Cancer is one of the five major causes of death in the world, and in the United States is the second leading cause of death after cardiovascular diseases. It is the third leading cause of death in Iran, with 30,000 deaths each year. ¹ , ² Five percent of all cancers occur in the head and neck, and about half of them occur in the oral cavity. Oral cancer accounts for about 3% of malignancies in the United States and the United Kingdom. ² , ³ The incidence of oral cancer in men varies from 1 to 10/100,000 people in different countries. In Iran, Male to female ratio was ^0.9/ ₁and age average was 53.52 ± 17.66. ⁴ Oral cancer often occurs in patients over 53 years of age. ³

If oral malignancies are not diagnosed in time, the tumor will spread further and organ dysfunction will occur. As a result, the patient experiences more pain and discomfort and the patient's death is not unexpected. ¹ The overall quality of life of people with oral cancer is lower than healthy individuals. ⁵ To reduce mortality and disability following oral cancer, people should be aware of the primary symptoms and risk factors. ⁶ In the past two decades, the prevalence of head-and-neck cancers, including oral and pharynx squamous cell carcinomas (SCCs) had increased. Prevalence increasing especially in young people without the common risk factors, suggests the presence of other factors in the etiology of head-and-neck SCCs. Other etiological factors such as genetics, diet, oncogenic viruses, and their effect on the physiological mechanism of cell proliferation control have been recommended. ⁷

Early diagnosis of oral cancer is the most effective way to improve survival and reduce the complications of the disease. ⁸ However, about 30% of patients refer to specialist 3 months late. ⁹

Horowitz et al. reported 83% of adults knew that excessive alcohol consumption causes cirrhosis of the liver, but only 16% reported alcohol consumption as a risk factor for oral cancer. Hence, American adults have little information about the risk factors for oral cancer and its symptoms. ¹⁰ The results of other studies in different years and regions of the world have shown that public awareness of the causes of oral cancer is low. ¹¹ , ¹² , ¹³ , ¹⁴ In Razavi's et al.'s study, about 80% of patients were unaware of the initial manifestations of oral cancer, and only 18% of them knew the most common areas of involvement. ⁶

According to the results of previous studies and the need for more education and information to the public, the purpose of this study was to determine the level of knowledge of patients referred to dental centers about the symptoms of oral cancer and its risk factors. In this way, the effects of the passage of time and people's access to cyberspace on the level of people's awareness of this issue are determined.

This descriptive-analytical (cross-sectional) study (no: IR.MUI.RESEARCH.REC.1399.773) was approved by the Ethics Committee of Isfahan University of Medical Sciences. A researcher-made questionnaire was used to assess the knowledge of oral cancer in dental patients in Isfahan, Shahinshahr, Najafabad, Khomeini Shahr, Harand, and Zarrinshahr cities in 2020. The first part of the questionnaire was about patients' characteristics (age, gender, occupation, marital status, degree of education, source of information about oral cancer, and history of the death of relatives due to oral cancer). The second part consisted of 25 items on patients' knowledge of the risk factors for oral cancer, signs and symptoms, oral sites with more susceptibility, etc. The two previous studies of Tahani et al. and Razavi et al. were also used to prepare this questionnaire. ⁵ , ⁶ The quantitative and qualitative face and content validity of the questionnaire were assessed. In the qualitative stage of content validity, six professors including three professors of oral and maxillofacial pathology, one oral public health professor, and two professors of oral diseases evaluated the questionnaire. The numerical value of the content validity ratio (CVR) was determined using the Lawshe table. To determine the content validity index (CVI) of each item, six experts were asked to express their opinions on three criteria of simplicity, relevance, and clarity based on a four-point Likert scale. The mean CVI was calculated based on the mean scores of the CVI of all questionnaire items. Finally, the CVI was 0.78, and the CVR was above 0.6. Moreover, the Guttman method was used to measure the reliability of the questionnaire, which was equal to 0.776 in a pilot of 50 patients out of the study. ¹⁵

The study population of the present study included patients referred to dental centers in Isfahan and some cities of Isfahan province in 2020. Data were collected by the multistage sampling method. Five regions of Isfahan province were randomly selected to cover the different geographic parts. Then, from each region, a dental center, including public and private centers, was randomly selected. Eventually, 30 patients were selected by convenience sampling method from any dental center to complete the questionnaire. The sample size was calculated to be 150 patients in Isfahan city and 150 in cities around Isfahan. Patients' knowledge scores below 33.3, between 33.3 and 66.6, and more than 66.6 were considered poor, moderate, and good, respectively.

The data were inserted into SPSS software (version 26, IBM Corp, Armonk, NY, USA). Independent t-test, ANOVA, Pearson and Spearman correlation coefficients were used to analyze the data. P < 0.05 was statistically significant.

This study was conducted to evaluate dental patients' knowledge of oral cancer in 2020. An additional 34 questionnaires were completed. 334 completed questionnaires were obtained. The age range of patients was 13-61 years, with a mean of 32.5 ± 10.4 years. Most of the patients were female (59%, n = 197) and were married (61.1%, n = 204) and had academic education (45.8%, n = 153). Most of the participants (26.3%, n = 88) used virtual networks (Telegram, WhatsApp, and Instagram) to obtain information about oral cancer Table 1. Further, most of them (35.6%, n = 119) were self-employed. Moreover, 20 patients reported a history of the death of relatives due to oral cancer in their families and 18 reported a history of oral cancer among their relatives.{Table 1}

Patients' knowledge scores ranged from 0 to 96, with a mean of 51.3 ± 19.9 out of 100. Therefore, it can be stated that patients' knowledge of oral cancer was at a moderate level. Moreover, 50% (n = 78) of patients in Isfahan and 63.5% (n = 113) of them in the surrounding small cities had moderate knowledge, and no significant difference was observed between them (P = 0.08) Table 2. Taking into account the good knowledge of patients, which accounted for 24.3% (n = 81) of the total population, it can be argued that the dental patients' knowledge of oral cancer in Isfahan province is at a moderate level and higher.{Table 2}

The mean knowledge score was slightly higher in female patients than male patients, but the independent t-test showed no significant difference between them (P = 0.12). Further, the mean knowledge score was not significantly different between single and married patients (P = 0.86).

Spearman correlation coefficient showed a direct correlation between patients' knowledge score and their level of education (P = 0.004, r = 0.161). In other words, with an increase in the patients' level of education, their knowledge scores also increased, but there was no significant relationship between patients' knowledge score and their ages (P = 0.93, r = 0.005).

ANOVA test showed a significant relationship between patients' knowledge score and their jobs (P = 0.03), and the highest score was related to the retired patients. The independent t-test showed that patients who obtained oral cancer information from the medical team (P = 0.001), virtual networks (P = 0.004), and other sources (journals and books) (P = 0.04) had a higher mean score of knowledge Table 3. The independent t-test showed that patients with a history of oral cancer among their relatives had significantly higher knowledge than other patients (P = 0.03). 73.1% of the participants were aware of the lack of relation between surgery and biopsy with malignancy and metastasis but a few percent of them (15.6%) were aware of the importance of rapid detection of lesions in the success of the treatment.{Table 3}

The patients' knowledge of oral cancer was at a moderate level. A significant percentage of the participants did not know about the risk factors and even the prevention and diagnosis methods. Despite the lack of access of patients living in small cities to the advanced facilities of the provincial capital, their level of knowledge about oral cancer was not significantly different compared to patients living in Isfahan. Most of the patients obtained information from social networks such as Telegram, WhatsApp, and Instagram. In the study of Kakoei et al. the participants' mean score of knowledge about the causes of oral cancer was 6 out of 15, and their mean score of knowledge about the symptoms of it was 2 out of 6, ¹⁶ which is lower than those of the present study. Lack of access to the Internet and virtual media can be one of the reasons for such differences between these studies. In another study conducted by Razavi et al. the patients in Isfahan had poor knowledge of oral cancer. ⁶ Ease of access to the Internet and the use of software such as WhatsApp and Instagram, which has increased significantly in recent years, can be the reason for this difference. The results of the present study are in contrast with those of Razavi et al. and Kakoei et al. ⁶ , ¹⁶ In their research in 2016, Shaeeb et al. reported that the average knowledge about oral cancer was not at an appropriate level. They examined the knowledge of oral cancer in the clients of Shahid Beheshti Dental School and showed that their knowledge score was 36.1 out of 100. Therefore, the results of the present study are not in line with those Shaeeb et al. ¹⁷ Zolfaghari et al. indicated that 66.6% of citizens in Tehran had poor knowledge and 9% of them had good knowledge of the warning signs of cancer. ¹⁸ In 2018, Shimpi et al. reported that the level of knowledge of patients referring to dentistry was 40%, which is less than the level reported in the present study. ¹⁹ The results of the present study are in contrast with those of Zolfaghari et al. and Shimpi et al. ¹⁸ , ¹⁹ Hertrampf et al. showed that poor knowledge was associated with poor socioeconomic factors, and patients did not have good knowledge of oral cancer. ²⁰ Awojobi et al. reported that 20% of respondents had never heard of oral cancer and 77% had little information about oral cancer. ²¹ Srikanth Reddy et al. also indicated that a small percentage of respondents had information about oral cancer. ²²

One of the important factors in patients' awareness is their level of academic education. Al-Maweri et al. reported participants with lower academic education had less knowledge than the others. ²³ In the present study, most of the participants had an academic education, which may be a reason for their increased knowledge compared to previous studies. Kakoei et al. reported that the knowledge of risk factors was significantly higher only in people with education higher than a high school diploma than those with lower literacy. ¹⁶ In the present study, a significant difference was observed between the level of education and the level of knowledge, as people with higher education had a higher level of knowledge.

Another factor influencing the patients' knowledge of oral cancer symptoms is their jobs so that the retired patients had a higher level of knowledge, which may be because these people have more free time to obtain information and use virtual networks and programs. Patients' gender, marital status, as well as residence (Isfahan and other cities in the province) did not affect their knowledge. Moreover, in terms of sources of information about oral cancer, most patients used virtual networks (Telegram, WhatsApp, and Instagram), and the medical team was introduced as the last source of information. In the study of Jafari and Naseri, dentists were introduced as the first source of information for patients. ²⁴ Therefore, the results of the present study are inconsistent with the findings of Jafari and Naseri, Peker and Alkurt, Nagarajappa et al., and Babiker et al. reported radio and television were the first sources of information, and dentists were the last source of information about oral cancer for patients. ²⁴ , ²⁵ , ²⁶ , ²⁷

The results obtained in foreign studies and the contradictory results in the present study can be due to the lack of educational content in Iranian radio and television programs. In contrast, the content of radio and television programs is richer in terms of educational, cultural, and health programs in some other countries than in Iran. Social networks and their information delivery have become more and more popular in the world over the past few years so that people can easily access whatever they want via a mobile phone. Numerous specialists, doctors, and dentists are also seriously involved in this process, and their social media pages can be accessed by a simple search. Therefore, ways of receiving information by patients have changed in recent in the past 5 years, which can justify the results of Peker and Alkurt, Nagarajappa et al. and Babiker et al. ²⁵ , ²⁶ , ²⁷ Considering the positive role of education through medical staff and radio and television programs in raising the awareness of people about the correct beliefs about diseases such as oral cancer, it seems that more active involvement of doctors and radio and television in this regard will be very useful.

Based on the results obtained in the present study, it can be argued that dental patients in Isfahan have moderate and relatively desirable knowledge about oral cancer. Because most patients receive their information from social networks, and in most cases, the accuracy of the content in these databases is under question in terms of credibility and citation sources, it is necessary to optimize social channels and provide better and more useful information in this regard. SCC is the most common oral and maxillofacial cancer, and it is necessary to increase people's awareness of its primary symptoms and risk factors. ²⁸ It can be done through social networks and virtual media and physicians and dentists should always consider oral examination in terms of suspicious lesions.

Dental patients have moderate knowledge of oral cancer in Isfahan and the surrounding cities, but they need more education to increase their awareness. In addition, it is highly important to enhance people's knowledge through virtual education or radio and television training programs.

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Conflicts of interest

The authors of this manuscript declare that they have no conflicts of interest, real or perceived, financial or non-financial in this article.

Questionnaire 1: The questionnaire about dental patients' knowledge of oral cancer in Isfahan

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