Clinical evaluation of intensity-modulated radiotherapy for head and neck cancers

Radiotherapy and surgery are the principal curative modalities in treatment of head and neck cancer. Conventional two-dimensional and three-dimensional conformal radiotherapy result in significant side effects and altered quality of life. Intensity-modulated radiotherapy (IMRT) can spare the normal tissues, while delivering a curative dose to the tumour-bearing tissues. This article reviews the current role of IMRT in head and neck cancer from the point of view of normal tissue sparing, and also reviews the current published literature by individual head and neck cancer subsites. In addition, we briefly discuss the role of image guidance in head and neck IMRT, and future directions in this area.     

Resectability issues with head and neck cancer

Head and neck surgeons often rely on imaging to determine if a neoplasm is resectable. Many of the critical issues are outlined in the American Joint Committee on Cancer Staging Manual, wherein T4a and T4b head and neck cancers are defined as resectable and unresectable, respectively. Even within the T4a advanced resectable classification, there are critical determinants that define whether the surgical option is such that major morbidity and mortality could be expected. This review article examines the imaging literature to determine the accuracy and diagnostic criteria of different modalities for evaluating these critical T4a and T4b factors, which include the following: 1) arterial encasement, 2) prevertebral fascia involvement, 3) mediastinal infiltration, 4) tracheal and esophageal extension, 5) laryngeal cartilage penetration, 6) pre-epiglottic fat involvement, 7) dural spread, 8) bone (mandible/maxilla and skull base) infiltration, 9) perineural spread, 10) orbital involvement, and 11) brachial plexus invasion. For the most part, the studies find MR imaging with higher sensitivity but lower specificity than CT. An ever-increasing role for PET/CT is suggested. Imaging is of great value in the determination of resectability issues listed previously for head and neck cancers, with the possible exception of prevertebral fascia involvement.     

Survival of patients with head and neck cancer

Background

Prognostic factors (e.g., gender, tumor stage, and hypoxia) have an impact on survival in patients with head and neck cancer. Thus, the impact of physical status and comorbidities on treatment decision and survival were evaluated.

Patients and methods

A total of 169 primary, inoperable patients with squamous cell cancer of the head and neck were retrospectively investigated. Patients were treated with hyperfractionated accelerated radio(chemo)therapy (HARcT) or hypofractionated radio(chemo)therapy (HypoRcT). Depending on the individual patient??s situation (Karnofsky Performance Index, KPI), treatment for patients with a KPI of 80?C100% was generally radiochemotherapy and for patients with a KPI????70% treatment was radiotherapy alone. In addition, all comorbidities were evaluated. Uni- and multivariate proportional hazards model were used, and overall survival (OS) was estimated by the Kaplan?CMeier method.

Results

Treatment consisted of HARcT for 76?patients (45%), HART for 28?patients (17%), HypoRcT for 14?patients(8%), and HypoRT for 51?patients (30%). Of the patients, 107?patients (63%) presented with a KPI of 80?C100%. OS (20%) was significantly better for patients with a KPI of 80?C100%, while the OS for patients with a KPI????70% was 8% (p??70?Gy), and chemotherapy were significant prognostic factors for better OS.

Conclusion

Our retrospective analysis shows that performance status with dependency on comorbidities was an independent risk factor for OS.     

Imaging evaluation of head and neck infections

Infections of the head and neck are frequent and usually have a good prognosis even though complications may sometimes be life threatening. In addition to airway compromise, intracranial and thoracic extension may occur. Diagnosis usually is made on clinical examination and imaging may play a significant role in assessing the extent of the disease, detecting complications and assist in surgical planning. The imaging protocol should be appropriate for the proposed diagnosis and suspected complications. CT of the soft tissues of the neck and chest is the imaging test of choice. Interpretation requires knowledge of the anatomy to understand the modalities of local and distant spread of the disease. Imaging evaluation is important but should not delay emergently needed treatment for entities such as epiglottitis and necrotizing fasciitis.     

Treatment of head and neck cancer with combined modalities

Patients with advanced epidermoid carcinoma of the head and neck are often treated with combinations of radiation therapy and surgery. Patients with more advanced malignancies may also receive adjuvant chemotherapy. Prospective randomized protocols provide the most effective means of determining the value of combined modalities versus a single modality only. Preoperative assessment includes direct visualization, palpation, endoscopy and, in selected incidents, CT or MRI scanning. CT scan may provide objective evidence of tumor response when preoperative adjuvant treatment, either as radiation or chemotherapy, is given.     

Clinical and dosimetric evaluation of RapidArc versus standard sliding window IMRT in the treatment of head and neck cancer

Background

Several planning studies have already proven the substantial dosimetric advantages of RapidArc (RA) over standard intensity-modulated radiotherapy. We retrospectively compared RapidArc and standard sliding window IMRT (swIMRT) in locally advanced head and neck cancer, looking both at dosimetrics as well as toxicity and outcome.

Methods

CT datasets of 78 patients treated with swIMRT and 79 patients treated with RA were included. To compare the resulting dose distributions, the dose–volume parameters were evaluated for the planning target volumes (PTVs), clinical target volumes (CTVs), and organs at risk (OARs), and the number of MU were calculated. Acute toxicity was assessed by the Common Toxicity Criteria version 3.0.

Results

PTV coverage with the 95?% isodose was slightly better for RA. Dose distribution has proven to be significantly more homogenous with RA and led to a reduction of 62?% in MU with better OAR sparing. As for toxicity, more grade 3 mucositis and dysphagia was observed for swIMRT, though we observed more grade 3 dermatitis for RA.

Conclusion

In our retrospective analysis, RA had better target coverage and better sparing of the OAR. Overall, the grade of acute toxicity was lower for RA than for swIMRT for the same types of tumor locations, except for the grade of dermatitis.

     

M-PLF-P'方案对头颈部肿瘤及晚期食管癌近期疗效观察

目的 观察M-PLF-P'方案(MTX、CF5-FU、CDDP、UFT、PYM)对头颈部肿瘤及晚期食管癌的疗效.方法 40例头颈部肿瘤及晚期食管癌患者均接受M-PLF-P'方案,21 d为1个周期.15例为初治患者.结果 M-PLF-P'方案总有效率为59%(17/39),其中CR率为15.4%(6/39),中位缓解期为3.2个月.而初治患者有效率达80%,与复治患者相比有显著性差异(P<0.05).毒性反应主要为消化道反应,口腔溃疡、腹泻发生率分别为66.7%和47.3%,白细胞下降发生率(Ⅲ°以上)为35.9%.结论 M-PLF-P'对头颈部肿瘤及晚期食管癌是一有效的、完全能耐受的化疗方案,值得进一步研究.     

Radiotherapy for head and neck cancer

Radiotherapy plays an important role in therapy for head and neck cancers from the aspect of functional and cosmetic conservation. In 2001, 130,000 patients underwent radiotherapy for the first time, and those with head and neck cancer accounted for 12.5% of this population. However, we cannot consider the management of head and neck cancer without understanding the similarities and differences among the primary sub-sites, because there is a significant difference in the natural history of cancer among these sub-sites. Treatment results are improving with the popularization of stereotactic radiotherapy and concurrent chemotherapy, in addition to traditional brachytherapy. Trends in radiotherapy for head and neck cancer are summarized in this article by discussing the specificities and similarities among sub-sites.     

Hypoxia in head and neck cancer

A high level of hypoxia in solid tumours is an adverse prognostic factor for the poor outcome of cancer patients following treatment. This review describes the status of research into finding a practical method for measuring hypoxia and treating hypoxic tumours. The application of such methodology would enable the selection of head and neck cancer treatment based on an individual's tumour oxygenation status. This individualization would include the selection not only of surgery or radiotherapy, but also of novel hypoxia-modification strategies.     

Clinical experience transitioning from IMRT to VMAT for head and neck cancer

To quantify clinical differences for volumetric modulated arc therapy (VMAT) versus intensity modulated radiation therapy (IMRT) in terms of dosimetric endpoints and planning and delivery time, twenty head and neck cancer patients have been considered for VMAT using Nucletron Oncentra MasterPlan delivered via an Elekta linear accelerator. Differences in planning time between IMRT and VMAT were estimated accounting for both optimization and calculation. The average delivery time per patient was obtained retrospectively using the record and verify software. For the dosimetric comparison, all contoured organs at risk (OARs) and planning target volumes (PTVs) were evaluated. Of the 20 cases considered, 14 had VMAT plans approved. Six VMAT plans were rejected due to unacceptable dose to OARs. In terms of optimization time, there was minimal difference between the two modalities. The dose calculation time was significantly longer for VMAT, 4 minutes per 358 degree arc versus 2 minutes for an entire IMRT plan. The overall delivery time was reduced by 9.2 ± 3.9 minutes for VMAT (51.4 ± 15.6%). For the dosimetric comparison of the 14 clinically acceptable plans, there was almost no statistical difference between the VMAT and IMRT. There was also a reduction in monitor units of approximately 32% from IMRT to VMAT with both modalities demonstrating comparable quality assurance results. VMAT provides comparable coverage of target volumes while sparing OARs for the majority of head and neck cases. In cases where high dose modulation was required for OARs, a clinically acceptable plan was only achievable with IMRT. Due to the long calculation times, VMAT plans can cause delays during planning but marked improvements in delivery time reduce patient treatment times and the risk of intra-fraction motion.     

Perfusion CT of head and neck cancer

We aim to review the technique and clinical applications of perfusion CT (PCT) of head and neck cancer. The clinical value of PCT in the head and neck includes detection of head and neck squamous cell carcinoma (HNSCC) as it allows differentiation of HNSCC from normal muscles, demarcation of tumor boundaries and tumor local extension, evaluation of metastatic cervical lymph nodes as well as determination of the viable tumor portions as target for imaging-guided biopsy. PCT has been used for prediction of treatment outcome, differentiation between post-therapeutic changes and tumor recurrence as well as monitoring patient after radiotherapy and/or chemotherapy. PCT has a role in cervical lymphoma as it may help in detection of response to chemotherapy and early diagnosis of relapsing tumors.     

MR spectrsocopy of head and neck cancer

The aim of this review is to discuss the technique and potential applications of magnetic resonance spectroscopy (MRS) in head and neck cancer. We illustrate the technical issues related to data acquisition, post processing and interpretation of MRS of head and neck lesions. MRS has been used for differentiation of squamous cell carcinoma from normal tissue. The main potential clinical application of proton MRS (¹H-MRS) is monitoring patients with head and neck cancer undergoing therapy. Pretreatment prediction of response to therapy can be done with phosphorus MRS (³¹P-MRS). Although performance of MRS of head and neck is challenging, technological advances in both software and hardware has the potential to impact on the clinical management of patients with head and neck cancer.