| Abstract|| |
Background: Gastric cancer is one of the most common cancers in the world and is responsible for over a million deaths. Gastric cancer broadly consists of two main histological types, diffuse and intestinal, and can be further classified as proximal (cardia) and distal (corpus and pylorus) cancers. The presence of Her2neu in certain cancers including gastric cancers has helped in throwing some light on the prediction of prognosis of the tumours. This study was carried out to assess and evaluate the role of Her2neu immunohistochemical expression in gastric cancers. Methodology: This study was carried out as a retrospective study on paraffin blocks of 70 gastrectomy specimens in the pathology department of our hospital. After the histological assessment and interpretation of data, appropriate blocks were chosen and sections of 3 micron thickness were cut and immunohistochemical staining of Her2neu was done and scoring was carried out. Results: We found that gastric cancer occurred predominantly in men as compared to women. Antrum was the most common site involved in gastric cancer (60%). In our study Grade 2 predominated (54%) than Grade 1 (4.2%) and Grade 3 (41%). According to the scoring system of Her2neu expression by immunohistochemistry in gastric cancer it was positive (3+) in 8 cases (11.4%), equivocal (2+) in 10 cases (14.3%) and negative (0+,1+) in 52 cases (74.3%). Her2neu was seen positive 13.7% of intestinal type tumours and in only 5.3% of diffuse type of tumours (P < 0.05). Conclusion: Her2neu testing in gastric adenocarcinomas especially in histologically identified early gastric carcinoma is recommended.
Keywords: Adenocarcinoma, gastric cancer, Her2neu, immunohistochemistry
|How to cite this article:|
Sukanya J S, Raj PV, Thanka J. Role of HER2neu expression in gastric cancer. Indian J Pathol Microbiol 2021;64:58-64
| Introduction|| |
Gastric cancer is prevalent all over the world, with over 70% of the cases occurring in developing countries. The most common risk factors include dietary habits and Helicobacter pylori infection prevalence. It is the second most common neoplasm worldwide and the third leading cause of cancer-related deaths (3-10%). Each year, over 3 million new cases and 2 million deaths occur due to gastrointestinal tract cancer, which includes oesophageal, stomach, liver, colon, and pancreas cancers.
The etiology of gastric cancer is likely to be a combination of environmental factors and specific genetic alterations. Gastric cancer exists as two main histological types, diffuse and intestinal, as described by Lauren, and can be subdivided into proximal (cardia) and distal (corpus and pylorus) cancers. Inflammation triggers precancerous process, resulting in gastrointestinal cancers. This is initiated by oxidative stress, which results in the initiation of the regenerative processes. As a result of this, the cell division ensues without replacement of lost and injured cells. This paves way for the accumulation of genetic damage. Characteristically there is initiation of dysplasia (abnormal cells) which results in the development of pre-neoplastic lesions and later on results in invasive carcinoma.
Surgery remains the mainstay of any curative treatment. Unfortunately, in advanced gastric cancer, currently available treatments including surgery, chemotherapy and radiotherapy have limited success. HER-2neu is a proto-oncogene located on chromosome 17q21 and a member of the human epidermal growth factor receptor (EGFR) family. It encodes a 185 kD transmembrane tyrosine kinase receptor protein that, through dimerization with other family members, regulates signal transduction in cellular processes including proliferation, differentiation, and cellular survival.
HER2neu has been frequently detected in a wide range of human tumours. Normal cell secretion is associated with HER-2neu protein, but destruction of normal cell control causing protein overexpression, increases the rate of cell division and growth inducing precancerous changes.
Overexpression of HER2neu gene and its protein are associated with breast cancer patient's prognosis and therapy and expression of HER2neu is strongly required for tumor growth. Recently, Her2neu was introduced as a predictive biomarker for the treatment of gastric cancer with Trastuzumab which is an antibody targeting Her2neu. This biomarker is applied in combination with conventional chemotherapy for the treatment of Her2neu-positive advanced gastric cancer. Since the costs for Trastuzumab therapy are high and side effects are significant, accurate selection of eligible patients for this therapy is crucial.,
HER2neu protein expression assessment is done by immunohistochemical technique (IHC), fluorescence in situ hybridization (FISH) is used in cases where the Her2neu positivity by IHC is equivocal. We studied Her2neu IHC expression in gastric cancers. This will help in targeted therapy with Trastuzumab leading to better clinical outcome.
- To evaluate Her2neu immunohistochemical expression in gastric cancer cases
- To analyze its relationship with various histological types, grade, primary tumor localization and stage of the disease.
| Methodology|| |
This is a retrospective study on paraffin blocks of gastric cancer specimens.
Gastrectomy specimens from patients with gastric cancer received in the Department of Pathology at Sri Ramachandra University, Porur, Chennai.
The study was carried out for a period of 4 years between 2011 and 2015.
Sample size and sampling
All the samples received during the study period were included in the study. A total of 70 Gastrectomy specimens formed the sample size.
Data collection tools
Age, sex, site, histological type, grade, and stage of the disease were obtained from the medical records. Processed paraffin sections of 5 micron thickness from relevant tumor areas were made, stained with H and E and mounted on glass slides. The histological diagnosis, staging and grading was identified based on these stained sections. Staging of gastric cancer was evaluated depending upon the TNM staging of tumours. After the histological assessment and interpretation of data, appropriate blocks were chosen and sections of 3 micron thickness were cut and immunohistochemical staining of Her2neu was done. Monoclonal antibody detected against Her2neu was observed as brown color in the cell membrane of the tumor cells.
Ethical approval and informed consent
Permission of the institutional ethics committee was obtained prior to commencing the study.
The staging of gastric cancers based on TNM staging of tumours is given in [Table 1].
A semiquantitative approach was used to score Her2neu immunostaining. At least 10 representative fields with maximum staining under high-power magnification (x400) were chosen and 1000 cells were counted for each case. If the number of cells was less than 1000, then all available cells were counted and the results were expressed as mean percentage. Scoring of the expression of Her2neu is given in [Table 2].
|Table 2: Assessment of Her2neu grading in resected specimens of gastric cancer|
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Statistical analysis was carried out using the “SSPS Version 11” statistical software. Pearson Chi-square test was used to determine significant clinicopathological differences between Her2neu expression in positive and negative tumours. Differences were considered statistically significant when P value was <0.05.
| Results|| |
We had studied histopathologically proven cases of 70 gastric carcinomas. The age of the patients in our study ranged between 30 to 80 years. Highest incidence was noted in the age group of above 60 years (41%) [Table 3]. We found that gastric cancer occurred predominantly in men as compared to women with a male to female ratio of 2.3:1. Antrum was the most common site involved in gastric cancer (60%) [Table 4] when compared to the other sites namely fundus, body, pylorus and gastroesophageal junction.
In this study Grade 2 predominated (54%) than Grade 1 (4.2%) and Grade 3 (41%). According to Lauren's classification of gastric carcinoma, Intestinal type of histology predominated (73%) when compared to diffuse type of histology in carcinoma stomach (27%) [Table 4].
According to the TNM (primary tumor, regional lymph nodes and distant metastasis) classification, most of the tumours (40%) had belong to pT3 followed by pT2 (33%) [Table 5].
Regional lymph node metastasis was seen in 64.3% of the cases with N1 (8.5%), N2 (27%) and N3 (28.5%) whereas absent in 35.7%. Six cases (8.6%) had distant metastasis (cM1), while the others had clinically no metastasis (cM0). [Table 5] According to the clinical staging system of gastric carcinoma, Stage 2 (34.2%) and Stage 3 (41.1%) predominated than Stage 1 (17.1%) and Stage 4 (7.1%) [Table 7]. According to the scoring system of Her2neu expression by immunohistochemistry in gastric cancer it was positive (3+) in 8 cases (11.4%), equivocal (2+) in 10 cases (14.3%) and negative (0+,1+) in 52 cases (74.3%) [Figure 1].
There was no significant difference in expression of Her2neu according to site of gastric carcinoma [Figure 2], since the P value was 0.492 [Table 6]. Expression of Her 2 neu was analyzed for various age groups, higher expression of Her2neu was seen in 41-50 years (16.7%) of age, followed by <60 years (13.8%) [Figure 3].
Expression of Her2neu was analyzed for different grades of gastric carcinoma. Her2neu was seen positive in 33.3% of Grade 1 ; 15.8% of Grade 2 and 3.4% of Grade 3. The P value was 0.032 and it was significant. [Figure 4]. Expression of Her2neu was analyzed for histological types of carcinoma. Her2neu was seen positive 13.7% of intestinal type tumours and in only 5.3% of diffuse type of tumours. This was again significant with a P value of 0.048 [Figure 5] and [Table 8].
|Figure 5: Immunohistochemistry Findings. (a) Hematoxylin and Eosin – x100) - - Nodal metastasis of gastric adenocarcinoma. (b) Immunohistochemistry –Her2neu -- (x100) - - control slide – Ductal carcinoma breast. (c) Immunohistochemistry –Her2neu -- (x100) - - score 0 + Positivity. (d) Immunohistochemistry –Her2neu -- (x400) - - score 1 + Positivity. (e) Immunohistochemistry –Her2neu -- (x200) - - score 2 + Positivity. (f) Immunohistochemistry –Her2neu -- (x100) - - score 3 + Positivity|
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Expression of Her2neu was also analyzed for pTNM staging. The expression of positivity of Her2neu in primary tumor staging was seen in 4 cases (23.5%) of pT4 (tumor directly invades adjacent structures), 3 cases (13%) of pT2 (tumor invades muscularis propria or subserosa) and only one case (3.6%) of pT3 (tumor penetrates serosa without involvement of adjacent structures [Figure 6]. The expression of positivity of Her2neu in lymph node staging was expressed in 6 cases (24%) in N0 (no regional lymph node metastasis) and only one case (5.3%) in N2 (metastasis in 7 to 15 perigastric lymph nodes) [Figure 7]. The expression of positivity of Her2neu in distant metastasis showed 16.7% in M1 (distant metastasis present) and 11% in M0 (no distant metastasis) [Figure 8].
Expression of Her2neu was also analyzed for the clinical stage. Stage I showed maximum expression (25%), followed by Stage IV (20%). Stage II (8.3%) and Stage III (6.9%) showed almost equal expression. [Figure 9].
The correlation of Her2neu expression and positivity with the prognostic variables of gastric cancer is shown in [Table 6].
| Discussion|| |
Gastric cancer is a currently emerging problem worldwide, being the 2nd leading cause of cancer mortality. Every year approximately 990,000 people are diagnosed to have gastric cancer out of which about 738,000 patients die from this condition. Previously gastric cancer was only prevalent in the western countries and Japan but now it causes a major threat to Asian countries including India. In 2001 the incidence of gastric cancer in India was 35,675 out of which 23,785 were men and 11,890 were women. The north eastern and southern states of India have the highest incidence of gastric cancer.
According to Abdi-Radi et al. the incidence of gastric cancer was significantly low below the age of 40 years which was similar to the results of our study. Considering the western literature the median age at diagnosis of gastric cancer is 70 years, which was also compatible with our study. So there was no major difference in the age distribution of gastric cancer between western countries and India according to our study. Both in western and eastern world, men are affected two times more than the females which are almost in par with our study of M:F ratio of 2.3:1.
According to Karimi, Parisa et al. in his study, he has mentioned that women are protected from gastric cancer by estrogen. Cherian et al. conducted a study in India, and reported that the highest number of gastric cancer were found in the antrum (67.3%) followed by body (23.3%), proximal stomach (5.6%) and gastro -oesophageal junction (3.8%) which is similar to the findings of our study. Sakaik K et al. from Japan was the first person to describe the implication of Her2neu immunohistochemistry in gastric cancer. In our study the percentage of Her2neu positive cases was 12%, comparable with several studies which showed a similar percentage of positivity of approximately 9% to 38%.,
One of the largest Chinese study done by Ling Shan et al. included 1463 gastric cancer patients and demonstrated Her2neu positivity in only 9.8% of them. Overall the Her2neu overexpression in gastric cancer lies between 8.2% and 27.5%, which is a very wide range. In the literature studied the variability of percentage of expression of Her2neu staining in gastric carcinoma may be attributed to the following reasons. First, there might be intra tumoral heterogenicity of Her2 neu in gastric cancer., Therefore there is more chance of sampling error especially in biopsies. Second, selection of primary antibody (monoclonal or polyclonal) will affect the result significantly.
Third, the assessment of Her2neu depends on the scoring system used, visual perception and expertise of the pathologist. Among the histological subtypes of gastric cancer (Lauren classification) namely intestinal and diffuse, our study showed increased Her2neu positivity in intestinal type (13.7%) than in diffuse type (5.3%) which is statistically significant with a P value of 0.048. This finding was well correlated with the studies conducted by de Mello et al. and Scartozzi M et al. who also had found a high expression of Her2neu in intestinal type of gastric cancer (32%) than diffuse (6%). Finally in ToGA trial there was a significant difference in Her2neu overexpression in different histological subtypes, intestinal (34%), diffuse (6%) and mixed (20%).
Furthermore, few literature, have mentioned that Her2neu was generally considered as a poor prognostic factor in gastric cancer and is strongly associated with intestinal type which is believed to have a better prognosis than diffuse type. According to Figueroa-Barojas et al. the explanation for this contradictory finding has its roots deep into the tumorogenesis/origin of gastric carcinoma. Since all intestinal type tumours are not positive for Her2neu, tumorogenisis may not be the only factor involved. Becker K F et al. suggests that Her2neu gene amplification associates inversely with E cadherin mutation. E cadherin mutation is characteristically seen in diffuse type gastric cancer and lobular carcinoma of breast. This relationship between Her2neu and E cadherin may be the reason for its overexpression in intestinal type which usually lacks E cadherin mutation.
We also compared Her2neu overexpression with the grade of the tumor, supporting the previous studies of Raziee H et al. who studied 100 surgically resected gastric adenocarcinoma cases and found that majority of the Her2neu positive patients had well differentiated tumors, grade1 (41%) followed by moderately differentiated, grade 2 (11.1%), poorly differentiated, grade 3 (7%) and it was clinically significant (P = 0.001). The grade of the tumor also showed a significant difference (P = 0.032) in Her2neu positivity with 33.3% of positive cases as grade1, 21.1% of positive cases as grade 2 and 3.4% of positive cases as grade 3. Jaehne et al. also reported similar findings.
In our study Her2neu expression with primary tumor site did not show statistical significance unlike the studies conducted by Tanner et al. and Gordon M.A et al. who observed that Her2neu expression was more common in gastro-oesophageal junction cancers than in gastric tumours. TNM staging is one of the most important factors in assessing the prognosis of gastric carcinoma. However it is not a single deciding factor, as the prognosis also varies within patients of same stage. Also, we did not find any significant correlation between tumor stage and Her2neu expression, similar to the findings of Lemoine et al. and Raziee et al. The possible reason for this finding in our study might be because of the small sample size.
| Conclusion|| |
From the above findings of our study we conclude that Her2neu has a role in the tumor progression of gastric carcinomas, since its expression is high in low grade and intestinal histologic type tumours. Her2neu positive patients could benefit from the targeted therapy with Trastuzumab. Hence Her2neu testing in gastric adenocarcinomas especially in histologically identified early gastric carcinoma is recommended.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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Pavithra Vittal Raj
Department of Pathology, Sri Ramachandra University, Porur, Chennai, Tamil Nadu
Source of Support: None, Conflict of Interest: None
[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7], [Table 8]