Table of Contents
- 1 Oral Cancer–The facts
- 2 The physical factors that increase the risk of oral cancer
- 3 Factors relating to epidemiology and mortality in patients with oral and laryngeal cancers
- 4 Facts about HPV
- 5 Age–Its relationship to mortality and epidemiology in oral and laryngeal cancers
- 6 Painless Lesions contribute to the mortality rate
If you have come here to look for images of lumps, bumps, sores, discolorations or abnormalities that you noticed in the mirror this morning, this is one of four pages with images you may find useful. Read this page,Then proceed to three other pages on which you will find more images of both normal and abnormal oral structures and lesions
Oral Cancer–The facts
(And why that lump you noticed in the mirror this morning is probably NOT cancer!)
Oral and pharyngeal (throat) cancer represents about 3% to 5% of all forms of cancer. Each year, more than 30,000 new cases of cancer of the oral cavity and pharynx are diagnosed and over 8,000 deaths due to oral cancer occur. If cancer of the larynx, which is quite similar to oral squamous cell cancer and has similar risk factors is included, an additional 14,000 diagnoses are added to the total. Approximately one person dies from oral cancer every hour around the clock in the US.
The five year survival rate for this type of cancer has remained at about 50% since the early 1960’s. About half of the cases occur in persons over the age of 65. 95% of all cases occur in persons over the age of 40. An increasing percentage is diagnosed in persons under the age of 40, although the incidence of oral cancer in younger persons is still very low by comparison.
Oral cancer attacks more men than women (male/female ratio = 2/1), and more blacks than whites (black/white ratio = 2/1). The survival rate is better for Caucasians (54%) than for Afro-Americans (34%). The most common sites of oral cancer are the floor of the mouth, the sides and undersurface of the tongue, the back of the throat, and the lips. Although it is not considered oral cancer in the strict sense, cancer of the larynx (the voice box) has a similar etiology (cause & origin) and causes approximately 2% of all forms of cancer. 90% of the victims of cancer of the larynx are males, and most are between 60 and 70 years old.
Indications that you may have developed oral or laryngeal cancer
- A sore in the mouth that does not heal spontaneously within three weeks;
- A lump or thickening in the cheek;
- A white or red patch on the gums, tongue, or lining of the mouth;
- Soreness or a feeling that something is caught in the throat;
- Difficulty chewing or swallowing;
- Difficulty moving the jaw or tongue;
- Numbness of the tongue or other area of the mouth; or
- Swelling of the jaw that causes dentures to fit poorly or become uncomfortable.
The general characteristics of oral cancer
90% of all oral cancers are of a type called Squamous cell carcinoma,which means that they derive from squamous cells which are the type of cells that make up the pink mucosa that lines the mouth. Laryngeal cancer (cancer of the vocal cords) is also generally caused by squamous cell carcinoma, and is also associated with heavy smoking. Most oral cancers tend to happen on the floor of the mouth or the sides and undersurface of the tongue. They also tend to be relatively painless during their early development. The image to the right shows a rather advanced cancer on the side of the tongue. (Click the image to see a larger version, as well as some other rather scary examples of oral cancer.) Note the mottled white and red appearance of the growth. As you will see, this is an important characteristic of these cancers.
It is interesting to note that squamous cell carcinoma is NOT USUALLY one of the more virulent cancers, and yet it kills about half of those that get it within 5 years. This is an important point since if it is diagnosed at a reasonably early stage (within the first year, or in some cases within the first two years–The earlier, of course, the better), it can generally be removed before it becomes locally invasive or spreads to other parts of the body and becomes a death dealing issue. Why would anyone let a problem like this progress until it is this large? (Click the image for more info on why this one got so big.) Why does does such a slow growing cancer have such a large mortality rate? (Mortality rate is the measure of the ratio of those who contract the disease to those who die from it. In the case of Squamous cell carcinoma, the mortality rate is about 50%, meaning that approximately half the people diagnosed with it will eventually die as a direct result of the cancer, or from complications associated with it.)
Since 90% of all oral cancers are of a type called Squamous Cell Carcinoma, when we speak of “risk factors” associated with oral cancer, we are talking about risk factors associated with this particular entity. These risk factors do not pertain to the other 10% of cancers which can occur in the oral cavity. This 10% are covered on the second page of this section. There are four factors that appear to increase the risk of developing oral squamous cell carcinoma:
(1)Tobacco AND (2)alcohol
When indulged in together over a long period of time, heavy alcohol and tobacco use are the most potent physical factors contributing to the development of squamous cell carcinoma. Those who both smoke and drink heavily, have a 15 times greater risk of developing oral cancer than those that have neither habit.
- Tobacco is a known carcinogen, which means that it is known to damage cellular DNA. Damaged DNA can cause the cellular reproductive machinery to malfunction, which is the first step in the growth of malignant cellular masses (cancer).
- Alcohol is known to inhibit a gene that functions in response to DNA damage. This gene is responsible for initiating cell death in cells in which the the DNA is damaged.
- Thus the tobacco causes malignant mutations in the cellular DNA, while the alcohol inhibits the body’s natural defense against malignancy.
Historically, the large majority of squamous cell carcinoma victims have, until relatively recently, been over the age of 40. This probably relates to the tendency of the immune system to become less and less competent at recognizing and eliminating mutated cells that arise in the body from time to time. It may also be associated with the time it takes for the above three factors discussed in this section to have their damaging effects. Unfortunately, since about 1975, the cohort with the largest increase of oral squamous cell cancers has been the age groups under40. This is due to the”sexual revolution”, and the larger number of people contracting the human papillomavirus (HPV)
The human papilloma virus. HPV is transferred from person to person by vigorous physical contact, especially oral sexual contact. A study in the New England Journal of Medicine (NEJM), shows that men and women who reported having six or more oral-sex partners during their lifetime had a nearly ninefold increased risk of developing cancer of the tonsils or at the immovable base of the tongue. Of the 300 study participants, those infected with HPV were also 32 times more likely to develop this type of oral cancer than those who did not have the virus. It should be noted that a history of heavy smoking increases the likelihood of contracting oral-pharyngeal cancers only three times while a history of heavy drinking increases the likelihood only 2.5 times. HPV is covered in more detail under the lifestyle discussion below.
(Epidemiology is the study of how a disease spreads and who is likely to get it.)
Lifestyle issues are behavior patterns which are considered under the control of the individual. They are the most important factors in the mortality (death rate) and epidemiology (how the disease spreads, and who is likely to get sick) associated with oral and laryngeal squamous cell cancers. Patient lifestyle choices probably accounted for the development of the lesions seen in the images on this page, and also contributed to the fact that they grew so large before diagnosis.
While alcohol is one of the major physical risk factors in the direct development of oral cancer, heavy drinking (the behavior) is associated with oral cancer’s high mortality (death) rate. Heavy drinkers are much less likely to notice, let alone seek professional help for a painless growth under their tongues!
Tobacco has a direct effect on the tissues that the smoke actually comes into contact with. This includes both the tissues of the mouth, and the tissues in the larynx (voice box). 75% of persons who develop oral squamous cell carcinoma are, or have been heavy smokers. It appears that the effects of tobacco are cumulative, so people who have been heavy smokers (or snuff dippers) for many years are more at risk for developing oral or laryngeal cancer than those who have only recently started.
Chewing tobacco and snuff use is on the rise as the use of cigarettes, cigars and pipes is on the decline. This is especially true among the young. Since smoking has become politically incorrect, the use of smokeless tobacco has gained a certain cachet. Here are some of the facts you should know about smokeless tobacco:
- Smokeless tobacco contains 28 cancer-causing agents (carcinogens).
- Smokeless tobacco is a known cause of human cancer; it increases the risk of developing cancer of the oral cavity and pancreas.
- Smokeless tobacco is also strongly associated with leukoplakia—a precancerous lesion of the soft tissue in the mouth that consists of a white patch or plaque that cannot be scraped off.
- Smokeless tobacco is associated with recession of the gums, gum disease, and tooth decay.
- Smokeless tobacco use during pregnancy increases the risks for preeclampsia (i.e., a condition that may include high blood pressure, fluid retention, and swelling), premature birth, and low birth weight.
- Smokeless tobacco use by men causes reduced sperm count and abnormal sperm cells.
- Smokeless tobacco use can lead to nicotine addiction and dependence.
- Adolescents who use smokeless tobacco are more likely to become cigarette smokers.
- Smokeless tobacco is a significant health risk and is not a safe substitute for smoking cigarettes.
When discussing the human papillomavirus (HPV) as it relates to oral cancer, the lifestyle issue here relates to sexual behavior. 25% of oral cancers appear in patients who have never smoked, and it has now been shown that human papillomavirus is the carcinogenic element involved in these cases. There are approximately 200 known strains of the human papillomavirus. Many of the strains of HPV cause ordinary warts, the kind that develop on the hands and feet, and even in the oral cavity. Most strains of HPV are thought to be harmless, and produce no symptoms in the host.
Eighteen strains are associated with cervical cancer but four types in particular (in descending order of importance), HPV-16, HPV-18, HPV-31, and HPV-45, have been shown to be the causative agents of cervical, anal, vulvar and penile cancers. (Cervical cancer affects the epithelial cellular layer–the surface cells–surrounding the opening of the uterus, and vulvar cancer affects the vaginal opening.) All four are spread by sexual means. HPV-16 is now known to be implicated as a causative agent in squamous cell cancer in the tonsillar area and on the immovable base of the tongue. (Note that the part of the tongue involved in HPV related carcinomas is actually in the throat, and is visible from the mouth only with a long handled mirror.) Since the virus itself is transmitted exclusively by vigorous physical contact, the implication is that oral/genital sexual contact (oral sex) may be the major means of transmission of the virus.
Five strains of HPV cause oral papillomas (warts). These include 6, 7 11, 16 and 32. Note that young persons who contract oral papillomas, even those infected with HPV-16, will probably clear the infection eventually if their immune systems are not adversely affected by other diseases or lifestyle issues like drug or alcohol addictions. While there is no known cure for HPV, for most people, an HPV infection will cure itself in time.
HPV is the most common sexually transmitted disease in the United States.
The most alarming statistic about the prevalence of HPV in most western countries is: “If a college woman has at least one different sex partner per year for four years, the probability that she will leave college with an HPV infection is greater than 85%. Condoms do not protect from the virus because the areas around the genitals including the inner thigh area are not covered, thus exposing these areas to the infected person’s skin.”
There is no known pharmacological cure for HPV, however, the human body builds up immune defenses against the virus and in most (but not all) cases is able to eliminate it from the body eventually. In young, healthy individuals, the body may clear the infection in a matter of several months. The exceptions are younger persons with chronic diseases or addictions to drugs or alcohol.
A 2005 study showed that HPV is associated with approximately 26% of all head and neck squamous cell carcinomas.
The data linking HPV to cancers of the posterior tongue, tonsils and throat is even stronger, with various published reports showing detection of HPV in 50% or more of cases.
Normal kissing does not seem to be implicated, however deep, open mouth (French) kissing may transmit the virus.
Monogamous couples composed of persons who have never engaged in sex outside of their relationship are not at risk.
As the incidence of smoking has declined over the last 30 years in the USA, the incidence of promiscuous sexual contact has risen. Thus the expected benefit of fewer people smoking has been offset by the liability of more widespread infection with HPV. This means that the rate of oral cancer diagnosis in the US has remained constant over the last twenty years, instead of falling as might have been expected with the decline in the number of smokers.
HPV related oral cancers occur toward the back of the throat, that is, in the tonsillar area, the non mobile base of the tongue and the oropharynx (the upper part of the throat). Squamous cell cancers involving the anterior tongue, the floor of the mouth, the mucosa that covers the inside of the cheeks and alveolar ridges (the ridge area in which the teeth reside) do not appear to be associated with HPV.
The problem of HPV is especially acute in the population of men who have sex with men.
GARDASIL and CERVARIX are vaccines which can immunize a person against four kinds of HPV, including HPV-16. They currently are being administered primarily to young girls and women between the ages of 9 and 26 to prevent the acquisition the most common forms of HPV which are implicated in causing cervical cancer. Both vaccines are given in three shots delivered over six months. They cannot be used to treat active HPV infections or any form of cancer, even if the cancer was caused by HPV.
There is a saliva test that a dentist can perform that can diagnose hidden cases of HPV. Dentists interested in offering this service to their patients can visit the website of Oral DNA Labs to learn about this simple and accurate process.
Note that even if a test such as this establishes that the patient actually has HPV 16, there is no known cure for the virus, so there is little that anyone can do except wait for the virus to disappear from the patient’s system on its own.
Remarkably, oral/pharyngeal cancers that ARE associated with HPV 16 have a much BETTER prognosis than those that are not.
In one study, all patients with HPV-positive tumors had a 59% reduction in risk of death from cancer when compared with HPV-negative HNSCC patients (Head and NeckSquamous Cell Carcinoma).
For more on the human papilloma virus, please see the website of the oral cancer foundation.
The most important factor associated with oral cancer is age. Even with the increased incidence of oral cancer in young persons due to the spread of HPV, the vast majority of persons who develop oral and laryngeal cancer still tend to be over the age of 40. 95% of oral cancer is diagnosed in people older than 45 years, with the median age of diagnosis at 64 years. Half of all oral cancers arise in persons over the age of 65.
Advanced age is probably the most important factor in the mortality associated with the development of any cancer. This is due to the fact that as a person ages, his or her immune system becomes less efficient at recognizing and eliminating aberrant cellular growths which arise from time to time in people of all ages. Since about half of all cases of oral cancer, and most cases of laryngeal cancer occur in patients over the age of 65, the advanced age of this cohort alone would account for a substantial portion of the mortality rate in these patients.
While HPV is the reason that many more squamous cell carcinomas are now being found in younger persons, many older people who have been diagnosed with oral cancers are also infected with HPV. Note that the prevalence of HPV decreases with age. This may be due to HPV infection being cleared by the immune system, or sinking to undetectable levels while still present in the body. Nevertheless, HPV will probably remain in the infected person’s cells for an indefinite time—most often in a latent state, but occasionally producing symptoms or disease.
In some persons with less competent immune systems, the virus may remain in an inactive state until and throughout old age. The factors that are associated with an incompetent immune system are various chronic disease states as well as drug and alcohol addictions. This suggests that advancing age, in combination with a long standing HPV infection (possibly contracted when that person was younger, but more likely when he or she was older but still sexually active), may place a person at a far greater risk of contracting squamous cell carcinoma. The data linking HPV to oropharyngeal cancers is very strong, with published reports showing detection of HPV in 50% or more of cases. Based upon this, it is even possible that an HPV infection contracted in earlier life may place a person at a greater risk of developing oral cancer as he or she ages than those persons without the virus, but with the active habits of heavy smoking and drinking.
(“Lesions” are abnormal growths, erosions or sores.)
The initial lesions of squamous cell carcinoma tend to be painless. The fact that they are painless makes them easily overlooked in the early stages. The lack of pain in early lesions combined with the tendency for this cancer to develop in heavy drinkers may be largely responsible for oral cancer’s 50% 5-year survival rate . These lesions start out as small white or red patches about 1 to 2 mm in diameter and progress toward larger lesions slowly. They will usually be noted by a patient when they are large enough to be felt during movements of the effected organ. They generally appear to be irregular sores with a white and red mottled center, surrounded by a red border. As the lesion enlarges, it may become more and more bound-down to the underlying tissues thus becoming less mobile. Pain and/or numbness generally develop later in the course of the lesion’s growth.