Hypopharyngeal cancer overview

# Overview
Hypopharyngeal cancer was discovered in 1970 by Dr.Harrison in London, U.K. Hypopharyngeal cancer is a disease in which malignant cells proliferate in the hypopharynx. Most hypopharyngeal cancers form in the  squamous cells, which are thin, flat cells lining  inside the hypopharynx. Hypopharyngeal cancer can be classified according to the anatomy regions and histopathological derivatives. The anatomic location of hypopharyngeal cancer is divided into 3 subtypes such as pyriform sinus cancer, postcricoid area cancer and posterior wall of the  hypopharynx. There are no direct causes of hypopharyngeal cancer, however tobacco abuse, abuse of alcohol consumption, HPV infection, Plummer-Vinsom syndrome, and asbestos have been associated with hypopharyngeal cancer. Genes involved in the pathogenesis of hypopharyngeal cancer include p16, NOTCH1, cyclin D1, and TP53. Hypopharyngeal cancer is associated with sideropaenic dysphagia and Paterson Brown Kelly syndrome. On gross pathology, flattened plaques, mucosal ulceration, and raised margins of the lesion are characteristic findings of hypopharyngeal cancer. On microscopic histopathological analysis, spindle cells, basaloid cells, and nuclear atypia are characteristic findings of hypopharyngeal cancer. The prevalence of hypopharyngeal cancer is estimated to be 2,500 new cases annually in U.S and hypopharyngeal cancer is a very rare type of cancer. Hypopharyngeal cancer commonly affects patients in 55 to 65 years of age. Males are mostly affected with a hypopharyngeal cancer compare to women. Hypopharyngeal cancer comprises about 7% of all cancers of the head and neck. According to the National Cancer Institute and American Cancer Society, screening test for hypopharyngeal cancer is not recommended.The majority of patients with hypopharyngeal cancer are initially asymptomatic. Most patients with hypopharyngeal cancer clinically manisfest symptoms at a late stage (III and IV) because of the tumor aggression which metastasizes to lymph nodes and submucosa. Once the tumor has expanded from its original site, it may obstruct the aerodigestive tract. Most common clinical presentations are neck mass, dysphagia with weight loss, non healing sore throat, odynophagia, and hoarseness. Common complications of hypopharyngeal cancer include upper airway obstruction and disfigurement of the neck or face. The prognosis varies with the type of hypopharyngeal cancer. The Squamous cell carcinoma of the hypopharynx has a poor prognosis and small survival rate.The medical therapy with the combination of the radiotherapy has been used compared to surgical therapy for the treatment of hypopharyngeal cancer. Swallowing, speech and laryngeal preservation are important to consider during the treatment. The feasibility of surgery depends on the stage of hypopharyngeal cancer at the time of the diagnosis.The main goal of the surgery is to clear any margin that contains the tumor cells. The available surgery options are transoral laser surgery, total laryngectomy with partial pharyngectomy surgery, total laryngectomy and circumferential pharyngectomy.

# Historical Prospective
Hypopharyngeal Cancer is a rare type of malignant tumor. Hypopharyngeal cancer was discovered by Harrisson in 1970 with more than half in the postcricoid part.

# Classification
Hypopharyngeal cancer may be classified according to the location into 4 subtypes: pyriform sinus cancer, postcricoid area cancer, and posterior wall of hypopharynx cancer. A pyriform sinus cancer subtype is found in 60 to 85 percent of patients who are diagnosed with hypopharyngeal cancer. Hypopharyngeal cancer may also be classified based on the histopathology.

# Pathophysiology
Hypopharyngeal cancer arises from squamous cells, which are cells that are normally involved in protection of aerodigestive tract. Hypopharyngeal cancer is a rare type of malignant cancer which has a delayed onset of clinical manifestations. Hypopharyngeal cancer is usually diagnosed at an advanced stage and it spreads to other organs such as lungs, mediastinum, bones, brain, liver, esophagus, and thyroid gland. The metastatic invasion depends on the anatomic location of the hypopharyngeal cancer. Hypopharyngeal cancer is mostly differentiated as squamous cell carcinoma, but the undifferentiated type can be found in the pyriform sinus region. The exact pathogenesis of the hypopharyngeal cancer is not exactly understood, but the  p16, cyclin D1, NOTCH1, and TP53 gene mutations have been associated with the development of the hypopharyngeal cancer. Hypopharyngeal cancer is associated with sideropenic dysphagia and Paterson Brown Kelly syndrome. On gross pathology, flattened plaques, mucosal ulceration, and raised margins of the lesion are the characteristic findings of hypopharyngeal cancer. On microscopic histopathological analysis, spindle cells, basaloid cells, and nuclear atypia are the characteristic findings of hypopharyngeal cancer.

# Causes
There are no direct causes for hypopharngeal cancer however, there are some common risk factors that may lead to gene mutations and cause the hypopharyngeal cancer. Common risk factors for hypopharyngeal cancer can be found here.

# Differentiating Hypopharyngeal Cancer from other Diseases
Hypopharyngeal carcinoma must be differentiated from accessory salivary gland tumor, lymphoma, and retropharyngeal abscess.

# Epidemiology and Demographics
The prevalence of hypopharyngeal cancer is estimated to be 2,500 new cases annually in U.S and hypopharyngeal cancer is a very rare type of cancer. Hypopharyngeal cancer commonly affects patients in 55 to 65 years of age. Males are mostly affected with a hypopharyngeal cancer compare to women. Hypopharyngeal cancer comprises about 7% of all cancers of the head and neck.

# Risk Factors
Common risk factors in the development of hypopharyngeal cancer are tobacco use, and abuse of alcohol consumption.

# Screening
According to the National Cancer Institute and American Cancer Society, screening test for hypopharyngeal cancer is not recommended.

# Natural History, Complications and Prognosis
The majority of patients with hypopharyngeal cancer are initially asymptomatic. Most patients with hypopharyngeal cancer clinically manisfest symptoms at late stage (III and IV) because of the tumor aggression which metastasizes to lymph nodes and submucosa. Once the tumor has expanded from its site of origin, it may obstruct the aerodigestive tract. Most common clinical presentations are neck mass, dysphagia with weight loss, non healing sore throat, odynophagia, and hoarseness. Common complications of hypopharyngeal cancer include upper airway obstruction and disfigurement of the neck or face. The prognosis varies with the type of hypopharyngeal cancer. Squamous cell carcinoma of hypopharynx has poor prognosis and small survival rate.

# Diagnostic Study of Choice and Staging
The diagnostic study of choice for hypopharyngeal cancer is CT scan with contrast of head and neck. The definitive diagnosis of hypopharyngeal cancer is biopsy of the tumor.
According to the American Joint Committee of Cancer (AJCC) TNM staging system, there are 5 stages of hypopharyngeal cancer based on the tumor size, lymph node involvement, and distant metastasis.

# History and Symptoms
The hallmark of hypopharyngeal cancer is dysphagia. A positive history of odynophagia and hoarseness is suggestive of hypopharyngeal cancer. Common symptoms include a lump in the neck, dysphagia, chronic sore throat and hoarseness.

# Physical Examination
Patients with hypopharyngeal carcinoma are usually well appearing. Physical examination of the patients with hypopharyngeal carcinoma is usually remarkable for the neck swelling.

# Laboratory Findings
There are no diagnostic laboratory findings associated with hypopharyngeal cancer.

# Electrocardiogram
There are no ECG findings associated with hypopharyngeal cancer.

# Chest X Ray
Chest X rays may be performed to detect metastasis of hypopharyngeal cancer to the lungs.

# CT
Head and neck CT scan may be helpful in the diagnosis of hypopharyngeal cancer. Findings on CT scan suggestive of hypopharyngeal cancer include soft tissue mass, irregular thickening of the mucosa, and necrotic region which is a sign of metastasis.

# MRI
MRI may be helpful in the diagnosis of hypopharyngeal cancer. Findings on the MRI suggestive of hypopharyneal cancer include tumors are hypointense on T1 and hyperintense on T2 for soft tissues.

# Other Imaging Findings
Ultrasound may be helpful to assess hypopharyngeal cancer along with endoscopy. Ultrasound may be use to detect, and localize primary tumors that invade neighboring organs such as esophagus, thyroid gland, and postcricoid area.

# Other Diagnostic Studies
Biopsy may be diagnostic of hypopharyngeal cancer. Findings on biopsy diagnostic of hypopharyngeal cancer include spindle cells, basaloid cells, and nuclear atypia.

# Medical Therapy
The medical therapy with the combination of the radiotherapy has been used compared to surgical therapy for the treatment of hypopharyngeal cancer.The optimal therapy for hypopharyngeal cancer depends on the stage at the time of the diagnosis. The combined treatment helps with organ preservation. Swallowing, speech and laryngeal preservation are important to consider during the treatment.

# Surgery
The feasibility of surgery depends on the stage of hypopharyngeal cancer at the time of diagnosis. The main goal of the surgery is to clear any margin that contains  tumor cells. The available surgery options are transoral laser surgery, total laryngectomy with partial pharyngectomy surgery, total laryngectomy and circumferential pharyngectomy.

# Primary Prevention
Effective measures for the primary prevention of hypopharyngeal cancer include smoking cessation, decrease alcohol consumption, increase vegetables and fruits consumption, and vaccination for HPV.

# Secondary Prevention
Secondary prevention measures of hypopharyngeal cancer include routine physical examination of head and neck and thyroid Screening are recommended among the patients who had received radiation therapy to the head and neck regions.