Chapter 1 Introductory Chapter : Be Careful ! It Can Be Cancer

Head and neck cancer includes the cancers of oral cavity, salivary glands, nasal cavity, paranasal sinuses, oropharynx, hypopharynx, pharynx, and larynx. It has a high rate among all cancer types in the world, and it constitutes a major public health problem. Although there are different histopathological types, the majority of the lesions are squamous cell carcinomas which usually arise from mucosal lining [1]. Males are more commonly affected from the condition compared to females [2].


Introduction
Head and neck cancer includes the cancers of oral cavity, salivary glands, nasal cavity, paranasal sinuses, oropharynx, hypopharynx, pharynx, and larynx. It has a high rate among all cancer types in the world, and it constitutes a major public health problem. Although there are different histopathological types, the majority of the lesions are squamous cell carcinomas which usually arise from mucosal lining [1]. Males are more commonly affected from the condition compared to females [2].
The signs and symptoms of head and neck cancer depend according to the localization of the lesion. The most common sign of laryngeal cancer is hoarseness, whereas difficulty in swallowing or sore throat is seen in pharyngeal cancers. Sometimes, a painless neck mass is present. The important point is that the clinician should be careful during the examination of patients with nonspecific signs and symptoms, or signs and symptoms mimicking benign pathologies [1]. Any of the following such as sore throat, hoarseness, stridor, difficulty in swallowing, lump in neck, unilateral ear pain, red or white patch in the oral cavity, oral ulcer, presence of an indurated or rolled border, loosened teeth over a short time, rapid swelling with no demonstrable cause, lateral neck mass, lymphadenopathy, rapidly growing thyroid mass, cranial nerve palsy, orbital mass, and unilateral ear effusion lasting for more than 3 weeks can be cancer [3,4].
When we look at the etiology and risk factors of head and neck cancer, tobacco and alcohol are reported to be the major ones. If the patient is smoking and drinking alcohol at the same time, the risk is multiplied [5]. Genetic predisposition is related with some cases. Genetic polymorphisms in genes encoding the enzymes, which are responsible from the metabolism of tobacco and alcohol, increase the risk of development of cancer [1]. Viruses are linked with head and neck cancer. Human papilloma virus (HPV) is reported to be a risk factor, especially for oropharyngeal cancer [6].
Premalignant lesions of the oral cavity are also suspected as risk factors. These lesions do not have a high-risk factor like the others addressed earlier but should be carefully examined and treated. Leukoplakia and erythroplakia are the common premalignant lesions. Oral lichen planus also has the potential of malignant transformation [7].
Patients with Fanconi anemia, ataxia telangiectasia, Bloom's syndrome, and Li-Fraumeni syndrome have the risk of developing head and neck cancer. In addition, the risk of developing malignancy increases in immunosuppressed patients. Although Kaposi's sarcoma and non-Hodgkin's lymphoma are the most prevalent lesions seen among HIV-positive patients, the risk of oropharyngeal squamous cell carcinoma is increased [7].
If you do not pay enough attention to the signs and symptoms of head and neck cancer and do not treat premalignant lesions and premalignant conditions, the requirement of a more aggressive treatment and even early death of the patient can occur [4]. Thus, be careful! It can be cancer.

Overview of the chapters of this book
Second chapter: "Head and Neck Cancer: Epidemiology and Role of MicroRNAs" written by Muhammad Babar Khawar, Naz Fatima, Muddasir Hassan Abbasi, Rabia Mehmood, Saira Kainat, and Nadeem Sheikh. This chapter starts with the epidemiology and then focuses on the role of microRNAs on head and neck cancer. The authors give information about the discovery and biology of microRNAs. Recently identified microRNAs that undergo deregulation in head and neck cancer and their role in nasopharyngeal carcinoma and oral carcinogenesis are presented in detail. A list of microRNAs, identified as potent biomarkers of head and neck cancer, is presented. This is particularly helpful to the readers. The authors emphasize that microRNAs may be used to improve treatment strategies of head and neck cancer.

Fifth chapter: "Medullary Thyroid Carcinoma: Recent Updates on the Diagnosis and Management" written by Andrei Cismaru, Iulia Coroian, Gabriel Cismaru, and Adrian
Udrea. This chapter describes updates on the diagnosis and treatment of medullary thyroid carcinoma. Fine-needle aspiration, serum calcitonin, computed tomography, and fludeoxyglucose-positron emission tomography (FDG-PET) are summarized. Biomarkers with prognostic value, such as plasma calcitonin, carcinoembryonic antigen, germ-like RET mutation, and matrix metalloproteinase, are given. Updates on the management and treatment of the pathology including surgical treatment, radiation therapy, systemic therapy angiogenesis inhibitors as well as transcatheter arterial embolization, percutaneous ethanol injection and gene therapy are described. Finally, the authors present a case of medullary thyroid carcinoma.
Sixth chapter: "Interventional Techniques for Head and Neck Cancer Pain" written by Victor M. Silva Ortíz, Guillermo E. Aréchiga Ornelas, José A. Flores Cantisani, J. Ignacio Reyes Torres, and Fernando Cantú Flores. This chapter gives information about factors associated with pain resulting from head and neck cancer and the methods used for the management of pain. The interventional techniques, which have been employed successfully for head and neck cancer pain such as sphenopalatine ganglion block, trigeminal ganglion block, glossopharyngeal nerve block, and stellate ganglion block, are described. In addition, vertebroplasty for cancerrelated cervical vertebral compression fractures, intrathecal drug delivery systems, peripheral nerve blocks, cervical epidural and medial branch block, and Botulinum neurotoxin are also included. This chapter provides valuable information about these techniques to the clinician.

Seventh chapter: "Oral Side Effects of Head and Neck Irradiation" written by Vlaho Brailo, Vanja Vučićević Boras, Danica Vidović Juras, Ana Andabak Rogulj, Božana Lončar Brzak, and Ivan
Alajbeg. This chapter gives information about the acute and chronic side effects of head and neck irradiation. Besides, the dentist's role in head and neck cancer team, dental management before radiation therapy, and oral care of these patients during and after head and neck radiotherapy are given in detail. The role of dentists for the management of such patients' is stressed in the chapter. The readers can benefit from practical strategies which could be applied in clinical practice.