Modern radiotherapy for head and neck cancer

Abstract

Radiation therapy (RT) plays a key role in curative-intent treatments for head and neck cancers. Its use is indicated as a sole therapy in early stage tumors or in combination with surgery or concurrent chemotherapy in advanced stages. Recent technologic advances have resulted in both improved oncologic results and expansion of the indications for RT in clinical practice. Despite this, RT administered to the head and neck region is still burdened by a high rate of acute and late side effects. Moreover, about 50% of patients with high-risk disease experience loco-regional recurrence within 3 years of follow-up. Therefore, in recent decades, efforts have been dedicated to optimize the cost/benefit ratio of RT in this subset of patients. The aim of the present review was to highlight modern concepts of RT for head and neck cancers considering both the technological advances that have been achieved and recent knowledge that has informed the biological interaction between radiation and both tumor and healthy tissues.

Introduction

Squamous cell carcinoma of the head and the neck (HN) is the seventh most common malignancy [1]. The main risk factors, tobacco smoking and alcohol consumption, are responsible for the majority of HN tumors occurring in the oral cavity, pharynx, and larynx. Human papillomavirus (HPV) is increasingly appreciated as a risk factor that is both important and frequently found in oropharyngeal cancer.

Along with surgery, radiation therapy (RT) represents one of the main curative-intent treatment options both in early and advanced stages with doses ranging from 54 to 70 Gy, administered with a standard fractionation schedule of 2 Gy/fraction, one fraction/day, 5 fractions/week [2]. Moreover, in high-risk settings the combination of RT with concurrent cisplatin (100 mg/m² every 3 weeks) is the standard nonsurgical approach.

Despite the multimodality approach, treatment of HN cancer patients is still burdened by a not yet satisfactory clinical outcome with approximately 50% local recurrence at 3 years and a relatively high rate of severe RT-related toxicity. In order to increase the local tumor control without worsening the toxicity profile, the radiation approach is profoundly changing and moving from the concept that “one size fits all” toward a personalized treatment approach. Indeed, not only have technologically-driven advances in the field of photons significantly improved the conformity of dose distribution, but the introduction of heavy particle RT (hadrontherapy) together with greater insight into the interaction between photons and tumor/host immune response have opened up new exciting scenarios and fields of ongoing investigation. Moreover, the increasing incidence of human papillomavirus (HPV)-related oropharyngeal cancers has offered the possibility to test new deintensified treatment strategies.

Thus, RT remains a crucial and cost-effective treatment for patients with a diagnosis of HN cancers [3]. The present review aimed to point out the modern approach of RT in this subset of patients highlighting the new fields of interest and searches.