Intensity-modulated radiation therapy in the treatment of head and neck cancer

Multi-organ segmentation of organ-at-risk (OAR's) of head and neck site using ensemble learning technique

INTRODUCTION

This paper presents a novel approach to automate the segmentation of Organ-at-Risk (OAR) in Head and Neck cancer patients using Deep Learning models combined with Ensemble Learning techniques. The study aims to improve the accuracy and efficiency of OAR segmentation, essential for radiotherapy treatment planning.

METHODS

The dataset comprised computed tomography (CT) scans of 182 patients in DICOM format, obtained from an institutional image bank. Experienced Radiation Oncologists manually segmented seven OARs for each scan. Two models, 3D U-Net and 3D DenseNet-FCN, were trained on reduced CT scans (192 × 192 x 128) due to memory limitations. Ensemble Learning techniques were employed to enhance accuracy and segmentation metrics. Testing was conducted on 78 patients from the institutional dataset and an open-source dataset (TCGA-HNSC and Head-Neck Cetuximab) consisting of 31 patient scans.

RESULTS

Using the Ensemble Learning technique, the average dice similarity coefficient for OARs ranged from 0.990 to 0.994, indicating high segmentation accuracy. The 95% Hausdorff distance (mm) ranged from 1.3 to 2.1, demonstrating precise segmentation boundaries.

CONCLUSION

The proposed automated segmentation method achieved efficient and accurate OAR segmentation, surpassing human expert performance in terms of time and accuracy.

IMPLICATIONS FOR PRACTICE

This approach has implications for improving treatment planning and patient care in radiotherapy. By reducing manual segmentation reliance, the proposed method offers significant time savings and potential improvements in treatment planning efficiency and precision for head and neck cancer patients.

Dosimetry audit in advanced radiotherapy using in-house developed anthropomorphic head & neck phantom

The treatment of head and neck (H&N) cancer presents formidable challenges due to the involvement of normal tissue and organs at risk (OARs) in the close vicinity. Ensuring the precise administration of the prescribed dose demands prior dose verification. Considering contour irregularity and heterogeneity in the H&N region, an anthropomorphic and heterogeneous H&N phantom was developed and fabricated locally for conducting the dosimetry audit in advanced radiotherapy treatments. This specialized phantom emulates human anatomy and incorporates a removable cylindrical insert housing a C-shaped planning target volume (PTV) alongside key OARs including the spinal cord, oral cavity, and bilateral parotid glands. Acrylonitrile Butadiene Styrene (ABS) was chosen for PTV and parotid fabrication, while Delrin was adopted for spinal cord fabrication. A pivotal feature of this phantom is the incorporation of thermoluminescent dosimeters (TLDs) within the PTV and OARs, enabling the measurement of delivered dose. To execute the dosimetry audit, the phantom, accompanied by dosimeters and comprehensive guidelines, was disseminated to multiple radiotherapy centers. Subsequently, hospital physicists acquired computed tomography (CT) scans to generate treatment plans for phantom irradiation. The treatment planning system (TPS) computed the anticipated dose distribution within the phantom, and post-irradiation TLD readings yielded actual dose measurements. The TPS calculated and TLD measured dose values at most of the locations inside the PTV were found comparable within ± 4%. The outcomes affirm the suitability of the developed anthropomorphic H&N phantom for precise dosimetry audits of advanced radiotherapy treatments.

Definitive radiotherapy for squamous cell carcinoma of the oral cavity: a single-institution experience

Background

Surgery is standard of care for oral cavity cancer (OCC). We provide a single-institution experience using definitive radiotherapy (RT) with or without concurrent systemic therapy for primary unresectable OCC.

Patients and methods

We retrospectively examined 49 patients with non-metastatic primary unresectable OCC treated with definitive RT between 2000 and 2019. The majority of patients (63.3%) were treated with definitive chemoradiotherapy while 26.5% were given single-agent cetuximab weekly simultaneous to definitive RT. Five patients were treated with definitive RT alone because of limited disease and no nodal involvement.

Results

Median follow-up was 73 months (range, 6–236 months), median progression free survival (PFS) was 42 months (range, 2–157 months), median local disease-free survival (LDFS) was 44 months (range, 2–157 months) and median overall survival (OS) from the time of RT initiation was 52 months (range, 5–236 months). There were 65.3% locoregional failures, 84.4% local and 15.6% distant metastasis. The majority of patients with local failure presented with American Joint Committee on Cancer (AJCC) Stage III–IV disease (59.2%). The 5-year Kaplan-Meier estimates for OS (III–IV vs. I–II) was 22.8% vs. 54.2 % (p = 0.03, HR 2.090, 1.1–4.2). Patients who were treated with systemic therapy had a significant better 5-year overall survival compared to those with RT alone (43.9% vs. 23.1%, p = 0.05, 1.0–4.1). RT with doses less than 70 Gy (p = 0.046, HR 2.1 (1.0–4.5) was associated with worse overall survival. Mucositis was the most common ≥ grade 3 acute toxicity and occurred in 19 patients (39%). Incidences of chronic toxicities were loss of taste, trismus, osteoradionecrosis and xerostomia.

Conclusions

Definitive RT with or without concurrent systemic agents in patients with unresectable OCC resulted in an eloquent rate of locoregional control and good overall survival rates and is currently the best available treatment option in this patient collective.

Comparison between Dual Arc VMAT and 7F-IMRT in the protection of hippocampus for patients during whole brain radiotherapy

PURPOSE

The purpose of this study was to compare the dosimetric characteristics for protection of the hippocampus between dual arc VMAT (volumetric modulated arc therapy) and 7 fields intensity-modulated radiation therapy (7F-IMRT) for patients with brain metastases from lung cancer under the whole brain radiotherapy.

METHODS

Based on ten cases with brain metastases from lung cancer, two types of radiotherapy plans were designed, namely, dual arc VMAT and 7F-IMRT. Provided that the clinical requirements were satisfied, the comparisons of target dose distribution, conformity index (CI), homogeneity index (HI), dose of organs at risk (OARs), monitor units (MU) and treatment time between dual arc VMAT and 7F-IMRT were investigated for their dosimetric difference.

RESULTS

Both treatment plans met the requirements of clinical treatments. However, the PTV-HA conformity and homogeneity of dual arc VMAT were superior to those of 7F-IMRT (P < 0.05). As to OARs, the mean maximum doses (Dmax) of hippocampus, eyes and optic nerves in the dual arc VMAT plan were all lower than those in 7F-IMRT plan (P < 0.05), but the result had no statistical significance (P < 0.05) for the maximum dose of lens. Compared with 7F-IMRT, dual arc VMAT reduced the average number of MU by 67% and the average treatment time by 74%. Therefore, treatment time was shortened by dual arc VMAT.

CONCLUSION

With regards to the patients with brain metastases from lung cancer under the whole brain radiotherapy, the PTV-HA conformity and homogeneity of dual arc VMAT were superior to those of 7F-IMRT under the precise of meeting the clinical requirements. In addition, dual arc VMAT remarkably reduced the irradiation dose to OARs (hippocampus, eyes and optic nerves), MU and treatment time, as well, guaranteed patients with better protection.

Effective Biomarkers and Radiation Treatment in Head and Neck Cancer

CONTEXT

Radiation is a key arm in the multidisciplinary treatment of patients with head and neck squamous cell carcinoma. During the past 2 decades, significant changes in the way radiation therapy is planned and delivered have improved efficacy and decreased toxicity. Refined approaches in the application of radiation and chemoradiation have led to organ-sparing treatment regimens for laryngeal and pharyngeal cancers and have improved local and regional control rates in the postoperative, adjuvant setting. The molecular and genetic determinants of tumor cell response to radiation have been studied, and several potential biomarkers are emerging that could further improve application and efficacy of radiation treatment in head and neck squamous cell carcinoma.

OBJECTIVE

To discuss the current understanding of potential biomarkers related to radiation response in head and neck squamous cell carcinoma.

DATA SOURCES

Existing published literature.

CONCLUSIONS

Several potential biomarkers are actively being studied as predictors and targets to improve the use and efficacy of radiation therapy to treat head and neck squamous cell carcinoma. Several promising candidates have been defined, and new markers are on the horizon.

Image Guidance-Based Target Volume Margin Expansion in IMRT of Head and Neck Cancer

This study quantifies the setup uncertainties to optimize the planning target volume (PTV) margin based on daily image guidance, its dosimetric impact, and radiobiological implication for intensity-modulated radiation therapy (IMRT) in head and neck cancer. Ten patients were retrospectively chosen who had been treated with IMRT and with daily image-guided radiation therapy (IGRT). The daily setup errors of the 10 patients from on-board imaging for the entire treatment were analyzed. Planning target volumes were generated by expanding the clinical target volumes (CTVs) with 0 to 10 mm margins. The IMRT plans with the same dose-volume constraints were created in an Eclipse treatment planning system. The effect of volume expansion was analyzed with biological indices such as tumor control probability, normal tissue complication probability (NTCP), and equivalent uniform dose. Analysis of 906 daily setup corrections using daily IGRT showed that 98% of the daily setups are within ± 5 mm. The relative increase in PTV-CTV volume from 0 to 10 mm margins provides nearly 4-fold volume increase and is linearly related to monitor unit (MU). The increase in MU is about 5%/mm margin increase. The relative increase in NTCP of parotids from 5 to 10 mm margins is 3.2 ± 1.15. Increase in PTV margin increases extra tissue volume with a corresponding increase in MU for treatment and NTCP values. Even a small margin increase (eg, 1 mm) may result in increase of more than 20% in relative extra volume and 15% in NTCP value of organs at risk (OARs). With image guidance, the setup uncertainty could be achieved within ± 5 mm for 98% of the treatments, and a margin <5 mm for PTV may seem desirable to reduce the extra tissue irradiated, but at the expense of a more demanding setup accuracy.

Molecular radiobiology: the state of the art

Traditional cytotoxic agents used in cancer therapy were initially discovered based on their ability to kill rapidly dividing cells. The targets of these early-generation agents were typically one or more aspects of DNA synthesis or mitosis. Thus, dose-limiting toxicities commonly associated with these agents include GI dysfunction, immunosuppression, and other consequences of injury to normal tissues in which cells are replicating under normal physiologic conditions. Although many of these agents still play an important role in cancer therapy when given concurrently with radiation therapy, the major thrust of radiobiology research in the last two decades has focused on discovering tumor-specific traits that might be exploited for more selective targeting that would enhance the efficacy of radiotherapy with less normal tissue toxicity. These newer generation molecular targeted therapies interfere with the growth of tumor cells by inhibiting genes and their protein products that are needed specifically by the tumor for survival and expansion. These agents can be complementary to radiotherapy, a spatially targeted agent. Although there have been extraordinary technical advances in radiotherapy in recent years, we are reaching the limits of improvements that radiotherapy delivery technology can bring and need different approaches. This review will highlight promising new tumor biology-based targets and other novel strategies to reduce normal tissue injury, increase tumor control, and expand the use of radiotherapy to treat widespread metastatic disease.

Effect of irradiation on cell transcriptome and proteome of rat submandibular salivary glands

Salivary glands (SGs) are irreversibly damaged by irradiation (IR) treatment in head and neck cancer patients. Here, we used an animal irradiation model to investigate and define the molecular mechanisms affecting SGs following IR, focusing on saliva proteome and global transcription profile of submandibular salivary gland (SSG) tissue.We show that saliva secretion was gradually reduced to 50% of its initial level 12 weeks post-IR. Saliva protein composition was further examined by proteomic analysis following mass spectrometry (MS) analysis that revealed proteins with reduced expression originating from SSGs and proteins with increased expression derived from the serum, both indicating salivary tissue damage. To examine alterations in mRNA expression levels microarray analysis was performed. We found significant alterations in 95 genes, including cell-cycle arrest genes, SG functional genes and a DNA repair gene.Tissue damage was seen by confocal immunofluorescence of α-amylase and c-Kit that showed an increase and decrease, respectively, in protein expression. This was coherent with real-time PCR results.This data indicates that IR damages the SSG cells' ability to produce and secrete saliva and proteins, and maintain the physiological barrier between serum and saliva. The damage does not heal due to cell-cycle arrest, which prevents tissue regeneration. Taken together, our results reveal a new insight into IR pathobiology.

Evidence-based review: quality of life following head and neck intensity-modulated radiotherapy

Inverse planned Intensity modulated radiotherapy (IMRT) can minimize the dose to normal structures and therefore can reduce long-term radiotherapy-related morbidity and may improve patients' long-term quality of life. Despite overwhelming evidence that IMRT can reduce late functional deficits in patients with head and neck cancer, treated with radiotherapy, a review of the published literature produced conflicting results with regard to quality of life outcomes. Following a critical appraisal of the literature, reasons for the discrepant outcomes are proposed.

Spontaneous and x-ray-triggered crystallization at long range in self-assembling filament networks

We report here crystallization at long range in networks of like-charge supramolecular peptide filaments mediated by repulsive forces. The crystallization is spontaneous beyond a given concentration of the molecules that form the filaments but can be triggered by x-rays at lower concentrations. The crystalline domains formed by x-ray irradiation, with interfilament separations of up to 320 angstroms, can be stable for hours after the beam is turned off, and ions that screen charges on the filaments suppress ordering. We hypothesize that the stability of crystalline domains emerges from a balance of repulsive tensions linked to native or x-ray-induced charges and the mechanical compressive entrapment of filaments within a network. Similar phenomena may occur naturally in the cytoskeleton of cells and, if induced externally in biological or artificial systems, lead to possible biomedical and lithographic functions.

IMRT dose fractionation for head and neck cancer: variation in current approaches will make standardisation difficult

INTRODUCTION

Altered fractionation has demonstrated clinical benefits compared to the conventional 2 Gy/day standard of 70 Gy. When using synchronous chemotherapy, there is uncertainty about optimum fractionation. IMRT with its potential for Simultaneous Integrated Boost (SIB) adds further to this uncertainty. This survey will examine international practice of IMRT fractionation and suggest possible reasons for diversity in approach.

MATERIAL AND METHODS

Fourteen international cancer centres were surveyed for IMRT dose/fractionation practised in each centre.

RESULTS

Twelve different types of dose fractionation were reported. Conventional 70-72 Gy (daily 2 Gy/fraction) was used in 3/14 centres with concurrent chemotherapy while 11/14 centres used altered fractionation. Two centres used >1 schedule. Reported schedules and number of centres included 6 fractions/week DAHANCA regime (3), modest hypofractionation (< or =2.2 Gy/fraction) (3), dose-escalated hypofractionation (> or =2.3 Gy/fraction) (4), hyperfractionation (1), continuous acceleration (1) and concomitant boost (1). Reasons for dose fractionation variability include (i) dose escalation; (ii) total irradiated volume; (iii) number of target volumes; (iv) synchronous systemic treatment; (v) shorter overall treatment time; (vi) resources availability; (vii) longer time on treatment couch; (viii) variable GTV margins; (ix) confidence in treatment setup; (x) late tissue toxicity and (xi) use of lower neck anterior fields.

CONCLUSIONS

This variability in IMRT fractionation makes any meaningful comparison of treatment results difficult. Some standardization is needed particularly for design of multi-centre randomized clinical trials.

Clinical practice guidance for radiotherapy planning after induction chemotherapy in locoregionally advanced head-and-neck cancer

PURPOSE

The use of induction chemotherapy (IC) for locoregionally advanced head-and-neck cancer is increasing. The response to IC often causes significant alterations in tumor volume and location and shifts in normal anatomy. Proper determination of the radiotherapy (RT) targets after IC becomes challenging, especially with the use of conformal and precision RT techniques. Therefore, a consensus conference was convened to discuss issues related to RT planning and coordination of care for patients receiving IC.

METHODS AND MATERIALS

Ten participants with special expertise in the various aspects of integration of IC and RT for the treatment of locoregionally advanced head-and-neck cancer, including radiation oncologists, medical oncologists, and a medical physicist, participated. The individual members were assigned topics for focused, didactic presentations. Discussion was encouraged after each presentation, and recommendations were formulated.

RESULTS

Recommendations and guidelines emerged that emphasize up-front evaluation by all members of the head-and-neck management team, high-quality baseline and postinduction planning scans with the patient in the treatment position, the use of preinduction target volumes, and the use of full-dose RT, even in the face of a complete response.

CONCLUSION

A multidisciplinary approach is strongly encouraged. Although these recommendations were provided primarily for patients treated with IC, many of these same principles apply to concurrent chemoradiotherapy without IC. A rapid response during RT is quite common, requiring the development of two or more plans in a sizeable fraction of patients, and suggesting the need for similar guidance in the rapidly evolving area of adaptive RT.

A predictive model for swallowing dysfunction after curative radiotherapy in head and neck cancer

INTRODUCTION

Recently, we found that swallowing dysfunction after curative (chemo) radiation (CH) RT has a strong negative impact on health-related quality of life (HRQoL), even more than xerostomia. The purpose of this study was to design a predictive model for swallowing dysfunction after curative radiotherapy or chemoradiation.

MATERIALS AND METHODS

A prospective study was performed including 529 patients with head and neck squamous cell carcinoma (HNSCC) treated with curative (CH) RT. In all patients, acute and late radiation-induced morbidity (RTOG Acute and Late Morbidity Scoring System) was scored prospectively. To design the model univariate and multivariate logistic regression analyses were carried out with grade 2 or higher RTOG swallowing dysfunction at 6 months as the primary (SWALL(6months)) endpoint. The model was validated by comparing the predicted and observed complication rates and by testing if the model also predicted acute dysphagia and late dysphagia at later time points (12, 18 and 24 months).

RESULTS

After univariate and multivariate logistic regression analyses, the following factors turned out to be independent prognostic factors for SWALL(6months): T3-T4, bilateral neck irradiation, weight loss prior to radiation, oropharyngeal and nasopharyngeal tumours, accelerated radiotherapy and concomitant chemoradiation. By summation of the regression coefficients derived from the multivariate model, the Total Dysphagia Risk Score (TDRS) could be calculated. In the logistic regression model, the TDRS was significantly associated with SWALL(6months) ((p<0.001). Subsequently, we defined three risk groups based on the TDRS. The rate of SWALL(6months) was 5%, 24% and 46% in case of low-, intermediate- and high-risk patients, respectively. These observed percentages were within the 95% confidence intervals of the predicted values. The TDRS risk group classification was also significantly associated with acute dysphagia (P<0.001 at all time points) and with late swallowing dysfunction at 12, 18 and 24 months (p<0.001 at all time points).

CONCLUSION

The TDRS is a simple and validated measure to predict swallowing dysfunction after curative (CH) RT for HNC. This classification system enables identification of patients who may benefit from strategies aiming at prevention of swallowing dysfunction after curative (CH) RT such as preventive swallowing exercises during treatment and/or emerging IMRT techniques aiming at sparing anatomical structures that are involved in swallowing.

Multidisciplinary approach to cancer treatment: focus on head and neck cancer

This article focuses on squamous cell carcinoma of the head and neck (SCCHN), the most common malignancy of the head and neck area. Early detection limits morbidity of treatment and increases the chances of a cure. The treatment of SCCHN is often multidisciplinary in nature and provides a model for how multimodality therapy may be applied for optimal patient management. The role of surgery in SCCHN is continually undergoing evolution, and the surgeon's role in the multidisciplinary treatment of head and neck cancers has changed as more cancers are being treated by chemoradiotherapy. Salvage surgery has become more common, and with it the increased challenges in managing metastatic disease to neck nodes as well as managing failure of organ preservation treatments. Surgeons continue to develop and refine reconstruction techniques to optimize cosmetic and functional outcomes.

Individual patients' data meta-analyses in head and neck cancer

PURPOSE OF REVIEW

This is a review of the experience obtained at the Institute Gustave Roussy, evaluating the role of chemotherapy and of altered fractionated radiotherapy in locally advanced head and neck cancer. The database included nearly 120 randomized trials, and about 25,000 patients, with a median follow-up of 6 years.

RECENT FINDINGS

In the chemotherapy database (Meta-Analysis of Chemotherapy in Head, Neck Cancer and Meta-Analysis of Chemotherapy in Nasopharynx Carcinoma), concomitant cisplatin-based radiotherapy-chemotherapy provided the most significant benefit on locoregional control and survival, both in head and neck squamous cell carcinomas and nasopharyngeal carcinomas. In head and neck squamous cell carcinomas, the benefit of adding concomitant chemotherapy was found to be in the same order of magnitude whether radiotherapy was postoperative or definitive. In the altered radiotherapy database (Meta-Analysis of Radiotherapy in Carcinoma of Head and Neck), among the different types of altered fractionated radiotherapy, hyperfractionation provided the most significant benefit. The benefit associated with altered fractionated radiotherapy and of concomitant chemotherapy markedly decreased with increasing age.

SUMMARY

This database provided a unique tool to evaluate long-term effects of chemotherapy and altered fractionated radiotherapy in head and neck cancer. This allowed the oncological community to obtain a reliable characterization of the magnitude of the treatment benefits in this type of cancer and to base patient care and future research on strong evidence.

Segmentation and leaf sequencing for intensity modulated arc therapy

A common method in generating intensity modulated radiation therapy (IMRT) plans consists of a three step process: an optimized fluence intensity map (IM) for each beam is generated via inverse planning, this IM is then segmented into discrete levels, and finally, the segmented map is translated into a set of MLC apertures via a leaf sequencing algorithm. To date, limited work has been done on this approach as it pertains to intensity modulated arc therapy (IMAT), specifically in regards to the latter two steps. There are two determining factors that separate IMAT segmentation and leaf sequencing from their IMRT equivalents: (1) the intrinsic 3D nature of the intensity maps (standard 2D maps plus the angular component), and (2) that the dynamic multileaf collimator (MLC) constraints be met using a minimum number of arcs. In this work, we illustrate a technique to create an IMAT plan that replicates Tomotherapy deliveries by applying IMAT specific segmentation and leaf-sequencing algorithms to Tomotherapy output sinograms. We propose and compare two alternative segmentation techniques, a clustering method, and a bottom-up segmentation method (BUS). We also introduce a novel IMAT leaf-sequencing algorithm that explicitly takes leaf movement constraints into consideration. These algorithms were tested with 51 angular projections of the output leaf-open sinograms generated on the Hi-ART II treatment planning system (Tomotherapy Inc.). We present two geometric phantoms and 2 clinical scenarios as sample test cases. In each case 12 IMAT plans were created, ranging from 2 to 7 intensity levels. Half were generated using the BUS segmentation and half with the clustering method. We report on the number of arcs produced as well as differences between Tomotherapy output sinograms and segmented IMAT intensity maps. For each case one plan for each segmentation method is chosen for full Monte Carlo dose calculation (NumeriX LLC) and dose volume histograms (DVH) are calculated. In all cases, the BUS method outperformed the clustering, method. We recommend using the BUS algorithm and discuss potential improvements to the clustering algorithms.

Implications of learning effects for hospital costs of new health technologies: The case of intensity modulated radiation therapy

Objectives: The impact of learning effects on the variability of costs of new health technologies in a prospective payment system (PPS) through the case of intensity modulated radiation therapy (IMRT) was studied.

Methods: A series of consecutive patients treated in nine medical centers was enrolled in a prospective study. Direct costs were assessed from the perspective of the healthcare providers. We used a two-level model to explain the variability of costs: patients nested within centers. Learning effects at the center level were considered through a fixed effect (the learning curve slope) and a random effect (the initial cost level). Covariates were introduced to explain the patterns of variation in terms of patient characteristics.

Results: The mean direct cost of IMRT was €5,962 (range, €2,414–€24,733). Manpower accounted for 53 percent of this cost. Learning effects explained 42 percent of the variance between centers (which was 88 percent of the total variance) and were associated with a substantial decrease in treatment costs. The mean initial treatment direct cost was €6,332 in centers with a previous experience of IMRT, whereas it was €14,192 in centers implementing IMRT for the first time. Including logistics costs and overhead, the full cost of IMRT was €10,916. Average reimbursement was €6,987.

Conclusions: Learning effects are a strong confounding factor in the analysis of costs of innovative health technologies involving learning effects. In a PPS, innovative health technology involving learning effects necessitates specific reimbursement mechanisms.

The chemoradiation paradigm in head and neck cancer

In this article, we use the example of head and neck cancer to show how concurrent chemoradiotherapy is used to treat a cancer where locoregional control is central for treatment success. The advent of concurrent chemoradiation has significantly contributed to the curability of head and neck cancer, including locoregionally advanced disease. Preserving organ function and reducing toxic effects are increasingly the focus of clinical trials. We review the available chemoradiotherapy platforms used for head and neck cancer, with initial discussions focused on single-agent cytotoxic-based regimens. We then assess the literature on multiagent-based regimens and include a discussion of the integration of novel agents, such as EGFR inhibitors, and antiangiogenic drugs into treatment platforms. Although single-agent cisplatin-based chemoradiotherapy is still widely used as a standard therapy, we propose that evidence increasingly shows that multiagent-based chemoradiotherapy, and EGFR-inhibitor-based treatments, offer distinct advantages. We provide guidance for clinicians based on current clinical trial evidence on how to choose appropriate treatment platforms for their patients.

The Clinical Application of Intensity-Modulated Radiation Therapy

Intensity-modulated radiation therapy is a delivery system that, when coupled with a treatment-planning optimization system, presents the opportunity to conform the dose to the target better than 3-dimensional conformal therapy, particularly in the case of concave targets. Appropriate clinical applications of this technology to challenging patient treatment scenarios requires careful consideration of issues related to target volume-dose heterogeneity and the influence of patient setup uncertainties. These issues are reviewed and illustrated. To date, clinical reports of these treatments for prostate and head and neck cancers have the most mature data. Those results are summarized here. Future applications of this technology can be expected to take careful, considered advantage of this technology to further rearrange dose distributions across target volumes to produce an integrated overall gain in treatment objectives. However, these innovative applications need to be approached with caution, preferably in prospective clinical trials that would help determine if the hypothetical clinical benefits are in fact realizable.

Adjuvant Therapy in Patients With Resected Poor-Risk Head and Neck Cancer

In patients with locally or regionally advanced head and neck carcinomas, postoperative radiotherapy has historically been the adjuvant therapy applied for patients with prognostically worrisome pathologic features. Any improvement in therapeutic index achieved by adding cytotoxic agents to postoperative radiotherapy remained controversial. However, two recent randomized trials, conducted in parallel in Europe and the United States, produced level I evidence regarding improved efficacy in this setting for the concurrent administration of chemotherapy and radiotherapy. High-dose cisplatin and irradiation can now be considered the standard therapeutic approach for resected poor-risk disease. The presence of positive margins and/or nodal extracapsular spread in the surgical specimens are the subgroups that appear to benefit in the most significant way from the addition of chemotherapy to radiation. Many questions regarding the optimization of adjuvant treatments still remain unanswered, especially with respect to improvement of patient compliance, integration of novel drugs targeting both locoregional and systemic control, and modulation of treatment intensity according to risk levels.