Introduction

Globally, oral cancer ranks as the sixth most prevalent type of cancer, with India bearing a significant portion of this burden, accounting for nearly one-third of all cases and ranking as the second country with the highest number of oral cancer cases. Within India, oral cancer stands as the most frequently diagnosed cancer among males and the third most common among females.1

Oral Squamous Cell Carcinoma (OSCC) presents numerous histopathologic prognostic parameters, encompassing tumor grade/histologic grade, worst Pattern of Invasion (WPOI), lymph-nodal Involvement (LNI), depth of Invasion (DOI), perineural Invasion (PNI), lymphovascular Invasion (LVI), lymphocytic host response (LHR), and mitotic Activity/Index (MI).2

The quest for dependable and straightforward immunological biomarkers is crucial for refining treatment approaches. The immune response holds significant sway over the survival rates of cancer patients. Recent advancements in immuno-oncology and cancer biomarkers underscore the importance of tumor-infiltrating lymphocytes (TILs) as a promising prognostic factor across different tumor types, including Oral Squamous Cell Carcinoma (OSCC).3

This study delves into recent discoveries concerning Tumor-infiltrating lymphocytes (TILs) in Oral Squamous Cell Carcinoma (OSCC) and their potential as a robust prognostic biomarker for guiding clinical decisions. The evaluation of TILs involves assessing the ratio of lymphocytes infiltrating the stromal area, offering valuable insights into disease prognosis and treatment strategies.4, 5, 6, 7, 8, 9

Objectives

The objective is to correlate the possible association between Tumor-infiltrating lymphocytes (TILs) and clinicopathological factors of Oral Squamous Cell Carcinoma (OSCC).

Materials and Methods

A two-year retrospective study was conducted on 30 cases of Oral Squamous Cell Carcinoma (OSCC) to analyse routine clinicopathological factors alongside Tumor-infiltrating lymphocytes (TILs) in Hematoxylin and Eosin (H&E) stained sections. The study period spanned from January 2020 to February 2022. TILs were categorized into three grades: low, moderate, and high.

Results

The study encompassed an examination of 30 cases of OSCC, evaluating both histopathological parameters and TILs. The age spectrum ranged from 25 to 70 years, with a mean of 51.40 ± 10.27 years (Table 1). The male-to-female ratio was 2:1. Predominantly, OSCC manifested in the buccal mucosa (56.7%), followed by the tongue (20.0%), lip (6.6%), and lateral border of the tongue (6.6%) (Table 2). Among the 30 cases, 20 (66.7%) showed well differentiation, 9 (30%) moderate differentiation, and only 1 (3.3%) poor differentiation (Figure 5). Lymph node metastasis was evident in 5 cases (16.7%), while lymphovascular invasion and perineural invasion were observed in 2 (6.7%) and 3 cases (10.0%) respectively. TILs were notably present in 16 cases (53.3%) at high levels (Figure 3, Figure 4), 12 cases (40.0%) at moderate levels (Fig.2), and 2 cases (6.7%) at low levels (Figure 1), with a significant correlation observed with histological grade (p-value = 0.001) (Table 3). Regarding tumor staging, 50% of cases were classified as pT1, 20% as pT2, 20% as pT3, and 10% as pT4, with TILs demonstrating a significant correlation with pT stage (p-value = 0.001) (Figure 6) (Table 4).

Figure 1

Low level TILs: 0% to ≤30% (H&E, X20)

Figure 2

Moderate level TILs: 31% to ≤70% (H&E, X20)

Figure 3

High level TILs: 71% to ≤99% (H&E, X20)

Figure 4

High level TILs: 70% to ≤99% (H&E, X40)

Figure 5

Distribution of oral squamous cell carcinoma based on histopathological grade

Figure 6

Distribution of oral squamous cell carcinoma based on pT stage

Discussion

The importance of tumor-infiltrating lymphocytes (TILs) in predicting cancer outcomes has been underscored in numerous studies. A high abundance of TILs typically signifies a robust anti-tumor immune response, potentially leading to more favorable survival outcomes. In recent years, the recognition of TILs as a dependable prognostic marker has grown significantly across various tumor types, including breast, colorectal, gastric, and lung cancers. 3

In the present retrospective study involving 30 cases of OSCC, the mean age at presentation was 51.40 ± 10.27 years, ranging from 25 to 70 years. A study conducted by B Chaitra et al. examined 69 cases of OSCC, revealing an age range of 25 to 87 years with a mean age of 49.9 years and a male-to-female ratio of 4.3:1. The primary site of OSCC in their study was predominantly the buccal mucosa (49%), followed by the tongue (43%), with the lateral border of the tongue being the most common site. Similarly, in our study, the buccal mucosa was the most frequent site. Among the 69 cases reviewed by B Chaitra et al., 57 cases (82.6%) were grade 1 tumors, 9 cases (13%) were grade 2, and only 3 cases (4.3%) were grade 3 tumors. Furthermore, moderate TILs were observed in 46 cases (66.7%), followed by mild TILs in 13 cases (18.8%) and severe TILs in 10 cases (14.5%). Notably, TILs exhibited a significant correlation with various factors including WPOI, PNI, pT stage, and outcome.2

In a study conducted by Hitomi Suzuki et al., which involved 153 patients with an average age of 65.7 ± 11 years (124 males and 29 females), a cut-off value for TILs was set at 50%. The overall survival (OS) rates were 69.8% and 40.2% (P = 0.01) for patients with high and low TIL levels, respectively. Similarly, progression-free survival (PFS) rates were 58.4% and 31.6% (P = 0.003) in the high and low TIL groups, respectively.1

In a cohort study conducted by Alhadi Almangush et al., which included 140 (76.9%) men and 42 (23.1%) women, the median follow-up time was 4.48 years (range 3.51–5.00 years). They found that 49 (26.9%) tumors exhibited low infiltration of TILs (<20%), while 133 (73.1%) tumors showed high infiltration (≥20%) of TILs. Their analysis revealed a significant association between T-classification and TILs, indicating that smaller tumors were associated with a higher infiltration of TILs (P = 0.01). 3 Similarly, in our study, we also observed a significant correlation between TILs and pT stage.10, 11, 12, 13, 14, 15

In a retrospective cohort study by Qiaoshi Xu et al., the records and pathological sections of 202 patients with HNSCC who underwent surgical treatment were reviewed. They determined that a cutoff value of 70% could be utilized as a threshold for assessing TILs, with a TIL level exceeding 70% being linked to a more favorable prognosis. Specifically, they found that patients with TIL levels higher than 70% exhibited a disease-free survival rate (DFS rate) of 51.9% (P = .018) and a disease-specific survival rate (DSS rate) of 59.3% (P = .049).16, 17, 18, 19, 20, 21, 22, 23, 24, 25

The findings of the present retrospective study underscored a significant association between higher TILs and improved histological grade and T stage in Oral SCC. Furthermore, multivariate analyses revealed that TILs serve as robust independent prognostic factors. Therefore, investigating TILs in Oral SCC holds considerable promise. TILs could potentially serve as sensitive markers for chemoradiotherapy response. Notably, the assessment of TILs was deemed feasible with just HE staining, emphasizing the importance of standardizing and establishing a simple evaluation method. Moving forward, multicentre, prospective clinical trials will be essential to elucidate the true utility of TILs in guiding treatment decisions and improving patient outcomes.

Conclusion

The observation that well-differentiated tumors exhibit high TILs while poorly differentiated tumors show low TILs underscores the potential prognostic significance of TILs in Oral SCC. Furthermore, the significant correlation between TILs and pT stage suggests their relevance in tumor staging and prognosis. Given their ease of assessment and their prognostic value, TILs could serve as valuable prognostic tools for guiding treatment planning. Therefore, routine evaluation of TILs in both resection and preoperative biopsy specimens should be considered standard practice, facilitating more informed management decisions and potentially improving patient outcomes.

Conflict of Interest

The authors declare no conflicts of interest.

Source of Funding

No financial support of interest.