Knowledge of Oral Cancer among the Fourth and Fifth Year Dental Students.

BACKGROUND: The literature data show insufficient knowledge and awareness about oral cancer among dental and medical students.
OBJECTIVE: To assess the knowledge of graduating dental students regarding oral cancer and to assess their awareness regarding the prevention and early detection of oral cancer. Also student's smoking status was examined aimed to investigate their attitude towards smoking as a risk factor for development of oral cancer and to assess the prevalence of smoking among dental students. SUBJECTS AND METHODS: The study group consisted of 83 students of the fourth and fifth years of dental medicine study who answered the questions written in the original 16-item questionnaire.
RESULTS: More than half of the students considered their knowledge to be good, a quarter of them regarded their knowledge as being poor. Almost 16% of students considered their knowledge to be very good, whereas only two students rated their knowledge as 'excellent'. Students of the fifth year were more likely to be smokers compared to fourth year students (39.5% vs. 22.5%). Higher percentage of non-smokers than smokers had marked 'stop smoking' as an important preventive measure (non-smokers 91.2%, smokers 84.3%, p = 0.01).
CONCLUSION: Majority of the students of fourth and fifth year of study rate their knowledge about oral cancer as good. A large number of students of both years considered hairy leukoplakia a potentially malignant disorder. Students non smokers recognize "stop smoking" as an important preventive measure unlike students smokers who show a more realistic attitude towards smoking as a risk factor for oral cancer.

Introduction

Oral cancer is among the ten most common malignant tumors in people worldwide mainly with a poor prognosis (). According to the data of GLOBOCAN, about 300,373 people in the world were affected by lip/oral cavity cancer in 2012. The highest frequency is recorded in the South-East Asia region (6.4 per 100,000) (). Malignant diseases are among the leading public health problems in Croatia. In the year 2014, 21,434 new cancer cases in both sexes were registered among which 890 new cases of oral cancer out of which 746 were males ().

More than 90% of oral cancers are squamous cell carcinomas (SCC), which may arise from the potentially malignant disorders (PMDs) which include oral leukoplakia, erythroplakia and erythroleukoplakia, or verrucous leukoplakia, but can also develop in apparently normal tissue (). In addition to smoking and alcohol, which have long been recognized as major risk factors, increasing epidemiological significance is attributed to human papillomavirus (HPV) infection the high risk genotypes of which carry a high carcinogenic potential (, ).

Most commonly, oral cancer occurs in middle aged and elderly adults (median 62 years), but the increasing occurrence among younger individuals imposes a more serious approach to the examination of the oral cavity with the aim of early detection of malignant changes in the oral mucosa. When patients are diagnosed in a timely manner they have the best chance for cure and long-term survival. The literature data show insufficient knowledge of oral cavity cancer among dental and medical students, but also among family physicians and even dentists (–).

Although the oral cavity is readily available for examination, studies show that over half of the cases of intraoral cancer are discovered late and that some cases remain unrecognized. It is important during the course of dental medicine study that students gain knowledge on oral cavity cancers and develop awareness of the need for early detection of PMDs on oral mucosa including a routine examination of all oral mucosa regions and cervical lymph nodes at each dental examination (–).

Therefore, the primary objective of this study was to assess the knowledge of graduating dental students regarding oral cancer and to assess their awareness of the prevention and early detection of oral cancer.

Specific objectives were to:

compare the knowledge of students of fourth and fifth years of study

compare attitudes of smokers and non-smokers among students towards the risk of smoking

compare attitudes towards prevention and treatment of cancer of students who evaluate their knowledge poor in relation to those who consider their knowledge to be good.

Subjects and Methods

The study group consisted of 83 students of fourth and fifth years of dental medicine study of whom the informed consent was obtained who were expected to answer all items in a list in the original 16-item questionnaire that was developed by Carter and Ogden () and modified (Appendix 1). This questionnaire consisted of 3 groups of questions. The first group referred to the knowledge of the students on etiology and topography of oral cavity cancer, the second group referred to self-assessment of early diagnosis and oral cancer prevention during the course, and the third group referred to procedures for prevention and treatment of patients with oral cancer. The students were also asked whether they were smokers or not. The intention was to determine the prevalence of smoking among dental students and to examine a possible impact of smoking status on their attitude towards smoking as a risk factor for development of oral cancer.

This study has been approved by the Ethics Committee of the School of Dental Medicine University of Zagreb and was conducted from April to July in 2016. All participants had previously signed a written informed consent. The students participated in the survey voluntarily and anonymously. After the classes, the students were asked to fill in a questionnaire, which lasted about 15 minutes. The results were analyzed using a chi-square test in Medcalc (v11, MedCalc software, Belgium) and statistical significance was determined with p <0.05.

Results

The students of the fourth and fifth years of dental medicine study, aged 21- 28 years (median 24 years) participated in the study and filled out the questionnaire. The students gained knowledge of oral cancer through general pathology, oncology, oral surgery and oral medicine courses and clinical lectures.

The fourth year of dental medicine study was represented by 40 students, including 7 men (17.5%) and 33 women (82.5%), average age 23 years (range 21 - 26 years). In the fifth year, out of a total of 43 students, there were 14 men (25.3%) and 29 women (74.7%) aged 23 – 28 years (median 24 years). Twenty six students responded positively to the question of whether they were smokers or not. Men were more frequent smokers than women (66.7% vs. 19.3%). Likewise, students of the fifth year were more likely to be smokers compared to the fourth year students (39.5% vs. 22.5%).

In this study, we aimed to investigate into a possible impact of students smoking status on their attitude towards smoking as a risk factor for oral cancer. By comparing the smokers’ and non-smokers’ responses we did not find a statistically significant difference in the attitude regarding smoking among the students and their knowledge of smoking as a risk factor for oral cancer. However, a slightly higher percentage of non-smokers than smokers had marked 'stop smoking' as an important preventive measure (non-smokers 91.2%, smokers 84.3%, p = 0.01).

Table 1 shows the distribution of responses to the question of self-assessment of the knowledge about oral cavity cancer. More than half of the students considered their knowledge to be good, a quarter of them regarded their knowledge as being poor, and only 2 students have rated their knowledge positively as 'excellent'. Other students (15.66%) considered their knowledge to be very good. Regarding the self-assessment, there were no any significant differences between the students of fourth and fifth years.

Table 1

Self-assessment of students’ knowledge on oral cancer

OcjenaGrade	Studenti 4. godine4th year students		Studenti 5. godine5th year students		UkupnoTotal
	N	%	N	%	N	%
vrlo loševery poor	1	2.50	2	4.65	3	3.61
lošepoor	12	30.00	7	16.28	19	22.89
dobrogood	24	60.00	22	51.16	46	55.42
vrlo dobrovery good	2	5.00	11	25.58	13	15.66
izvrsnoexcellent	1	2.50	1	2.33	2	2.41
UkupnoTotal	40	100.00	43	100.00	83	100.00

Knowledge of oral cavity cancer was investigated through five questions (questions three to seven). There were no significant differences in responses between the students of fourth and fifth years. When asked the question three whether oral cavity cancer is among the ten most common cancers, 80% of respondents answered positively. Similarly, when asked the question four about the most common types of cancer, 82.5% of respondents answered correctly. When asked about the prognostic significance of localization of oral cancer, the majority of students marked the tongue.

According to students’ responses, the most common risk factors are smoking and alcohol consumption, hairy leukoplakia and HPV infection. Interestingly, when asked the question six, a large number of students of both years considered a benign hairy leukoplakia and oral lichen planus as PMD ((Figure 1). Also, a large number of the fourth year students considered HPV and hairy leukoplakia an important risk factor compared to the fifth year students. However, this difference is not statistically significant.

Figure 1

Lesions of the oral mucosa that students consider as PMD

Regarding the satisfaction with the information obtained during lectures on oral cancer, there is a statistically significant difference since 39.5% of fifth year students stated that they were sufficiently informed as opposed to 15% of fourth year students (p = 0.01).

Regarding the question nine, "How many times during the study you had the opportunity for independent examination of patients with PMDs and cancerous lesions?" most of the students (81.93%) responded negatively. Four students of the fourth year and nine of the fifth year examined patients less than five times, and only two students of the fifth year had the opportunity to examine them five to ten times.

The students of the fifth year talked with patients about prevention more often than fourth year students. The vast majority of fifth year students (58.13%) responded positively to question number ten compared to 14 students of the fourth year (41.3%), which is significantly more frequent (p = 0.035). The vast majority of students (97.6%) believed that patients were insufficiently or very poorly informed about oral cancer. Only two of the fifth year students stated that patients were sufficiently informed or well informed about oral cancer.

In terms of preventive measures, a slightly larger number of fourth year students stated smoking cessation and frequent visits to dentists as an important preventive measure (92.5% vs. 76.8%). There were no differences among the examined groups regarding other responses (Figure 2).

Figure 2

Preventive measures which students have identified to decrease the risk for oral cancer

The vast majority of the survey respondents believed that all regions of the oral cavity and cervical lymph nodes should be examined. Regarding the question 15, ''To whom would you refer patients with PMDs? “, almost all students answered ‘‘to a specialist of oral medicine” (Figure 3).

Figure 3

The specialist to whom the students would refer the patient with PMD

The last question involved duration of treatment of PMDs. The students were more inclined to long-term treatments (27.7% of students stated that a six months treatment is needed and 38.6% stated that patients should be treated for a period longer than a year).

Discussion

The results of this study showed that students of the fourth and fifth year of study rated their knowledge on oral cancer mostly as good. The students of the fifth year were better informed about oral cancer, more often assessed the patients, and were having preventive conversations with the patients compared to the fourth year students. Concerning the theoretical knowledge, it is interesting that the students of the fourth year of study do not lag behind their more advanced fellow students.

For example, responding to the question of risk factors, the students of the fourth and fifth year recognized smoking and alcohol as equally important risk factors, which is a progress compared to similar research by Lončar-Brzak et al. from 2012 () in which only a few students of the fourth year recognized alcohol as a risk factor. They also considered a HPV infection to be an equally important risk factor. However, it is interesting that students of both years have identified benign hairy leukoplakia as PMD, thus pointing to a need for better knowledge and differentiation of clinically similar lesions during clinical lectures and oral examination. Soares et al. () have also found that students do not sufficiently recognize clinical features of oral lesions despite good knowledge of etiology of oral cancer and awareness of the need for a thorough oral examination. Therefore, a supplementation of knowledge of differential diagnosis of oral lesions is needed during the teaching process. It is equally important to gain knowledge from earlier referrals of patients with suspected lesions to facilitate further diagnostics and treatment if no healing of the lesion occurs within a week.

In this study, the students also responded to the question regarding their smoking habits. The purpose of this question was to determine the prevalence of smoking among students and to examine a possible impact of smoking status on the attitude towards smoking as a risk factor for development of oral cancer. One third of the students stated that they were smokers, and among them more common smokers were men than women. Likewise, the students of the fifth year were more likely to smoke compared with the fourth year students. The rate of smokers among the students is somewhat lower than that among smokers in the general population of the same age but it still remains worrisome (). By comparing the smokers' and non-smokers' responses we did not find a statistically significant difference in the smoking attitude and their perception of smoking as a risk factor. However, a higher percentage of non-smokers than smokers considered smoking cessation an important preventive measure. This attitude confirms the attitude of students regarding smoking as risk factor for oral cancer. Therefore, a more constructive approach and education of students about the harmful effects of tobacco and benefits of smoking cessation in the disease prevention and treatment during teaching process should also be featured because it is much easier for non-smokers to promote and advocate smoking abstinence among patients.

More than a half of the students of both years rated their knowledge on oral cancer as good, a quarter of them rated it as poor, and only a small number of students considered their knowledge to be very good or excellent. We have not found a statistically significant difference in the responses among the students who considered their knowledge poor compared to those who evaluated their knowledge as being good, very good, or excellent.

Regarding the satisfaction with oral cancer education, a significantly larger number of fifth year students stated that they were sufficiently informed, unlike a small number of fourth year students. Likewise, the fifth year students had better opportunities to examine patients with cancer or those with oral mucosa lesions, as well as talk to patients about avoiding risk factors and taking preventive measures compared to the fourth year students. This difference is easily explained by the fact that students of more advanced years of dental study attend a considerably larger number of oral medicine clinical lectures. Our results coincide with those of similar studies, which also showed that students of more advanced years of study had greater knowledge of oral cancer. Also, they had a more developed awareness about risk factors and it is a well-known fact that awareness regarding risk factors is a prerequisite for the prevention of oral cancer (–).

The vast majority of students believed that patients were insufficiently or very badly informed, which implies the conclusion of the need for implementing better educational programs. Leaflet printing, video presentations as well as preventive interviews at each dental examination would significantly improve the knowledge and awareness of oral cancer patients. Students themselves can greatly contribute to these efforts through their active participation in specific activities, for example free examinations for early detection of oral cavity cancers organized at the School of Dental Medicine during the Oral Cancer World Awareness Week.

With regard to preventive measures, most students of both years have stated that regular dental examinations, smoking cessation and maintenance of oral hygiene are important preventive measures. Most of the students believed that all regions of the oral cavity should be examined at each examination. In addition to that, they stated that the major lymph nodes of the neck area should be palpated. Almost all the students claimed they would refer a patient with PMDs to oral medicine specialists, which is in line with the results of similar studies (–).

Conclusion

Although the oral cavity is readily available for clinical assessment, a larger proportion of patients are diagnosed with oral cancer at a late stage and some cases remain unidentified. A timely diagnosis provides the greatest chance for cure and long-term survival of the patients. Therefore, it is important that students gain knowledge about PMD of the oral mucosa and their significance in the development of oral cancer during the course of the study as well as to learn clinical criteria to differentiate clinically similar lesions. Furthermore, they need to develop awareness of the need for early detection of PMDs including routine examination of all oral mucosa areas at each dental examination. Our research shows that theoretical knowledge seems to be retained better than practical skills. Therefore, the level of practical clinical skills should be elevated. In the teaching process, communication skills of students should be developed by including them in patient screening and counseling programs.

Inclusion of the students smokers in preventive programs against smoking is important in order to self-correct their attitude towards smoking as a risk factor and advocate smoking cessation as a preventive measure among their future patients as well.