Gastric Cancer

21.03.2024

STOMACH CANCER DIAGNOSIS AND TREATMENT

Stomach cancer is a malignant disease that begins in the surface cells of the stomach and is characterized by the uncontrolled proliferation of these cells over time. This type of cancer, which usually progresses slowly, can be difficult to diagnose because it does not show symptoms in the early stages. Stomach cancer, which is a major public health problem worldwide, has an important place among cancer-related deaths. It is more common in developing countries and is more common in men than women. Risk factors include Helicobacter pylori infection, long-term acid reflux, dietary habits, smoking and family history. Early diagnosis greatly increases the treatability of stomach cancer. Therefore, individuals with risk factors are recommended to undergo regular screening and medical check-ups for early diagnosis. Stomach cancer is an important focus in efforts to reduce the global cancer burden and improve quality of life. Understanding and managing this disease plays an important role in cancer research and development of treatment strategies.

Image 1: Many environmental and genetic risk factors are responsible for the development of stomach cancer.

WHAT ARE THE RISK FACTORS?

Stomach cancer may be associated with various environmental, lifestyle and genetic factors.

Some factors that may increase the risk of stomach cancer:

Helicobacter pylori Infection: Chronic infection caused by this bacteria on the stomach lining can significantly increase the risk of stomach cancer.

Smoking: Smoking increases the risk of stomach cancer, especially in areas close to the entrance of the stomach.

Family History of Stomach Cancer: The risk is higher in people with a family history of stomach cancer.

Nutrition habits: Consumption of high-salt, smoked or nitrate-containing foods may increase the risk. Low fruit and vegetable consumption is also a risk factor.

Obesity: Excess weight and especially fat in the abdominal area can increase the risk of stomach cancer.

Chronic Gastritis or Stomach Ulcer: Long-term stomach inflammation or ulcers may increase the risk of developing stomach cancer.

Pernicious Anemia: This condition, associated with vitamin B12 malabsorption, may increase the risk of stomach cancer.

Stomach Polyps: Some types of stomach polyps, especially adenomas, can turn into cancer.

Ethnicity and Geographic Factors: Some ethnic groups and geographic regions have a higher risk of stomach cancer.

Alcohol Consumption: Excessive alcohol consumption may also increase the risk of stomach cancer.

Previous Stomach Surgeries: Some surgical interventions, especially for stomach ulcers or obesity, may increase the risk of stomach cancer in the long term.

Each of these risk factors may increase the likelihood of developing stomach cancer to different extents. While some risk factors can be modified (smoking, diet), some cannot (genetic factors, family history). Therefore, individuals with risk factors are recommended to undergo regular screening and medical check-ups for early diagnosis.

HOW DOES IT OCCUR?

The development of stomach cancer begins with genetic and molecular changes that occur in the stomach surface cells, and these changes lead to abnormal and uncontrolled proliferation of the cells. This process usually takes years and is triggered by the interaction of environmental, dietary and genetic factors. In particular, chronic infection caused by Helicobacter pylori bacteria leads to inflammation and damage to the stomach lining, which paves the way for the development of cancer. Other factors may include consumption of salty and processed foods, smoking, excessive alcohol use and a family history of stomach cancer. Genetic mutations may also play a role, especially some hereditary cancer syndromes, which increase the risk of stomach cancer. These factors cause DNA damage in stomach cells and disrupt the cells' normal growth and death processes. Over time, these abnormal cells accumulate and form tumors. In advanced stages, these cancerous cells can spread (metastasize) through the stomach wall and to lymph nodes and other organs. These interactions in the development of gastric cancer highlight the complex nature of the disease and the importance of various risk factors. This process makes it difficult to diagnose cancer early and develop effective treatment strategies.

Image 2: Stomach cancer can cause many complaints such as weight loss, nausea, vomiting and digestive disorders.

WHAT ARE THE SYMPTOMS?

Stomach cancer usually has no symptoms in the early stages, or its symptoms may be mild and vague. However, as the disease progresses, more pronounced symptoms appear. Symptoms of stomach cancer may include:

Abdominal Pain or Discomfort: There may be constant or intermittent pain or discomfort, especially in the stomach area.

Feeling of Fullness After Meal: An abnormal feeling of fullness may occur even after eating less than usual.

Anorexia: A general loss of appetite, especially decreased interest in favorite foods, may be observed.

Weight Loss: Unexplained, sudden weight loss may occur.

Difficulty in Swallowing (Dysphagia): Difficulty in swallowing may occur, especially as the disease progresses.

Heartburn or Digestive Disorders: Constant heartburn, acid reflux or digestive problems may be detected.

Nausea and Vomiting: Especially blood may be detected in vomiting.

Blood or Darkness in Stool: Black color of the stool or obvious blood in the stool may be a sign of bleeding.

Fatigue and Weakness: A general lack of energy or feeling of fatigue may be observed.

Anemia: Iron deficiency anemia, which may occur due to hidden blood loss, may be detected.

These symptoms can also be seen in many other conditions besides stomach cancer. That's why it's important for people experiencing any of these symptoms to seek medical help for proper diagnosis and treatment. Early diagnosis can significantly increase the success rate of stomach cancer treatment.

HOW IS IT DIAGNOSED?

The diagnosis of stomach cancer is usually made through a combination of the patient's symptoms, medical history, and various diagnostic tests. The first step is a detailed evaluation of the patient's symptoms and family history. Then, upper gastrointestinal endoscopy, which is the most common and reliable diagnostic method, is performed. During this procedure, a thin, flexible tube (endoscope) with a camera and light source is inserted into the patient's stomach, allowing direct observation of the stomach surface. A biopsy is taken from suspicious areas and examined under a microscope. Additionally, the spread and stage of the cancer is evaluated using imaging tests such as computed tomography (CT) scan, ultrasonography, and sometimes positron emission tomography (PET) scan. These tests help determine the size of the cancer, its spread to the stomach wall and surrounding tissues, and the possibility of metastasis to lymph nodes or other organs. This comprehensive diagnostic process ensures that the correct diagnosis is made and an effective treatment plan is created.

WHAT ARE THE PATHOLOGICAL TYPES?

Gastric cancer is divided into different pathological types according to their histological features. These types are based on how cancer cells look under a microscope and how the cancer grows on the surface of the stomach.

The main pathological types of stomach cancer:

Adenocarcinoma: It is the most common type of stomach cancer and begins in the glandular cells of the stomach surface. Adenocarcinomas can be further divided into two subgroups:

Intestinal Type Adenocarcinoma: It is usually seen in elderly individuals and people exposed to stomach cancer risk factors.

Diffuse Type Adenocarcinoma (Linitis Plastica): It spreads and thickens the stomach wall and is more common in young patients.

Squamous Cell Carcinoma: It is a rare type of stomach cancer and begins in the squamous cells of the stomach surface.

Leiomyosarcoma and Gastrointestinal Stromal Tumors (GIST): These are rare types of cancer that arise from the smooth muscle or stromal (support) tissues of the stomach wall.

Lymphoma: It accounts for a small percentage of stomach cancers and originates from the lymphatic tissue of the stomach surface.

Carcinosarcoma: It is a rare type of stomach cancer that has characteristics of both glandular and sarcoma.

Neuroendocrine Tumors: They are rare tumors arising from neuroendocrine cells on the stomach surface and can show various behaviors.

Each pathological type has different importance in terms of diagnosis, treatment and prognosis of gastric cancer. Adenocarcinoma, in particular, accounts for the vast majority of stomach cancers and is often the focus of treatment and research studies. Microscopic examination of these types allows accurate classification of cancer and determination of appropriate treatment strategies. In the treatment of stomach cancer, it is important to examine the molecular characteristics of the tumor. For this purpose, some receptors and genetic markers are taken into account. In particular, the presence of the HER2/neu receptor may influence the response to certain targeted therapies (e.g., trastuzumab). The presence of these receptors and genetic changes can affect the behavior of the tumor and the patient's response to treatment, so these factors are taken into account when planning treatment and determining prognosis.

HOW IS TUMOR STAGING DONE?

Tumor staging in stomach cancer is a process to determine how far the cancer has spread. This process is usually done according to the TNM system. The TNM system consists of three main categories: Tumor (T), Lymph Node (N), and Metastasis (M).

Stomach cancer tumor staging, item by item:

T (Tumor):

T1: The tumor has affected the mucosa (the innermost layer of the stomach lining) or the submucosa (the layer under the mucosa).

T2: The tumor has spread to the submucosal layers, but not outside the stomach.

T3: The tumor has completely penetrated the stomach wall but has not spread to surrounding organs.

T4: The tumor has spread to surrounding tissues or organs.

N (Lymph Node):

N0: There are no cancer cells in the lymph nodes.

N1: There are a small number of cancer cells in nearby lymph nodes.

N2: There are cancer cells in more or more distant lymph nodes.

N3: There are cancer cells in many distant lymph nodes.

M (Metastasis):

M0: There is no distant metastasis.

M1: There is metastasis to distant organs or lymph nodes.

This staging system helps determine appropriate treatment options by evaluating the spread of the disease. However, clinical evaluation and various diagnostic methods by your doctor are essential for definitive diagnosis and staging.

Image 3: Stomach cancer is divided into stages according to spread on the stomach surface, lymph node involvement, and spread to distant organs.

HOW IS TREATMENT DONE ACCORDING TO STAGES?

Stomach cancer treatment varies depending on the stage of the disease. Different treatment approaches can be applied at each stage. Below are common treatment methods according to different stages of stomach cancer:

Stage 0 (In situ Cancer):

Early-stage tumors can be removed with minimally invasive procedures such as endoscopic mucosal resection (EMR) or endoscopic submucosal dissection (ESD).

Stage I:

Surgery: It is the process of removing the tumor and some surrounding tissues (gastrectomy).

Adjuvant therapy: In some cases, chemotherapy or radiotherapy may be applied after surgery.

Stage II and III:

Neoadjuvant therapy: Chemotherapy or chemoradiation before surgery may be used to shrink the tumor and increase the success of surgery.

Surgery: Gastrectomy and removal of surrounding lymph nodes may be performed.

Adjuvant therapy: Additional treatment (usually chemotherapy or chemoradiotherapy) may be recommended after surgery.

Stage IV (Metastatic Cancer):

Palliative care: Treatments are given to relieve pain and other symptoms.

Chemotherapy: May be administered to slow the spread of the disease, reduce symptoms, and improve quality of life.

Targeted therapies: Some biological agents and immunotherapy may be used depending on the characteristics of the tumor.

Radiotherapy: May be used to control pain or relieve certain symptoms.

Supportive and symptomatic treatment: Nutritional support, pain management and other palliative care approaches are important.

Treatment options may vary depending on the biological characteristics of the tumor, the patient's general health status and preferences. Therefore, it is important to have a detailed evaluation with an oncologist for the most appropriate treatment plan.

WHAT ARE THE DRUGS USED IN TREATMENT?

Drugs, chemotherapies, smart (targeted) drug treatments and immunotherapies used in the treatment of stomach cancer vary.

Here's an item-by-item look at some of these drugs:

Chemotherapy Drugs:

• Fluorouracil (5-FU): Often used together with other medications.

• Capecitabine: It is a drug taken orally.

• Cisplatin: Often combined with other chemotherapy drugs.

• Oxaliplatin: Often combined with other chemotherapeutic agents.

• Docetaxel: Often included in combination therapy.

• Epirubicin: Can be used with other medications.

• Irinotecan: An agent of choice in some cases.

Targeted (Smart) Drug Therapies:

• Trastuzumab: Used in HER2 positive stomach cancers.

• Ramucirumab: Angiogenesis inhibitor prevents angiogenesis in gastric cancer.

• Pertuzumab: Used in some HER2 positive cancers.

Immunotherapies:

• Pembrolizumab (PD-1 inhibitor) is especially effective in cancers with certain genetic alterations, such as MSI-H or dMMR.

• Nivolumab: Often used to treat advanced or metastatic stomach cancer.

The use of these medications varies depending on the characteristics of the patient's cancer, general health status, and previous treatments received. Additionally, the use of these drugs may be associated with various side effects, so they should be used under the supervision and recommendation of a doctor. The medications on this list may change with ongoing research and developments in the field of treatment.

HOW SHOULD FOLLOW-UP BE DONE AFTER RECOVERY?

Follow-up after gastric cancer treatment is critical to monitor the patient's condition and detect possible recurrence early. More frequent doctor visits are generally recommended in the first years after treatment. During these visits, a physical examination, blood tests (for example, complete blood count, liver function tests), and imaging tests (for example, computed tomography or endoscopy) are performed if necessary. Patients' nutritional status and weight changes are also closely monitored, as stomach cancer treatment may affect eating habits. Patients should also share symptoms and any health changes with their doctors. The follow-up period may vary depending on the patient's general health condition, the stage of the cancer and the type of treatment. In this process, regular follow-up and early intervention play a vital role in managing possible relapses or complications.