Purpose
Radiation-induced fibrosis (RIF) is a long-term side effect of external beam radiation therapy for the treatment of cancer. It results in a multitude of symptoms that significantly impact quality of life. Understanding the mechanisms of RIF-induced changes is essential to developing effective strategies to prevent long-term disability and discomfort following radiation therapy. In this review, we describe the current understanding of the etiology, clinical presentation, pathogenesis, treatment, and directions of future therapy for this condition.

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Radiation-induced fibrosis: mechanisms and implications for therapy.

Oral cavity carcinoma (OCC) remains a major cause of morbidity and mortality in patients with head and neck cancer. Although the incidence has decreased over the last decade, outcomes remain stagnant with only a 5% improvement in overall survival in the last 20 years. Although surgical resection remains the primary treatment modality, several areas of controversy exist with regard to work-up, management of the primary and neck tumors, and adjuvant therapy. As surgical techniques evolve, so has the delivery of radiotherapy and systemic treatment, which have helped to improve the outcomes for patients with advanced disease. Recently, the addition of cetuximab has shown promise as a way to improve outcomes while minimizing toxicity, and this remains an active area of study in the adjuvant setting. Advances in microvascular free-flap reconstruction have extended the limits of resection and enabled enhanced restoration of function and cosmesis. While these advances have led to limited survival benefit, evaluation of alternative modalities has gained interest on the basis of success in other head and neck subsites. Organ preservation with definitive chemoradiotherapy, though proven in the larynx and pharynx, remains controversial in OCC. Likewise, although the association of human papillomavirus is well established in oropharyngeal carcinoma, it has not been proven in the pathogenesis or survival of OCC. Future study of the molecular biology and pathogenesis of OCC should offer additional insight into screening, treatment selection, and novel therapeutic approaches.

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Oral Cavity Carcinoma: Current Management, Controversies, and Future Directions

Intensity-modulated radiation therapy for head and neck cancer: systematic review and meta-analysis.

The treatment planning process for patients with head and neck (H&N) cancer is regarded as one of the most complicated due to large target volume, multiple prescription dose levels, and many radiation-sensitive critical structures near the target. Treatment planning for this site requires a high level of human expertise and a tremendous amount of effort to produce personalized high quality plans, taking as long as a week, which deteriorates the chances of tumor control and patient survival. To solve this problem, we propose to investigate a deep learning-based dose prediction model, Hierarchically Densely Connected U-net, based on two highly popular network architectures: U-net and DenseNet. We find that this new architecture is able to accurately and efficiently predict the dose distribution, outperforming the other two models, the Standard U-net and DenseNet, in homogeneity, dose conformity, and dose coverage on the test data. Averaging across all organs at risk, our proposed model is capable of predicting the organ-at-risk max dose within 6.3% and mean dose within 5.1% of the prescription dose on the test data. The other models, the Standard U-net and DenseNet, performed worse, having an averaged organ-at-risk max dose prediction error of 8.2% and 9.3%, respectively, and averaged mean dose prediction error of 6.4% and 6.8%, respectively. In addition, our proposed model used 12 times less trainable parameters than the Standard U-net, and predicted the patient dose 4 times faster than DenseNet.

https://iopscience.iop.org/article/10.1088/1361-6560/ab039b/pdf

3D radiotherapy dose prediction on head and neck cancer patients with a hierarchically densely connected U-net deep learning architecture.

Based on its potent capacity to induce tumor cell death and to abrogate clonogenic survival, radiotherapy is a key part of multimodal cancer treatment approaches. Numerous clinical trials have documented the clear correlation between improved local control and increased overall survival. However, despite all progress, the efficacy of radiation-based treatment approaches is still limited by different technological, biological, and clinical constraints. In principle, the following major issues can be distinguished: (1) The intrinsic radiation resistance of several tumors is higher than that of the surrounding normal tissue, (2) the true patho-anatomical borders of tumors or areas at risk are not perfectly identifiable, (3) the treatment volume cannot be adjusted properly during a given treatment series, and (4) the individual heterogeneity in terms of tumor and normal tissue responses toward irradiation is immense. At present, research efforts in radiation oncology follow three major tracks, in order to address these limitations: (1) implementation of molecularly targeted agents and ‘omics’-based screening and stratification procedures, (2) improvement of treatment planning, imaging, and accuracy of dose application, and (3) clinical implementation of other types of radiation, including protons and heavy ions. Several of these strategies have already revealed promising improvements with regard to clinical outcome. Nevertheless, many open questions remain with individualization of treatment approaches being a key problem. In the present review, the current status of radiation-based cancer treatment with particular focus on novel aspects and developments that will influence the field of radiation oncology in the near future is summarized and discussed.

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Current concepts in clinical radiation oncology.

Three-dimensional conformal radiotherapy (3D-CRT) versus intensity modulated radiation therapy (IMRT) in squamous cell carcinoma of the head and neck: a randomized controlled trial.

Sandeep Jain

Papers

Three-dimensional conformal radiotherapy (3D-CRT) versus intensity modulated radiation therapy (IMRT) in squamous cell carcinoma of the head and neck: a randomized controlled trial.