Relationship between biological behavior and phenotypic expression in undifferentiated-type gastric carcinomas

Association between mucin phenotype and lesion border detection using acetic acid-indigo carmine chromoendoscopy in early gastric cancers

BACKGROUND

For successful treatment of early gastric cancers (EGCs), it is crucial to define the horizontal border of the lesion with high accuracy. Acetic acid-indigo carmine (AI) chromoendoscopy has been used to determine the horizontal border in EGCs, but this technique is less potent in certain situations. Mucin phenotype in gastric cancers refers to biological differences in precursor lesions and differences in histopathologic findings, and it might affect AI chromoendoscopy findings. We aimed to investigate the association between mucin phenotype and AI chromoendoscopy findings in EGCs.

METHODS

We prospectively evaluated 126 lesions in 126 patients with endoscopically diagnosed EGCs. Conventional endoscopy and AI chromoendoscopy findings of these lesions before treatment were prospectively analyzed. The border distinction between the lesion and surrounding mucosa was classified as distinct or indistinct on conventional endoscopy and AI chromoendoscopy, respectively. Mucin phenotypes were classified as gastric, intestinal, gastrointestinal, or null type by immunohistochemistry.

RESULTS

The lesion borders were distinct in 46.8% (59/126) of the lesions assessed using conventional endoscopy and in 73.0% (92/126) of those assessed with AI chromoendoscopy (p < 0.001). The border distinction rate of differentiated-type cancers on AI chromoendoscopy was significantly higher than that on conventional endoscopy (66/71 [93.0%] vs. 34/71 [47.9%], p < 0.001), but the border distinction rate of undifferentiated-type cancers on AI chromoendoscopy was not different from that on conventional endoscopy (26/55 [47.3%] vs. 25/55 [45.5%], p = 0.848). Compared with conventional endoscopy, AI chromoendoscopy identified borders in a significantly higher percentage of gastric, intestinal, and gastrointestinal mucin types; however, there was no difference in AI chromoendoscopy findings according to the mucin phenotype (p = 0.271).

CONCLUSION

AI chromoendoscopy was effective in horizontal border delineation in differentiated-type EGCs, but not in undifferentiated-type EGCs. Mucin phenotype had no effect on border distinction using AI chromoendoscopy.

The nature of the white opaque substance within colorectal neoplastic epithelium as visualized by magnifying endoscopy with narrow-band imaging

Background and study aims: We previously reported our discovery of a white opaque substance (WOS) that is opaque to endoscopic light inside the epithelium while using magnifying endoscopy (ME) to examine gastric epithelial neoplasia. Histopathologic analysis revealed that the WOS comprises minute lipid droplets (LDs) accumulated within the neoplastic epithelium. In addition, the WOS was found in colorectal epithelial neoplasia, although it was unclear whether this WOS corresponded to an accumulation of LDs, as in the stomach. Therefore, the aim of the current study was to elucidate whether the WOS observed in colorectal epithelial tumors comprises LDs. Patients and methods: A consecutive series of 40 WOS-positive and 40 WOS-negative colorectal epithelial tumors was analyzed. One biopsy specimen was taken from each neoplasm. Cryostat sections were stained with oil red O for LD, and sections after formalin-fixation for LD were immunostained with anti-adipophilin antibody. Results: The prevalence of LDs stained with oil red O in WOS-positive vs. WOS-negative lesions was 47.5 % (19/40) vs. 5 % (2/40), respectively (P < 0.001). Furthermore, the WOS coincided with the expression of adipophilin; the prevalence of LDs stained by anti-adipophilin antibody in WOS-positive vs. WOS-negative lesions was 100 % (40/40) vs. 62.5 % (25/40), respectively (P < 0.001). Conclusions: This study elucidated for the first time that endoscopically visualized WOS in colorectal epithelial neoplasia may be composed of LDs accumulated in the neoplastic epithelium.

Expression of immunohistochemical markers according to histological type in patients with early gastric cancer

OBJECTIVE

We compared the biological characteristics of early gastric cancer (EGC) using immunohistochemical (IHC) staining among histological types.

MATERIALS AND METHODS

IHC staining results were analyzed in 86 EGCs resected with endoscopic submucosal dissection to identify mucin phenotype and biological characteristics.

RESULTS

The histological type was classified as tubular adenocarcinoma (TAC), mixed adenocarcinoma (MAC), or poorly cohesive carcinoma (PCC). Significant differences in MUC-2 (34.4% vs. 10.7%, p < 0.05) and MUC-5AC (59.4% vs. 85.7%, p < 0.05) expression were observed between TAC and PCC. The poorly cohesive component of MAC showed stronger immunoreactivity to CD10 (46.2% vs. 14.3%, p < 0.05) but weaker reactivity to MUC-5AC (57.7% vs. 85.7%, p < 0.05), compared to that of PCC. E-cadherin and β-catenin expression levels significantly decreased in the poorly cohesive component of MAC (15.4% vs. 90.6%, p < 0.05; 7.7% vs. 90.6%, p < 0.05, respectively) and PCC (10.7% vs. 90.6%, p < 0.05; 14.3% vs. 90.6%, p < 0.05, respectively), compared to TAC. However, vascular endothelial growth factor expression significantly increased in the poorly cohesive component of MAC (42.3% vs. 9.4%, p < 0.05) and PCC (39.3% vs. 9.4%, p < 0.05), compared to TAC.

CONCLUSION

IHC analysis showed that EGC histological types differ in terms of mucin phenotype and biological characteristics. The poorly cohesive components showed decreased E-cadherin and β-catenin expression levels and increased vascular endothelial growth factor expression. These characteristics may contribute to the poor prognosis of patients with MAC and PCC.

Can we resect EGC with Signet ring cells in Europe?

PURPOSE

The proposed guideline for performing endoscopic resection of early gastric carcinoma (EGC) in Paris classification is a well-differentiated carcinoma with maximum involvement Sm1. Signet ring cell carcinomas (SRC) are excluded from this recommendation. Authors from Eastern countries have proposed extending this resection to include selected undifferentiated EGC. Via an analysis of a series of cases of signet ring carcinoma, we will discuss whether it is possible to resect EGC with signet ring cells in Europe.

METHODS

We retrospectively included patients with histological classification pT1 of EGC showing SRC. Data was extracted from the hospital gastrectomy register. Lymphadenomectomy D1.5 was performed on all patients. Histology results were retrospectively obtained from the electronic patient file.

RESULTS

Twelve patients (mean age = 55.4, four women, eight men) underwent surgery, without previous chemotherapy, between 2000 and 2012, for EGC with SRC. Mean size of the lesions was 20.2 mm (5-35 mm). Seven lesions were located in the antrum, five in the fundus. In the case of nine patients, histology showed no lymphovascular involvement. None of these nine patients presented lymph node metastases (LNM). Five patients had intramucosal carcinoma, four were classified as Sm1, one patient was Sm2, and one patient was Sm3. On surgery, the three patients with lymphovascular invasion showed LNM.

CONCLUSION

Endoscopic resection of EGC with SRC does not systematically imply complementary treatment by surgery, although criteria for endoscopic resection are difficult to determine because of the lack of data in Europe.

Re-evaluation of phenotypic expression in undifferentiated-type early gastric adenocarcinomas using mucin core protein and CDX2

BACKGROUND

Undifferentiated-type early gastric adenocarcinomas are generally classified into two groups: pure undifferentiated-type adenocarcinomas, which naturally develop as undifferentiated-type without a glandular component; and mixed differentiated/undifferentiated-type adenocarcinomas, which are associated with some vestigial glandular component and presumably develop from differentiated-type adenocarcinoma. The differences in phenotypic expression between these two groups were examined using mucin core protein and CDX2.

METHODS

A total of 210 lesions of undifferentiated-type early gastric adenocarcinoma less than 25 mm in diameter were classified into four categories (gastric type, gastrointestinal type, intestinal type, and null type) based on their MUC5AC, MUC6, MUC2, and CDX2 immunoprofiles.

RESULTS

Gastric type was significantly (p < 0.01) decreased and gastrointestinal type was significantly (p < 0.01) increased both in pure undifferentiated-type adenocarcinomas and in mixed differentiated/undifferentiated-type adenocarcinomas when CDX2 was applied to mucin core protein. In the pure undifferentiated-type adenocarcinomas, gastric type decreased and gastrointestinal type increased as tumor size increased (p < 0.05). In contrast, in the mixed differentiated/undifferentiated-type adenocarcinomas, gastrointestinal type was most common even in small-sized (≤10 mm) carcinomas and was generally stable regardless of tumor size. In submucosal carcinomas, gastrointestinal type decreased and gastric type and intestinal type increased during carcinoma invasion from the intramucosal to submucosal parts (p < 0.05). The positivity rates for all phenotypic markers, especially gastric markers, tended to decrease during submucosal invasion.

CONCLUSIONS

CDX2 is a sensitive marker for assessing intestinal phenotypic expression, and it is likely that there are two different pathways of tumor progression in undifferentiated-type adenocarcinoma of the stomach, according to phenotypic expression.

Nature of white opaque substance in gastric epithelial neoplasia as visualized by magnifying endoscopy with narrow-band imaging

BACKGROUND AND AIMS

Magnifying endoscopy (ME) with narrow-band imaging (NBI) revealed a white opaque substance (WOS) within the superficial part of the gastric neoplasia; however, its nature has remained obscure. A WOS noted within the duodenum was reported to comprise lipid droplets (LD) absorbed by the duodenal epithelium. We attempted to ascertain whether the WOS within gastric neoplasia could also comprise LD and whether the presence of this WOS could be correlated with a specific phenotype.

METHODS

Forty-three patients with early gastric epithelial neoplasia underwent ME with NBI. The presence or absence of WOS in the neoplasias was recorded based on the findings of ME with NBI. One biopsy specimen was taken from each of the neoplasias. Cryostat sections underwent oil red O staining for LD. Serial sections were immunostained using the first antibody of CD10, MUC2, CDX2, human gastric mucin, MUC5AC and MUC6. The tissue phenotype was classified as intestinal (I), gastric (G) and gastrointestinal (GI) type based on the results of immunostaining. In total, 49 gastric neoplasias from 43 patients were investigated.

RESULTS

Prevalence of LD in WOS-positive versus WOS-negative lesions was 96.2% (25/26) and 4.3% (1/23), respectively (P < 0.001, Fisher's exact test). WOS was present in GI- and I-type lesions, but not in G-type lesions.

CONCLUSIONS

WOS may be LD that have been accumulated in the superficial part of the gastric neoplasia of a certain intestinal phenotype.

Histopathological phenotypes of early gastric cancer and its background mucosa

Recent advances in endoscopic submucosal dissection (ESD) techniques contribute to endoscopic treatment of early gastric cancer (EGC). Recognition of chronic atrophic gastritis as the background is important for high-quality detection and diagnosis of EGC. But, relationships between EGC and atrophy of the background gastric mucosa caused by Helicobacter pylori are not well understood. The present study demonstrated histopathological phenotypes of EGC, as well as chronic atrophic gastritis as background mucosa of EGC. We evaluated mucosal heights, number of glands, and degree of intestinal metaplasia (IM) of the background gastric mucosa, using 81 cases of EGC resected by ESD. Gastric phenotype cancer cases showed IM of the background gastric mucosa less frequently, compared with intestinal phenotype cancer cases (score of IM, 1.15 vs. 1.65, P = 0.012). The average mucosal heights around EGC were lower in moderately to poorly differentiated adenocarcinoma cases than well differentiated adenocarcinoma cases (442.6 µm vs. 500.2 µm, P = 0.011). The mucosal atrophy indicated by average heights of background mucosa was low in the gastric phenotype cancer cases, compared with the intestinal phenotype cancercases (452.8 µm vs. 505.6 µm, P = 0.018). In the fundic gland area, the mucosal heights were low in the gastric phenotype cancer cases, compared with the intestinal phenotype cancer cases (413.2 µm vs. 495.5 µm, P = 0.015). Our results using EGC specimens indicated that gastric phenotype cancer and moderately to poorly differentiated adenocarcinoma had atrophic background mucosa with lower mucosal heights and less IM. The atrophic gastric mucosa with less IM is thought to play an important role in gastric carcinogenesis, especially tumoriogenesis of gastricphenotype cancer.

Mucin phenotype of gastric cancer and clinicopathology of gastric-type differentiated adenocarcinoma

Differentiated adenocarcinoma of the stomach is classified into gastric or intestinal phenotypes based on mucus expression. Recent advances in mucin histochemistry and immunohistochemistry have highlighted the importance of such a distinction, and it is important clinically to distinguish between gastric- and intestinal-type differentiated adenocarcinoma. However, a clinical and pathological diagnosis of this type is often difficult in early gastric cancer because of histological similarities between a hyperplastic epithelium and low-grade atypia. Furthermore, determining tumor margins is often difficult, even with extensive preoperative examination. It is therefore critical to consider these diagnostic difficulties and different biological behaviors with high malignant potential when treating patients with gastric-type differentiated adenocarcinoma.

Relationship between clinicopathological features and mucin phenotypes of advanced gastric adenocarcinoma

AIM

To investigate a relationship between the clinicopathological features and mucin phenotypes in advanced gastric adenocarcinoma (AGA).

METHODS

Immunohistochemical staining was performed to determine the mucin phenotypes in 38 patients with differentiated adenocarcinomas (DACs), 9 with signet-ring cell carcinomas (SIGs), and 48 with other diffuse-type adenocarcinomas (non-SIGs) of AGA. The mucin phenotypes were classified into 4 types: gastric (G), gastrointestinal (GI), intestinal, and unclassified.

RESULTS

The G-related mucin phenotypes were highly expressed in all the histological subtypes of AGA. The expression of the GI phenotype in SIG patients was lower than that in DAC patients (P = 0.02), and this phenotype was observed in 56% of the non-SIG patients in the intramucosal layer. Among non-SIG cases, the expression of the GI phenotype was significantly higher in patients with extended adenocarcinomas and those with positive rates of lymph node metastasis. There was no difference between the expressions of the G and other GI phenotypes factors. Among DAC and non-SIG patients, there were no differences between the survival rates of the corresponding patient groups.

CONCLUSION

The GI phenotype might possess more invasive characteristics than the G phenotype in non-SIG. Neither of the phenotypes indicated a poor prognosis of DAC and non-SIG.