Cancer: Know All You Can About It
Cancer is one of the scariest words in our language. If you’re one of a growing number of people determined to take an active role in your health care now and in the future, you’ll want to learn what you can about one of the principal killers in developed nations today. Knowledge is power; let’s arm ourselves with as much knowledge as we can. We will begin with an overview then apply the information to a more specific type: oral cancer.
What is Cancer?
Cancers are a class of diseases characterized by the uncontrolled division of cells and the ability of these cancerous cells to spread. They can grow into nearby tissue through a process known as invasion, or they can be transported through the bloodstream or lymphatic system (a complex system of glands and ducts active in the body’s defense against disease), to distant areas by what is called metastasis. I’ll attempt to provide what we know today about this major threat.
There are many types of cancers; how severe the symptoms are generally depends on the nature of the malignancy, which refers to cancerous cells that usually have the ability to spread, invade, and destroy tissue. Most cancers can be treated and some even cured, depending on the type, location in the body, and at what stage the cancer is diagnosed. However, once diagnosed, cancer is usually treated with a combination of surgery, “chemotherapy” (drugs which destroy cancerous cells) and “radiotherapy” (killing cancerous cells with radiation).
How is a Normal Cell Transformed?
The unregulated growth of cells that characterizes cancer is caused by damage to DNA — the stuff that genes are made of. The genes are the command machinery which informs the cells what to do. Mutations, changes to the DNA, alter and damage proper cell function. Many mutation events may take place to transform a normal cell into a malignant one. What causes these mutations to occur? They can be caused by radiation, chemicals or physical agents known as carcinogens, or by certain viruses that are able to insert their own genetic material into human cells. There are two alarming characteristics of mutations:
• they can occur spontaneously, and
• they may be passed down from one cell generation to the next.
Cancer: A “Multifactorial” Disease
There are many reasons or factors that cause normal cells to mutate into cancerous ones. Among the most important are:
• predisposing factors — an innate capacity to develop disease that can be triggered under certain conditions, e.g. genetics (genes that are altered or mutate have a tendency to occur along family lines), and
• risk factors — conditions or behaviors that increase the possibility of disease e.g. smoking, chewing tobacco and alcohol use, diets low in fruits and vegetables, viral infections — primarily the human papilloma virus “HPV 16” (the same one that’s been in the news lately which causes cervical cancer in women), and an immune (protective) system that is not functioning normally in response to infections or inherited disease.
Oral Cancer & Precancerous Conditions
Now that we have more of a background about cancer, its causes as well as its risk factors, let’s take that knowledge and apply it to a specific area, the mouth.
Oral cancer accounts for roughly 3% of all cancers in men and 2% in women. Men still outnumber women 2 to 1, but this is changing as women become more exposed to the same risk factors as men. Like all cancers, oral cancer is associated with aging. Did you know that more than 90% of all oral cancers occur in individuals over 40? We now know that African-Americans have a higher incidence than Caucasians and a disturbing number of cases in young people regardless of ethnicity, have been seen in recent years.
Just ponder this staggering statistic: in 2008, it is estimated that more than 34,000 cancers of the oropharynx (oro-mouth and pharynx-throat), will be diagnosed in the USA. Get familiar with the main areas where oral carcinomas (cancers) occur:
• the oral cavity proper (the mouth),
• the lip, tongue, and
• the pharynx (back of the mouth and throat).
You might say that the mouth and lips are accessible for direct examination all the time by routine visits to the dentist. Thinking along those lines, it’s probably easy for a dentist to notice anything unusual in the mouth within a matter of months, right? Here’s the scary aspect of oral cancer: it is not usually detected until a late stage. So despite all the advances in treatment, survival is poor, with only 58% surviving 5 years after treatment.
Most oral cancers are “squamous” (small scale-shaped) cell carcinomas, occurring in the lining of the mouth and are often preceded by identifiable surface changes (lesions) of the oral membranes. White or red patches begin to form in the pre-cancerous stage, and as the cancer develops, a non-healing ulcer may appear.
Stick Out Your Tongue
The tongue, particularly the sides are the most common sites for oral cancer , with the floor of the mouth (under the tongue) coming in second . Lip cancers mostly affect the lower lip and frequently there is a history of chronic sun exposure and preceding damage, which shows up as scaling and crusting at the site. The thing to remember here is that recurring ulcers in the lip area can also be mistaken for cold sores. Since the tongue has a rich blood supply and lymphatic drainage (the lymphatic system is a major component of our immune protection system) 30% of cancers have spread or metastasized by the time they are diagnosed. That’s a frightening fact. Now let’s take that fact a step further — up to 15% of people diagnosed with oral cancer are normally found to have a second primary cancer.
However, when detected early while a lesion is small, survival rate exceeds 80%. Bear in mind, early detection is key. If you notice any unusual lesions (sores or ulcers), or color changes (white or red patches), anywhere in your mouth that do not heal within two-three weeks get to your dentist or physician as soon as possible.
Diagnosis Can Be Complicated
Earlier we talked about the fact that oral cancers are most often detected when they are at a late stage, with early diagnosis only taking place in about one third of the cases. Unfortunately, recognition is complicated. Why? Because the early signs can mimic harmless sores that occur in the mouth such as canker sores, minor infections, or irritations that occur from biting or even certain foods. When we’re given a proper oral cancer exam which includes the oropharynx, the health care professional will feel the neck for lumps; inspect the lips and all inside surfaces of the mouth, including the tonsils at the back of the throat.
Further, we must remember that oral cancers can occur on any surface that lines the mouth and throat, with tongue being the most common site. These changes — as I mentioned earlier — can appear as white or red patches, ulcers and lumps that may or may not be associated with any discomfort or pain.
An appropriately trained dentist should evaluate any such changes that persist for more than two-three weeks. Definitive diagnosis requires the microscopic examination of a piece of the lesion (tissue biopsy). This is a procedure usually carried out with local anesthesia, numbing of the involved site with the removal of a sample or all of the abnormal tissue, if small enough. The tissue specimen is then sent to the lab for analysis where it undergoes microscopic evaluation for a more thorough diagnosis.
Treatment of Pre-Cancerous Conditions
Pre-cancerous lesions must be assessed by biopsy (tissue sampling for disease). If pre-cancerous changes disappear by removing irritants, e.g. tobacco, alcohol, biting, or other chemical or physical irritants, there is no need to biopsy. Follow up is necessary together with determining a frequency for continued monitoring and evaluation. This will, of course, depend upon the findings at the time of biopsy. The ultimate treatment of pre-cancerous lesions is surgical removal however the use of lasers has been very helpful. Diets, vitamins and other drug or chemical approaches have not been useful.
If there is some reason to delay biopsy, other techniques are available to help evaluate a suspicious lesion. While these non-invasive “adjunctive” techniques are helpful in shedding light on a suspicious lesion, they do not substitute for biopsy confirmation. These FDA-approved devices include the use of light reflections, tissue staining (tolonium chloride), cytology (brush biopsy), and fluorescence. These adjunctive techniques do not require anesthesia and are helpful in accelerating the need for further testing or referral. These techniques are available to general dental practitioners, however biopsy remains the gold standard.
When Cancer is Diagnosed
Once the diagnosis is definitive, the extent of disease has to be determined so that a treatment plan and prognosis can be formed. Staging is the term used to describe the level a cancer has reached. Involved in staging are clinical, microscopic findings and imaging with techniques such as magnetic resonance imaging (MRI). Depending upon the stage, your health care professional will formulate a treatment plan that will most likely include considerations for surgery and/or radiation and/or chemotherapy. With all treatments, the teeth and membranes of the mouth must be protected from further incidence of decay, gum disease and other infections, dryness of the mouth, and other more subtle changes.
A treatment team is usually comprised of surgeons, radiation and medical oncologists (cancer specialists), dentists, dental hygienists, nurses, and other professional specialists.
In summary, as a health care professional, I hope you understand the importance of knowing all you can about one of the principal killers in developed nations today. Obviously, risk factors can and must be minimized wherever possible and proper periodic oral cancer screening exams should be a priority. Keep in mind, the more you know about this class of diseases, the more empowered you’ll be toward paving your road to victory.
Review Date: 5/1/2008
Authored By: Dr. Sol Silverman, Jr.
Reviewed By: Dr. Garry A. Rayant, Editor-in-Chief, Dear Doctor, Inc.
Reprinted with permission. This content provided is for general informational purposes only. No action should be taken by you based on this content. We urge you to consult with your dental health professional on all matters relating to you and your family’s dental health. Copyright ® 2011 Dear Doctor, Inc.