Conventional Radiotherapy Techniques Research Articles

Dose-volume Analysis of Heart and Lung during 3D Planning of Tangential Breast Cancer Irradiation

Introduction: Breast cancer is becoming more frequently diagnosed at early stages with improved long-term outcomes. Radiation-related heart disease and lung cancer can occur following radiotherapy for breast cancer. The aim of this study was to evaluate some dosimetric parameters of heart and lung during whole breast radiotherapy. Materials and Methods: Twenty-five consecutive patients with breast cancer who underwent radiotherapy were included in this study. Plans that employed the 3D conventional radiotherapy technique (Tangential Technique) were generated for each patient. Dose-volume histograms (DVHs) were calculated and dosimetric parameters such as, mean dose/volume receiving a dose 30 Gy (V30), mean dose/ volume receiving a dose 20 Gy (V20) for heart and lung were assessed, respectively. Results: The average of mean dose of heart on left and right side irradiation was 9.68±5.10 Gy and 1.23±1.51 Gy, respectively. The average of mean dose of ipsilateral lung on left and right-sided irradiation was 14.49±4.07 Gy and 11.69±3.37 Gy, respectively. The percentage of heart volume that received at least 30 Gy was 16.32±9.56% for left-sided treatment. The percentage of lung volume that received at least 20 Gy was 23.47±11.05% and 24.12±7.77% respective on the left and right-sided breast irradiation. Conclusion: Tangential beam conventional radiotherapy of the chest wall of postmastectomy breast cancer patients provides the potential to significantly keep the DVH parameters of heart and lung as low as the QUANTEC constrains.

A dosimetric study of skin toxicity induced by 3-D conventional and intensity-modulated radiotherapy techniques using immobilization mask for treatment of head-and-neck (nasopharyngeal cancer) carcinoma: a prospective study

AbstractBackgroundThe purpose of this study was to investigate variations in surface dose, with and without the use of a Klarity® Mask (Orfit Industries America, Wijnegem, Belgium), using intensity-modulated radiotherapy (IMRT) and 3-D conventional radiotherapy (3D-CRT).Materials and methodsThermoluminescent dosimeters (TLDs) together with a phantom were used to examine acute skin toxicity during nasopharyngeal cancer treatment. These plans were sequentially delivered to the perspex phantom. Dosimeters were placed in five fixed regions over the skin. A Klarity mask for immobilization was used for covering the head, neck, and shoulder. The phantom was irradiated with and without a Klarity Mask, using IMRT and 3D-CRT, respectively.ResultsThe Klarity mask increased the skin doses for IMRT and 3D-CRT approximately 18·6% and 8·6%, respectively, from the prescribed maximum skin dose using treatment planning system (TPS). Additionally, the average percentage dose between IMRT and 3D-CRT received on the surface region was 30·9%, 24·9% with and without Klarity mask respectively. The average percentage dose received on surfaces from the total therapeutic dose 70 Gy, without using the mask was 7·7% and 5·7%, for IMRT and 3D-CRT, respectively. The TPS overestimated the skin dose for IMRT planning by 20%, and for 3D-CRT by 16·6%, compared with TLD measurements.ConclusionsThe results of this study revealed that IMRT significantly increases acute skin toxicity, compared with CRT. Although it is recommended to use Klarity mask as a sparing tool of normal tissue, it increases the risk of skin toxicity. In conclusion, skin dose is an important issue of focus during radiotherapy.

A Simplified Three-Isocenter VMAT for Craniospinal Irradiation

Craniospinal irradiation (CSI) has become an important treatment method for Central nervous system (CNS) relapse of hematological malignancies. However, conventional CSI is technically very challenging and field edge matching is needed because of the mechanical limitations of standard linear accelerators. We have developed a simple Linac based volumetric modulated arc therapy (VMAT) technique for CSI. The aim of this study is to report initial clinical experience of CSI-VMAT for CNS relapse of hematological malignancies and compare dose homogeneity and dose to organs at risk (OAR) with conventional three-dimensional conformal radiotherapy (3D-CRT) technique. Seven patients with CNS relapse of hematological malignancies were treated with CSI using a novel VMAT technique and seven patients were previously underwent conventional 3D-CRT technique. A dose of 22.5 Gy was prescribed to be delivered in 15 fractions. Planning target volume (PTV) included the whole brain and spinal canal to the S3 vertebral level. Patient is positioned supine and immobilized using a face mask and Vac-Lock in the body. The VMAT plan used three full arcs, each with a unique isocenter (Brain, Superior Spine, Inferior Spine). Spinal two arcs turned off lateral beams (225-315o and 45-135o) to minimize lung dose. Adjacent fields were intentionally overlapped to eliminate the issues of beam edge matching, and the optimization process smoothly integrated the dose inside the overlapped junction. The 3D-CRT plan used edge matching field sets and shifted junctions three times. Comparing the VMAT plan with the 3D-CRT plan, the average simplified homogeneity index (HI=Dmax/Dmin) of PTV was 1.19 ± 0.11 and 1.46 ± 0.13, respectively. Mean doses to avoidable OAR were significantly decreased (for the heart: 5.3 Gy and 11.1 Gy, for the esophagus: 11.6 Gy and 19.7 Gy, for the parotid glands: 8.8 Gy and 20.5 Gy, using VMAT and 3D-CRT, respectively). The lung V5, V10 and Dmean were 28.3%, 5.4%, 3.4 Gy, in VMAT, 20.1%, 15.3 %, 4.6 Gy, in 3D-CRT. The doses of lung except V5 were lower in VMAT. Short term follow-up evaluations revealed no unexpected toxicity associated with this novel VMAT technique. We have developed a simplified three-isocenter Linac based VMAT approach for CSI. The dose to the brain and spine is significantly improved, compared to the conventional 3D-CRT. The single VMAT plan is easier to manage. This new technique simplifies the set up and eliminates the need for shifting junctions during course of CSI treatment and saves OAR of patients with CNS relapse of hematological malignancies.

Strategies to Preserve Cognition in Patients With Brain Metastases: A Review.

Brain metastases are common to the natural history of many advanced malignancies. Historically, whole brain radiation therapy (WBRT) has played a key role in the management of brain metastases, especially for patients with multiple lesions. However, prospective trials have demonstrated consistent neurocognitive toxicities after WBRT, and various pharmacologic and anatomic strategies designed to mitigate these toxicities have been studied in recent years. Memantine, an NMDA receptor antagonist, taken during and after WBRT improved cognitive preservation in a randomized trial over placebo. Deliberate reductions in radiation dose to the hippocampus, via hippocampal-avoidance (HA)-WBRT, resulted in improved cognition over historic controls in a phase II trial, and follow-up randomized trials are now ongoing to evaluate cognitive outcomes with HA vs. conventional brain radiation techniques. Nevertheless, some of the most promising strategies currently available to reduce the cognitive effects of brain radiation may be found in efforts to avoid or delay WBRT administration altogether. Stereotactic radiosurgery (SRS), involving focused, high-dose radiation to central nervous system (CNS) lesions with maximal sparing of normal brain parenchyma, has become the standard for limited brain metastases (classically 1–3 or 4 lesions) in the wake of multiple randomized trials demonstrating equivalent survival and improved cognition with SRS alone compared to SRS plus WBRT. Today, there is growing evidence to support SRS alone for multiple (≥4) brain metastases, with comparable survival to SRS alone in patients with fewer lesions. In patients with small-cell lung cancer, the routine use of prophylactic cranial irradiation (PCI) for extensive-stage disease has been also been challenged following the results of a randomized trial supporting an alternative strategy of MRI brain surveillance and early salvage radiation for the development of brain metastases. Moreover, new systemic agents are demonstrating increasing CNS penetration and activity, with the potential to offer greater control of widespread and microscopic brain disease that was previously only achievable with WBRT. In this review, we endeavor to put these clinical data on cognition and brain metastases into historical context and to survey the evolving landscape of strategies to improve future outcomes.

Intensity-modulated radiation therapy and volumetric modulated arc therapy versus conventional conformal techniques at high energy: Dose assessment and impact on second primary cancer in the out-of-field region.

The aim of this work was to estimate peripheral neutron and photon doses associated with the conventional 3D conformal radiotherapy techniques in comparison to modern ones such as Intensity modulated radiation therapy and volumetric modulated arc therapy. Assessment in terms of second cancer incidence ought to peripheral doses was also considered. For that, a dosimetric methodology proposed by the authors has been applied beyond the region where there is no CT information and, thus, treatment planning systems do not calculate and where, nonetheless, about one third of second primary cancers occurs.

Anal and rectal function after intensity-modulated prostate radiotherapy with endorectal balloon

Background and purposeLate anorectal toxicity influences quality of life after external beam radiotherapy (EBRT) for prostate cancer. A daily inserted endorectal balloon (ERB) during EBRT aims to reduce anorectal toxicity. Our goal is to objectify anorectal function over time after prostate intensity-modulated radiotherapy (IMRT) with ERB. Material and methodsSixty men, irradiated with IMRT and an ERB, underwent barostat measurements and anorectal manometry prior to EBRT and 6 months, one year and 2 years after radiotherapy. Primary outcome measures were rectal distensibility and rectal sensibility in response to stepwise isobaric distensions and anal pressures. ResultsForty-eight men completed all measurements. EBRT reduced maximal rectal capacity 2 years after EBRT (250 ± 10 mL vs. 211 ± 10 mL; p < 0.001), area under the pressure–volume curve (2878 ± 270 mL mmHg vs. 2521 ± 305 mL mmHg; p = 0.043) and rectal compliance (NS). Sensory pressure thresholds for first sense and first urge (both p < 0.01) increased. Anal maximum pressure diminished after IMRT (p = 0.006). ConclusionsRectal capacity and sensory function are increasingly affected over time after radiotherapy. There is an indication that these reductions are affected less with IMRT + ERB compared to conventional radiation techniques.

Stereotactic Radiotherapy and Particle Therapy for Pancreatic Cancer.

Pancreatic cancer is a devastating disease with poor survival outcomes. Recent studies have shown that the addition of radiotherapy to chemotherapy in the setting of locally advanced pancreatic cancer did not improve overall survival outcome. These studies commonly utilize conventional radiotherapy treatment fractionation and technique (typically 3-D conformal radiotherapy or intensity modulated radiotherapy). Although no clear benefit in overall survival was demonstrated in those studies, those who received radiotherapy did have a clear benefit in terms of local control. Therefore, there is increasing interest in exploring different techniques and/or modality of radiotherapy and dose/fractionation. Stereotactic radiotherapy, which employs a hypofractionated regimen, has the potential advantage of delivering a high dose of radiation to the tumor in a short period of time (typically over 5 days) with minimal dose to the surrounding normal structures. Particle therapy such as proton and carbon ion therapy are being explored as potential radiation modality that could cause greater biological damage to the tumor compared to photon treatment, with rapid dose falloff resulting in minimal to no dose to adjacent structures. This review will discuss the current literature and emerging roles of stereotactic radiotherapy and particle therapy in pancreatic cancer.

Partial breast irradiation: The time is there!

The conventionally fractionated partial breast irradiation (PBI) IMPORT LOW trial represents the perfect example of how an adequate selection of patients led to a minimal local relapse rate for patients. Coles and colleagues, demonstrated a 5-year non-inferiority local relapse rate for PBI compared to standard whole breast irradiation, together with a significant reduction in terms of breast toxicity using a conventional radiation technique implementable worldwide. Most of enrolled patients had early stage node negative, grade1-2, oestrogen receptor positive, human epidermal growth factor receptor 2 negative tumours. An exponential decrease in term of local relapse rate was observed from the first published PBI studies. The new high-level evidence provided by these results clearly demonstrates that while toxicity and cosmetic outcome concerns are strongly dependent on the technique, the efficacy of PBI is closely related to the adequate choice of patients. Upcoming data from several studies and from matured follow up of the published ones will be critical to confirm if also accelerated PBI could be accepted as a standard alternative to whole breast irradiation. However, we feel that IMPORT LOW inclusion criteria, together with tumour biology should be definitively integrated in the decision-making process.

Prospective evaluation of skin toxicities in patients receiving post-mastectomy irradiation of chest wall, supra/infraclavicular and internal mammary nodes delivered by conventional versus intensity-modulated radiotherapy technique.

BackgroundTo determine whether IMRT could decrease skin toxicities in patients undergoing PMRT of chest wall, supra/infraclavicular (SCV), and internal mammary nodes (IMN) as compared to conventional technique.Materials and MethodsBetween 2009 and 2013, 106 patients treated with IMRT and 138 treated with conventional technique were followed up regularly. The skin toxicities were graded according to the CTCAE v4.0 issued by the NCI, and compared between groups.ResultsGrade 3 radiation dermatitis occurred in 49 patients (35.5%) in the conventional group and 14 (13.2%) in the IMRT group, and the difference was statistically significant (p < 0.001), favoring IMRT. Moist desquamation at the area associated with adjacent fields’ junctions or overlaps was observed in 35 patients (71.4%) in the conventional group and none in the IMRT group (p = 0.023). Grade 2 telangiectasia occurred in 32 patients (23.1%) in the conventional group and 9 (8.5%) in the IMRT group; this difference was statistically significant (p = 0.002), in favor of IMRT as well. Telangiectasias at the sub-sites associated with adjacent fields’ junctions or overlaps were observed in 26 patients (81.2%) in the conventional group and none in the IMRT group (p < 0.001). Further, 21 in the conventional group, who had initial moist desquamation at the sub-sites associated with adjacent fields’ overlaps or junctions, subsequently developed skin telangiectasias at the identical sub-sites.ConclusionsIMRT-based post-mastectomy irradiation of chest wall, SCV and IMN might decrease the occurrence of initial moist desquamation as well as subsequent telangiectasia at the subsites associated with adjacent fields’ junctions or overlaps as compared to conventional technique.

Incidental Dose to Pelvic Nodal Regions in Prostate-Only Radiotherapy.

Pelvic lymph nodal regions receive an incidental dose from conformal treatment of the prostate. This study was conducted to investigate the doses received by the different pelvic nodal regions with varying techniques used for prostate radiotherapy. Twenty patients of high-risk node-negative prostate cancer treated with intensity-modulated radiotherapy to the prostate alone were studied. Replanning was done for intensity-modulated radiotherapy, 3-dimensional conformal treatment, and 2-dimensional conventional radiotherapy with additional delineation of the pelvic nodal regions, namely, common iliac (upper and lower), presacral, internal iliac, obturator, and external iliac. Dose-volume parameters such as Dmean, D100%, D66%, D33%, V40, and V50 to each of the nodal regions were estimated for all patients. The obturator nodes received the highest dose among all nodal regions. The mean dose received by obturator nodal region was 44, 29, and 22 Gy from 2-dimensional conventional radiotherapy, 3-dimensional conformal treatment, and intensity-modulated radiotherapy, respectively. The mean dose was significantly higher when compared between 2-dimensional conventional radiotherapy and 3-dimensional conformal treatment ( P < .001), 2-dimensional conventional radiotherapy and intensity-modulated radiotherapy ( P < .001), and 3-dimensional conformal treatment and intensity-modulated radiotherapy ( P < .001). The D33% of the obturator region was 64, 39, and 37 Gy from 2-dimensional conventional radiotherapy, 3-dimensional conformal treatment, and intensity-modulated radiotherapy, respectively. The dose received by all other pelvic nodal regions was low and not clinically relevant. The incidental dose received by obturator regions is significant especially with 2-dimensional conventional radiotherapy and 3-dimensional conformal treatment techniques as used in the trials studying elective pelvic nodal irradiation. However, with intensity-modulated radiotherapy, this dose is lower, making elective pelvic irradiation more relevant. Advances in Knowledge: This study highlights that incidental dose received by obturator regions is significant especially with 2-dimensional conventional radiotherapy and 3-dimensional conformal treatment techniques.

Long-term effect of chemotherapy–intensity-modulated radiation therapy (chemo-IMRT) on dentofacial development in head and neck rhabdomyosarcoma patients

ABSTRACTDentofacial developmental abnormalities have been reported in head and neck rhabdomyosarcoma (HNRMS) patients treated with conventional radiotherapy technique and chemotherapy. This current study investigates dentofacial long-term effects among HNRMS survivors managed with intensity-modulated radiotherapy (IMRT) and chemotherapy. In general, IMRT is a more effective 3D-conformal radiotherapy technique, which delivers high doses of radiation to the tumor target while minimizing doses received by the surrounding normal tissues. The medical records and radiographs of thirteen patients were reviewed to identify the following: 1. Facial asymmetry and jaw hypoplasia. 2. Effects on the dental tissue causing tooth agenesis/hypodontia, root agenesis/stunting/malformation, and/or enamel hypoplasia. 3. Trismus, hyposalivation/xerostomia. Seven patients presented with facial asymmetry and jaw hypoplasia, 9 patients presented with effects on the dental tissue [root agenesis/stunting/malformation (9), tooth agenesis/hypodontia (7) and enamel hypoplasia (3)] and 7 patients developed trismus and /or xerostomia. All patients with facial asymmetry and jaw hypoplasia also developed dental abnormalities. Patients with dentofacial developmental abnormalities were ≤7 years of age at treatment. Our study shows that dentofacial developmental abnormalities are still a burden in the era of IMRT and as prognosis of childhood malignancy improves and more patients survive, these late dentofacial sequelae among childhood cancer survivors will become more common. Dental oncologists should be integral members in the management of children with head and neck cancers.

Factors Predictive of Protracted Course of Radiation Therapy in Patients Treated with Definitive Chemoradiation for Cervical Cancer

BackgroundThere is a benefit to completing definitive chemoradiotherapy (CRT) for cervical cancer within 56 days. However, many patients experience delays due to missed radiation treatments that prolong the overall course of therapy. In order to improve patient care, we performed a quality improvement project to determine factors predictive of protracted treatment and develop strategies to enable timely treatment completion.Methods Seventy-one patients treated for cervical cancer with CRT were identified. Medical records were reviewed to gather demographic, clinical, and treatment data. Prolonged treatment was defined as >56 days per the American Brachytherapy Society guidelines. The following variables were evaluated using paired t-tests and univariate logistic regression: demographics, Intensity Modulated Radiotherapy (IMRT) versus conventional radiation technique, use of a boost, time to stent placement, time to first brachytherapy (BT), and genitourinary (GU) or gastrointestinal (GI) toxicity.ResultsThe median treatment length for all patients was 59 days. Factors associated with prolonged treatment were time to cervical stent placement (p=0.001), delay ≥2 days between final external beam radiation therapy (EBRT) and initial BT (p=0.0195), any grade GU toxicity (p=0.0007), or GI toxicity (p=0.0002), and the presence of a boost (p=0.0006). Age, stage, and IMRT versus conventional technique were not associated with protracted treatment.Conclusion In this series of patients, acute toxicity, increased time to cervical stent placement, and time to first BT treatment were associated with prolonged treatment time. The patients who completed treatment in ≤56 days had a lower average time to cervical stent placement, 27 versus 31 days. Our results suggest that cervical stent placement during week four of treatment can enhance patient care and improve outcomes.

Importance of Radiation Oncologist Experience Among Patients With Head-and-Neck Cancer Treated With Intensity-Modulated Radiation Therapy.

Over the past decade, intensity-modulated radiation therapy (IMRT) has replaced conventional radiation techniques in the management of head-and-neck cancers (HNCs). We conducted this population-based study to evaluate the influence of radiation oncologist experience on outcomes in patients with HNC treated with IMRT compared with patients with HNC treated with conventional radiation therapy. We identified radiation providers from Medicare claims of 6,212 Medicare beneficiaries with HNC treated between 2000 and 2009. We analyzed the impact of provider volume on all-cause mortality, HNC mortality, and toxicity end points after treatment with either conventional radiation therapy or IMRT. All analyses were performed by using either multivariable Cox proportional hazards or Fine-Gray regression models controlling for potential confounding variables. Among patients treated with conventional radiation, we found no significant relationship between provider volume and patient survival or any toxicity end point. Among patients receiving IMRT, those treated by higher-volume radiation oncologists had improved survival compared with those treated by low-volume providers. The risk of all-cause mortality decreased by 21% for every additional five patients treated per provider per year (hazard ratio [HR], 0.79; 95% CI, 0.67 to 0.94). Patients treated with IMRT by higher-volume providers had decreased HNC-specific mortality (subdistribution HR, 0.68; 95% CI, 0.50 to 0.91) and decreased risk of aspiration pneumonia (subdistribution HR, 0.72; 95% CI, 0.52 to 0.99). Patients receiving IMRT for HNC had improved outcomes when treated by higher-volume providers. These findings will better inform patients and providers when making decisions about treatment, and emphasize the critical importance of high-quality radiation therapy for optimal treatment of HNC.

Phase I/II Trial Evaluating Carbon Ion Radiotherapy for Salvaging Treatment of Locally Recurrent Nasopharyngeal Carcinoma.

Background: Radiation therapy is the mainstay strategy for the treatment of nasopharyngeal cancer (NPC). Intensity-modulated X-ray therapy (IMXT) alone is the current standard for stage I and II NPC. For stage III and IV A/B diseases, concurrent chemotherapy should be provided in addition to IMXT. However, optimal treatment for locally recurrent NPC after previous definitive dose of radiotherapy is lacking. Various techniques including brachytherapy, IMXT, stereotactic radiosurgery or radiotherapy (SRS or SBRT) have been used in the management of locally recurrent NPC. Due to the inherent limitation of these techniques, i.e., limited range of irradiation or over-irradiation to surrounding normal tissues, moderate efficacy has been observed at the cost of severe toxicities. Carbon ion radiotherapy (CIRT) offers potential physical and biological advantages over photon and proton radiotherapy. Due to the inverted dose profile of particle beams and their greater energy deposition within the Bragg peak, precise dose delivery to the target volume(s) without exposing the surrounding organs at risk to extra doses is possible. In addition, CIRT provides an increased relative biological effectiveness (RBE) as compared to photon and proton radiotherapy. Such advantages may translate to improved outcomes after irradiation in terms of disease control in radio-resistant and previously treated, recurrent malignancies. It is therefore reasonable to postulate that recurrent NPC after high-dose radiotherapy could be more resistant to re-irradiation using photons. Reports on the treatment of radio-resistant malignancies in the head and neck region such as melanoma, sarcoma, and adenoid cystic carcinoma (ACC) have demonstrated superior local control rates from CIRT as compared to photon irradiation. Thus patients with recurrent NPC are likely to benefit from the enhanced biological effectiveness of carbon ions. As effective retreatment strategy is lacking for locally recurrent NPC, carbon ion radiation therapy offers an ideal alternate to conventional X-ray irradiation.Methods and Design: The recommended dose of re-irradiation using CIRT for locally recurrent NPC will be determined in the dose-escalating phase (Phase I) of the study. Efficacy in terms of local progression-free survival (LPFS) and overall survival (OS) will be studied in the second phase of the study. Increasing doses of CIRT using raster scanning technology from 55GyE (22×2.5 GyE) to 65 GyE (26× 2.5 GyE) will be delivered in the Phase I part of the study. The primary endpoint of the Phase I part of the study is acute and sub-acute toxicities; the primary endpoint in the Phase II part is local progression-free survival and overall survival. Using the historical 2-year OS rate of 50% in locally recurrent NPC patients treated with photon or proton, we hypothesize that CIRT can improve the 2-year OS rate to 70%.Discussion: The utilization of conventional radiation techniques including IMXT, brachytherapy, or stereotactic radiation therapy provides moderate efficacy in the treatment of locally recurrent NPC due to the limitations in dose distribution and biological effectiveness. Improved outcome in terms of treatment-induced toxicity, LC, LPFS, and OS are expected using CIRT due to the physical and biological characteristics of carbon ion beam. However, the recommended dose of CIRT used in re-irradiation for the local NPC focus remain to be determined. The recommended dose as well as the efficacy of CIRT in the treatment of locally recurrent NPC will be evaluated in the present trial.

Clinical utility of RapidArc™ radiotherapy technology.

RapidArc™ is a radiation technique that delivers highly conformal dose distributions through the complete rotation (360°) and speed variation of the linear accelerator gantry. This technique, called volumetric modulated arc therapy (VMAT), compared with conventional radiotherapy techniques, can achieve high-target volume coverage and sparing damage to normal tissues. RapidArc delivers precise dose distribution and conformity similar to or greater than intensity-modulated radiation therapy in a short time, generally a few minutes, to which image-guided radiation therapy is added. RapidArc has become a currently used technology in many centers, which use RapidArc technology to treat a large number of patients. Large and small hospitals use it to treat the most challenging cases, but more and more frequently for the most common cancers. The clinical use of RapidArc and VMAT technology is constantly growing. At present, a limited number of clinical data are published, mostly concerning planning and feasibility studies. Clinical outcome data are increasing for a few tumor sites, even if only a little. The purpose of this work is to discuss the current status of VMAT techniques in clinical use through a review of the published data of planning systems and clinical outcomes in several tumor sites. The study consisted of a systematic review based on analysis of manuscripts retrieved from the PubMed, BioMed Central, and Scopus databases by searching for the keywords “RapidArc”, “Volumetric modulated arc radiotherapy”, and “Intensity-modulated radiotherapy”.

Results of Radiation Therapy (RT) for Primary Extranodal Lymphoma of the Head and Neck: RT Techniques and Literature Review

Radiation therapy (RT) is an important treatment modality for extra-nodal lymphoma (ENL) of the head and neck (H&N). Intensity Modulated radiation therapy (IMRT) has been shown to be associated with decrease in the incidence of late side effects in squamous cell carcinoma of the H&N region. The purpose of the study is to determine the treatment outcomes and late toxicities in 14 patients with ENL of H&N treated with two different RT techniques. Median age was 60 years (range: 42-95). Median follow up was 28 months (range: 1-52). Thirteen patients were treated with RT (8 with IMRT) while one patient with chemotherapy only. Majority of the patients had stage I disease (64%). Overall response rate after combined modality treatment was 100%. There were no local or neck node relapses and none with grade 3 or 4 toxicities. Radiation therapy following chemotherapy or used alone was associated with better local and distant disease control and IMRT is associated with less toxicity profile compared with conventional radiotherapy techniques.

Role of reradiation in head and neck cancer from limits to option

AbstractLocoregional recurrence (LRR) or second primary malignancy in the previously treated area continues to be a major cause of treatment failure with significant morbidity and mortality in head and neck cancer. Prognosis of recurrent disease is dismal. To manage LRR is a therapeutic challenge for multidisciplinary head and neck team and more so if it is in a previously irradiated area. Though surgery is the mainstay of treatment but curative resection is feasible in only minority of patients. Systemic therapy alone has no long-term response rate or survival advantage in the management of inoperable recurrences. Full dose reradiation (RERT) with or without concurrent systemic therapy (CRERT) remains the only viable treatment option offering long-term survival in carefully selected patients. RERT is not a new concept but traditionally been avoided because of concern regarding toxicity due to limitations of conventional radiotherapy techniques. Initial studies were restricted to brachytherapy with its limitations. During the past two decades with the revolution in radiation therapy treatment delivery, more precise treatment techniques such as intensity-modulated radiation therapy, image-guided radiation therapy (IGRT), adaptive radiation therapy, stereotactic body radiotherapy, stereotactic radiosurgery, tomotherapy, intensity modulated proton therapy, image-guided brachytherapy in combination with better imaging modalities to define the target with the concept of biological target volume, offer various options for RERT with improved survival and limited toxicity. Pattern of failure even after full dose RERT is mainly infield, inside recurrent gross tumor volume (r GTV); radioresistance and tumor hypoxia may be the probable explanation. Though RERT has been established as a mainstream treatment option, there is a lack of prospective multi-institutional studies and absence of phase III randomized trial except one in adjuvant setting. Optimum treatment is yet to be defined. We have reviewed the literature and attempt has been made to provide guidance to the priorities on which future investigation should focus. There is a need to reevaluate prognostic factors for survival, selection criteria for patients undergoing RERT, measures to reduce the infield recurrence and morbidity, reradiation tolerance of normal tissue in IGRT era, toxicity antagonist and molecular marker as a diagnostic and prognostic tool. There is a need of multi-institutional prospective randomize trial with uniform data reporting.

Image-guided radiotherapy for cardiac sparing in patients with left-sided breast cancer.

Patients with left-sided breast cancer are at risk of cardiac toxicity because of cardiac irradiation during radiotherapy with the conventional 3-dimensional conformal radiotherapy technique. In addition, many patients may receive chemotherapy prior to radiation, which may damage the myocardium and may increase the potential for late cardiac complications. New radiotherapy techniques such as intensity-modulated radiotherapy (IMRT) may decrease the risk of cardiac toxicity because of the steep dose gradient limiting the volume of the heart irradiated to a high dose. Image-guided radiotherapy (IGRT) is a new technique of IMRT delivery with daily imaging, which may further reduce excessive cardiac irradiation. Preliminary results of IGRT for cardiac sparing in patients with left-sided breast cancer are promising and need to be investigated in future prospective clinical studies.

SU‐E‐T‐34: An in Vivo Study On Pulsed Low Dose‐Rate Radiotherapy for Prostate Cancer

Purpose:Re‐irradiation with conventional radiotherapy techniques (CRT) may pose significant risks due to high accumulative radiation doses. Pulsed low dose‐rate radiotherapy (PLDR) has been used in clinical trials for recurrent cancer treatment. In our previous studies, PLDR irradiation showed significantly lower toxicity than CRT, resulting in much longer survival of mice after PLDR total body irradiation (TBI) than conventional TBI. The purpose of this study was to investigate tumor control efficacy of PLDR treatment for prostate cancer with an animal model of prostate cancer LNCaP.Methods:We used an orthotopic murine model of LNCaP cell line for this study. LNCaP cells were implanted into immune‐suppressed male nude mice via surgery. We monitored the tumor growth with MRI. The tumor‐bearing mice were allocated into a PLDR(n=9), CRT(n=7), and control group(n=7) randomly. The mice in the PLDR and CRT groups were irradiated with 2Gy dose for one time. For the CRT treatment, the mice received 2Gy at a dose‐rate of 300 MU/minute. For the PLDR treatment, the 2Gy dose was further divided into ten pulses of 0.2Gy at the same dose‐rate with an interval of 3 minutes between the pulses.Results:Sizable tumor growth delays were observed for the PLDR and CRT groups through weekly MRI scans. The mean values of the normalized tumor volumes (± standard deviation of the mean) were 1.53±0.07, 1.53±0.14, and 1.81±0.09 at one week after treatment, 2.28±0.13, 2.19±0.16, and 3.04±0.25 at two weeks after treatment, and 3.31±0.23, 3.14±0.24 and 4.62±0.49 at three weeks after treatment, for the PLDR, CRT, and control groups, respectively.Conclusion:The PLDR and CRT treatments showed comparable tumor control rates in this study. Our in vivo results indicate that PLDR may be a viable option for treating recurrent prostate cancer due to its equivalent tumor control but low normal tissue toxocities.

Nasopharyngeal carcinoma: Current treatment options and future directions

The prevalence of nasopharyngeal carcinoma (NPC) has remained high in endemic regions. Various genetic and epigenetic changes synergistically contribute to NPC pathogenesis. Although NPC is highly radiosensitive and chemosensitive, treatment of patients with advanced locoregional disease remains challenging. RT with or without chemotherapy remains the standard treatment for nasopharyngeal carcinoma with IMRT now the preferred technique over conventional radiotherapy techniques because of its ability to deliver high doses of radiations to target structures while sparing the surrounding healthy tissues. New treatment options including targeted monoclonal antibodies and small molecule tyrosine kinase inhibitors are being studied as well. In this article we will review the current standards of care, new techniques and treatment options for NPC.