Reducing the Burden of Oral and Pharyngeal Cancers

By Deborah M. Winn, PhD;
Ann L. Sandberg, PhD;
Alice M. Horowitz, PhD;
Scott R. Diehl, PhD;
Silvio Gutkind, PhD;
Dushanka V. Kleinman, DDS, MScD

In the United States, oral and pharyngeal cancers continue to result in significant morbidity and mortality. Dental professionals play a pivotal role in all facets of controlling the burden of oral and pharyngeal cancer -- from efforts to prevent its occurrence, to ensuring that oral cancers are detected at the earliest possible stage, to treating these cancers, and to ensuring maximum quality of life and function for oral and pharyngeal cancer survivors. Individually and by making linkages within the community and beyond, dentists can help patients modify their risk of these cancers and can take steps to screen for them, thereby potentially improving survival and function of those who develop oral cancer. Creative partnerships between community dentists and academic and other research centers will help move knowledge of the biological processes involved in carcinogenesis and innovations in treatment into clinical practice. Partnerships between dental and medical professionals may also help efforts to reduce the morbidity related to oral and pharyngeal cancers. Local, state and national multidisciplinary initiatives are emerging that focus more broadly on risk factor control or oral and pharyngeal cancer issues. These many forms of cooperative approaches offer excellent opportunities to make a significant impact on reducing the incidence of and in treating these debilitating and disfiguring malignancies.

Article copyright 1998 Journal of the California Dental Association.
Photographs copyright of the authors.

During the past 25 years, remarkable progress has been made in both the elucidation of the molecular bases of cancers and their treatment. Yet monumental challenges remain. Cancers of the oral cavity, lip and pharynx affect more than 30,000 people each year;1 and, collectively, they remain the sixth most common cancer among U.S. white males and the fourth most common among U.S. black males.2 These malignancies are among the most debilitating and disfiguring of all cancers, and annual costs of care are estimated to be about $2 billion.3 Tobacco and alcohol are major risk factors for these cancers.4

It is encouraging that oral and pharyngeal cancer incidence (the number of new cases of oral and pharyngeal cancers per 100,000 people) has declined recently. This decline has been most notable among white males. Only in the past few years has a decline in incidence rates for black males occurred. This, fortunately, is a reversal of rates that increased by 1.6 percent per year during the period 1973-1992. Very recently, the incidence rates for black and white females have also declined.5 However, the U.S. population is increasing, and the baby boomers are aging. Thus, the actual number of individuals with oral and pharyngeal cancers has increased by about 20 percent from 1973 to 1992. Similarly, the number of people with many other forms of cancer is also increasing.5

A decline in the overall mortality (deaths per 100,000 people) from oral and pharyngeal cancers has also occurred.5 However, a striking exception to this finding is that, among people younger than 40, mortality from cancers of the tongue, the most common cancer site within the oral cavity, has been rising for decades.5 The mortality from oral and pharyngeal cancers in California is similar to that in the United States.6 However, California has a greater number of these malignancies than most states because of its large population. Of the newly diagnosed patients with oral and pharyngeal cancers in the United States in 1995, 3,000, or 11 percent, were in California.6 Nasopharyngeal cancers may be more common in California than elsewhere in the United States since a disproportionately large number of people of Chinese descent, who appear to be more susceptible to these specific cancers,7 reside in California.

The overall survival rate for individuals with oral and pharyngeal cancers is 52 percent at five years after diagnosis. This is lower than that for colon cancer, cancer of the cervix, and breast cancer.2 Although survival has improved for many cancers, the five-year survival of individuals with oral and pharyngeal cancers has not increased over the past four decades. The survival of blacks has actually decreased.2 Most oral and pharyngeal cancers (64 percent) are not diagnosed at an early and more easily treatable stage; black people with oral cancer are even less likely to have an early stage diagnosis (Figure 1). Yet, it is clear that survival is better when the cancer is found at an early stage (Figure 2). Also, individuals who survive an initial primary oral cancer are at an elevated risk of developing new primary tumors. The rate of second primaries among oral and pharyngeal cancer patients exceeds that for any other type of cancer.8,9

Oral and pharyngeal cancers, like other cancers, result from a multistage accumulation of genetic aberrations. The genetic changes that have been associated with oral and pharyngeal cancers are not localized to any one chromosome but, rather, are found on many human chromosomes. Mutations in certain genes may promote uncontrolled cell growth by overproducing either growth stimulatory factors or their receptors that, following ligand binding, trigger numerous intracellular processes. Mutations in other genes result in a loss of tumor suppressors, proteins that prevent excessive cell growth. Additional genetic alterations favor vascularization of tumors or enable oral tumor cells to invade the surrounding tissues and migrate within lymph nodes to the lymph nodes in the neck. The intricacies of cancers are further increased by genetic aberrations in transcription factors that regulate the expression of other genes.10

Oral cancers are often preceded by premalignant lesions including leukoplakia (white mucosal changes) and erythroplakia (red mucosal changes) or mixed white and red lesions.11 Biomarkers are cellular, biochemical, or molecular alterations measurable in human tissues and fluids.12 Alterations in certain genes may occur in premalignant lesions and may, therefore, provide excellent biomarkers for determination of those individuals who require close monitoring or who may benefit from chemoprevention, that is, the use of natural or synthetic chemicals such as vitamin A-related compounds to prevent oral cancer.13 Major efforts are currently under way to identify genetic biomarkers both for the early detection of oral and pharyngeal cancers and as indicators for prognosis.14 For example, the normal p53 suppressor gene inhibits cell growth. Mutations of the gene (resulting in failure of the normal inhibitions of growth) are common in oral cancers.15 In addition, p53 alterations appear in premalignant oral lesions16 and also predict recurrence and second head and neck primary cancers.17 Behavioral and molecular factors are both important in oral cancer etiology. Of interest are recent studies suggesting that individuals with a genetic predisposition to rapidly metabolize alcohol and who also consume large quantities of alcohol are at the highest risk for development of oral and pharyngeal cancers.18

The primary objective of any therapeutic regimen for treatment of head and neck cancers is cure. However, current modalities also focus on preservation or restoration of function and appearance. Surgery or radiotherapy, either alone or in combination, is generally utilized for early stage tumors. Although surgery is commonly favored, radiotherapy may be essential because of the size or location of the tumor. In late-stage disease (tumor greater than 4 cm and/or lymph node involvement), more aggressive treatment, with resultant functional consequences, may be necessary. Chemotherapy is often added to the treatment regimen in advanced tumors or tumors of certain sites in the hope of increasing control;19 by itself, chemotherapy is only palliative.20 New techniques and approaches in treatment are emerging. For example, for instances when reconstruction of the mandible or soft tissue is required, techniques have now been developed for tumor resection and bone or skin grafting in a single surgical procedure. Investigators also are now exploring the possibilities of applying immunotherapy and gene therapy to the treatment of cancers of the head and neck.

Although we are moving ahead in understanding the etiology and pathogenesis of this disease, there are actions that can be taken now to prevent and control it. Reducing the burden of oral and pharyngeal cancers will require multiple approaches to prevent tobacco use and excessive alcohol consumption, identify precancerous lesions and tumors at the earliest possible stage, ensure prompt and coordinated treatment of people with oral cancer, and move promising scientific discoveries rapidly into practice. Dental professionals can contribute to these efforts to reduce the burden of the occurrence of oral cancer and its potentially devastating effects through practice-based efforts to reduce or eliminate patients' risk behaviors and by diagnosing these cancers earlier. Dental professionals can also make a difference through partnerships with the greater community, state and nation.

National and State Programs

Over the past several years, the Centers for Disease Control and Prevention, the National Institute of Dental Research, and the American Dental Association have developed a strategic plan for the prevention and reduction of oral cancer in the United States.21 It is hoped that this plan will stimulate an effective national campaign for the prevention and control of oral and pharyngeal cancers. Recommendations are made in five broad areas:

* Advocacy, collaboration, and coalition-building;
* Public health policy;
* Public education;
* Professional education and practice; and
* Data collection, evaluation, and research.

Implementation of the plan is under way and involves a wide range of dental, medical, and social service organizations that work with oral cancer patients and those at risk for oral cancer. The national health promotion and disease prevention objectives for the nation have highlighted oral cancer reductions and actions needed for tobacco control.22

There are several other initiatives at the national level that specifically focus on prevention and control of tobacco use and involve dental professionals. For the past several years, the National Dental Tobacco-Free Steering Committee under the sponsorship of the National Cancer Institute has mobilized a consortium to:

* Assess recent developments in tobacco use intervention strategies;
* Define opportunities of dental involvement in tobacco use intervention activities; and
* Promote cooperation among dental and other professional and public interest organizations.

A national program focused on chewing tobacco and snuff, the National Spit Tobacco Education Progam, has been under way since 1994. This program was initially funded by Oral Health America, the National Institute of Dental Research, and the National Cancer Institute and is now funded by the Robert Wood Johnson Foundation. Six regional coordinating centers across the country have been established. The National Cancer Institutes' COMMIT program, an acronym for Community Intervention Trial for Smoking Cessation, also included a focus on dental professionals.23

One example of a state-initiated program focuses on spit tobacco use. The Spit Tobacco Education and Prevention Plan for the State of Texas is funded by the Texas Cancer Council and administered by the Dental Oncology Education Program in cooperation with the Texas Dental Association. The extremely high use of spit tobacco in Texas stimulated this special initiative. The goal is to diminish and eliminate use of spit tobacco through collaborative integrated research, education, and public policy activities.24

The development, implementation, and evaluation of state models has been suggested as one approach to oral cancer prevention and early detection.21,25 A state model is defined as a comprehensive plan that includes implementation and evaluation criteria of appropriate interventions based on the needs of the particular state. The rationale for this approach is that each state has different oral cancer incidence, mortality, and survival rates; racial and ethnic groups; practice acts for health care providers; and laws concerning tobacco use and enforcement practices, as well as differences in both smoking and chewing patterns. Thus, no one model could fit the needs of all states. Today, no state has a comprehensive state model for oral cancer prevention and early detection, but several states have taken some initial steps to do so. For example, Maryland has begun a partnership for the prevention and early detection of oral cancers. The partnership, which is spearheaded by the state dental director, includes representatives from provider associations, advocacy and consumer agencies, organizations, and other interested groups. It is the intent of the partnership to assist Maryland dental and medical practitioners, policy-makers, and residents in receiving the benefits of appropriate and quality oral cancer prevention, education, and training and by advocating oral cancer-related policies that promote and protect health and support healthy behaviors and lifestyles.

Oral Cancer Prevention

Finding innovative means of preventing people from using tobacco and alcohol and developing effective methods to get users to quit will be essential in reducing the occurrence of new cases and the risks of second primary cancers. Based on a very large epidemiologic study in four areas of the United States, it is estimated that about three-fourths of oral and pharyngeal cancers are associated with the use of any form of tobacco and heavy alcohol intake.26 Tobacco and alcohol independently increase the risk of oral and pharyngeal cancer, and people who use both are at much higher risk than would be expected from the risks among those who only smoke or only drink.26 Quitting smoking reduces the risk of oral and pharyngeal cancer.26 An advisory group to the surgeon general stated that smokeless tobacco (snuff and chewing tobacco) can cause cancer in humans.27 Although cigarette smoking rates have been declining in adults and have probably contributed to the declines in incidence rates of these cancers, disturbing trends have emerged. Cigarette smoking is increasing among adolescents.28 Smokeless tobacco use remains common, based on a survey in 1995 that found that 11.4 percent of high school youth had used smokeless tobacco in the previous month; for white adolescents the figure was 25.1 percent.29 Also of serious concern is the recent popularity of cigar smoking. Compared to non-users of cigars, cigar smokers experience a four to tenfold higher risk of dying from oral, laryngeal, and esophageal cancer.30

Dentists seldom determine patients' use of tobacco and alcohol products.31 Currently, one-third of dental schools do not assess patient risk behavior on their standard patient history forms;32 also, routine risk behavior assessments are not universally used in medical and dental hygiene schools.33,34 Provider knowledge of the patient's risk profile is an essential first step in changing patient behavior.

Emerging evidence is demonstrating that interventions in the dental practice setting may be effective in reducing use of tobacco. One recent study compared methods to stimulate smokeless tobacco users to quit. The intervention compared usual care with a routine oral examination, an explanation of the health risks of smoking, unequivocal advice to quit, and a nine-minute video, a self-help manual, and a brief counseling session with a dental hygienist. This intervention led to a 50 percent increase in the number of quitters at one year compared to usual care.35 Brief interventions for smokers and other tobacco users suitable for the dental office have also been developed and made available.36,37

New approaches to help tobacco users quit are emerging. One promising strategy is suggested by the recent results of a clinical trial of the anti-depressant Bupropion. The results indicated that 19.6 percent of smokers receiving the lowest dosage of the anti-depressant were abstinent after one year of follow-up compared to 12.4 percent among the placebo group, and rates of abstinence for higher dosages of Bupropion were even greater.38 However, because those at highest risk of oral and pharyngeal cancer are smokers who also abuse alcohol, interactions between drugs designed to curb tobacco and alcohol and the challenges of multiple drug dependencies must be considered.

Other mechanisms are also being used to influence tobacco use behaviors. California, for example, has had remarkable success in reducing tobacco consumption through Proposition 99, the tobacco tax initiative. The result of implementation of Proposition 99, which raised taxes on tobacco products and used the funds from the increase to fund tobacco control activities, has been a 27 percent decline in the prevalence of tobacco use in California from 1988 to 1993, a rate of decline three times that of the rest of the United States.39

Early Identification

Identifying cancers at the earliest possible stage is another critical component in mitigating the burden of oral and pharyngeal cancer. Both the patient and the dentist can play a role. White and/or reddish lesions in the oral cavity can progress to malignancies.40 Nonhealing sores, pain and swelling are additional signals to a patient to seek a medical or dental examination. However, early detection of oral and pharyngeal cancers is impeded by the public's poor understanding of the risk factors for and the signs and symptoms of oral cancers.41,42 For example, only 25 percent could identify one early sign of oral cancer, and 44 percent responded that they did not know any early signs.42 Dental professionals can educate patients about their risk for oral and pharyngeal cancer and encourage compliance with visits and examinations to monitor oral and pharyngeal mucosal health. This function in part depends upon undergraduate training and practical experience, as well as continuing education updates.

Oral cancers may be diagnosed and treated earlier if dentists provide oral cancer examinations. Currently, only 14 percent of U.S. adults report that they have ever had an oral cancer examination and only 7 percent had the exam in the past year,43 the frequency recommended by the American Cancer Society for adults 40 years of age and older.6 Based on a recent survey in two Maryland counties,44 many dentists and other health care providers do not examine all adult patients for oral cancers. In addition, a recent national pilot study showed that dentists' level of knowledge regarding risk factors for and signs and symptoms of oral cancer is inconsistent and less than optimal.45 Many dentists have not attended a continuing education course on oral cancer during the past five years.45

There are additional barriers to reducing the proportion of oral cancers that are diagnosed at late stage. A significant problem is the lack of reimbursement for oral cancer examinations under the Medicare and Medicaid systems.

Professional Education and Association Opportunities

Dental and dental hygiene schools are uniquely positioned to provide additional training in oral cancer prevention, detection, and care. Also, educational programs have been developed by non-academic groups including state American Cancer Society groups, the National Oral Cancer Awareness Program, and the National Oral Health Information Clearinghouse, the latter in conjunction with an advisory group that has representatives from patient groups, the Centers for Disease Control and Prevention, the American Dental Association, and the Federation of Special Care.

Associations of dental professionals, working with their medical and other health care personnel colleagues, can also contribute to efforts to reduce oral cancer and encourage activities that improve early detection. State dental and medical boards could require that dental and medical personnel take a special course on oral cancer prevention and early detection prior to licensure and relicensure.41 Such a requirement has several precedents in California, for example, the newly enacted requirement for all dental personnel to complete continuing education in infection control. Many state and local dental/dental hygiene organizations sponsor cancer education programs at their annual or periodic meetings.

Dental, Medical, and Research Partnerships

Partnerships can focus attention on particular public health problems, potential solutions, and mechanisms for implementing those solutions. Two special types of partnerships will be important: those with the medical community and those with the research community. Other, broader partnerships will be important as well.

Concerted and coordinated effort on the part of dental and medical professionals is essential to make an impact in risk factor management. Responsibility for diagnosis is shared between the dental and medical professions because of the nature of the presenting symptoms, which may lead patients to seek out dentists, otolaryngologists, or internal medicine specialists, among others. The patterns of health care utilization by older people suggest that both medical and dental professionals may have opportunities to screen for previously undetected lesions. For example, in one study of head and neck cancer patients residing in Boston, subjects had a median of 10.5 health care visits in the 24-month period just prior to diagnosis, and these visits included a wide range of health care professions and care settings.46 Thus, monitoring through both the medical and dental care systems can potentially optimize early detection. Efforts are under way to increase the diagnostic capacity of all health professionals and to introduce preliminary examinations in settings such as the health service centers for homeless shelter residents.47

The medical, psychological, and social problems associated with both tobacco use and alcohol abuse are well-known. Thus, it is clear that the individuals at highest risk for oral cancer may have enormous difficulty quitting either of these habits. They may also have medical or emotional problems that can compromise compliance with health care appointments intended to monitor risk factors or oral lesions. Smoking and alcohol abuse and their consequences may complicate oral cancer treatment. Finally, once diagnosed and treated for oral cancer, many patients face functional and other problems that impact oral and systemic health and must be closely monitored for recurrences and new primaries. Ongoing dental-medical communication and coordination should help maximize function, quality of life, and early detection of new problems in these patients.

The research community and dental practitioners can form new relationships in the future to take advantage of scientific innovations. The Internet provides the practicing dentist with excellent opportunities to follow these advances: The National Institute of Dental Research and the National Cancer Institute Web pages are constantly updated with new research findings. The research community needs to establish links with dentists in communities as a source of patients for studies and as a possible setting for studies of the effectiveness of procedures for risk factor control, early detection, and follow-up after diagnosis and initial therapy.

Conclusion

Dental professionals play a pivotal role in all facets of oral and pharyngeal cancers. They must be involved in attempts to prevent occurrence of these malignancies through promotion of tobacco and alcohol control and be well-versed in examination procedures to detect lesions at the earliest possible stages. They must also be instrumental in reducing the morbidity and mortality of oral pharyngeal cancers by promptly referring patients for appropriate treatment and, subsequently, monitoring them for recurrence or the development of second primary tumors. Close teamwork among dentists, hygienists, physicians, maxillofacial or head and neck surgeons, radiation and medical oncologists, prosthodontists, psychologists or psychiatrists, and rehabilitation specialists would optimize diagnosis, therapy, and maintenance or restoration of function and quality of life. Consortia that focus on the control of oral and pharyngeal cancers in the United States have been established. Their multidisciplinary cooperative approaches, in addition to escalated progress in research and more rapid translation of research findings to a clinical setting, would make a significant impact on reducing the incidence of and treating these debilitating and disfiguring malignancies.

Authors

Deborah M. Winn, PhD, is a senior investigator in the Division of Intramural Research, National Institute of Dental Research, National Institutes of Health. (photo)
Ann L. Sandberg, PhD, is director of the Neoplastic Diseases Program and the Comprehensive Oral Health Research Centers of Discovery Program in the Division of Extramural Research, National Institute of Dental Research, National Institutes of Health.
Alice M. Horowitz, PhD, is a senior scientist in the Office of Science Policy and Analysis, National Institute of Dental Research, National Institutes of Health. (photo)
Scott R. Diehl, PhD, is chief of the Molecular Genetic Epidemiology Section in the Division of Intramural Research at the National Institute of Dental Research, National Institutes of Health. (photo)
Silvio Gutkind, PhD, is chief of the Oral and Pharyngeal Cancer Branch, Division of Intramural Research, National Institute of Dental Research, National Institutes of Health.
Dushanka V. Kleinman, DDS, MScD, is deputy director, National Institute of Dental Research, National Institutes of Health. (photo)

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To request a printed copy of this article, please contact/Deborah Winn, PhD, Division of Intramural Research, National Institute of Dental Research, Natcher Building, Room 4AS-19F, 45 Center Drive, Bethesda, MD 20892-6401.