Stomach Cancer (Gastric Adenocarcinoma)

What is Gastric Cancer (Gastric Adenocarcinoma)?

Gastric cancer, also known as gastric adenocarcinoma or simply “stomach adenocarcinoma,” is a type of cancer that originates from the glandular cells lining the inner surface of the stomach. It is the most common form of stomach cancer and accounts for the majority of gastric cancer cases.

Onset and Spread of Cancer

Gastric adenocarcinoma usually develops from the mucus-producing cells in the inner lining of the stomach, known as the gastric mucosa, or from the cells inside the gastric glands. The cancer can spread to the inner layers of the stomach walls and may metastasize to lymph nodes or other organs.

What is Gastric Cancer Genetic Testing?

Gastric cancer genetic testing is a medical test used to determine an individual’s risk of developing cancer and to assess genetic predisposition. This test looks for a “mutation” (also known as a “variant”) that increases susceptibility to cancer in genes associated with gastric cancer or a “change” in a gene that may alter its function.

Who Should Consider Gastric Cancer Genetic Testing?

Gastric cancer genetic testing is recommended for individuals with specific risk factors or a family history of gastric cancer. The following factors should be considered:

Family History: Individuals with a family history of gastric cancer, especially those with first-degree relatives (parents, siblings) affected, should consider genetic testing. The importance of testing increases significantly when multiple cases exist within the family.
Genetic Mutations: People carrying certain genetic mutations may be at increased risk. For example, mutations in the CDH1 gene can raise the risk of hereditary diffuse gastric cancer. Therefore, those carrying such mutations should consider genetic testing.
Personal History of Gastric Cancer: Individuals diagnosed with gastric cancer or those who have had cancer in the past should consider genetic testing. In such cases, family history and genetic factors gain even more importance and should be thoroughly investigated.
Other Cancer Types: Those with personal or family histories of other cancers (e.g., colorectal cancer, breast cancer) should also consider genetic testing, as certain genetic syndromes may increase the risk of multiple cancer types.
Multiple Cancer History: Individuals or families with multiple cancers or multiple occurrences of the same cancer may require genetic testing, as this could indicate a genetic predisposition.
Personal Risk Factors: People with risk factors such as smoking, excessive alcohol consumption, or diets high in salt or smoked foods should be evaluated for gastric cancer genetic testing.

Genetic testing should be conducted alongside genetic counseling and evaluated under the supervision of a healthcare professional. Test results can help create a personalized medical plan based on individual and family medical history.

Screening Tests for Determining the Hereditary Nature of Gastric Cancer

These tests are used to understand whether a cancer in an individual or family is hereditary. The goal of these tests is to determine both the risk of recurrence or the risk of developing cancer in another organ for the affected person, and to identify other at-risk family members.

Familial Cancer Predisposition Screening: Screening for genetic changes that increase cancer risk.
- Hereditary Cancer Screening Panel: This panel includes approximately 220 genes known to be associated with cancer, and about 400 “candidate” genes suspected of having a cancer link. New cancer-related genes are added as they are identified, and the panels are regularly updated. A blood sample is taken from the patient for this test.
- The test helps individuals better understand their disease risk, make informed decisions about early detection and preventive strategies, and determine the appropriate screening and follow-up plans.

The Role of Genetic Testing in Determining Gastric Cancer Risk

Let’s also discuss how genetic testing can be used for risk reduction and prevention of gastric cancer. About 15% of individuals diagnosed with cancer have hereditary cancer. In hereditary cancers, treatment approaches and prevention strategies differ. Family members of individuals with hereditary cancer are also at risk. Therefore, identifying hereditary cancer is essential for both guiding treatment and protecting at-risk family members. All individuals diagnosed with cancer, whether actively undergoing treatment or in remission, should undergo genetic testing.

Furthermore, individuals with a family history of cancer should consider testing to assess their own risk. Based on test results, decisions can be made about follow-up frequency, early detection strategies, and the most suitable screening methods for the individual. It also helps identify which family members should undergo genetic testing. Lifestyle recommendations (e.g., avoiding smoked foods) may also be provided.

Genetic Diagnostic Tests Used in Gastric Cancer

These tests support diagnosis in individuals with gastric cancer, predict disease progression, and guide treatment decisions:

HER2/ CerbB2 (Immunohistochemical Staining/Count) (IHC studies are performed separately on all blocks)
HER2/ CerbB2 (FISH)
MSI (Microsatellite Instability)
PDL1 Expression
KIT (c.2394C>T)
PIK3CA (Next-Generation Sequencing - NGS)
(Exon 9: E542 and E545; Exon 20: H1047) for MTOR (inhibitors)
Tumor Mutation Panel: Genetic panel tests that evaluate multiple genetic changes simultaneously using NGS (Next-Generation Sequencing). These tests can be performed on tumor tissue or on serum obtained via liquid biopsy from a patient’s blood. They assess mutations across numerous genes, calculate microsatellite instability, and determine the tumor mutation burden. These panels offer a more detailed analysis of the tumor’s genetic profile.

These tests are crucial for determining personalized treatment options and prognosis by identifying the unique characteristics of the tumor. Different centers offer tests with varying gene numbers. The panel used in our center includes an extensive range of gene mutations and evaluates tumor mutation burden (TMB), PDL/PDL1, and microsatellite instability. It also assesses polymorphisms related to potential toxic effects and drug efficacy of classical chemotherapeutic agents.

Gastric Cancer Genetic Testing and Treatment Planning

How can gastric cancer genetic testing influence treatment options?

The medications commonly referred to as “targeted therapies” or “smart drugs” are designed to specifically bind to the mutation site, reducing or eliminating the harmful effects of the gene.

Therefore, gastric cancer genetic testing plays a key role in risk assessment and developing personalized health plans. However, test results must always be interpreted under the guidance of a healthcare professional. Such tests can be valuable tools in creating a personalized health plan and reducing cancer risk.

What Are the Symptoms of Gastric Cancer?

Symptoms may vary from person to person and may not always be obvious. Common symptoms of gastric cancer include:

Stomach Pain and Dyspepsia: A persistent or frequent feeling of stomach pain may be an early symptom. Dyspepsia includes bloating, indigestion, and heartburn.
Difficulty Swallowing: May cause trouble swallowing, especially with solid foods, leading to a choking sensation.
Nausea and Vomiting: May cause digestive issues like nausea and vomiting, often occurring after or during meals.
Weight Loss: Sudden and significant weight loss, often due to loss of appetite or digestive issues, can be a symptom in advanced stages.
Bloody or Black Stools: Bleeding in the stomach can cause stools to appear bloody or black (melena), indicating bleeding from the stomach or upper intestines.
Fatigue and Weakness: Can result from impaired nutrient absorption.
Loss of Appetite: May lead to a reduced desire to eat.
Yellow Skin and Eyes: Jaundice, which may occur in advanced stages of certain cancers like gastric cancer, is characterized by yellowing of the skin and whites of the eyes due to liver involvement.

Please note that these symptoms can also be caused by other conditions. Do not self-diagnose as “cancer.” The most important point we emphasize is not to ignore health complaints. Early diagnosis increases the chance of effective treatment, so it is important to consult a doctor and seek professional medical advice if symptoms are present.