Clinical use of intensity-modulated radiotherapy: part I

Does shortening the duration of radiotherapy treatment in breast cancer increase the risk of radiation pneumonia: A retrospective study

Randomized studies evaluating hypofractionation and conventional fractionation radiotherapy treatments (RT) in patients with breast cancer have shown that hypofractionation achieves similar results to conventional fractionation in terms of survival and local control rates. It has also been shown that their long-term toxicities are similar. This study aimed to evaluate the effects of hypofractionated radiotherapy (H-RT) and conventional radiotherapy (C-RT) on lung toxicity and identify factors affecting this toxicity in patients with breast cancer. The study included 118 patients who underwent adjuvant RT following breast-conserving surgery (BCS). Out of these, 63 patients were assigned to receive C-RT, while the remaining 55 were assigned to receive H-RT. To clarify, we treated 63 patients with C-RT and 55 patients with H-RT. 60 patients were treated using 3-dimensional conformal radiotherapy (3DCRT) and 58 patients were treated using intensity modulated radiotherapy (IMRT). The patients were evaluated weekly for toxicity during radiotherapy (RT) treatment and were called every 3 months for routine controls after the treatment. The first control was performed 1 month after the treatment. Statistical analysis was performed using the SPSS20 program, and a P value of <.005 was considered statistically significant. The study found that the median age of the participants was 54.9 years and tomographic findings were observed in 70 patients. Radiological findings were detected at a median of 5 months after RT. The mean lung dose (MLD) on the treated breast side (referred to as ipsilateral lung or OAR) was 10.4 Gy for the entire group. Among patients who received 18 MV energy in RT, those with an area volume (V20) of the lung on the treated breast side >18.5%, those with a mean dose of the treated breast side lung (ipsilateral lung) >10.5 Gy, and those who received concurrent hormone therapy had significantly more tomographic findings. However, patients treated with YART had fewer tomographic findings. No symptomatic patients were observed during the follow-up period. Our findings show that the risk of lung toxicity is similar with H-RT and C-RT, and H-RT can be considered an effective and safe treatment option for breast cancer. The key factors affecting the development of lung toxicity were found to be the type of RT energy used, RT to the side breast, volume receiving 20 Gy in the side lung, side lung mean dose, and simultaneous hormonal therapy.

Survival effect of pre-RT PET-CT on cervical cancer: Image-guided intensity-modulated radiation therapy era

Condensed abstract

No large-scale, well-designed randomized study with a long-term follow-up has evaluated the survival effect of pretreatment 18-fluorodeoxyglucose positron emission tomography-computed tomography (¹⁸FDG-PET-CT) on patients with stage IB-IVA cervical cancer receiving image-guided intensity-modulated radiation therapy (IG-IMRT). This is the first head-to-head propensity score-matched, nationwide population-based cohort study evaluating this survival effect. The results revealed that pretreatment ¹⁸FDG-PET-CT might be associated with longer survival in patients with stage IB-IVA cervical cancer receiving radiotherapy or concurrent chemoradiotherapy, especially in the IG-IMRT era.

Purpose

No large-scale, well-designed randomized study with a long-term follow-up has evaluated the survival effect of pretreatment 18-fluorodeoxyglucose positron emission tomography-computed tomography (¹⁸FDG-PET-CT) on patients with stage IB-IVA cervical cancer receiving image-guided intensity-modulated radiation therapy (IG-IMRT). Therefore, in this propensity score-matched, population-based cohort study, we investigated these survival effects.

Patients and methods

We included 4167 patients with stage IB-IVA cervical cancer receiving radiotherapy (RT) or concurrent chemoradiotherapy (CCRT) through the IG-IMRT technique. The patients were categorized into two 1:2 propensity score-matched groups depending on whether they underwent pretreatment ¹⁸FDG-PET-CT, and their outcomes were compared.

Results

We included 2778 and 1389 patients with cervical cancer in the nonpretreatment and pretreatment PET-CT groups, respectively. Univariable and multivariable analyses revealed an association between pretreatment PET-CT and improved survival in the patients (in the adjusted model, the adjusted hazard ratio [aHR] was 0.88; 95% confidence interval [CI], 0.80-0.97: P = 0.010). Regardless of the cancer stage (early or advanced), pretreatment PET-CT was significantly superior to nonpretreatment PET-CT in terms of all-cause death (aHR, 0.78; 95% CI, 0.60-0.92; P = 0.013 and aHR, 0.90; 95% CI, 0.81-0.99; P = 0.039 for the early [IB-IIA] and advanced stages [IIB-IVA], respectively).

Conclusions

Pretreatment ¹⁸FDG-PET-CT might be associated with longer survival in patients with stage IB-IVA cervical cancer receiving RT or CCRT, especially in the era of IG-IMRT.

Knowledge-Based Volumetric Modulated Arc Therapy Treatment Planning for Breast Cancer

Purpose:

To create and to validate knowledge-based volumetric modulated arc therapy (VMAT) models for breast cancer treatments without lymph node irradiation.

Materials and Methods:

One hundred VMAT-based breast plans (manual plans [MP]) were selected to create two knowledge-based VMAT models (breast left and breast right) using RapidPlan™. The plans were generated on Eclipse v15.5 (Varian Medical Systems, Palo Alto, CA) with 6 MV of a Novalis Tx equipped with a high-resolution multileaf collimator. The models were verified based on goodness-of-fit statistics using the coefficients of determination (R²) and Chi-square (χ²), and the goodness-of-estimation statistics through the mean square error (MSE). Geometrical and dosimetrical constraints were identified and removed from the RP models using statistical evaluation metrics and plots. For validation, 20 plans that integrate the models and 20 plans that do not were reoptimized with RP (closed and opened validation). Dosimetrical parameters of interest were used to compare MP versus RP plans for the Heart, Homolateral_Lung, Contralateral_Lung, and Contralateral_Breast. Optimization planning time and user independency were also analyzed.

Results:

The most unfavorable results of R² in both models for the organs at risk were as follows: for Contralateral_Lung 0.51 in RP right breast (RP_RB) and for Heart 0.60 in RP left breast (RP_LB). The most unfavorable results of χ² test were: for Contralateral_Breast 1.02 in RP_RB and for Heart 1.03 in RP_LB. These goodness-of-fit results show that no overfitting occurred in either of the models. There were no unfavorable results of mean square error (MSE, all < 0.05) in any of the two models. These goodness-of-estimation results show that the models have good estimation power. For closed validation, significant differences were found in RP_RB for Homolateral_Lung (all P ≤ 0.001), and in the RP_LB differences were found for the heart (all P ≤ 0.04) and for Homolateral_Lung (all P ≤ 0.022). For open validation, no statistically significant differences were obtained in either of the models. RP models had little impact on reducing optimization planning times for expert planners; nevertheless, the result showed a 30% reduction time for beginner planners. The use of RP models generates high-quality plans, without differences from the planner experience.

Conclusion:

Two RP models for breast cancer treatment using VMAT were successfully implemented. The use of RP models for breast cancer reduces the optimization planning time and improves the efficiency of the treatment planning process while ensuring high-quality plans.

Dose escalation (81 Gy) with image-guided radiation therapy and volumetric-modulated arc therapy for localized prostate cancer: A retrospective preliminary result

OBJECTIVES

The objective of the study is to report the acute and late toxicity and preliminary results of localized prostate cancer treated with high-dose radiation therapy (RT).

MATERIALS AND METHODS

Between March 2010 and October 2018, a total of 53 patients with clinically localized prostate cancer were treated with definitive RT at our institution. All patients were planned to receive a total dose of 81 Gy with the volumetric-modulated arc therapy technique. Patients were stratified by prognostic risk groups based on the National Comprehensive Cancer Network risk classification criteria. Acute and late toxicities were scored by the Radiation Therapy Oncology Group morbidity grading scales. The definition of biochemical failure was using the 2005 ASTRO Phoenix consensus definition. Median follow-up time was 46.5 months (range: 4.7-81.0 months).

RESULTS

The 3-year biochemical failure-free survival rates for low-, intermediate-, and high-risk group patients were 100%, 87.5%, and 84%, respectively. The 3- and 5-year overall survival rates were 83% and 62%, respectively. Three (5.6%) patients developed Grade II acute gastrointestinal (GI) toxicity. Four (7.5%) patients developed Grade II acute genitourinary (GU) toxicity, and none experienced Grade III or higher acute GI or GU symptoms. One (1.8%) patient developed Grade II or higher late GI toxicity. Six (11.3%) patients experienced Grade II late GU toxicity. No Grade III or higher late GI and GU complications have been observed.

CONCLUSIONS

Data from the current study demonstrated the feasibility of dose escalation with image-guided and volumetric-modulated arc therapy techniques for the treatment of localized prostate cancer. Minimal acute and late toxicities were observed from patients in this study. Long-term prostate-specific antigen controls are comparable to previously published results of high-dose intensity-modulated RT for localized prostate cancer. Based on this favorable outcome, dose escalation (81 Gy) has become the standard treatment for localized prostate cancer at our institution.

SUPR-3D: A randomized phase iii trial comparing simple unplanned palliative radiotherapy versus 3d conformal radiotherapy for patients with bone metastases: study protocol

Background

Bone metastases in the lower spine and pelvis are effectively palliated with radiotherapy (RT), though this can come with side effects such as radiation induced nausea and vomiting (RINV). We hypothesize that high rates of RINV occur in part because of the widespread use of inexpensive simple unplanned palliative radiotherapy (SUPR), over more complex and resource intensive 3D conformal RT, such as volumetric modulated arc therapy (VMAT).

Methods

This is a randomized, multi-centre phase III trial of SUPR versus VMAT. We will accrue 250 patients to assess the difference in patient-reported RINV. This study is powered to detect a difference in quality of life between patients treated with VMAT vs. SUPR.

Discussion

This trial will determine if VMAT reduces early toxicity compared to SUPR and may provide justification for this more resource-intensive and costly form of RT.

Trial registration

Clinicaltrials.gov identifier: NCT03694015.

Date of registration: October 3, 2018.

Palliation of Vertebral Metastases with Radiotherapy: Exploration of Volumetric-Modulated Arc Therapy From Development to Implementation in Routine Clinical Practice

The development of volumetric-modulated arc therapy (VMAT) in radiation therapy has allowed for improved dose escalation and a decrease in radiation-induced toxicities for patients. This article will describe a single centre's experience in development and implementation of VMAT for palliation of vertebral metastases. A retrospective planning analysis of 10 cases identified that utilization of VMAT decreases overall planning time with a statistically significant improvement in target coverage when compared with the current conventional technique. PTV Dmax (P = .02), PTV V95_{19Gy (95%)} (P = .01), dose conformation (P = 1.8e-004), and the homogeneity index (P = .019) were all superior for VMAT plans with an average PTV length of 22.46 cm. Another benefit of VMAT utilization is a significant decrease in treatment delivery time, which reduced treatment times from 9.95 minutes to 2.98 minutes. Immobilization was also carefully considered, and rotational errors were measured and fell within institutional tolerances when VMAT was delivered using simple immobilization devices. Clinical implementation of this technique, utilizing a highly conformal target volume to decrease radiation-induced toxicities and minimizing the length of time patients are required to maintain their treatment positions, aims to improve the palliative radiotherapy experience for patients with painful spinal metastases.

Modulated radiotherapy for head and neck carcinomas: an outcome study

Background

To evaluate the survival outcomes and toxicities experienced by non-metastatic head and neck cancer (HNC) patients receiving modulated radiotherapy (RT).

Materials and methods

A total of 608 HNC patients treated consecutively from March 2010 to December 2014 with common subsites (oral cavity, oropharynx, hypopharynx, larynx and nasopharynx) of HNCs formed the study group. Eligible patients included those treated with radical or postoperative RT between March 2010 and December 2014. More than 90% patients received modulated RT [intensity-modulated radiotherapy (IMRT) or volumetric-modulated arc therapy (VMAT)] with concurrent chemotherapy as per stage guidelines. Demographic parameters and disease-related factors were analysed. Disease-free survival (DFS) was calculated from end date of RT till last follow-up or last date of disease control. Overall survival (OS) was calculated from date of registration to last follow-up date if alive. The primary endpoint was survival. The statistical analyses were performed using SPSS version 20.0 and Kaplan–Meier method was used for calculation survival.

Results

Among the evaluable patients, the median age was 60 years (range: 16–93) with male preponderance (male:female – 513:95). Majority were squamous cell carcinoma 93·4% (568/608). The subsites treated were oral cavity 36·8% (224). oropharynx 26·4% (161), larynx 19·7% (120), hypopharynx 10% (62) and nasopharynx 6·4% (41). RT intent was radical in 63·5% (386) and postoperative in 36·5% (222), with 59·5% (362) receiving concurrent chemotherapy. At last follow-up, 348 (57·2%) patients were alive, 169 (27·7%) patients had succumbed to disease and 120 (24·6%) patients had recurrent disease. Out of 120 recurrent cases loco-regional recurrence, nodal recurrence and distant metastases were seen in 62 (51·7%), 25 (20·8%), 33 (27·5%), respectively. In the entire study cohort at 2 year OS and DFS was 80 and 79% whereas 3 years OS and DFS was 70 and 75%, respectively.

Conclusions

In our study, 2 years and 3 years OS and DFS rates are found comparable to the international data with acceptable toxicity profile with the use of modulated RT. It seems to be possible because of stringent departmental protocols and good medical physics support. Our data re-validates need and benefit of advanced RT techniques like IG-IMRT and VMAT for both postoperative and radical HNC treatment at the cost of minimal long-term side effects. Future stringent follow-up and quality of life issues are being considered in a prospective manner.

Dosimetric Effect of Jaw Tracking in Volumetric-Modulated Arc Therapy

The aim of this study was to investigate the potential of jaw tracking with the volumetric-modulated arc therapy (VMAT) to reduce the normal tissue dose. Plans of nasopharynx, lung, and prostate cancers (10 plans for each) were used to perform VMAT with and without jaw tracking. The dose reduction was evaluated in terms of organ doses and integral doses. Organ-dose reduction with jaw tracking was statistically significant in the volume receiving a dose of 5 Gy (V₅) of bladder, rectum, and lung, the volume receiving a dose of 10 Gy (V₁₀) of bladder, rectum, and lung, and the mean dose of lung (P < 0.05). Integral-dose reduction with jaw tracking was statistically significant in almost all the treatment plans (P < 0.05). For organ-dose reduction, jaw tracking in VMAT plan was effective in reducing V₅ and V₁₀. For integral-dose reduction, jaw tracking in VMAT plan is an efficient method for decreasing V₅.

Nanotechnology Strategies To Advance Outcomes in Clinical Cancer Care

Ongoing research into the application of nanotechnology for cancer treatment and diagnosis has demonstrated its advantages within contemporary oncology as well as its intrinsic limitations. The National Cancer Institute publishes the Cancer Nanotechnology Plan every 5 years since 2005. The most recent iteration helped codify the ongoing basic and translational efforts of the field and displayed its breadth with several evolving areas. From merely a technological perspective, this field has seen tremendous growth and success. However, an incomplete understanding of human cancer biology persists relative to the application of nanoscale materials within contemporary oncology. As such, this review presents several evolving areas in cancer nanotechnology in order to identify key clinical and biological challenges that need to be addressed to improve patient outcomes. From this clinical perspective, a sampling of the nano-enabled solutions attempting to overcome barriers faced by traditional therapeutics and diagnostics in the clinical setting are discussed. Finally, a strategic outlook of the future is discussed to highlight the need for next-generation cancer nanotechnology tools designed to address critical gaps in clinical cancer care.

Intensity-Modulated Radiosurgery for Patients with Brain Metastases: A Mature Outcomes Analysis

The purpose of this study was to evaluate the outcomes of patients with brain metastases treated by tomotherapeutic Intensity-modulated Radiosurgery (IMRS). Using retrospective chart review, we analyzed the outcomes of 78 patients (age 33–83 years, median 57 years) who underwent 111 sessions of IMRS (1 to 7 sessions per patient, median 1) for brain metastases (1 to 4 targets per IMRS session, median 1) treated between 2000 and 2005 using a serial tomotherapeutic intensity-modulated radiotherapy treatment (IMRT) planning and delivery system (Peacock, Nomos Corp., Cranberry Township, PA). Treatment planning was performed using an inverse treatment planning optimization algorithm that was optimized for IMRS. A median prescription dose of 15 Gy in combination with WBI, and median 20 Gy for IMRS alone was delivered using 2–4 couch angles over 4–24 rotational arcs. Overall survival was calculated using Kaplan-Meier analysis. To determine the effects of prognostic variables on survival, univariate and multivariate analyses using proportional hazards were performed to assess the effects of age, tumor size, the combination with whole brain irradiation, presence of multiple brain metastases, and presence of extracranial disease. The median overall survival was 6.5 months (95% CI, 5.5–7.9). One- and two-year survival rates were 24% and 10%. In multivariate analyses, age greater than 60 years was the only statistically significant variable that affected survival (hazard rate 1.29, p=0.049). We conclude that tomotherapeutic IMRS is safe and effective to treat patients with brain metastases.

Successful treatment of quintuple primary cancer, including esophageal cancer: A case report

The present study reports the rare case of a patient with quintuple primary cancer that underwent systematic treatment, including surgical intervention. A 63-year-old male patient was initially diagnosed with primary esophageal cancer and hypopharyngeal cancer. The patient underwent total pharyngolaryngoesophagectomy using a thoracoscopic method and reconstruction using the free jejunal flap and gastric tube and was subsequently administered adjuvant chemotherapy (80 mg/m2 intravenously on day 1, cisplatin; 800 mg/m2 continuous intravenous administration on days 1-5, 5-fluorouracil). At 66 years old, the patient was diagnosed with left maxillary sinus cancer and underwent chemoradiotherapy (four 100 mg/m2 arterial cisplatin injections; 70 Gy/35 f radiotherapy, 2 Gy per day over 35 days). At 68 years old, the patient was diagnosed with gastric tube cancer and underwent gastric tube resection followed by pedicled jejunum flap reconstruction. At 69 years old, the patient was diagnosed with tongue cancer and underwent resection and reconstruction of the tongue by pectoralis major myocutaneous flap. Six years subsequent to the primary surgery, the patient remains alive, without metastasis of the lesions. To the best of our knowledge, the present study is the first report of a patient that underwent a curative procedure for the treatment of five primary multiple cancers in five organs, including esophageal cancer.

Nanotechnology in radiation oncology

Nanotechnology, the manipulation of matter on atomic and molecular scales, is a relatively new branch of science. It has already made a significant impact on clinical medicine, especially in oncology. Nanomaterial has several characteristics that are ideal for oncology applications, including preferential accumulation in tumors, low distribution in normal tissues, biodistribution, pharmacokinetics, and clearance, that differ from those of small molecules. Because these properties are also well suited for applications in radiation oncology, nanomaterials have been used in many different areas of radiation oncology for imaging and treatment planning, as well as for radiosensitization to improve the therapeutic ratio. In this article, we review the unique properties of nanomaterials that are favorable for oncology applications and examine the various applications of nanotechnology in radiation oncology. We also discuss the future directions of nanotechnology within the context of radiation oncology.

Volumetric modulated arc therapy: a review of current literature and clinical use in practice

Volumetric modulated arc therapy (VMAT) is a novel radiation technique, which can achieve highly conformal dose distributions with improved target volume coverage and sparing of normal tissues compared with conventional radiotherapy techniques. VMAT also has the potential to offer additional advantages, such as reduced treatment delivery time compared with conventional static field intensity modulated radiotherapy (IMRT). The clinical worldwide use of VMAT is increasing significantly. Currently the majority of published data on VMAT are limited to planning and feasibility studies, although there is emerging clinical outcome data in several tumour sites. This article aims to discuss the current use of VMAT techniques in practice and review the available data from planning and clinical outcome studies in various tumour sites including prostate, pelvis (lower gastrointestinal, gynaecological), head and neck, thoracic, central nervous system, breast and other tumour sites.

Contribution of PET-CT to staging, gross tumour volume definition, planning and response assessment in IMRT for nasopharyngeal carcinoma

The effectiveness of PET-CT (positron emission tomography–computed tomography) was investigated for staging target delineation compared with CT-MR (computed tomography–magnetic resonance) and early response of intensity-modulated radiotherapy (IMRT). Gross tumour volume–clinical target volume (GTV-CTV) differences between PET-CT and CT-MR for 14 nasopharyngeal carcinoma (NPC) patients were compared. Evaluation of doses of organs at risk (OARs) was done by IMRT plans. Responses of IMRT were evaluated with both sets. PET-CT changed MR-based TNM (Tumour Lymph Nodes Metastasis) in 11 of 14 patients. The median GTVNP (nasopharyx gross tumour volume) was 49.25 and 18.8 cm3 for CT-MR and PET-CT, respectively. In eight cases, GTVNP in the PET-CT was smaller than the CT-MR. The PET-CT presented a larger GTVNP than the CT-MR for six cases. Mean doses for the parotid glands were found to be higher than in CT-MR-based plan in one patient although he had smaller GTVNP at the PET-CT. The median follow-up was 16 months. Only one patient experienced recurrence in the CTVNP (nasopharyx clinical target volume). MR showed a decrease in the size-number of lymph nodes in four patients whereas PET-CT showed no uptake. All patients had positive responses to IMRT in their second control MR and PET-CT. PET-CT could improve tumour delineation. This enables an increase in dose inside the CTV. PET-CT provided significant information on the control scans for most of our patients whose MR imaging showed residual or recurrence.

Parotid-sparing intensity modulated versus conventional radiotherapy in head and neck cancer (PARSPORT): a phase 3 multicentre randomised controlled trial

Background

Xerostomia is the most common late side-effect of radiotherapy to the head and neck. Compared with conventional radiotherapy, intensity-modulated radiotherapy (IMRT) can reduce irradiation of the parotid glands. We assessed the hypothesis that parotid-sparing IMRT reduces the incidence of severe xerostomia.

Methods

We undertook a randomised controlled trial between Jan 21, 2003, and Dec 7, 2007, that compared conventional radiotherapy (control) with parotid-sparing IMRT. We randomly assigned patients with histologically confirmed pharyngeal squamous-cell carcinoma (T1–4, N0–3, M0) at six UK radiotherapy centres between the two radiotherapy techniques (1:1 ratio). A dose of 60 or 65 Gy was prescribed in 30 daily fractions given Monday to Friday. Treatment was not masked. Randomisation was by computer-generated permuted blocks and was stratified by centre and tumour site. Our primary endpoint was the proportion of patients with grade 2 or worse xerostomia at 12 months, as assessed by the Late Effects of Normal Tissue (LENT SOMA) scale. Analyses were done on an intention-to-treat basis, with all patients who had assessments included. Long-term follow-up of patients is ongoing. This study is registered with the International Standard Randomised Controlled Trial register, number ISRCTN48243537.

Findings

47 patients were assigned to each treatment arm. Median follow-up was 44·0 months (IQR 30·0–59·7). Six patients from each group died before 12 months and seven patients from the conventional radiotherapy and two from the IMRT group were not assessed at 12 months. At 12 months xerostomia side-effects were reported in 73 of 82 alive patients; grade 2 or worse xerostomia at 12 months was significantly lower in the IMRT group than in the conventional radiotherapy group (25 [74%; 95% CI 56–87] of 34 patients given conventional radiotherapy vs 15 [38%; 23–55] of 39 given IMRT, p=0·0027). The only recorded acute adverse event of grade 2 or worse that differed significantly between the treatment groups was fatigue, which was more prevalent in the IMRT group (18 [41%; 99% CI 23–61] of 44 patients given conventional radiotherapy vs 35 [74%; 55–89] of 47 given IMRT, p=0·0015). At 24 months, grade 2 or worse xerostomia was significantly less common with IMRT than with conventional radiotherapy (20 [83%; 95% CI 63–95] of 24 patients given conventional radiotherapy vs nine [29%; 14–48] of 31 given IMRT; p<0·0001). At 12 and 24 months, significant benefits were seen in recovery of saliva secretion with IMRT compared with conventional radiotherapy, as were clinically significant improvements in dry-mouth-specific and global quality of life scores. At 24 months, no significant differences were seen between randomised groups in non-xerostomia late toxicities, locoregional control, or overall survival.

Interpretation

Sparing the parotid glands with IMRT significantly reduces the incidence of xerostomia and leads to recovery of saliva secretion and improvements in associated quality of life, and thus strongly supports a role for IMRT in squamous-cell carcinoma of the head and neck.

Funding

Cancer Research UK (CRUK/03/005).

Radiation therapy for children: evolving technologies in the era of ALARA

The evolution of ever more sophisticated oncologic imaging and technologies providing far more precise radiation therapy have combined to increase the utilization of sophisticated radiation therapy in childhood cancer. For a majority of children with common central nervous system, soft tissue, bone, and dysontogenic neoplasms, local irradiation is fundamental to successful multi-disciplinary management. Along with more precise target volume definition and radiation delivery, new technologies provide added certainty of patient positioning (electronic portal imaging, cone beam CT) and conformality of dose delivery (3-D conformal irradiation, intensity modulated radiation therapy, proton beam therapy). Each of the major areas of technology development are able to better confine the high-dose region to the intended target, but they are also associated with the potential for larger volumes of uninvolved tissues being exposed to low radiation doses. The latter issue plays a role in documented levels of secondary carcinogenesis, sometimes with greater anticipated incidence than that seen in conventional radiation therapy. Parameters related to carcinogenesis, such as dose-volume relationships and neutron contamination that accompanies high-energy photon irradiation and proton therapy, can be identified, sometimes modulated, and accepted as part of the clinical decision process in fine tuning radiation therapy in this more vulnerable age group.

The phosphoinositide 3-kinase signalling pathway as a therapeutic target in squamous cell carcinoma of the head and neck

Squamous cell carcinoma of the head and neck (SCCHN) is associated with high morbidity and mortality. Despite significant surgical advances and refinement in the delivery of chemotherapy and radiotherapy, prognosis has improved little in recent decades. Better local control has led to the late presentation of distant metastases and novel therapeutic agents are urgently required to prevent relapse, control disseminated disease and thus improve survival. PIK3CA encodes the p110alpha isoform of phosphoinositide 3-kinase (PI3-K) and is important in SCCHN, aberrations in its activity occurring early in the oncogenic process. PI3-K signalling promotes cell survival, proliferation, invasion and angiogenesis, all contributing to tumour progression. Activation of the PI3-K pathway may also mediate resistance to chemotherapy, radiotherapy and novel therapeutic agents such as epidermal growth factor receptor inhibitors. Elements of this signalling matrix, therefore, offer attractive therapeutic targets in SCCHN as inhibition of many malignant characteristics, as well as sensitisation to multiple treatment modalities, could be anticipated.

Four-dimensional computed tomography-based respiratory-gated whole-abdominal intensity-modulated radiation therapy for ovarian cancer: a feasibility study

This study assesses the feasibility and implementation of respiratory-gated whole-abdominal intensity-modulated radiation therapy (RG-WAIMRT). Three patients were treated with RG-WAIMRT. The planning target volume (PTV1) included the entire peritoneal cavity and a pelvic boost field was created (PTV2). The dose prescribed was 30 Gy to PTV1 and 14.4 Gy to PTV2. For comparison, a conventional three-dimensional (3D) plan was generated for each patient. In the WAIMRT plan, an average of 90% of PTV1 received 30 Gy compared to 70% for the conventional 3D plan. The percent volume receiving 30 Gy (V30) for liver averaged 54% (WAIMRT) vs 43% (3D). The percent volume receiving 20 Gy (V20) for kidneys averaged 19% vs 0%, and the mean V20 for bone marrow was 74% vs 83%, respectively. Major acute toxicities were anemia (grade 2: 1/3), leukopenia (grade 3: 2/3 patients), and thrombocytopenia (grade 2: 1/3 patients, grade 3: 1/3 patients). One patient could not complete the whole-abdomen field after 19.5 Gy because of persistent nausea. No major subacute toxicity has been reported. WAIMRT demonstrated superior target coverage and reduced dose to bone marrow, with a slightly increased dose to liver and kidneys. WAIMRT is a novel and feasible technique for ovarian cancer treatment.

Recent Advances in Radiation Therapy for Head and Neck Cancer

The treatment of locally advanced or recurrent head and neck cancers has improved from single modality interventions of surgery and radiation therapy alone to include combined modality therapy with surgery, chemotherapy and radiation. Combined therapy has led to improved local control and disease-free survival. New developments in radiation oncology such as altered fractionation, three-dimensional conformal radiotherapy, intensity-modulated radiotherapy, stereotactic radiosurgery, fractionated stereotactic radiotherapy, charged-particle radiotherapy, neutron-beam radiotherapy, and brachytherapy have helped to improve this outlook even further. These recent advances allow for a higher dose to be delivered to the tumor while minimizing the dose delivered to the surrounding normal tissue. This article provides an update of the new developments in radiotherapy in the management of head and neck cancers.

Advanced imaging applied to radiotherapy planning in head and neck cancer: a clinical review

Head and neck squamous cell carcinoma represents an ideal model to investigate the application of recent advances in medical imaging to radiotherapy planning. Tumours usually remain localized, and are potentially curable with local radiation. The steep radiation dose-response relationships support the strategies of radiation dose escalation to increase local control. Two-dimensional simulator-based planning and CT planning have significant drawbacks in terms of accurate target volume definition. MRI has enhanced soft tissue delineation, but has to be fused with CT to allow dose calculation. Functional imaging using dynamic contrast enhanced CT or MRI sequences may allow improved knowledge of tumour function. Positron emission tomography (PET) may allow further physiological information to be determined. This review summarizes the current techniques in clinical development in this area.

The IMRT information process—mastering the degrees of freedom in external beam therapy

The techniques and procedures for intensity-modulated radiation therapy (IMRT) are reviewed in the context of the information process central to treatment planning and delivery of IMRT. A presentation is given of the evolution of the information based radiotherapy workflow and dose delivery techniques, as well as the volume and planning concepts for relating the dose information to image based patient representations. The formulation of the dose shaping process as an optimization problem is described. The different steps in the calculation flow for determination of machine parameters for dose delivery are described starting from the formulation of optimization objectives over dose calculation to optimization procedures. Finally, the main elements of the quality assurance procedure necessary for implementing IMRT clinically are reviewed.

Is tomotherapy the future of IMRT?

Intensity-modulated radiotherapy (IMRT) has become established in many clinics round the world and is, arguably, technically feasible in any facility. Serial tomotherapy contributed an extensive role in its introduction into the mainstream in the second half of the 1990s. In tomotherapy, literally "slice therapy", highly conformal treatments are possible because of the advantages available within the treatment planning of the IMRT process. Currently the majority of clinics implementing IMRT are doing so using conventional clinical linear accelerators (Linacs) fitted with an integrated multileaf collimator (MLC). At this point in time we may wonder if there is any scope for further dramatic changes in this new technology. As we venture from IMRT initial implementation into image guided therapy it is clear that major changes in approach are still valid and needed. If, at each treatment fraction, we can ensure that treatments are delivered accurately by integration of volumetric imaging into on-line validation, then we can attempt higher levels of conformality. A new treatment machine, the helical tomotherapy system, is available that combines the benefits of tomotherapy with on-line volumetric imaging. In this article we will review this approach and explore its features.

Clinical use of intensity-modulated radiotherapy: part II

Intensity-modulated radiotherapy (IMRT) is a novel conformal radiotherapy technique which is gaining increasingly widespread use. This second clinical article aims to summarize the published data pertaining to prostate cancer, pelvic irradiation, gynaecological and breast cancer. Prostate cancer patients represent the largest group treated to date. The main indication has been radiation dose escalation within acceptable normal tissue late toxicity. Phase II data are promising, but no randomized clinical trial data are available to support its use. Pelvic IMRT aims to deliver radical radiation doses to pelvic lymph nodes while sparing the bowel and bladder. Indications for breast IMRT data are reviewed, and current data presented. Further data from randomized trials are required to confirm the anticipated benefits of IMRT in patients.