Close to 37,000 Americans will be diagnosed with oral or pharyngeal cancer this year. It will cause over 8,000 deaths, killing roughly 1 person per hour, 24 hours per day. Of those 36,000 newly diagnosed individuals, only slightly more than half will be alive in 5 years. (Approximately 57%). This is a number that has not significantly improved in decades. The death rate for oral cancer is higher than that of cancers we hear about more routinely such as cervical cancer, Hodgkin’s lymphoma, or skin cancer (malignant melanoma).
Oral cancer is part of a group of cancers called head and neck cancers. Oral cancer can develop in any part of the oral cavity or oropharynx, which is the oral part of the pharynx that reaches from the Uvula to the level of the hyoid bone.
Oral cancer is very common and can frequently be avoided through lifestyle choices. Excessive intake of alcohol and cigarettes and other forms of tobacco should be avoided. Oral cancer is a major global threat to public health, causing great morbidity and mortality rates.
There are many forms of oral cancer. It can involve the tongue, lips, throat and other parts of the mouth. In all cases, the disease involves an abnormal growth process, which if left untreated, can result in death. Common names for it include oral cancer, pharyngeal cancer, mouth cancer, tongue cancer, and throat cancer.
Understanding the causative factors of cancer will contribute to the prevention of the disease. As a dental professional you are on the front lines for recognizing oral cancer so familiarizing yourself with the risk factors, signs and symptoms of this disease can make a big impact on the fight against oral cancer.
The number one cause of oral cancer is tobacco, both inhaled and smokeless. Patients who smoke cigarettes, cigars, pipes or other inhaled products are at increased risk.
Smokeless tobacco products, such as snuff, are also very detrimental. Approximately 80% of people with oral cancers use tobacco. The risk increases with the amount and length of tobacco use.
Age is also frequently named as a risk factor for oral cancer, as historically it occurs in those over the age of 40. The age of diagnosed patients may indicate a time component in the biochemical or biophysical processes of aging cells that allows malignant transformation, or perhaps, immune system competence diminishes with age. With this being stated, data acquired within the last three years has indicated that the fastest growing segment of the oral cancer population are non-smokers under the age of fifty, which would indicate a paradigm shift in the cause of the disease, and in the locations where it most frequently occurs in the oral environment.
The anterior of the mouth (tobacco and alcohol associated) cancers have declined along with a corresponding decline in smoking. Posterior of the oral cavity sites (associated with the HPV16 viral causes) are increasing. However, it is likely that the accumulative damage from other factors, such as tobacco use, alcohol consumption, and persistent viral infections such as HPV, are the real culprits. It may take several decades of smoking for instance, to precipitate the development of a cancer. Having said that, tobacco use in all its forms, as noted, is still number one on the list of risk factors in individuals over 50. When tobacco use is combined with heavy alcohol use, the risk is significantly increased, as the two act synergistically. Those who both smoke and drink, have a 15 times greater risk of developing oral cancer than others. It does not appear that the HPV16 viral causes act synergistically with tobacco or alcohol, and represent a completely unique and independent disease process.
Tobacco and alcohol are essentially chemical factors, but they can also be considered lifestyle factors, since we have some control over them.
Besides these, there are physical factors such as exposure to ultraviolet radiation. This is a causative agent in cancers of the lip, as well as other skin cancers. Cancer of the lip is one oral cancer whose numbers have declined in the last few decades. This is likely due to the increased awareness of the damaging effects of prolonged exposure to sunlight, and the use of sunscreens for protection.
Another physical factor is exposure to x-rays. Radiographs regularly taken during examinations, and at the dental office, are safe, but remember that radiation exposure is accumulative over a lifetime. It has been implicated in several head and neck cancers.
Biological factors include viruses and fungi, which have been found in association with oral cancers. We briefly touched on the human papilloma virus, particularly HPV16, which has been definitively implicated in oral cancers, particularly those that occur in the back of the mouth. (Oropharynx, base of tongue, tonsillar pillars and crypt, as well as the tonsils themselves.) HPV is a common, sexually transmitted virus, which infects about 40 million Americans today. There are over 130 strains of HPV, most thought to be harmless. Most Americans will have some version of HPV in their lifetimes, and even be exposed to the oncogenic / cancer causing versions of it. Only approximately 1% of those infected, have a lack of immune response to the HPV16 strain which is the primary causative agent in cervical cancer (with HPV18), cancers of the anus and penis, and now also oral cancer, as well.
Infection with even a high risk HPV virus does not mean that an individual will develop oral cancer. Most people’s immune systems will clear the infection before a malignancy has the opportunity to occur.
There are other minor risk factors, which have been associated with oral cancers, but have not yet been definitively shown to participate in their development. These include lichen planus, an inflammatory disease of the oral soft tissues, and genetic predispositions.
There are also suggested causative links in individuals who use conventional “smokeless” chewing or spit tobacco. Promoted by some as a safer alternative to smoking, it has in actuality not proven to be any safer when referring to oral cancers.
From a gender perspective, for decades this has been a cancer that affected 6 men for every woman. That ratio has now become 2 men to 1 woman.
Oral cancer is the 6th most common cancer in men and the 14th most common cancer in women. Oral cancer is most common in men, African Americans, Native Americans, adults over age 40, smokers, and heavy alcohol drinkers. However, one out of four cases occur in non-smokers and people under age 30. Oral cancer is the most common cancer among men in India, mainly due to the habit of using smokeless tobacco.
SIGNS OF ORAL CANCER
One of the real dangers of this cancer, is that in its early stages, it can go unnoticed. It can be painless, and little in the way of physical changes may be obvious. As a dental professional, when you know what to look for, you may see or feel the precursor tissue changes, or the actual cancer while it is still very small, or in its earliest stages long before the patient is aware.
It may appear as a white or red patch of tissue in the mouth, or a small indurated ulcer which looks like a common canker sore.
Because there are so many benign tissue changes that occur normally in the mouth, and some things as simple as a bite on the inside of the cheek may mimic the look of a dangerous tissue change, it is important to pay close attention to any sore or discolored area of the mouth, which does not heal within 14 days.
Other signs /symptoms include:
a lump or mass which can be felt inside the mouth or neck
pain or difficulty in swallowing, speaking, or chewing
wart like mass
any numbness in the oral/facial region
Unilateral persistent earache
Swelling, thickening or roughness on the tongue, cheek or on the floor of the mouth
White patches along the side of the tongue or on the lip.
Unexplained bleeding in the mouth or throat.
Soreness in the back of the mouth or in the throat
Hoarseness or changes in the voice
chronic sore throat
Persistent sores in the lips, tongue, palate or throat
Skin lesion, lump, or ulcer that do not resolve in 14 days
Additional symptoms that may be associated with this disease:
Pain and paraesthesia are late symptoms
Common areas for oral cancer to develop in the anterior (front) of the mouth are on the tongue and the floor of the mouth. Individuals that use chewing tobacco, are likely to have them develop in the sulcus between the lip or cheek and the soft tissue (gingiva) covering the lower jaw (mandible) where the plug of tobacco is held repeatedly. There are also a small number of cancers that are unique to the salivary glands, as well as the very dangerous melanoma.
While the occurrence of these are dwarfed by the other oral cancers, they are responsible for a small percentage of the total incidence rate. In the US, cancers of the hard palate are uncommon, though not unknown. The base of the tongue at the back of the mouth, the oropharynx (the back of the throat) and on the pillars of the tonsils, and the tonsillar crypt and the tonsil itself, are other sites where it is now more commonly found, particularly in young non smoking individuals.
If anything suspicious is found it is best to do a biopsy of the area. It is important to have a firm diagnosis as early as possible. The biopsy is usually completed by a specialist.
The death rate associated with this cancer is high not because it is hard to discover or diagnose, but rather due to the cancer being routinely discovered late in its development. There is not a comprehensive program in the United States to opportunistically screen for the disease, and without that; late stage discovery is more common.
Another obstacle to early discovery is that the contributing HPV 16 virus incidences many times do not produce visible lesions or discolorations that have historically been the early warning signs of the disease process.
Cancer screenings can be a regular part of an annual visit. Screening involves examination for early stages in the development of the disease even though there are no apparent symptoms.
Studies show that dentists and dental hygienists may be the most thoroughly trained and the most sensitive to early, subtle changes in the mouth that could signal trouble later on.
When the diagnosis of oral cancer is made, surgical excision is the treatment of choice. Fortunately, if this is performed early, survival is often assured. Unfortunately, early detection is sometimes not made, and the survival rate is low.
TREATMENT FOR ORAL CANCER
Oral cancer is curable. Treatment depends on the type and location of the cancer, as well as the extent of its spreading. When detected early, treatment tends to be more conservative, producing fewer complications.
After a definitive diagnosis has been made and the cancer has been staged, treatment may begin. Treatment of oral cancers is ideally a multidisciplinary approach involving the efforts of surgeons, radiation oncologists, chemotherapy oncologists, dental practitioners, nutritionists, and rehabilitation and restorative specialists. The actual curative treatment modalities are usually chemotherapy with concurrent radiation, oftentimes combined with surgery. Early stage cancers that are limited to the oral cavity may be treated by surgery alone.
Chemotherapy while able to kill cancer cells itself is currently not used as a monotherapy for oral cancers. Added to decrease the possibility of metastasis, to sensitize the malignant cells to radiation, to reduce the size of any malignancy prior to surgery, or for those patients who have confirmed distant metastasis of the disease, it is a powerful component of treatment.
Prior to the commencement of curative treatment, it is likely that other oral health needs will be addressed. The purpose is to decrease the likelihood of developing post therapeutic complications. Teeth with poor prognosis from periodontal problems, caries, etc. may be extracted. This avoidance of post radiotherapy surgery is important as it can sometimes induce osteonecrosis, a condition which can develop when tissue damaged by radiation exposes the underlying bone and remains chronically non healing. The bone, which has lost its ability to efficiently repair itself due to reduced blood supply, from radiation exposure, yields a chronic and difficult to treat situation. A thorough prophylaxis, or cleaning will likely be done as well prior to beginning treatments.
Whether a patient has surgery, radiation and surgery, or radiation, surgery, and chemotherapy, is dependent on the stage of development of the cancer. Each case is individual. Patients with cancers treated in their early stages, may have little in the way of post treatment disfigurement. For those whose cancer is caught at a later stage, the results of surgical removal of the disease may require reconstruction of portions of their oral cavity or facial features. There may be adjunctive therapy required to assist in speech, chewing and swallowing of foods, the problems associated with the lack of salivary function, as well as the fabrication of dental or facial prostheses.
This form of cancer is one of the most expensive forms to treat, with an advanced case costing upward of $200,000.
Unfortunately, patients with oral cancer have a poor prognosis, and the 5-year survival rate of approximately 50% has remained unchanged for the past 50 years. Perhaps the single most important reason for this is the fact that oral cancers continue to be diagnosed in advanced stages.
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