Among racial and ethnic groups, African-Americans have the highest oral cancer incidence and mortality rates.² The five-year relative survival rate (that is, the survival rate excluding all causes of death except oral cancer) for all races is only 56 percent for oral cancer.¹

	BACKGROUND

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The majority of oral cancers are squamous cell carcinomas found on the ventrolateral border of the tongue, floor of the mouth, lip and pharynx.³ More than 90 percent of oral cancers are diagnosed in people aged 45 years or older, and most cases are attributed to the use of tobacco (cigarettes, cigars, pipes and smokeless tobacco) and alcohol.^4,5 However, oral leukoplakia attributed to smokeless tobacco may be reversed within two to six weeks if the patient discontinues use of the product.⁶ Other risk factors for oral cancer include infection with human papillomavirus (HPV), low consumption of fruits and vegetables and long-term sun exposure (particularly for lip cancer).^6–9

Our national health objectives, as articulated in Healthy People 2010, include several important objectives addressing oral and pharyngeal cancer.^10,11 Cancer Objective 3–6 in Healthy People 2010 is to "reduce the oropharyngeal cancer death rate" from 3.0 to 2.7 deaths per 100,000 population.¹⁰ Oral Health Objective 21–6 aims to "increase the proportion of oral and pharyngeal cancers detected at the earliest stage" from 35 to 50 percent.¹¹ If practitioners do not know how to perform oral cancer examinations (or choose not to perform them), the lack of knowledge may contribute to the diagnosis of oral cancer being made at a more moderately advanced to advanced stage.^3,5 An increase in the availability of oral cancer examinations may increase the percentage of oral cancers diagnosed at an earlier stage.¹²

The American Cancer Society recommends that people aged 40 years and older receive an oral cancer examination annually, and those aged 20 to 39 years be checked every three years.¹³ Although recent findings from the 1998 National Health Interview Survey (NHIS) indicate that 20.1 percent of adults aged 40 years and older have received an oral cancer examination at some point in their lives, only 13 percent of adults reported having had such an examination within the previous 12 months.^10,11,14 Thus, Oral Health Objective 21–7 is to "increase the proportion of adults who, in the past 12 months, report having had an examination to detect oral and pharyngeal cancers" to 20 percent.¹¹

The 1996 proceedings of the National Strategic Planning Conference for the Prevention and Control of Oral and Pharyngeal Cancer, sponsored by the American Dental Association, Centers for Disease Control and Prevention, and the National Institute of Dental Research/National Institutes of Health, stated that health care professionals need to be aware of oral cancer, know its risk factors and know how to properly perform an oral cancer examination as a routine part of a complete patient examination.¹⁵ Previous studies of dental and medical students, dentists, physicians, dental hygienists and nurse practitioners have shown that health care professionals are not as knowledgeable about oral cancer as they should be, and that they do not perform prevention and early detection procedures on a uniform basis.^16–26

Eighty-nine percent of the students knew that squamous cell carcinoma is the most common form of oral cancer.

One of the many recommendations resulting from the National Strategic Planning Conference was to assess undergraduate medical and dental curricula for evidence of ample exposure to cancer prevention methods and oral cancer examination procedures.¹⁵ In preparing dental students to conduct oral cancer screening examinations as practicing dentists, educators need to consider the oral cancer knowledge and practice skills that students need to acquire in the course of their dental education.

South Carolina has the fourth highest oral cancer mortality rate in the United States.²⁷ Thus, it is especially critical that dental students at the Medical University of South Carolina (MUSC), Charleston, have the requisite knowledge and skills to prevent oral cancer and to detect it at an early stage. The objectives of this study were to assess MUSC dental students’ knowledge of oral cancer risk and nonrisk factors, as well as diagnostic signs, symptoms and examination procedures, and to describe the relationship between academic year and dental students’ knowledge about oral cancer.

	SUBJECTS AND METHODS

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To address these objectives, this study, which was approved by the institutional review board of MUSC, used information obtained from the South Carolina Dental Student Survey (unpublished data, 2002). This survey was adapted from a previous survey used nationally and in Maryland to question dentists about oral cancer prevention and early detection.^20,26,28 We included additional questions from a survey of pediatric dentists regarding tobacco-use intervention.²⁹

In April 2002, two of us (G.C., S.R.) administered the questionnaire to 163 dental students during scheduled class time. The students were in their first through fourth years. The overall response rate was 79.1 percent (Table 1). Because of an initially low response rate for the senior class (40.8 percent), we made two additional attempts during scheduled class time to increase their participation, but without success.

Each correct response to items in the indexes received a score of "1." For each of the indexes, we classified students into one of three categories depending on the number of correct responses. For the risk factors index, the categories were low score (zero to five items), medium score (six items) and high score (seven to nine items). For the nonrisk factors index, we used the following categories: low score (zero to two items), medium score (three or four items) and high score (five to seven items). The diagnostic index categories were low score (zero to five items), medium score (six or seven items) and high score (eight to 10 items).

We used SAS to analyze the unweighted data. Univariate and bivariate analyses were used to statistically evaluate all findings at a Bonferroni-corrected .025.

	RESULTS

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Knowledge of risk and nonrisk factors. With regard to knowledge of oral cancer risk factors, almost all of the 163 students correctly identified the use of tobacco products (98.8 percent), having had an oral cancer lesion in the past (98.2 percent) and the use of alcohol (93.9 percent) as oral cancer risk factors. One hundred thirty students (79.8 percent) correctly identified HPV as a risk factor, and 119 (73 percent) knew that lip cancer is related to sun exposure. Although 112 (68.7 percent) of 163 students correctly identified older age as a risk factor, only 29 (17.8 percent) knew that the majority of oral cancers are diagnosed at age 60 years or older. Eighty-six students (52.8 percent) knew that low consumption of fruits and vegetables is an oral cancer risk factor, and only 41 students (25.1 percent) knew that smoking put them at greater risk of developing oral cancer than does the use of smokeless tobacco.

Regarding nonrisk factors, more than 70 percent of students knew that consumption of hot beverages (78.5 percent) and spicy foods (74.2 percent) was not an oral cancer risk factor. One hundred six (65 percent) of 163 respondents knew that obesity is not a risk factor, and 99 respondents (60.7 percent) recognized that having poorly fitting dentures is not a risk factor for oral cancer. Between 40 and 50 percent of students knew that poor oral hygiene and familial clustering of cancer are not risk factors for oral cancer. However, only 10 students (6.1 percent) knew that having a family history of cancer is not a risk factor.

Knowledge of diagnostic signs, symptoms and examination procedures. Regarding knowledge of oral cancer diagnostic signs, symptoms and examination procedures, 145 (89 percent) of the 163 students knew that squamous cell carcinoma is the most common form of oral cancer. One hundred twenty-two students (74.8 percent) knew that the clinical appearance of an early oral cancer lesion is a small, painless, red or white area. One hundred six (65 percent) of the students knew that the most likely oral cancer site is the ventrolateral border of the tongue, and 103 students (63.2 percent) knew that cancerous lymph nodes, when palpated, can be hard, painless, mobile or fixed.

Ninety-four (57.7 percent) of the 163 students knew all of the components of a tongue examination, and they knew that oral cancer lesions are most often diagnosed in advanced stages. Ninety students (55.2 percent) correctly identified the tongue and floor of the mouth as the two most common oral cancer sites, and 91 students (55.8 percent) knew that patients are asymptomatic in the early stages of the disease. Eighty-one students (49.7 percent) knew that early lesions caused by use of smokeless tobacco generally resolve when patients discontinue use of the smokeless tobacco. Finally, only about one-third of the students knew that erythroplakia and leukoplakia, in that order, are the two conditions most likely to be associated with oral cancer.

Effect of academic year on knowledge. We found significant associations between academic year and knowledge of oral cancer risk and non-risk factors and diagnostic signs, symptoms and examination procedures for all items (P .025; data not shown). For the risk factors index, the survey results showed an overall increasing trend for more correct knowledge scores by academic year (P = .002; Table 2). Specifically, while more than 80 percent of juniors and seniors had medium or high scores on this index, one-half of sophomores and one-third of freshmen received a low score with regard to knowledge of risk factors.

	DISCUSSION

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The results of this survey closely parallel those of previous surveys of dentists in Maryland and nationwide.^20,23,25,26 When comparing the results of our study with those of previous studies of senior dental students, we find that an inadequate level of knowledge about oral cancer is evident in more than one U.S. dental school.^16,30 A survey conducted at seven dental schools found that graduating dental students perceived themselves to be lacking in oral cancer knowledge and examination skills.¹⁶ Another survey of senior dental students at three Texas dental schools found that the students did not believe they were sufficiently prepared to perform biopsies of suspicious lesions; however, the majority did report that they were comfortable conducting oral cancer examinations and advising patients about oral cancer risk factors.³⁰ However, the survey did not examine the students’ level of oral cancer knowledge.

Study limitations. One obvious limitation of this study is that it was based on a cross-sectional survey of 163 students attending one dental school. Therefore, the findings cannot be generalized to other dental schools. Also, the high nonresponse rate for seniors (59.2 percent) creates an unknown selection bias for the seniors. Moreover, as a result of the low response rate for seniors, the sampling variability may be too high to detect statistical differences between the seniors and the other three classes, even when percentage differences suggest that meaningful differences may exist.

Finally, bias due to confounding because of background experiences, such as previous work as a dental hygienist or dental assistant, may have been pertinent to students’ knowledge in the area of oral cancer. Curriculum alterations, clinical emphasis or both also may be related to students’ knowledge of oral cancer. These confounders should be measured further.

Nearly one-half of the students did not know that the tongue and floor of the mouth are the two most common oral cancer sites.

The National Strategic Planning Conference for the Prevention and Control of Oral and Pharyngeal Cancer has recommended that health care curricula be developed and implemented to "require competency in prevention, diagnosis, and multidisciplinary management of oral and pharyngeal cancer."¹⁵ A 1998 assessment of the cancer curricula in U.S. dental schools indicated that only 64 percent of responding schools included direct patient contact as part of their instruction on identifying precancerous lesions, and only 45 percent reported that students had performed biopsies before graduation.³¹

Although curricular guidelines are in place to help ensure that dental students are taught how to conduct an oral cancer examination, state dental boards do not require that candidates perform an oral cancer examination for licensure. This failure to require a demonstration of oral cancer examination expertise implies that oral cancer examinations are not seen as important to the health of the patient and that dental care providers are not encouraged to provide this service in clinical practice.¹²

Continuing education. The American Dental Association has received a $1.2 million grant from the National Cancer Institute to provide oral cancer continuing education for practicing dentists nationwide.³² This training will focus on early detection of oral cancer and tobacco-use cessation training in an approach that is projected to decrease oral cancer incidence, mortality and morbidity.³² New York state already has passed legislation requiring all dentists to have, as part of their continuing education requirements, at least two hours of oral cancer prevention and early detection training.³³ However, this training also should be required by dental schools before new dentists begin clinical practice.

Although the dental students in this study correctly identified most oral cancer risk factors, 20 percent of seniors and nearly one-half of juniors received low or medium scores on the nonrisk factors index. This indicates that a proportion of these dental students were misinformed about scientifically supported oral cancer risk factors. Also, the results of this survey showed that 42 percent of students did not know all of the components of a tongue examination or that oral cancer lesions usually are diagnosed in advanced stages. Nearly one-half of the students did not know that the tongue and floor of the mouth are the two most common oral cancer sites. These findings suggest that educators need to place stronger emphasis on oral cancer prevention and detection in dental school.

Evidence shows that when dental students are routinely taught certain preventive regimens in both didactic and clinical courses, they perform these procedures in clinical practice.^34,35 Emphasis on oral cancer competence could be incorporated into the South Carolina continuing education or state dental board licensing requirements to ensure that dental students and dentists in the state are prepared. Increasing the knowledge of graduating dental students will increase the number of practicing dentists who are trained to provide proper oral cancer examinations for their patients, and who are knowledgeable about the risk factors for oral cancer.

	CONCLUSIONS

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These data highlight the need for improvements in the oral cancer curricula and clinical training in dental schools, in particular more instructional time devoted to prevention and detection of the disease. It is essential that MUSC dental students be taught how to prevent and detect oral cancer if the Healthy People 2010 oral cancer objectives are to be achieved in South Carolina.