Discussion
Despite recent advancements in diagnostic and therapeutic approaches for LSCC, the overall survival rate for this common neoplasm remains modest (17). Currently, the UICC/TNM staging system is used to determine the prognosis of LSCC by considering factors such as surgical margin status, tumor differentiation, lymphovascular invasion, perineural invasion, and recipient of adjuvant therapy (18, 19). However, studies have shown that even among patients with the same tumor stage, there is significant discordance in the predictability of routinely reported prognostic factors (12). Furthermore, upstaging or downstaging occurs in a third of LSCC patients, impacting margin status, therapeutic approaches, and recurrence rate (20). It is essential to identify an independent prognostic factor to determine which patients are suitable for organ-preserving treatment, as the impact of total laryngectomy on psychological and functional aspects can be significant (21). Our research indicates that a significant percentage of cases, over 62%, were classified as stage IV, despite exhibiting well-differentiated features in more than 62% of cases. Additionally, although the mortality rate was high at 63%, vascular and perineural invasion were present in less than 30% of cases. These findings highlight the potential discrepancies between clinical and histopathological prognostic factors.
Recent studies suggest that a combined TB/CNS-based grading system holds promise in predicting outcomes for SCC patients across various sites (22). TB is recognized as an independent prognostic factor in many solid tumors (18) and even preoperative biopsies can provide valuable information about invasion depth, lymph vascular invasion, and invasion patterns (23). In oral SCC, TB has been shown to negatively impact survival outcomes, regardless of tumor location or pathological stage (24, 25). Therefore, validating the prognostic significance of TB and CNS is beneficial, as routine H&E-stained slides can assess them with high interobserver, and intraobserver agreement (26). However, studies on SCCs of the larynx and hypopharynx are limited, and results vary due to differences in pathological and clinical variables.
Various methods for detecting TB have been suggested, but the scoring system proposed by Boxberg et al. is sufficient for the risk stratification of LSCCs. Boxberg et al. developed their approach based on a validated grading system for esophageal SCC, which incorporates the budding activity score and intratumoral CNS score. TB quantifies the dissociative growth of cancer cells, while CNS represents the highest level of cellular discohesion qualitatively. Combining these two factors provides insight into tumor invasion and can identify early signs of metastasis (27). This grading system is an independent prognostic factor for patient survival in SCCs of the larynx, hypopharynx, esophagus, oral cavity, and lung (12, 28).
Our analysis indicates that the presence of TB is significantly correlated with nodal involvement, vascular invasion, and mortality rate. Ekmekci et al. also found a statistical correlation between lymph node metastasis, perineural invasion, and lymphovascular invasion with TB, although their scoring system differed from ours (29). We found that categorizing TB into low-budding and high-budding activity is more practical and reproducible than the three-tier semiquantitative grading used in Ekmekci’s study. However, some studies suggest that the 3-tier system has better prognostic power (30). The correlation between TB and lymph node metastases was confirmed in the study of Abd Raboh et al., who evaluated the predictive value of TB in LSCC using pan-cytokeratin immunostaining (31). Similar results were observed in oral, nasopharyngeal, hypopharyngeal, lung, and cervical SCCs (27, 32-34). Synchronous increased TB activity and perineural invasion were also reported in oral SCCs (35).
Additionally, TB was considered an independent predictor of regional metastases in patients with clinically node-negative T1 and T2 oral SCCs (36, 37). The study by Karpathiou et al. further confirmed the association between TB and advanced T classification (14). The predictive ability of TB for lymph node metastasis is valuable as routinely reported lymph node status can be underestimated due to inadequate dissection and sampling (38).
Furthermore, there is no agreement on the most effective predictive methods for detecting regional metastases in patients with node-negative head and neck SCCs in the early stages (36, 39). As a result, including TB analysis in pathology reports can alert clinicians to patients with a poor prognosis. Elseragay et al. have even proposed that TB analysis can enhance the predictive accuracy of the WHO histopathologic grading system in early oral SCCs.
Our study observed that high TB scores were significantly linked to a greater likelihood of extra-laryngeal extension and a higher clinical stage. Patients with high TB scores also had a considerably higher death rate compared to those with low TB scores. Similarly, Pasaoglu et al. reported a substantial decline in disease-free and overall survival in patients with high TB scores (15). Additionally, Imai et al. conducted a retrospective analysis of the risk factors for cervical lymph node metastasis in endoscopically resected superficial hypopharyngeal cancers. This study suggested that high tumor budding is a robust predictor of cervical nodal involvement; however, the multivariate analysis did not support a significant correlation between these two factors, potentially due to limitations caused by focusing solely on a specific site and procedure (40).
It is worth noting that the TB score is associated with lymph node metastasis, local recurrence, lymphoid infiltration, and infiltrative pattern of invasion, which has been validated in oral SCCs (41). Caruntu et al. also discovered a link between high TB scores and larger tumor dimensions as well as advanced clinical stages (35). As a result, it is recommended to report the TB score for each case to emphasize the significance of implementing a more rigorous follow-up plan.
Although research on CNS is significantly more limited than TB studies, the literature reports a correlation between single-cell invasion and a worse prognosis (13, 42, 43). ). Our study discovered a significant connection between a smaller CNS, a higher clinical stage, and a more significant extra-laryngeal extension. We also found that smaller CNS were linked to a higher mortality rate, particularly in cases of single-cell invasion. These results align with the existing, limited data in the literature. Karpathiou et al. explored the prognostic significance of TB and CNS in laryngeal and hypopharyngeal SCCs, tumor-stroma ratio, and stroma type. Their data confirms the adverse prognostic effect of smaller CNS accompanied by poorer lymphocytic reaction, which indicates the relation of tumor microenvironment with cancer progression (14, 44). Tan et al. found the association of perineural invasion and stage with CNS, in addition to the significance of TB in predicting overall survival. They suggested adding TB and CNS to pathologic reports as histopathologic biomarkers that indicate a higher probability of recurrence, metastases, and poor survival (45).
Our multivariate analysis indicates that TB, CNS, and clinical stage are independent prognostic factors for mortality. This aligns with prior research that indicates high TB and smaller CNS are linked to adverse outcomes in oral SCC (46). Sarioglu et al. have also suggested that TB is a valuable prognostic factor for distant-metastases-free survival (47). Likewise, Jesinghaus et al. have confirmed the prognostic impact of TB and CNS on overall, disease-free, and disease-specific survival independent of clinical stage in esophageal SCCs. They have also demonstrated the efficacy of TB and CNS in predicting the depth of infiltration and nodal involvement in biopsy samples (48). Yadav et al. have identified TB as an independent poor prognostic marker in oral SCCs exhibiting de-differentiation, loss of adhesion, and epithelial-to-mesenchymal transformation (49).
Our study has further revealed that TB is associated with a significant decrease in disease-free survival. Additionally, single-cell invasion, small CNS, and intermediate CNS have a statistically significant negative effect on DFS. These results, together with the findings reported in the literature, support the recognition of TB and CNS as independent risk factors for poor DFS in LSCC(50). High TB has also been correlated with shorter DFS and reduced overall survival in head and neck and oral SCC (31). Clinical stage is another associated factor with DFS.
However, our study found no correlation between DFS and the histopathologic grade of differentiation. The impact of histologic grade on the survival of LSCC patients remains a topic of debate, with some studies confirming its association with tumor aggressiveness and metastases, while others find the relationship to be unclear (51, 52). To clarify this ambiguity, a larger population matched-pair analysis could aid in more accurately comparing survival rates across different histologic grades.
Despite its limitations, our study supports the potential role of TB and CNS in determining the prognosis of LSCC. The two-parameter scoring system used in our study is easily evaluated during basic histopathologic examination and does not require additional ancillary or biomolecular studies. While differences in parameters, follow-up duration, and study designs may confound the results of our study and previous ones, the overall conclusion underscores the importance of the TBNS grading system in LSCC. Given its accessibility and low interobserver variability, including TBNS scores in pathology reports could facilitate individualized risk assessment and treatment planning. Several studies have validated the association of TB with lymph node metastasis and overall survival, highlighting the detrimental impact of higher TB. Integrating TBNS scores into pathology reports can aid personalized patient care regardless of the scoring method.