Squamous cell carcinoma of the head and neck is a type of cancer that begins in the thin, flat cells lining the moist surfaces inside the mouth, throat, voice box, and nose. These cancers affect highly visible parts of the body that are essential for speaking, eating, breathing, and facial expression. While they can be challenging to treat, understanding the risk factors and symptoms can help with early detection and better outcomes.
Understanding Head and Neck Squamous Cell Carcinoma
Head and neck squamous cell carcinoma, often shortened to HNSCC, represents a group of cancers that develop in the mucosal surfaces—the moist tissue layers—of the head and neck region. The term “squamous cells” refers to the thin, flat cells that naturally line these surfaces, much like tiles on a floor. When these cells begin growing abnormally and out of control, they can form tumors in several different locations.[2]
This type of cancer can occur in the oral cavity, which includes the lips, tongue, gums, and inside of the cheeks. It can also develop in the throat, which doctors divide into three sections: the nasopharynx at the top near the nose, the oropharynx in the middle including the tonsils, and the hypopharynx at the lower part. Other locations include the voice box, the nasal cavity and sinuses, and the salivary glands that produce saliva.[2]
What makes these cancers particularly challenging is their location. The structures they affect are complex and crucial for daily activities that many people take for granted, such as speaking clearly, swallowing food and drinks, breathing normally, and maintaining facial appearance. This means that both the cancer itself and its treatment can significantly affect a person’s ability to function in everyday life.[4]
How Common Is This Cancer?
Squamous cell carcinoma of the head and neck is the seventh most common cancer worldwide. Each year, approximately 600,000 new cases are diagnosed globally, with about 50,000 of those occurring in the United States. This means that roughly 4.5 percent of all cancer diagnoses worldwide fall into this category.[3][6]
Historically, this cancer has been most common in men in their 50s or 60s, though this pattern is changing. The shift in who gets this cancer is linked to changing risk factors. While tobacco-related head and neck cancers have been declining in many developed countries, cancers linked to human papillomavirus infection are on the rise, and these tend to affect younger people, including those under 50.[3][14]
About half of people diagnosed with head and neck squamous cell carcinoma survive more than five years after diagnosis. This survival rate depends heavily on several factors, including how early the cancer is detected, where exactly it’s located, and the person’s overall health when treatment begins.[3]
What Causes This Type of Cancer?
Squamous cell carcinoma of the head and neck develops when something damages the DNA inside cells, causing them to grow and multiply uncontrollably. Several factors can cause this damage, and understanding them is crucial for prevention.
Tobacco use stands as one of the strongest risk factors. This includes all forms of tobacco—cigarettes, cigars, pipes, and smokeless tobacco products like chewing tobacco or snuff. When tobacco products are used, they expose the delicate tissues of the mouth and throat to harmful chemicals that can damage cells over time. This damage accumulates with continued use, eventually leading to cancer in some people.[2][3]
Heavy alcohol consumption is another major cause. People who drink large amounts of alcohol regularly face increased risk because alcohol can act as an irritant to the tissues in the mouth and throat. What’s particularly concerning is that tobacco and alcohol work together in a dangerous way: people who both smoke and drink heavily face far greater risk than those who do only one or the other.[2][4]
Infection with certain strains of human papillomavirus, particularly HPV-16, has emerged as an increasingly important cause, especially for cancers of the oropharynx (the middle part of the throat, including the tonsils). HPV is a sexually transmitted infection, and HPV-related head and neck cancers have been increasing, particularly in younger populations. These HPV-positive cancers tend to have different characteristics and often a better prognosis than cancers caused by tobacco and alcohol.[3][6]
Researchers have identified mutations in several genes associated with HNSCC. Some of these genes, like TP53, NOTCH1, and CDKN2A, normally function as tumor suppressors—proteins that keep cells from growing and dividing too rapidly. When these protective genes are damaged, cells can escape normal growth controls and form tumors. However, cancer typically doesn’t result from a single genetic change; rather, it’s usually a series of changes in multiple genes that accumulates over time.[3]
Who Is at Higher Risk?
Several factors can increase a person’s chances of developing head and neck squamous cell carcinoma. Understanding these risk factors can help people make informed decisions about their health.
Tobacco users face the highest risk. This includes people who smoke cigarettes, cigars, or pipes, as well as those who use smokeless tobacco products. The risk increases with both the amount used and the duration of use—someone who has smoked a pack a day for 20 years faces higher risk than someone who smoked half a pack a day for 10 years. Even secondhand smoke exposure can increase risk, though to a lesser degree than direct use.[2]
People who consume large amounts of alcohol regularly also face elevated risk. Heavy drinking is typically defined as several drinks per day on most days. The combination of heavy tobacco use and heavy alcohol consumption creates particularly high risk—much higher than either factor alone would suggest.[2][4]
Sexual behaviors that increase exposure to HPV represent another risk factor. Because certain strains of HPV can cause oropharyngeal cancer, people with multiple sexual partners or those who engage in oral sex may have increased risk of exposure to the virus.[12]
Age plays a role, as these cancers are more common in people over 50, though the age at diagnosis has been shifting younger with the increase in HPV-related cases. Men have historically been at higher risk than women, likely because they were more likely to use tobacco and drink heavily, though these differences are narrowing as behaviors change.[3][14]
Prolonged sun exposure increases risk specifically for lip cancer, as the sun’s ultraviolet rays can damage the skin cells on the lips. Certain occupational exposures, such as to wood dust, paint fumes, or certain chemicals, may also increase risk for some types of head and neck cancer.[2]
Recognizing the Symptoms
The symptoms of head and neck squamous cell carcinoma can vary depending on where the cancer is located, but certain warning signs should prompt a visit to a healthcare provider. The challenge is that many of these symptoms can also be caused by much less serious conditions, which sometimes leads to delays in diagnosis.
A sore throat that persists for more than two weeks is one of the most common symptoms. Unlike a sore throat from a cold or flu, which typically resolves within a week or so, a sore throat caused by cancer doesn’t improve with time or typical remedies. This persistent quality—the fact that it simply won’t go away—is what makes it concerning.[5][14]
A lump in the neck is another important warning sign. These lumps are often painless and may appear in the area below the jaw or along the sides of the neck. They represent swollen lymph nodes where cancer cells have spread. Sometimes these lumps are discovered by the person themselves while washing or shaving, or by someone else who notices the swelling.[2]
Changes in the mouth that don’t heal should raise concern. These might include sores or ulcers on the tongue, gums, or inside the cheeks that persist for more than two weeks. White or red patches in the mouth that don’t go away can also be warning signs. People might notice these changes while brushing their teeth or during routine dental care.[3][5]
Difficulty or pain when swallowing, medically called dysphagia, can indicate cancer in the throat or at the base of the tongue. This might start as a feeling that food is getting stuck or a sensation that swallowing requires more effort than usual. Some people describe feeling like there’s a lump in their throat even when they’re not eating or drinking.[3]
Voice changes that persist can signal cancer of the larynx or voice box. This might present as persistent hoarseness, a raspy quality to the voice, or difficulty speaking clearly. While temporary hoarseness is common with colds or from overusing the voice, hoarseness that lasts more than two weeks warrants medical evaluation.[3][5]
Other symptoms can include persistent ear pain, especially when only one ear is affected and there’s no visible ear infection; frequent nosebleeds or bloody saliva; persistent congestion in the sinuses that doesn’t respond to usual treatments; difficulty breathing; unexplained weight loss; and persistent bad breath that doesn’t improve with dental hygiene.[3][5]
Prevention Strategies
The good news about head and neck squamous cell carcinoma is that many cases are preventable through lifestyle choices and medical interventions. Because the major risk factors are well understood, people can take concrete steps to reduce their risk.
Avoiding tobacco in all its forms is the single most important preventive measure. For people who currently use tobacco, quitting at any age can reduce cancer risk, though the benefit is greater the earlier someone quits. Even people who have used tobacco for many years can benefit from stopping. For those who have never used tobacco, choosing not to start protects against this and many other cancers. Avoiding secondhand smoke is also important, though the risk it poses is lower than direct tobacco use.[2][14]
Limiting alcohol consumption helps reduce risk, particularly when combined with tobacco avoidance. Guidelines generally suggest no more than one drink per day for women and two for men, with many experts recommending even less. For people who both smoke and drink heavily, addressing both behaviors provides the greatest risk reduction.[4]
HPV vaccination offers protection against the strains of virus most commonly associated with head and neck cancers. The vaccine works best when given before a person is exposed to HPV, which is why it’s recommended for preteens and teenagers. However, young adults who haven’t been vaccinated can still benefit. Currently, one HPV vaccine called Gardasil-9 is approved for preventing infections that can lead to several types of cancer, including head and neck cancer.[12]
Regular dental checkups serve an important preventive function beyond just maintaining oral health. Dentists and dental hygienists are often the first to notice suspicious changes in the mouth that could indicate early cancer or precancerous conditions. They can spot red or white patches, unusual lumps, or sores that aren’t healing properly. Having dental examinations at least once or twice a year provides opportunities for early detection.[14]
Sun protection for the lips is important for preventing lip cancer. This can be as simple as using lip balm with SPF protection and avoiding prolonged sun exposure during peak hours. People who work outdoors or spend significant time in the sun should be particularly attentive to lip protection.[2]
Maintaining a healthy diet rich in fruits and vegetables may offer some protective benefits, though the evidence is less clear than for tobacco and alcohol avoidance. Good overall health practices, including regular exercise and maintaining a healthy weight, support the immune system and general well-being, which may help the body resist cancer development.[14]
How the Disease Develops in the Body
Understanding how head and neck squamous cell carcinoma develops and spreads helps explain why early detection is so important and why treatment approaches vary depending on the stage of disease.
The development of cancer in the head and neck typically follows a progression. In areas exposed to carcinogens like tobacco and alcohol, cells may first show abnormal changes called dysplasia. These are areas where cells look abnormal under a microscope but haven’t yet become fully cancerous. Dysplasia can range from mild to severe, and in some cases, it can progress to invasive cancer over time. However, not all dysplasia becomes cancer, and some cases may even reverse if the harmful exposures are eliminated.[4][6]
Despite this progression from normal tissue through dysplasia to invasive cancer, most patients are diagnosed only when they already have invasive disease. This is because the early changes often don’t cause noticeable symptoms, and there are no routine screening programs for most head and neck cancers in people without symptoms or known high risk.[4]
Once cancer develops, it can grow locally, invading deeper into surrounding tissues and structures. The cancer may spread to nearby lymph nodes—small, bean-shaped organs that are part of the immune system and are found throughout the neck. When cancer cells break away from the original tumor and travel through the lymphatic vessels to lymph nodes, doctors call this lymph node involvement or regional spread. This is why lumps in the neck can be an important sign of head and neck cancer.[2]
If left untreated or if the cancer is very aggressive, it can spread to distant parts of the body, most commonly the lungs. This distant spread is called metastasis, and it represents advanced disease. When cancer has metastasized, it becomes much more difficult to treat and has a poorer prognosis.[2]
HPV-positive head and neck cancers develop through a different mechanism. The virus infects cells, particularly in the tonsils and base of the tongue, and integrates its genetic material into the cell’s DNA. Viral proteins then interfere with the cell’s normal tumor suppressor functions, leading to uncontrolled growth. These cancers tend to have different characteristics than tobacco-related cancers and often respond better to treatment.[4][6]
The physical changes cancer causes in affected tissues help explain the symptoms people experience. A tumor growing on the vocal cords interferes with their normal vibration, causing hoarseness. A tumor in the throat can make swallowing painful or difficult by physically blocking the passage of food or irritating the sensitive tissues. Tumors can also press on nerves, causing pain that may be felt in unexpected locations—for example, a throat tumor might cause ear pain even though the ear itself is normal.[5]
The staging system for head and neck cancers takes into account the size of the primary tumor, whether cancer has spread to lymph nodes and how many nodes are involved, and whether there is distant metastasis. A newer staging system introduced in 2017 recognizes that HPV-positive cancers behave differently and uses separate staging criteria for these cancers, reflecting their generally better prognosis.[4][6]
