선종. adenoma. EndoTODAY 이준행

[Lecture note] Gastric adenoma: to resect, ablate, or not (2014-7-12. 2014 International Hub in Advanced Endoscopy at Konkuk University)

There are no generally accepted definitions of dysplasia and adenoma of the stomach. Dysplasia is best defined as an unequivocal neoplastic epithelial alteration. Detailed histological findings of gastric dysplasias have been described in many literatures. However, endoscopic or gross findings of gastric dysplasia need to be studied in more detail. Macroscopically, two types of dysplasias are recognized: elevated dysplasia and flat/depressed dysplasia.

Definition for adenoma is somewhat confusing. In the western countries, adenomas mean elevated or nodular lesions with dysplasia in histology, so only elevated type of dysplasias are considered as adenomas. In the eastern countries, however, both elevated and flat/depressed types of dysplasia are considered as adenomas. Actually, the terms dysplasia and adenoma are thought to be the same thing in the clinical practice. The difference is who prefers what. Usually, pathologists prefer dysplasia, and endoscopists prefer adenoma.

Dysplasias are graded as either high grade or low grade. So, adenomas (= dysplasias) can be divided as adenoma with low grade dysplasia (LGD) and adenoma with high grade dysplasia (HGD). In Korean pathologists' tradition, adenoma usually means adenoma with LGD.

In Korea, gastric adenomas with HGD are usually treated by endoscopic resection. In the final pathology for the resected specimen, 1/3 to 1/2 of adenomas with HGD are upgraded as cancer. Therapeutic approach for adenomas with HGD should be the same for early gastric cancers within absolute indications for endoscopic submucosal dissection (ESD).

Situations for gastric adenomas with LGD are quite different. After endoscopic resection of adenoma with LGD, the risk of histological upgrading is relatively small. About 10-20% of adenomas with LGD are upgraded to adenoma with HGD and 5-10% are upgraded to early gastric cancers. So, the clinical options for adenomas with LGD can be resection (EMR or ESD), ablation, and observation. In the lecture, some data regarding the advantages and disadvantages of each treatment options will be discussed.

We need to start from the definition of dysplasia. What is dysplasia? Most simply, it is an unequivocal neoplastic transformation.

There are three important histological characteristics for gastric dysplasia. They are disorganized mucosal architecture, abnormal differentiation, and cellular atypia.

Based on those three characteristics, a lot of grading schemes have been proposed. Isn’t it confusing?

Recently, dysplasias are histologically divided into two groups, low grade dysplasia and high grade dysplasia.

Endoscopically, dysplasias can be divided into elevated dysplasias and flat/depressed dysplasias.

What is the relationship between dysplasia and adenoma? Definition of adenoma is somewhat confusing. In the western countries, adenomas mean elevated or nodular lesions with dysplasia in histology, so only elevated type dysplasias are considered as adenomas. In the eastern countries, however, both elevated and flat/depressed dysplasias are considered as adenomas. Actually, the two terms dysplasia and adenoma are thought to be the same thing in the clinical practice. The difference is who prefers what. Usually, pathologists prefer dysplasia, and endoscopists prefer adenoma.

Ideally, there should be no difference in the histological diagnosis of adenoma and cancer, because everybody is using the Vienna classification. However, it’s not so simple.

The concept of cancer may be different between countries. In Japan, structural and cytological features are important. In the western countries and in Korea, evidence of invasion is much more important. Actually, we think that most cases of HGD in the western system and Korea, as well as some LGD, become carcinoma in the Japanese system.

This is a famous study comparing the pathological diagnosis of gastric neoplasm between western countries and Japan. About half of the cases were adenomas by the western point of view. However, only 7 percent were adenomas by Japanese doctors. There is a huge difference. Korean pathologists seem to be close to western doctors in the diagnosis of gastric adenomas.

This is my understanding of this confusing situation. Three blocks are adenoma with LGD, adenoma with HGD and EGC in Korea. The next three blocks are diagnoses in Japan. So, most cases of adenoma with HGD in Korea may be EGCs in Japan.

Professor Sun Young Lee at Konkuk University discussed this dilemma in the recent editorial. Most cases of low grade dysplasias are endoscopically resected in Korea, but observation is frequently chosen in Japan. High grade dysplasias are endoscopically resected not only in Korea but also in Japan. But the diagnosis is different.

The natural history of adenoma is not clear yet. In this old study, the low grade adenomas progressed to cancer in 15% in 10 years.

Excluding palliative surgeries, we have endoscopically or surgically treated more than seventeen hundred gastric cancers in 2012 at Samsung Medical Center. Among them, 72% were early gastric cancers. In early gastric cancers, cases within absolute indications were 25%. There were 263 cases of gastric adenomas in a single year.

This is an example of endoscopically treated adenoma with low grade dysplasia.

Almost the same thing except that it was an adenoma with high grade dysplasia.

I performed ESD for a small depressed adenoma with LGD.

However, the final ESD pathology was adenocarcinoma.

It’s another example of gastric cancer with initial biopsy of adenoma. In this case, the initial biopsy was adenoma with low grade dysplasia.

In this old report from my institution, 7 out of 22 adenomas with HGD were actually carcinomas in the endoscopically resected specimen.

We reviewed the discrepancy between pre-treatment diagnostic groups and post-treatment diagnostic groups. As you can see in this complicated slide, the rate of discrepancy is more than expected. For adenoma with LGD, about 34 percents were upgraded as high grade dysplasias or cancers. For adenomas with HGD, 34 percents were upgraded as cancers.

This is a personal communication. About 1/3 to half of cases with high grade dysplasia are upgraded into cancers at Samsung Medical Center, Gangnam Severance Hospital, and Asan Medical Center.

In this report from Yonsei University, 51 out of 273 endoscopically resected low grade adenomas were upgraded into either HGD or adenocarcinoma. They evaluated the risk factors for upgrading, and recommended endoscopic resection for larger lesions and lesions without white discoloration

So, small pale flat elevated low graded adenomas can be easily treated by ablation therapy using argon plasma coagulation.

Ladies and gentlemen. I’d like to conclude my short presentation. For adenomas with HGD, endoscopic resection, preferably ESD, is recommended. For adenomas with LGD, endoscopic resection is preferred for larger lesions or lesions with central depression. Ablation is an easy and effective treatment for small pale flat/elevated adenomas with LGD.

Lecture note (WORD)

Presentation subnote (WORD)

[참고 자료]

1) EndoTODAY 선종

2) 위이형성의 진단과 치료 (text, PDF)

3) Lee SY. Gastric adenoma with low-grade dysplasia: two countries, two outcomes. Dig Dis Sci 2014 (PDF 0.2 M)

4) Shin-Fan Kuan. Pathology of gastric neoplasms (Available in the Internet, PDF 2.0 M)