Oral cancer stands as a considerable global health concern, and its occurrence is intricately linked to sociocultural habits, resulting in notable variations in incidence across different regions 19. Epidemiological studies indicate an overall decline in its occurrence, accompanied by a surge in the prevalence of HPV-positive oropharyngeal cancer in recent decades 20,21. Despite these trends, oral cancer remains the predominant malignancy among males in certain Asiatic countries 22.
According to the World Health Organization (WHO), in 2020, Iran reported 1,139 new cases of oral cancer, with an incidence rate of 1.3 per 100,000 individuals, including 532 females and 607 males. Tobacco use among individuals aged 15 and above was prevalent at 14%, with 3.3% in women and 24.7% in men. Per capita alcohol consumption for those aged 15 and above averaged 1 liter per year, with 0.3 liters for women and 1.8 liters for men 23.
The findings of the present study revealed an almost equal sex ratio of 0.99:1 between males and females. This finding contrasts with previous studies in Iran and other countries 4,18,24, which consistently reported a greater percentage of affected males. The higher prevalence among males in previous studies could be attributed to local cultural habits linked to the use of oral carcinogenic agents, particularly higher rates of smoking and alcohol consumption among men compared to women, both in Iran and globally 25–27. Moreover, occupational factors, such as outdoor work, may contribute to increased exposure to carcinogenic elements such as ultraviolet radiation and human papillomavirus among men 28,29. Nevertheless, a discernible decline in the global male-to-female ratio of oral cancer patients has become evident in recent decades. The disparity between earlier studies and our findings could be linked to the increasing tobacco and alcohol consumption among females in recent decades 30 and unique cultural differences specific to the Khorasan Province, where our study was conducted, contributing to a nearly equal prevalence of OSCC between genders.
In our study, the majority of OSCC patients were aged 50 and above, with the most affected age group being the seventh decade of life, consistent with findings from previous studies 4,7,10,18,19,24. Aging is recognized as a contributing factor to OSCC development and is influenced by a complex interplay of factors. Advanced age exposes individuals to heightened risk factors associated with OSCC 31. Additionally, the decrease in natural defense mechanisms in the body with age increases the susceptibility of older individuals to cancer development 32. Moreover, the reduced capacity of the body to repair DNA damage as individuals age may further contribute to the initiation of OSCC 33.
In this study, the tongue emerged as the predominant site for OSCC, consistent with findings from previous investigations in Iran and other countries 4,7,10,18,24. The increased incidence of tongue cancer can be ascribed to the proximity of the tongue to areas often exposed to carcinogens, such as tobacco and alcohol, thereby amplifying the risk of OSCC 4. Furthermore, persistent trauma in the form of prolonged irritation from orthodontic appliances, denture flanges, broken dental restorations, sharp teeth, and the positioning of the mandibular second molar may also be pivotal in the initiation and stimulation of neoplastic progression. Therefore, documenting the recent history of therapeutic procedures performed on patients is meaningful for understanding the potential contributing factors 34. Hence, considering the distribution of oral cancer across various sites, it appears impractical to concentrate solely on preventive and therapeutic strategies for one site. Instead, all sites with the potential for oral cancer should be taken into account. However, recognizing the limitations in resources, particularly within the healthcare system, and the necessity to prioritize therapy and prevention for this cancer, the suggestion is to prioritize the tongue due to its elevated rate of involvement.
Based on histological grades, our study revealed that Grade 1 oral squamous cell carcinoma was the most prevalent (54%), followed by Grade 2 (37.3%) and Grade 3 (2%). This pattern aligns with findings from Ramasamy et al. 35 and Akram et al. 36, who also reported a higher percentage of grade 1 OSCC patients. However, these findings contrast with the results of Madiha et al. 37, who reported a higher percentage of patients with grade 2 OSCC.
Our findings investigating the correlation between OSCC site and sex revealed a significantly higher prevalence of tongue OSCC in females and lip OSCC in males. This finding aligns with a study by Alshami et al. 18, which similarly revealed a significantly higher prevalence of lip OSCC in males, although other sites, including the tongue, showed no significant correlation with sex. Moreover, a comprehensive cohort study by Han et al. 38 in the United States, exclusively assessing the prevalence of lip OSCC, reported a sex ratio of 4:1 between males and females, indicating a significantly greater prevalence of lip OSCC in males. However, the underlying reasons remain unknown. Future epidemiological studies focusing on social and environmental factors among lip SCC patients may provide further insights into the true relationship between sex and the predisposition to lip SCC. Regarding our finding of a significantly higher prevalence of tongue OSCC in females, recent discussions in the literature have highlighted an alarming increase in the incidence of base-of-the-tongue OSCC in recent decades, particularly in women without traditional risk factors such as alcohol or tobacco use 39. This trend is believed to be partially related to the substantial increase in the incidence of HPV-associated oropharyngeal squamous cell carcinoma 40. Ongoing investigations into additional genetic etiologic factors may contribute to explaining this evolving demographic profile of the disease.
Furthermore, our findings indicate a significant occurrence of OSCC in patients aged above 50 years, particularly in the tongue, buccal mucosa, gingiva, and lips. Conversely, other sites showed comparable occurrence across both age groups. However, in the study by Alshami et al. 18, patients older than 40 years had a significantly greater incidence of OSCC in all locations. Regarding the association between histopathological grade and tumor site, all locations except for the lips and palate were found to have a significantly higher proportion of Grade 1 cases. Notably, this correlation has not been previously assessed in the literature.
The strengths of our study include the large number of cases evaluated and the comprehensive examination of various aspects of the disease. Additionally, our study stands out as one of the few to assess cases over a 53-year period, which should be regarded as a notable feature. Despite our efforts to consider risk factors and habits such as tobacco and alcohol consumption, as well as other variables such as prognosis, we omitted data from our analysis due to a lack of information and a significant number of cases with missing data, which could potentially limit our study. Future research should focus on investigating these risk factors and analyzing correlations in different populations to better understand geographical variations in risk factors and disease behaviors.