
==== Front
Discov Oncol
Discov Oncol
Discover Oncology
2730-6011
Springer US New York

39289291
1351
10.1007/s12672-024-01351-z
Research
Comprehensive analysis of clinicopathological characteristics in oral squamous cell carcinoma arising from oral submucous fibrosis: a retrospective study
Zeng Yiyu
Luo Jinyu
Zi Moxin
Jiang Shanshan
Ge Wenhui
Yu Yi
Chen Niya
Lin Jiaming
Xie Xiaoyan xyxie@csu.edu.cn

grid.452708.c 0000 0004 1803 0208 Department of Stomatology, The Second Xiangya Hospital, Central South University, 139 Renmin Middle Road, Changsha, 410011 People’s Republic of China
17 9 2024
17 9 2024
12 2024
15 45510 4 2024
13 9 2024
© The Author(s) 2024
2024
https://creativecommons.org/licenses/by-nc-nd/4.0/ Open Access This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if you modified the licensed material. You do not have permission under this licence to share adapted material derived from this article or parts of it. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by-nc-nd/4.0/.
Background

Oral squamous cell carcinoma arising from oral submucous fibrosis is recognized as a clinicopathologically distinct disease. This study aims to summarize and compare the population and clinicopathologic characteristics of OSCC-OSF with other OSCC in Hunan Province, China. The objective is to formulate treatment strategies more in line with regional characteristics.

Methods

A retrospective review of OSCC cases recruited from the Second Xiangya Hospital from 2010 to 2020 was conducted. A total of 1,413 OSCC patients were selected, including 481 patients with OSCC-OSF and 932 were other OSCC. Population characteristics, risk factors and clinicopathological manifestations were explored in OSCC-OSF and other OSCC, as well as thinprep cytologic test and DNA quantification.

Results

We found that OSCC-OSF patients were younger than those with other OSCC. Both types of disease were predominantly observed in males compared to females. Tumor biopsy analysis indicated that tumor cells within OSCC-OSF patients were more likely to be well differentiated and showed a higher frequency of lymph node metastases. Clinicopathological factors, such as the chewing betel nuts habit and smoking, were more prevalent in OSCC-OSF patients in contrast to other OSCC. DNA quantification revealed that the number of DNA aneuploid cells was higher in OSCC-OSF compared to other OSCCs.

Conclusion

In this study, OSCC-OSF is considered a clinicopathologically distinct disease. Compared with other OSCC, OSCC-OSF patients have a higher incidence of nodal metastases, an early clinical TNM stage, and a lower three-year survival rate. Therefore, early diagnosis and treatment are crucial to improving the prognosis of OSCC-OSF.

Keywords

Oral squamous cell carcinoma
Oral submucous fibrosis
Clinicopathological characteristics
Comparative analysis
Epidemiology
Fund of Hunan Provincial Health Commission20231422 Xie Xiaoyan issue-copyright-statement© Springer Science+Business Media, LLC 2024
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pmcIntroduction

Oral squamous cell carcinoma (OSCC) is the most common malignancy arising from the head and neck, considered the leading cause of death from oral diseases in many countries [1, 2]. Recent estimates of global cancer statistics show 58,450 new cases and 12,230 deaths in 2024 [3]. However, OSCC may arise from pre-existing oral lesions, such as oral submucous fibrosis (OSF), lichen planus [4], and oral leukoplakia [5, 6]. These are collectively referred to as oral potentially malignant disorders. The most common among these is OSF.

OSF has traditionally been described as a chronic, insidious, scarring disease of the oral cavity which has affected millions of individuals, especially in South and Southeast Asian countries7, 8. It has been presented as a common oral precancerous lesion in Asian countries in recent years. Since the malignant potential of OSF was first described in 1956 [9], the malignant transformation of OSF has become a hot topic of interest among dentists. A study showed that the malignant transformation rate of OSF was approximately 6% [10], indicating that the malignant potential of OSF might be underestimated.

Increasing studies are attempted to identify the difference between OSCC arising from OSF and other OSCC [11, 12]. The aim of this study is to explore the occurrence and development of OSF carcinogenesis. A prospective observational study has, for the first time, reported that areca nut-induced or supported OSCC is a clinicopathologically distinct disease [11]. Areca nut follows a unique molecular pathway in carcinogenesis, leading to distinct morphology, histology, and biology in patients with OSCC-OSF compared to those with OSCC alone. Patients with oral cancer accompanied by OSF are clinicopathologically different from those without OSF [13].

Specifically, 74% of patients with OSCC-OSF presented in early stages (pT1 and pT2), whereas nearly half (47.49%) of OSCC patients without OSF presented in advanced stages (pT3 and pT4). Additionally, OSCC tumors in OSF patients were less likely to be poorly differentiated compared to those in non-OSF OSCC patients (30.5% vs. 13.4%). The development of OSF varies by race and region and is closely linked to dietary habits [14]. However, the clinicopathological features of OSCC from different etiological sources do not show significant differences. Stimulation with high levels of arecoline, a component of areca nut, can induce elevated levels of reactive oxygen species (ROS) and lysyl oxidase (LOX) activity in cells, leading to DNA damage [15]. Consequently, betel nut chewing remains one of the most significant risk factors for OSF. In China, 62.3–99.85% of OSF patients report a history of betel nut chewing [16], with a notably higher prevalence in males compared to females. Unfortunately, targeted clinical treatments for OSCC-OSF and other forms of OSCC are currently lacking, highlighting the urgent need for effective therapies for this malignancy.

Betel nut chewing is a deeply ingrained cultural practice in Hunan Province, significantly contributing to the high incidence of OSF and OSCC [17]. The prevalence of these conditions in Hunan is comparable to regions like India, Taiwan, and Hainan, where betel nut use is similarly widespread [18]. Existing studies have explored the pathological features of OSCC, including the morphology of microvessels and lymphatic vessels in tissues surrounding OSCC-OSF. However, despite these pathological insights, there remains a critical gap in clinical evidence specific to OSCC patients in Hunan Province.

Studying OSCC in this population is of paramount importance for several reasons. First, the unique sociocultural context of Hunan, coupled with environmental and dietary factors, may influence the pathogenesis and progression of OSCC in ways that are not fully understood. This makes it essential to investigate OSCC in a local context, as findings from other regions may not be fully applicable. By focusing on Hunan's population, researchers can identify region-specific risk factors, disease patterns, and potential biomarkers that are crucial for early diagnosis and targeted interventions. Second, Hunan Province presents a unique opportunity to study OSCC in a population with a high prevalence of betel nut chewing, a known carcinogenic practice. The findings from such studies could contribute significantly to global knowledge on how areca nut consumption drives carcinogenesis. This could lead to the identification of molecular and genetic pathways unique to OSCC-OSF, paving the way for novel therapeutic targets and personalized treatment approaches. Furthermore, the impact of this research could extend beyond Hunan. As betel nut consumption continues to rise globally, understanding its role in OSCC development is increasingly relevant for public health. Insights gained from studying OSCC in Hunan could inform prevention strategies, policy changes, and health education campaigns in other regions facing similar challenges. Additionally, this research could help to standardize clinical practices and improve outcomes for OSCC patients by integrating local epidemiological data into broader treatment protocols. Finally, the urgency of addressing OSCC in Hunan is underscored by the lack of effective clinical treatments for OSCC-OSF and OSCC in general. By investigating the clinicopathological characteristics of OSCC in this region, researchers can contribute to the development of more efficient treatment strategies, ultimately improving patient survival rates and quality of life. Thus, the study of OSCC in Hunan Province is not just a local priority but a global imperative. The insights gained could lead to groundbreaking advancements in understanding, preventing, and treating this aggressive cancer, benefiting patients both within Hunan and beyond.

The aim of this study was to comprehensively investigate the impact of OSF on the clinicopathological manifestations of OSCC. Specifically, we focused on the population in Hunan Province to assess how OSF influences the characteristics and clinical outcomes of OSCC in this region. The findings from our study may offer valuable insights that could guide the development of more effective therapeutic strategies for OSCC, particularly in populations with a high prevalence of OSF. In addition to clinical implications, the data generated from this research could also inform public health policies. By identifying key risk factors and patterns associated with OSF-related OSCC, our study may support the creation of targeted prevention programs and awareness campaigns aimed at reducing betel nut consumption and its associated risks. This may lead to policy changes that address the underlying causes of OSCC in high-risk populations, ultimately improving both prevention and treatment efforts.

Methods and materials

Data source

To ensure a comprehensive representation of OSCC patients, a total of 1,413 cases diagnosed with OSCC based on clinicopathological criteria were recruited from the Second Xiangya Hospital between 2010 and 2020. These patients were hospitalized in the Oral and Maxillofacial Surgery Department. Among them, 481 cases were identified as OSCC arising from OSF, while the remaining 932 cases were other forms of OSCC. The sample size was determined based on several factors, including the study objectives, expected effect size, and the need for statistical significance. Specifically, the sample size calculation considered the expected differences in clinicopathological features between OSCC arising from OSF and other OSCC types, with a significance level (α) of 0.05 and a power (1-β) of 80%. Additionally, adjustments were made to account for potential data loss, ensuring that the study remains adequately powered. Thus, this study requires a minimum of 374 OSCC cases arising from OSF. To enhance the study's robustness, we aimed to recruit as many samples as possible during the specified period.

Definitions and standards

All cases included in this study were pathologically diagnosed as OSCC. OSF is defined as the presence of pale or gray mucosal lesions in the mouth, with scar-like fibrous cords that may be palpable, and restricted mouth opening in severe cases (pale or gray areas in the oral mucosa, strand-like scars, restricted mouth opening) [19].

Betel nut chewing is defined as chewing betel nut at least once per day for more than 3 months. Smoking is defined as smoking continuously or cumulatively for 6 months or more over a lifetime. Drinking is defined as consuming alcohol at least once per week for more than 1 year.

Inclusion and exclusion criteria

Inclusion criteria (1) Preoperative or intraoperative histopathological examination was diagnosed as OSCC; (2) Patients with OSCC are resident in Hunan Province; (3) Patients have detailed medical history and complete physical examination.

Exclusion criteria (1) Non-Hunanese (2) Incomplete medical history data; (3) No pathological diagnosis report or incomplete pathological diagnosis report. The selected pathological type in this study was OSCC, and other pathological types were excluded.

Thinprep cytologic test (TCT) and quantitative DNA analysis

Exfoliated cells from the surface of the diseased tissue were collected using a cotton swab for smear preparation. Subsequently, stained samples underwent microscopic examination and quantitative DNA analysis.

Statistical analysis

We utilized three main statistical methods in this study: the Mann–Whitney U test, Kruskal–Wallis test, and chi-square test. Patient demographic data were summarized as total numbers and percentages, with all parameters tabulated and analyzed. Specifically, the Mann–Whitney U test was applied to compare non-parametric data between two independent groups, while the Kruskal–Wallis test was used to assess differences across multiple groups for non-parametric data. The chi-square test (χ2) was employed to evaluate associations between categorical variables and to determine the statistical significance of differences between the three groups. A p-value of less than 0.05 was considered statistically significant for all analyses. The level of statistical significance was set at 0.05 for all tests.

Survival analysis was performed using the Kaplan–Meier method to compare survival times between OSCC-OSF patients and other OSCC patients. Statistical analysis was conducted using SPSS version 23.0.

Results

Clinicopathological characteristic of OSCC-OSF and other OSCC

This study included 1,413 patients diagnosed with OSCC. Of these, 932 (65.9%) had OSCC without OSF, while 481 (34.0%) had OSCC with OSF (OSCC-OSF). The cohort exhibited a higher prevalence of males, with a male-to-female ratio of 8.81:1. Patients' ages ranged from 19 to 87 years, with an average age of 50.4 years. The majority of patients (70.7%, 999/1,413) were between 40 and 60 years old.

The study included cases from 13 prefecture-level cities and one autonomous prefecture in Hunan Province, with 74.3% (1,051/1,413) of patients concentrated around Dong-ting Lake. In terms of tumor differentiation, 76.2% (n = 1,077) of cases were well-differentiated, 14.5% (n = 206) were moderately differentiated, and 9.2% (n = 130) were poorly differentiated.

As shown in Table 1, there are statistically significant differences (p < 0.05) between patient sex and characteristics of OSCC. OSCC-OSF patients are predominantly male, with a male-to-female ratio of 11.66:1, compared to other OSCC patients who have a male-to-female ratio of 7.79:1. No significant differences were observed between the two groups in terms of age, region, or disease site. However, OSCC-OSF patients are slightly younger on average (50.7 years) compared to other OSCC patients (50.0 years). A significantly higher proportion of other OSCC cases were found on the tongue, whereas the distribution between the tongue and buccal mucosa is relatively balanced in OSCC-OSF cases. OSCC-OSF patients are more likely to have well-differentiated tumors compared to other OSCC patients (p = 0.02) and higher in lymph node metastases (p = 0.16). Additionally, OSCC-OSF cases are more frequently diagnosed at an early stage (pT1 and pT2) with 71.4%, compared to 61.7% in other OSCC cases (p = 0.0007).Table 1 Comparative analyses of clinicopathological characteristics between OSCC–OSF and other OSCC

Parameters assessed	OSCC-OSF (%)	Other OSCC (%)	p value	
Sex	
 Male	443 (92.0)	826 (88.6)	0.041	
 Female	38 (7.9)	106 (11.3)	
Age	
 < 40	66 (13.7)	114 (12.2)	0.103	
 40–60	349 (72.5)	650 (69.7)	
 > 60	66 (13.7)	168 (18.0)	
Region	
 Around Dong-ting Lake	356 (74.0)	695 (74.5)	0.582	
 Xiangxi area	74 (15.3)	132 (14.1)	
 Shonan area	51 (10.6)	105 (11.2)	
Disease site	
 Tongue	233 (48.4)	593 (63.6)	0.101	
 Buccal mucosa	209 (43.4)	243 (26.0)	
 Gingiva	15 (3.1)	33 (3.5)	
 Palate	10 (2.0)	22 (2.3)	
 Mouth floor	11 (2.2)	32 (3.4)	
 Lip	3 (0.6)	9 (0.9)	
Differentiation	
 Well-differentiated	387 (80.4)	690 (74.0)	0.020	
 Moderately-differentiated	61 (12.6)	145 (15.5)	
 Poorly-differentiated	33 (6.8)	97 (10.4)	
Classification (pT)	
 T1	151 (31.3)	279 (29.9)	0.0007	
 T2	193 (40.1)	297 (31.8)	
 T3	41 (8.5)	84 (9.0)	
 T4	96 (19.9)	272 (29.1)	
Lymph node metastasis	
 N0	338 (70.2)	672 (72.1)	0.160	
 Nx	143 (29.7)	260 (27.8)	
Adverse habit	
 Chewing betel nut	
Yes	441 (91.6)	617 (66.2)		
No	40 (8.3)	315 (33.7)	< 0.0001	
Smoking	
Yes	412 (85.6)	667 (71.5)		
No	69 (14.3)	267 (28.4)	0.027	
Drinking	
Yes	379 (78.7)	607 (65.1)		
No	90 (21.2)	325 (34.8)	0.759	

Significant differences were observed in adverse habits: betel nut chewing (p < 0.0001) and smoking (p = 0.027). These findings align with previous evidence indicating that OSCC-OSF patients have higher rates of betel nut chewing and smoking history.

Clinicopathological Associations of Adverse Habits in OSCC

To further elucidate the clinicopathological significance of three adverse habits in OSCC, their associations with other parameters were investigated. As shown in Table 2, these habits including chewing betel nut (p < 0.0001), smoking (p < 0.0001), and drinking (p < 0.0001), showed a significant correlation with patients' sex. These adverse habits were notably more prevalent among male patients compared to female patients. Moreover, there was a significant positive correlation between age and the habits of chewing betel nuts (p < 0.0001) and smoking (p < 0.0001). Across three regional groups, there was a consistent observation of these habits, indicating their widespread distribution among patients (p > 0.05). Furthermore, patients who chewed betel nuts were more likely to have well-differentiated tumors (p = 0.008).Table 2 The adverse habits of OSCC patients in various groups

	Chewing betel nut	Smoking	Drinking	
Yes	No	Yes	No	Yes	No	
Sex	
 Male	1000 (78.8)	269 (21.2)	1033 (81.4)	236 (18.6)	945 (74.5)	324 (25.5)	
 Female	58 (40.2)	86 (59.8)	46 (31.9)	98 (68.0)	41 (28.4)	103 (71.5)	
 p value	p < 0.0001	p < 0.0001	p < 0.0001	
Age	
 < 40	157 (87.2)	23 (12.7)	142 (78.8)	38 (21.1)	130 (72.2)	50 (27.7)	
 40–60	785 (78.5)	214 (21.4)	784 (78.4)	215 (21.5)	703 (70.3)	296 (29.6)	
 > 60	116 (49.5)	118 (50.4)	154 (65.8)	80 (34.1)	153 (65.3)	81 (34.6)	
 p value	p < 0.0001	p < 0.0001	0.245	
Region	
 Around Dong-ting Lake	784 (74.5)	267 (25.4)	793 (75.4)	258 (24.5)	731 (69.5)	320 (30.4)	
 Xiangxi area	156 (75.7)	50 (24.2)	164 (79.6)	42 (20.3)	143 (69.4)	63 (30.5)	
 Shonan area	118 (75.6)	38 (24.3)	122 (78.2)	34 (21.7)	112 (71.7)	44 (28.2)	
 p value	0.918	0.371	0.844	
Differentiation	
 Well	828 (76.8)	249 (23.1)	832 (77.2)	245 (22.7)	747 (69.3)	330 (30.6)	
 Moderately	143 (69.4)	63 (30.4)	154 (74.7)	52 (25.2)	153 (74.2)	53 (25.7)	
 Poorly	87 (66.9)	43 (33.0)	93 (71.5)	37 (28.4)	86 (66.1)	44 (33.8)	
 p value	0.008	0.195	0.687	

Duration of adverse habits in OSCC patients

Regarding the duration of betel nut chewing, smoking, and drinking among OSCC patients, Table 3 shows that the majority of the 1,413 patients had been chewing betel nuts for over 6 years (84.5%). Additionally, our observations indicate that a significant proportion of OSCC patients in Hunan Province have extended histories of both smoking and drinking.Table 3 The duration of chewing betel nut, smoking, and drinking habits

Variables	Number of cases	Percentage	
Chewing betel nut	
 < 6 years	163	15.4	
 6–15 years	466	44.0	
 > 15 years	429	40.5	
Smoking	
 < 10 years	112	10.4	
 10–19 years	243	22.5	
 > 19 years	724	67.1	
Drinking	
 < 20 years	396	40.2	
 ≥ 20 years	590	59.8	

Analysis of disease sites of OSCC

We then examined the influence of various parameters on the site of OSCC. In Table 4,among the 1,413 patients included in our study, the distribution of cancer sites was as follows: tongue cancer (n = 826) at 58.4%, buccal cancer (n = 452) at 31.9%, gingival cancer (n = 48) at 3.3%, palate cancer (n = 32) at 2.2%, carcinoma of the mouth floor (n = 43) at 3.0%, and lip cancer (n = 12) at 0.8%. Notably, our findings indicate that the tongue is the most prevalent site for OSCC across all age groups, followed by the buccal mucosa.Table 4 Analyses of disease site in OSCC

	Tongue	Buccal mucosa	Gingiva	Palatine	Mouth floor	Lip	P value	
Sex	
Male							0.009	
 < 40	109

(63.4)

	56

(32.6)

	2 (1.2)	3 (1.7)	2 (1.2)	0 (0.0)	
40–60	524

(58.4)

	300

(33.4)

	31 (3.5)	13 (1.4)	26 (2.9)	4 (0.4)	
 > 60	118

(59.3)

	57

(28.6)

	4 (2.0)	8 (4.0)	9 (4.5)	3 (1.5)	
Total	751

(59.2)

	413

(32.5)

	37 (2.9)	24 (1.9)	37 (2.9)	7 (0.5)	
Female	
 < 40	5 (62.5)	0 (0.0)	1 (12.5)	0 (0.0)	2 (25.0)	0 (0.0)	
40–60	54 (53.5)	28 (27.7)	8 (7.9)	4 (4.0)	3 (2.9)	4 (4.0)	
 > 60	16 (45.7)	11 (31.4)	2 (5.7)	4 (11.4)	1 (2.9)	1 (2.9)	
Total	75 (52.0)	39 (27.0)	11 (7.6)	8 (5.5)	6 (4.1)	5 (3.4)	
Adverse habits	
Chewing betel nut	
 Yes	633 (59.9)	350 (34.1)	23 (2.2)	14 (1.3)	19 (1.8)	5 (0.4)	0.001	
 No	193 (56.5)	87 (26.4)	18 (5.4)	14 (4.2)	20 (6.0)	4 (1.2)	
Smoking	
 Yes	604 (57.7)	351 (33.5)	33 (3.1)	19 (1.8)	33 (3.1)	6 (0.5)	0.373	
 No	197 (63.7)	86

(27.8)

	8 (2.5)	9 (2.9)	6 (1.9)	3 (0.9)	
Drinking	
 Yes	558 (58.0)	321 (33.4)	29 (3.0)	18 (1.8)	30 (3.1)	5 (0.5)	0.354	
 No	243 (61.6)	116

(29.4)

	12 (3.0)	10 (2.5)	9 (2.2)	4 (1.0)	
Simultaneously	417 (59.6)	241 (34.4)	16 (2.2)	9 (1.2)	15 (2.1)	1 (0.1)	

In comparison to the female group, a higher proportion of cases involving the tongue and buccal mucosa was noted in the male group (p = 0.009). Additionally, we identified significant correlations between chewing betel nut and the disease sites of OSCC (p = 0.001). We observed a significant increase in the proportion of OSCC in the tongue and buccal mucosa when patients had the habit of chewing betel nut. Furthermore, there were 699 cases where individuals engaged in the simultaneous habits of betel nut chewing, smoking, and drinking—comprising 682 males and 17 females. Notably, the average age of this group was found to be 50.0 years old, suggesting that the interaction of these three adverse habits might contribute to an advanced age of tumor development.

Collectively, these results suggest that sex and adverse habit such as chewing betel nut have clinical significance in determining the disease sites among patients with OSCC.

TCT and DNA quantitative analysis of patients with OSCC-OSF and other OSCC

We conducted TCT and DNA quantification in patients with OSCC-OSF and compared the results with those from other OSCC patients. As depicted in Fig. 1A-B, the number of DNA aneuploid cells in OSCC-OSF is higher than that in other OSCC cases (3.73% vs 0.32%).Fig. 1 The DNA aneuploid analysis and survival analysis of OSCC-OSF and other OSCC. A OSCC-OSF; B other OSCC; C Kaplan–Meier analysis

Kaplan–Meier analysis

We delved deeper into the survival outcomes of patients with OSCC-OSF compared to those with other forms of OSCC. Kaplan–Meier survival analysis was conducted to assess the prognostic relationship between the presence of OSF and overall survival. As illustrated in Fig. 1C, the Kaplan–Meier survival analysis indicated a lower 3-year survival rate in the OSCC-OSF group compared to the OSCC group. The mean survival time for OSCC-OSF patients was 33.6 months, while for other OSCC patients, it was 34.2 months. However, this difference did not reach statistical significance (p > 0.05).

Discussion

Oral squamous cell carcinoma (OSCC) originating from oral submucous fibrosis (OSF) is now recognized as a distinct clinicopathological entity, with differences attributed to the unique mechanisms of betel nut carcinogenesis[20]. Importantly, understanding the malignant transformation process may contribute to the early diagnosis of OSCC arising from OSF. In Hunan Province, one of the regions with the highest incidences of oral cancer and oral submucous fibrosis globally, the prevalence of chewing betel nuts is a significant contributing factor. Therefore, it is crucial to analyze relevant population characteristics and clinicopathological features in OSCC patients in this region. This study aims to provide a comprehensive summary of the clinicopathological characterization of OSCC arising from OSF in Hunan Province. Our data reveal distinct clinicopathological features in patients with OSCC-OSF. In a prospective study encompassing 371 patients diagnosed with OSCC confirmed by microscopy, it was reported that around 30% of patients had a history of OSF[13]. Consistent with these findings, our study reveals that 34% of oral squamous cell carcinoma patients exhibit a coexisting history of OSF.

In this study, we observed a higher prevalence of OSCC-OSF and other forms of OSCC in male patients, a trend consistent with findings in other studies. This male predominance can be primarily attributed to the higher prevalence of adverse habits among males such as drinking and chewing betel nut[21]. The collected data indicates that the average age of the 1,413 patients with oral squamous cell carcinoma is 50.4 years, with the majority falling within the 40–60 years age range, aligning with results reported by Su CC [22]. Notably, the mean age of OSCC-OSF is slightly younger (50.0 vs 50.6 years) than those of OSCC, suggesting that the progression from OSF to OSCC may occur at a younger age. The incidence of tongue cancer, as reported by Li et al. in 2015 [23], has shown an increasing trend in the younger population. Our study supports these findings, revealing a higher incidence of tongue cancer in the < 40 years old age group compared to the other two age groups.

It is widely acknowledged that the habit of chewing betel nut, smoking, and drinking play a pivotal role in the carcinogenesis and progression of tumors including OSCC [24]. In Taiwan, a high percentage (85.4–100%) of OSF patients are reported to have the habit of chewing betel nut [25]. In our study, there was a significantly higher incidence of chewing betel nut in the OSCC-OSF group compared to the other OSCC group (p < 0.05). Similarly, a statistically significant difference was observed between the smoking and non-smoking groups. Studies have consistently demonstrated a close association between the occurrence of head and neck tumors and long-term exposure to risk factors such as smoking and alcohol consumption [26, 27]. Among patients with squamous cell carcinoma, 429 individuals had a history of chewing betel quid for more than 15 years, 724 patients had a smoking history of more than 20 years, and 590 patients had a history of alcohol consumption for more than 20 years.

The study results reveal a significant difference in disease site between the chewing betel nut group and the non-chewing group (p = 0.029). Betel nut chewers exhibited a significantly higher composition ratio of tongue and buccal mucosa, accounting for 94.0% of the total cases. Existing literature suggests that the hazard ratio of tongue lesions is 1.87 times higher than that of buccal lesions [28]. In addition, a multifactorial analysis [29] found that there was a significant correlation between cancer site and chewing betel nut habit, and the disease site in OSCC patients with betel nut chewing habit were mainly in the buccal mucosa and tongue, while those without betel nut chewing habit were mainly in the tongue. This may be attributed to the repetitive chewing motion involved in the process of betel nut consumption. Additionally, the physical damage inflicted on the buccal and tongue mucosa by the coarse fiber of betel nut, coupled with the chemical damage caused by betel nut alkali, collectively contribute to the development of chronic inflammation in the buccal and tongue mucosa. Over the long term, the combined effects of these factors progress from chronic inflammation to precancerous lesions, ultimately leading to the onset of oral cancer. In our study, when OSCC patients exhibited all three adverse habits simultaneously, the distribution of the disease site resembled that of patients with the singular chewing betel nut habit. This suggests that betel nut chewing may play a predominant role in the pathogenesis of oral squamous cell carcinoma. Further research is warranted to delve into the specific mechanisms underlying this association.

The standard treatment for OSCC typically involves the surgical excision of the primary tumor, with or without lymph node dissection [30]. The study has demonstrated that a significant proportion of cancer-related deaths and treatment failures in cancer patients are not primarily attributed to the primary tumor but rather to the migration and invasion of cancer cells [31]. Despite the implementation of comprehensive therapeutic strategies, there is still a need for further improvement in the long-term survival rate of OSCC patients with lymph node metastasis [32]. Therefore, it is imperative to investigate the differences in lymph node metastasis between OSCC-OSF and other forms of OSCC. In this study, while no statistical difference between the two groups was observed, lymph node metastasis (LNM) was predominantly observed in OSCC-OSF compared to other OSCC. This finding contrasts with a previous report that indicated a significantly higher incidence of LNM in OSCC[33]. These findings suggest that OSCC-OSF cases in Hunan Province may have a higher tendency for lymph node involvement compared to other OSCC cases, though further research is needed to confirm this observation.

DNA aneuploidy serves as an early marker of oral carcinogenesis and can contribute to the progression of cancer [34]. It is prevalent in most cancer cells and is defined as the gain or loss of chromosomes. The study revealed a significant correlation between DNA aneuploidy and lymph-node metastases [35]. Our findings further indicate that OSCC-OSF is associated with a high metastatic risk and exhibits aggressive behaviors.

In this study, we observed a slightly higher three-year survival rate in patients with other forms of OSCC (90.1%) compared to those with OSCC-OSF (88.5%), although the difference was not statistically significant. This trend may suggest that increased rates of nodal metastases are associated with shorter survival times in OSCC-OSF patients. One possible explanation for the lack of significance could be the heterogeneity within our patient population, which may have introduced variability not fully accounted for in our models. Additionally, the small sample size in the OSCC-OSF group may have diluted the observed differences. Future studies with larger and more homogeneous cohorts could provide clearer insights into these relationships. In contrast, other research has reported that OSCC-OSF patients have a lower likelihood of cervical metastasis, which is associated with a better prognosis and survival rate [33]. The high prevalence of OSF in Hunan may contribute to a lack of early-stage diagnosis, leading to patients seeking treatment only in more advanced stages. As OSF progresses and transforms into cancer, the increased incidence of lymph node metastases could account for the observed decrease in the three-year survival rate.

We acknowledge several limitations in our study. First, the reliance on retrospective data may introduce biases due to potential inaccuracies in historical records and incomplete data. Second, our cross-sectional design limits our ability to establish causality between adverse habits and OSCC and OSCC-OSF outcomes. Additionally, the generalizability of our findings may be constrained by the specific demographic and geographic characteristics of our patient cohort. Future research should address these limitations by using longitudinal designs to better understand causal relationships and enhance the applicability of findings. To advance our understanding of the link between adverse habits and OSCC-OSF, future studies should focus on longitudinal research to track disease progression over time, increase sample sizes for more robust analyses, and include diverse populations to improve generalizability. Mechanistic studies should explore biological pathways linking adverse habits with OSCC-OSF, and intervention trials should investigate strategies to reduce the prevalence of harmful habits such as betel nut chewing, smoking, and drinking. These approaches will help develop more targeted strategies for OSCC-OSF prevention and management.

Conclusions

In summary, the results of this study indicate that OSCC-OSF predominantly affects younger males and exhibits a better grade of tumor differentiation. These findings collectively support the consideration of OSCC-OSF as a clinicopathologically distinct disease. Notably, this patient group shows a higher incidence of nodal metastases and a lower three-year survival rate. Consequently, there is a need to explore more aggressive treatment strategies specifically tailored for OSCC-OSF.

Abbreviations

OSCC Oral squamous cell carcinoma

OSF : Oral submucous fibrosis

OS : Overall survival

TCT : Thinprep Cytologic Test

ROS : Reactive oxygen species

LOX : lysyl oxidase

Author contributions

Conceptualization and design: X.X. Data acquisition: YZ, JL, MZ, SJ, WG, YY, NC, and XJL. Methodology: YZ, JL, MZ, and SJ. Data analysis and interpretation: YZ, JL, MZ. Writing (original draft): YZ and JL. Writing (review and editing): X.X. All authors contributed to the article and approved the submitted version.

Funding

This study was supported by the Fund of Hunan Provincial Health Commission (20231422).

Data availability

The datasets used and/or analyzed during the present study are available from the corresponding author on reasonable request.

Declarations

Ethics approval and consent to participate

The study protocol was approved by the Ethics Committie of the Second Xiangya Hospital, Central South University, China (Project No: S408) and supported by Hunan Provincial Health Commission Fund and conducted in line with the principles of the Declaration of Helsinki.

Consent for publication

Informed consent was obtained from all participants involved in the study, and consent to publish was obtained from all authors.

Conflict of interest

The authors declare no competing interests.

Publisher's Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Yiyu Zeng and Jinyu Luo contribute equally to this manuscript.
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