustic) imaging techniques could significantly advance preclinical studies of the spinal cord. Such intrinsically high resolution and complementary imaging technologies could provide a powerful means of quantitatively monitoring changes in anatomy, structure, physiology and function of the living cord over time after traumatic injury, onset of disease, or therapeutic intervention. However, longitudinal in vivo imaging of the intact spinal cord in rodent models has been challenging, requiring repeated surgeries to expose the cord for imaging or sacrifice of animals at various time points for ex vivo tissue analysis. To address these limitations, we have developed an implantable spinal cord window chamber (SCWC) device and procedures in mice for repeated multimodal intravital microscopic imaging of the cord and its vasculature in situ. We present methodology for using our SCWC to achieve spatially co-registered optical-acoustic imaging performed serially for up to four weeks, without damaging the cord or induction of locomotor deficits in implanted animals. To demonstrate the feasibility, we used the SCWC model to study the response of the normal spinal cord vasculature to ionizing radiation over time using white light and fluorescence microscopy combined with optical coherence tomography (OCT) in vivo. In vivo power Doppler ultrasound and photoacoustics were used to directly visualize the cord and vascular structures and to measure hemoglobin oxygen saturation through the complete spinal cord, respectively. The model was also used for intravital imaging of spinal micrometastases resulting from primary brain tumor using fluorescence and bioluminescence imaging. Our SCWC model overcomes previous in vivo imaging challenges, and our data provide evidence of the broader utility of hybridized optical-acoustic imaging methods for obtaining multiparametric and rich imaging data sets, including over extended periods, for preclinical in vivo spinal cord research.

On the biologically effective dose (BED)-using convolution for calculating the effects of repair: II. Numerical considerations

We have previously shown analytically that the biologically effective dose (BED), including effects of repair during irradiation and of incomplete repair between fractions, can be formulated using a convolution between the absorbed dose rate function and the function describing repair. In this work, a discrete formalism is derived along with its implementation via the fast Fourier transform. The implementation takes the intrinsic periodicity of the discrete Fourier transform into consideration, as well as possible inconsistencies that may arise due to discretization and truncation of the functions describing the absorbed dose rate and repair. Numerically and analytically calculated BED values are compared for various situations in external beam radiotherapy, brachytherapy and radionuclide therapy, including the use of different repair models. The numerical method is shown to be accurate and versatile since it can be applied to any kind of absorbed dose rate function and allows for the incorporation of different repair models. Typical accuracies for clinically realistic examples are in the order of 10(-3)% to 10(-5)%. The method has thus the potential of being a useful tool for the calculation of BED, also in situations with complicated irradiation patterns or repair functions.

Local control and sequelae in localised Ewing tumours of the spine: a French retrospective study

OBJECTIVES

To evaluate both local outcome and sequelae of non-metastatic spinal Ewing tumours (EWT).

PATIENTS AND METHODS

A French cohort of patients ≤ 50years with localised spinal EWT treated between 1988 and 2009, was analysed in regard to tumour characteristics (e.g. volume, vertebral compartment, spinal cord compression, paraspinal soft tissue invasion), local treatment modalities (surgery (S) and margin quality, radiotherapy (RT) dose), response to treatment (e.g. histological response to neoadjuvant chemotherapy (CT)), tumour local control (LC) and sequelae.

RESULTS

Seventy-five patients treated in successive trials were evaluated for LC: SFOP-EW88 (n=14), SFOP-EW93 (n=17) and EuroEwing99 (n=44). Fifty-seven patients (79%) presented initial neurological compression and 69% had inaugural decompressive S. Local treatment modality was S+RT (n=50), RT alone (n=19) and S alone (n=6). Surgery was mainly intralesional (66%). Local recurrences had occurred in 19 patients (14 local, 5 loco-regional) with a median interval of 25 months (1-50). After a 7 year median follow-up (1-22 years), the 5-year LC, relapse-free survival (RFS) and overall survival (OS) reached 78.0% (95%CI: 62.6-84.6), 57.0% (95%CI: 45.2-68.9) and 70.0% (95%CI: 59.1-81.0), respectively. Vertebral compartment involved was the only prognostic factor (5-year LC rate 100% versus 71% for favourable and unfavourable compartment, p<0.03). Among 41 five-year survivors, we observed spinal curvature deformation (35%), growth retardation (28%), spinal reduction mobility (40%), spinal pain (25%) and neurological sequelae (32%) without any significant association with a particular local procedure.

CONCLUSION

RT is the backbone of a successful local treatment of spinal EWT. The place of S remains a pending question. Its actual benefit will likely evolve with new available RT techniques.

The value of image-guided intensity-modulated radiotherapy in challenging clinical settings

OBJECTIVE

To illustrate the wider potential scope of image-guided intensity-modulated radiotherapy (IG-IMRT), outside of the "standard" indications for IMRT.

METHODS

Nine challenging clinical cases were selected. All were treated with radical intent, although it was accepted that in several of the cases the probability of cure was low. IMRT alone was not adequate owing to the close proximity of the target to organs at risk, the risk of geographical miss, or the need to tighten planning margins, making image-guided radiotherapy an essential integral part of the treatment. Discrepancies between the initial planning scan and the daily on-treatment megavoltage CT were recorded for each case. The three-dimensional displacement was compared with the margin used to create the planning target volume (PTV).

RESULTS

All but one patient achieved local control. Three patients developed metastatic disease but benefited from good local palliation; two have since died. A further patient died of an unrelated condition. Four patients are alive and well. Toxicity was low in all cases. Without daily image guidance, the PTV margin would have been insufficient to ensure complete coverage in 49% of fractions. It was inadequate by >3 mm in 19% of fractions, and by >5 mm in 9%.

CONCLUSION

IG-IMRT ensures accurate dose delivery to treat the target and avoid critical structures, acting as daily quality assurance for the delivery of complex IMRT plans. These patients could not have been adequately treated without image guidance.

ADVANCES IN KNOWLEDGE

IG-IMRT can offer improved outcomes in less common clinical situations, where conventional techniques would provide suboptimal treatment.

[Localized Ewing sarcoma of the spine: a preliminary dose-escalation study comparing innovative radiation techniques in a single patient]

PURPOSE

Although radiosensitive, spinal locations of Ewing's sarcomas are challenging for the radiation oncologist due to poor radiation tolerance of the spinal cord. However, some favorable anatomical compartments - that may represent more than 20% - were associated with a better outcome and could benefit from a radiation dose escalation using the most recent radiation therapy techniques.

MATERIALS AND METHODS

We performed a dose escalation study on one patient, declined in two scenarios: (1) a tumour located within a single vertebral body and (2) a locally advanced disease involving the vertebral foramen and paraspinal soft tissues. Five dose-levels are proposed: 44.8Gy, 54.4Gy, 59.2Gy, 65.6Gy and 70.4Gy (1.6Gy per session, 8Gy per week). The 3D-conformational technique is compared with static intensity modulated radiation therapy (IMRT), helical tomotherapy, volumetric modulated arc therapy (VMAT), stereotactic body robotic radiation therapy (SBRT) and protontherapy (passive scattering). Two constraints had to be respected in order to skip to the next level: the planned target volume (PTV) coverage must exceed 95% and the D(2%) on the spinal cord shall not exceed a given constraint set at 50Gy in case 1 and 44Gy in case 2 due to initial neurological sufferance.

RESULTS

Only protontherapy, SBRT, helical tomotherapy and VMAT appear able to reach the last dose level while respecting the constraints in case 1. On the other hand, only helical tomotherapy seems capable of reaching 59.2Gy on the PTV in case 2.

CONCLUSION

With the most recent radiation therapy techniques, it becomes possible to deliver up to 70.4Gy in a favorable compartment in this sham patient. Unfavorable compartments can receive up to 59.2Gy. Definitive radiation therapy may be an interesting local treatment option to be validated in an early phase trial.

Delivering a third course of radiation to spine metastases using image-guided, intensity-modulated radiation therapy

Object

The objective of this study was to investigate the feasibility and safety of delivering a third course of radiation to patients with multiply recurrent metastatic disease to the spine.

Methods

Between 2009 and 2011, 10 patients received a third course of radiation to spinal metastases at Memorial Sloan–Kettering Cancer Center using image-guided intensity-modulated radiation therapy (IMRT). Patient and tumor characteristics, dosimetry details, and outcomes were obtained using retrospective chart review. Spinal imaging was performed prior to treatment and at regular follow-up intervals. The cumulative biologically effective dose (BED) to the spinal cord and cauda equina was calculated and was normalized to 2 Gy equivalents (Gy2/2). Toxicity and local control were assessed.

Results

The median time between the first and second courses of radiation was 18.5 months and the median time between the second and third courses was 11.5 months. The median follow-up from the third course of radiation was 12 months and the median overall survival was 13 months. Pain or neurological symptoms were improved in 80% of patients. The median spinal cord maximum dose normalized BED (nBED) for the whole cohort was 70.73 Gy2/2 (range 51.9–101.7 Gy2/2). The median dose to 5% of the spinal cord D05 nBED for the entire cohort was 59.4 Gy2/2. Acute toxicity was most commonly fatigue and dermatitis, with 1 patient experiencing Grade 3 fatigue and 1 patient Grade 3 dermatitis. Late toxicity was limited to 2 cases of Grade 1 dysphagia. There was 1 case of Grade 1 neuropathy and 1 case of Grade 2 neuropathy. The crude rate of local control was 80% with 1 in-field failure and 1 marginal failure.

Conclusions

In this cohort of patients, a third course of IMRT to the spine was well tolerated with no significant late toxicities. Used as salvage therapy for select patients, a third course of radiation is a safe and effective treatment strategy.

Definitive chemoradiotherapy for esophageal carcinoma

Radiation therapy plays an important role in the treatment of esophageal cancer. Radiation therapy may be combined with chemotherapy, used as a component of induction therapy, used in the adjuvant setting, or used for palliation of advanced disease. Chemotherapy is also occasionally used as a solitary treatment modality for patients with esophageal cancer. Current treatment protocols include multiple agents, and agents directed against specific molecular targets have been investigated in clinical trials. This article discusses future directions related to the selection of radiation treatment protocols, novel targeted chemotherapeutic agents, and the selection of patients for surgery.