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Table of Contents   
ORIGINAL RESEARCH  
Year : 2014  |  Volume : 25  |  Issue : 3  |  Page : 357-363
Comparative study of various grading systems in oral squamous cell carcinoma and their value in predicting lymph node metastasis


1 Department of Oral Pathology and Microbiology, The Oxford Dental College, Hospital and Research Centre, Bommanahalli, Bengaluru, Karnataka, India
2 Department of Oral Pathology and Microbiology, Career Dental College, Lucknow,Uttar Pradesh, India

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Date of Submission07-Jan-2011
Date of Decision05-Jul-2013
Date of Acceptance24-Jun-2014
Date of Web Publication7-Aug-2014
 

   Abstract 

Background: Regional lymph node (LN) metastasis is the single most prognostic factor for oral squamous cell carcinoma (OSCC). An analysis of the prognostic factors is important for predicting prognosis and reducing the mortality in these patients.
Objectives: (1) To compare the value of various grading systems in predicting LN metastasis. (2) To evaluate histopathological parameters, which could help in predicting LN metastasis.
Materials and Methods: A total of 20 excisional biopsies of OSCCs, were graded according to the four grading systems that is, Broder's, Jakobsson's, Anneroth and Hansen's, and Brynes. We also evaluated various histopathological parameters, which could help in predicting LN metastasis.
Results: Grading at the invasive front was most prognostic of LN metastasis. Tumors with total malignancy score ≥8 showed higher incidence of metastases.
Conclusion: The histopathological parameters that could help in predicting lymph node metastases (LNM) are keratinization, nuclear pleomorphism (NP), and the pattern of invasion (POI) when assessed at the invasive front. When the whole tumor was considered, histopathological parameters like NP and POI were significant in predicting LNM.

Keywords: Malignancy grading system, metastases, oral squamous cell carcinoma, prognostic parameters

How to cite this article:
Jamadar S, Narayan T V, Shreedhar B, Mohanty L, Shenoy S. Comparative study of various grading systems in oral squamous cell carcinoma and their value in predicting lymph node metastasis. Indian J Dent Res 2014;25:357-63

How to cite this URL:
Jamadar S, Narayan T V, Shreedhar B, Mohanty L, Shenoy S. Comparative study of various grading systems in oral squamous cell carcinoma and their value in predicting lymph node metastasis. Indian J Dent Res [serial online] 2014 [cited 2019 Sep 16];25:357-63. Available from: http://www.ijdr.in/text.asp?2014/25/3/357/138336
Cancer of the mouth and pharynx accounts for nearly 30,000 cases of cancer and approximately 7200 deaths/year in United States. In India, oral cavity is one of the five leading sites of cancer. [1] Squamous cell carcinoma (SCC) of the buccal mucosa (BM), alveolus, and retromolar trigone together grouped as gingivo-buccal complex, aptly called as the "Indian Oral Cancer", constitute 60% of oral cancer in India. [2] Tongue and floor of the mouth cancers form the bulk of cancers in the west. [3] Despite the therapeutic and diagnostic progresses in oncology, the clinical outcome of intraoral cancer has remained poor. [4] Patients with oral squamous cell carcinoma (OSCC) can die from failure to control the primary lesion or regional lymph node (LN) and distant metastasis. [5] Regional LN involvement is an important prognostic factor. The 5-year survival rate for patients with LN involvement is 20-36% after surgery as compared with 63-86% in patients without LN involvement. [6]

TNM staging has been widely used for treatment planning and estimate response to therapy. In early cases of OSCC; however, there are many patients who die despite the fact that their neoplasms were clinically Stage I or II. In such patients, a combined assessment of clinical staging and of cytomorphology might serve as a more precise measure for predicting the outcome of SCCs. [7] In view of this various grading systems have been proposed over the years. The paper describes a retrospective analysis of 20 cases of SCCs, graded using four grading systems that is, Broder's, Jacobsson's, Anneroth and Hansen's, and Bryne's invasive front grading.

Objectives

  • To compare the value of four grading systems in predicting lymph node metastases (LNM)
  • Evaluation of the histopathological parameters, which could aid in predicting LNM.



   Materials and methods Top


This study comprised of 20 excision specimens of OSCC with neck dissections retrieved from the files of Department of Oral Pathology and Microbiology, The Oxford Dental College, Bangalore and Karnataka Institute of Medical Sciences, Hubli. All tissues were fixed in 10% formalin; routinely processed and embedded in paraffin. The blocks of tissue were sectioned and stained with hematoxylin and eosin. The slides were assigned a different number, and hence the examiner being blinded to the clinical details and LN status of the patients. The clinical details and histopathological diagnosis of the cases are shown in [Table 1]. The tissue sections of the primary were graded according to the 4 grading systems. Two other parameters that is, perineural invasion (PNI) and desmoplastic response at the tumor stroma interface were also evaluated. Then the LN sections were evaluated for metastasis.
Table 1: Case details


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The value of the four grading systems in predicting LNMs was evaluated using the phi-coefficient. They were compared for their prognostic value based on the odd's ratio. The prognostic value of the various parameters was evaluated and compared using the Chi-square test and the Fisher exact test.


   Results Top


A total of 20 cases of OSCCs reviewed in this study included 15 cases of the BM, 3 cases of the tongue and 2 cases involving the alveolus. Males comprised of 60% of the cases and females 40%. The mean age of distribution was 50 years with a range of 35-65 years.

The slides of the primary were graded according to the four grading systems.

Broder's grading system

Based on the proportion of differentiated cells one of the four grades was assigned. There were 12 Grade I SCCs,

6 Grade II, no cases in Grade III and 2 were Grade IV. When assessed for LN status, 8 cases were positive for metastases, and 12 negative for metastases. The correlation of LN status to Broder's grading system is shown in [Table 2]. LNM was found in 4/12 patients (33.3%) with Grade I SCC, 4/6 patients (66.7%) with Grade II SCC. Both Grade IV cases showed no LNMs. Hence, Broder's grade showed no prognostic significance.
Table 2: Correlation of Broder's grading system to LN status


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Jakobsson's grading system

The scores for each parameter, the total malignancy score (TMS) for the respective cases and LN status is shown in [Table 3]. The TMS ranged from 10 to 26. The mean of these scores that is, 15 was taken as the cut off value. There were 9 cases, which had the TMS ≤15 and 11 cases with the score >15. The correlation of LNM to Jakobsson's grading system is shown in [Table 4]. Patients with a TMS of ≤15 showed a low incidence of metastases (22.2%) compared to cases with TMS of >15 (88.8%).
Table 3: Scores of parameters using Jakobsson's method and LN status


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Table 4: Correlation of Jakobsson's grading system to LN status


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Similar findings were observed in Anneroth and Hansen's grading [Table 5], where the criteria were similar except that the parameter vascular invasion (VI) was omitted. In the TMS ranged from 8 to 24. The mean of these scores that is, 13 was considered as the cut-off value.
Table 5: Correlation of Anneroth and Hansen grading system to LN status


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Bryne's grading system

This was performed at the invasive tumor front (ITF). The TMS ranged from 5 to 16. 8 was considered as the cut-off value. Two cases were not assessed since the tumor front was not seen in the available sections. The scores of the parameters at the ITF are shown in [Table 6]. Correlation between Bryne's grading system and LNM is shown in [Table 7]. Among the 6 patients with a TMS of ≤8, only one patient showed metastases, whereas 7/12 patients with a score >8 showed metastases. Though statistically significant results were not obtained, there was a weak positive correlation between LNM and histopathological grading at the ITF.
Table 6: Scores of parameters using Bryne's method and LN status


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Table 7: Correlation of Bryne's grading system to LN status


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When PNI and desmoplastic response was evaluated, 10 cases showed PNI and six cases showed desmoplastic response.

Comparison of various grading systems and their value in predicting LNM using the odds ratio is shown in [Table 8]. The Bryne's grading system is more predictive for LNM as compared with the multifactorial grading systems that is, Jakobsson's and Anneroth and Hansen's. Broder's grading system is of no prognostic value.
Table 8: Value of various grading systems in predicting LN status


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Individual histopathological parameters

Each individual parameter assessed by Jakobsson's grading system was correlated to LNM. 40% of cases with abundant keratinization [Figure 1] showed metastases. There were two cases with minimal keratinization, which did not show metastases.
Figure 1: Tumor cells showing abundant keratinization. 40x

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Among three cases, which showed mild nuclear pleomorphism (NP), none of them had metastasized. On the contrary 7/11 cases with score 3 that is, abundant NP [Figure 2] showed regional metastasis, and this was statistically significant.

Among tumors which showed less mitosis, only 1/6 cases showed LNMs. However, even in cases with increased number of mitosis that is, more than 5-6 on an average [Figure 3] only 2/6 cases had metastasized.
Figure 2: Tumor cells showing marked nuclear pleomorphism (×40)

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Figure 3: Tumor cells showing increased mitotic rate (×40)

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All the three patients with score 3 that is, tumors infiltrating in small groups [Figure 4] showed LNM. This value was of prognostic significance. 3/9 patients with tumors showing invasion in the form of solid islands, and pushing margins [Figure 5] had metastasized.
Figure 4: Tumor cells invading in strands and cords (×40)

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Figure 5: Tumor cells invading in solid islands (×40)

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Among the four cases with tumor extending into the deeper connective tissue, two cases were positive for LNM. Among the 16 cases, which had invaded further in the connective tissue including muscle invasion [Figure 6], six cases were positive for LNM.
Figure 6: Tumor cells showing muscle invasion (×40)

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6/14 cases with marked lympho-plasmacytic response (LPR) were positive for LNM. Among the three cases with minimal LPR, all were negative for LNM.

Among the 13 cases, which showed VI [Figure 7], 6 showed LNM, but 7 cases did not metastasize.
Figure 7: Intravascular tumor emboli (×40)

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Figure 8: Marked desmoplastic response to the tumor. x40

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The comparison of various histopathologic parameters within the tumor, which would be suggestive of LNM, is shown in [Table 9].
Table 9: Comparison of parameters using the Jakobsson's method


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The evaluation of five histopathological parameters was done at the ITF. The predictive value of the parameters was compared as presented in [Table 10]. The parameter keratinization when analyzed at the ITF was most prognostic of LNM. Both cases with score 3 (5-20% cells showing keratinization) showed metastases. 3/11 cases with abundant keratinization showed metastases.
Table 10: Comparison of parameters using Bryne's method


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Tumors exhibiting mild NP at the ITF had a low incidence of metastases. All the 3 cases with score 1 were negative for metastases. 3/4 cases with score 4 for NP had metastasized. This parameter showed statistically significant value.

When mitosis was considered at the ITF 2/7 cases with Grade I mitosis showed metastases. 3/5 cases and 2/4 cases with score 3 and score 4 respectively showed metastases.

Tumors showing invasion in the form of solid islands at the ITF metastasized less (25%) as compared to tumors invading in the form of strands (37.5%) and small groups of cells (66.7%).

6/14 cases with marked LPR at the ITF were positive for LNM. Two cases showed moderate response at the ITF, and both were positive for LNM. Two cases showed mild response and both of them did not show metastases.

Desmoplastic response

Six cases showed marked to moderate response [Figure 8], of which three cases were positive for LNM. Of the 14 cases, which showed no such response, five were positive for LNM.

Perineural invasion

Ten cases showed PNI [Figure 9] and 50% of these cases were positive for LNM. Of the other 10 cases, which did not show PNI, three cases were positive for LNM [Figure 10].
Figure 9: Perineural invasion of tumor cells (×40)

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Figure 10: Metastases in a lymph node showing keratin formation (×10)

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   Discussion Top


Many investigators have studied clinical and histopathological features of the primary tumor, such as tumor size, degree of differentiation, NP, stromal response and pattern of invasion (POI) to determine the propensity for LNM. [6] Broder initiated the quantitative grading of cancer in 1920, which has been used for many years. As in our study, a lack of correlation between Broder's grade and prognosis has been noted, the attributable factor for this being heterogeneity in the tumor cell population. [8],[9]

In 1973 , Jakobsson et al. developed a multifactorial grading system, which has been used both in its original form and modified versions. [10] In our study, correlation has been noted between the TMS and LNM. Cases with TMS <15 had lower incidence of metastases, than those with TMS above 15.

Anneroth et al. omitted the parameter "VI" in their modification of this system. The clinical validity of this system has been studied in numerous studies, and significant results have been noted. [11],[12] We have noted similar findings as in Jakobsson's grading system. Only 2 of 9 cases with TMS ≤13 were positive for LNM.

Recent data indicate that cells at the ITF in various human cancers reveal characteristics, which correlate with tumor aggressiveness. [13] Aberrant expression of adhesion related molecules like cadherins, integrins, CD-44, laminins, tenascin, and oligosaccharides is particularly observed at the ITF. Invasive front grading proposed by Bryne has proven to be of high prognostic significance. [4],[8],[14] Comparison of the four grading systems in our study showed that grading at the ITF was most prognostic of LNM.

The prognostic value of different histopathological parameters has been correlated in our study. When keratinization was considered within the entire tumor, we failed to observe any correlation between this parameter and LNM. Tumors that showed moderate and minimum keratinization (5-20% of the cells showing keratinization) at the ITF showed significantly higher LNM. Similar findings have been found in other studies. [15] Furthermore, IHC studies have shown that in 50% of SCCs, there is maximum expression of cytokeratins 8 and 18 at the ITF. [16]

In studies done by Jakobsson, the factors of greatest relevance in predicting outcome at 5-year were "NP" of the tumor cell population, and the "POI" of the tumor and the TMS. [10] We found our results were similar to the latter studies and this parameter correlated significantly to LNM. Tumors showing abundant NP (25-50% mature cells) and extreme NP (0-25% mature cells had higher propensity for metastases. It proved to be of significance when the whole tumor was considered as well as at the tumor front.

Although  Crissman et al., reported that the frequency of mitosis was a good predictor of LNM, this feature has not emerged as an independent prognostic factor in other studies. [6] Our study also had a similar finding. In recent modification of Bryne's grading system, this parameter was omitted, but the prognostic value remained highly significant and the reproducibility was slightly improved when mitotic count was excluded. [17]

Yamamoto and associates noted that carcinomas infiltrating the tissues as small aggregates or single cells had a high metastatic rate than those with pushing margins. The results of our study were consistent with these studies. [18] These aggressive patterns of invasion might imply that tumor cells have already reached a stage where they exhibit molecular events that permit metastases, such as expression of cellular receptors and production of proteolytic enzymes to facilitate their access to lymphatic vessels. [15] A significant association between POI and local recurrence has been noted in several studies. [19]

The presence of tumor emboli in vascular spaces is proved to be of prognostic significance in previous studies. [20] In our study, 50% of the cases with VI were positive for metastases.

The plasma-lymphocytic infiltrate at the tumor stroma interface was not a significant prognostic factor in our series. 43% of the cases with marked response, showed LNM. Difficulty in distinguishing an immune response from an inflammatory response to ulceration, previous biopsy procedure, or extracellular keratin may account for the uncertainty of this feature.

According to several studies, tumors that show PNI are biologically more aggressive. [21],[22] Studies have demonstrated that nodal involvement at the time of diagnosis of OSCC was significantly related to PNI. [23] Though not statistically significant, we found that 50% of the cases with PNI were positive for metastases.

Previous studies that compared stromal desmoplasia to LNM have failed to observe any correlation between the two. [24] Our study showed that 50% of the cases with such response had metastasized. About 35% of the cases, which showed no desmoplasia, showed LNM.

Evaluation of certain features, which are better predictors of LNM, will help us in reducing the morbidity and mortality of these patients. In our study, when we compared the different parameters in Jakobsson's and Bryne's grading system, we found that the parameters NP (25-50% mature cells) and POI (invasion in small groups) showed prognostic significance when entire tumor was considered. At the ITF NP and keratinization (0-20% of the cells showing keratinization), were better predictors of LNM.


   Conclusion Top


The status of the regional neck nodes is the single most prognostic factor for OSCC. The prognosis of patients with LNM has remained poor in spite of the extensive ongoing molecular studies and advances. These studies have been put forth to help in early diagnosis, predict the prognosis and thereafter modulate the treatment of cancer. Considering the scenario of our country's economy, TNM staging and grading of OSCC has remained the corner stone for prediction of LNM and advanced expensive techniques are not affordable to the majority of the population. There are numerous reports in the literature on histologic grading of OSCC and its value in predicting survival. Only a small number of previous studies have assessed which of these histologic factors predict LNM.

Our results suggest that in clinically N0 OSCCs, incisional biopsy assumes paramount importance and attempts should be made to include the ITF in the incisional biopsy. At the invasive front NP and keratinization (0-20% of the cells showing keratinization), were better predictors of LNM. The parameters NP (25-50% mature cells), and POI (invasion in small groups) showed prognostic significance when entire tumor was considered.

 
   References Top

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Correspondence Address:
Saleha Jamadar
Department of Oral Pathology and Microbiology, The Oxford Dental College, Hospital and Research Centre, Bommanahalli, Bengaluru, Karnataka
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0970-9290.138336

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    Figures

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    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7], [Table 8], [Table 9], [Table 10]



 

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