Introduction

What is cancer?¹

Cancer is a genetic disease where abnormal cells of the body grow uncontrollably, causing damage to normal healthy cells, spreading to different parts and destroying the normal form and function of the body.

Head and neck cancer (HNC) is a group of cancers that affect the mouth, throat, nose, sinuses and other parts of the head and neck region.

Types of head and neck cancer

Squamous cell carcinoma

Most common type of head and neck cancer typically starts in the squamous cells that line the inner surfaces of the mouth, nose and throat.²

Salivary gland tumors

These are cancers of the salivary glands

Adenocarcinoma

It forms in the glandular cells of the head and neck region 

Other less common types

• Cutaneous carcinoma 

Originates from the skin of the head and neck region

• Oral cavity cancer 

Originates from the mouth, lips, gums, tongue etc.

• Thyroid gland tumor 

Originates from the cells of the thyroid gland in the neck

• Pharyngeal tumors 

Originates from the throat area

Globally, head and neck cancers account for approximately 900,000 cases and 400,000 deaths annually. In the US alone, 71,000 cases and approximately 16000 deaths are reported annually.³ 

Risk factors

• Smoking
• Excessive alcohol use
• Tobacco chewing
• Human Papillomavirus (HPV) infection⁴
• Epstein Barr virus (EBV)⁵
• Poor oral hygiene
• Genetic factors
• Radiation
• Inhalation of asbestos, nickel, etc

Symptoms of head and neck cancer

The symptoms of head and neck cancers may vary depending on its location and spread to other areas. Common symptoms include:

• Pain
• Bleeding
• Swelling or lumps
• Bad breath
• Loose teeth
• Numbness in the affected area
• Nasal congestion, nosebleed, mucus discharge
• Sores
• Difficulty in swallowing
• Difficulty breathing
• Hoarseness of voice
• Ear aches
• Weight loss
• Changes in the physical appearance of the affected area

Traditional treatments 

Traditional treatments include surgery, radiation and chemotherapy. Surgery involves removal of the tumor and the affected lymph nodes, radiation uses high energy rays (X-rays) to kill the cancer cells and chemotherapy utilises drugs to destroy the cancer cells.

Limitations of traditional treatments

• Side effects

Chemotherapy has a lot of side effects which can result in individuals with cancer leaving the treatment midway

• Complications

Surgical approach may result in complications like bleeding, infection, delayed wound healing, swelling, etc.

• Appearance and functioning

Surgical removal of tumor may lead to changes in the appearance and functions

Challenges of treating head and neck cancers

Head and neck cancer is the sixth most common cancer and is difficult to treat because of its complex genetic makeup, higher rates of recurrence, higher chances of spread to other parts of the body (called metastasis) and resistance to traditional treatment alternatives.

Understanding targeted therapy

What is targeted therapy?

Targeted therapy is a type of cancer treatment that uses drugs or other substances to target specific molecules within the cancer cells to stop their growth and spread. 

Other names: Molecular targeted therapy, Biological therapy.

How targeted therapy works 

The cells in the human body grow and multiply through different signaling pathways. The role of the targeted therapy is to interfere with this pathway in order to slow or stop the growth and spread of the cancerous cells.

There are different mechanisms through which the targeted therapy works:

1. Starving cancer cells: the cancer cells are starved of hormones essential for their growth
2. Blocking signals: signals that communicate with the cell for its growth and spread are blocked
3. Monoclonal antibodies: the monoclonal antibodies attaches itself to the protein on the cancer cells and stop its spread
4. Killing cells: certain toxins or drugs are used with the monoclonal antibodies to kill the cancer cells
5. Boosting the immune system: they work as an aide to the natural immune system to kill the cancer cells and control its spread

Advantages of targeted therapy compared to traditional treatments

As the name suggests, in targeted therapy, the aim is to target and destroy the cancer cells without affecting the healthy cells. It has less side effects and is better tolerated by individuals suffering with the disease compared to traditional treatment alternatives. Targeted therapies have shown up to 80% success rate as opposed to chemotherapy with a success rate of 30%. 

Types of targeted therapies for head and neck cancer

Epidermal Growth Factor Receptor (EGFR) Inhibitors

EGFR Inhibitors are a promising targeted therapy for Squamous Cell Carcinoma that can be used alone or in combination with radiation and chemotherapy. 

Commonly used EGFR inhibitors (e.g., erlotinib, gefitinib)

Human Epidermal Growth Factor Receptor 2 (HER2) Inhibitors

HER2 is a protein that can help the cancer cell to grow. The targeted therapy drug used to stop the activity of this protein is called Trastuzumab.

Human Papillomavirus (HPV)

HPV is a commonly sexually transmitted infection. In case of head and neck cancers, the virus can enter from a break in the skin or lining of the mouth. If it is not treated, HPV can alter the genetic makeup of the cells leading to cancerous changes.

To treat head and neck cases with HPV, immunotherapy (Pembrolizumab) can be effective.

Current targeted therapies for head and neck cancer that are FDA-Approved⁶

•  Cetuximab (Erbitux)
•  Pembrolizumab (Keytruda)
•  Nivolumab (Opdivo)

Emerging therapies and research

Current therapies for cancer are limited to surgery, chemotherapy, immunotherapy and Cetuximab, many novel small molecules are under development and thoroughly researched. Understanding of the genomics and tumor micro environment of head and neck cancer has opened new avenues to deliver personalized and effective treatment alternatives.

Personalized medicine and targeted therapy

The most pressing challenge when it comes to treatment of head and neck cancers is its heterogeneity (genetic diversity). The current research focuses on using biomarker testing and studying the individual genetic variations and creating a more personalized targeted therapy. 

This can be achieved by combining the multi-omics data and creating a more individual based treatment plan.

Challenges to targeted therapy

• Resistance to targeted therapies
• Toxicity
• Cost and accessibility of targeted therapies

Summary

Targeted therapy is a type of modern treatment for cancer that uses specific drugs or molecules to stop the growth of cells by targeting specific proteins necessary for their growth. This approach is based on the concept of precision medicine and is more conservative than the traditional therapies like surgery, radiation and chemotherapy.

Advantages of targeted therapy:

• Aims at targeting individual’s genetic makeup
• Fewer side effects
• Improved response rates 
• Better quality of life for the patients

Challenges:

• Drug resistance and toxicity
• Cost 
• Accessibility to the therapy

The current research on targeted therapy focuses on improving outcomes by overcoming drug resistance.