Stomach Cancer: Causes, Symptoms, and Treatment Options

Introduction

Stomach cancer, also known as gastric cancer, is a formidable adversary in the realm of oncology. While its incidence has decreased in many parts of the world over the past few decades, it remains a significant health concern globally. This comprehensive guide will delve into the intricacies of stomach cancer, exploring its causes, symptoms, and the array of treatment options available to patients.

Understanding Stomach Cancer

Stomach cancer occurs when cells in the stomach grow and divide uncontrollably, forming a tumor. The stomach, a J-shaped organ in the upper abdomen, plays a crucial role in digestion. It's divided into five main regions: the cardia (near the esophagus), fundus (upper part), body or corpus (main part), antrum (lower part), and pylorus (bottom part connecting to the small intestine).

Types of Stomach Cancer

While several types of cancer can occur in the stomach, the most common is adenocarcinoma, accounting for about 90-95% of cases. Adenocarcinoma begins in the cells of the stomach's inner lining (mucosa). Other less common types include:

1. Lymphomas: Cancers of the immune system tissue

2. Gastrointestinal stromal tumors (GISTs): Rare tumors that start in specific stomach cells called interstitial cells of Cajal

3. Neuroendocrine tumors: Tumors that develop from cells of the nervous and endocrine systems

Adenocarcinomas are further classified into two main subtypes:

1. Intestinal type: More common, tends to form glandular structures, and is often preceded by precancerous changes in the stomach lining.

2. Diffuse type: Doesn't form glandular structures, can be more aggressive, and is more common in younger individuals.

Stomach Cancer Causes and Risk Factors

While the exact cause of stomach cancer isn't always clear, several factors can increase the risk:

1. Helicobacter pylori (H. pylori) infection: This bacteria, which can cause stomach ulcers, is a significant risk factor. Long-term infection can lead to chronic inflammation and precancerous changes in the stomach lining.

2. Diet: A diet high in smoked and salted foods, processed meats, and low in fruits and vegetables may increase risk. These foods may contain nitrates and nitrites, which can be converted into cancer-causing compounds in the body.

3. Smoking: Tobacco use can double the risk of stomach cancer. Smoking exposes the stomach lining to harmful chemicals that can damage DNA and lead to cancer development.

4. Obesity: Being overweight or obese is associated with an increased risk, particularly for cancers in the upper part of the stomach.

5. Genetic factors: Certain inherited conditions can increase risk, including:

   - Lynch syndrome

   - Hereditary diffuse gastric cancer

   - Familial adenomatous polyposis (FAP)

   - Peutz-Jeghers syndrome

6. Age: Stomach cancer is more common in people over 50. The average age at diagnosis is 68.

7. Gender: Men are more likely to develop stomach cancer than women, possibly due to hormonal factors or higher rates of risk factors like smoking.

8. Previous stomach surgery: Procedures that alter the stomach environment, such as those for ulcers, may increase cancer risk.

9. Pernicious anemia: This condition affects the body's ability to absorb vitamin B12 and is associated with an increased risk of stomach cancer.

10. Chronic gastritis: Long-term inflammation of the stomach lining can increase risk, particularly a type called atrophic gastritis.

11. Epstein-Barr virus infection: This virus has been linked to some cases of stomach cancer, particularly a type called lymphoepithelioma-like carcinoma.

12. Occupation: Workers in the coal, metal, and rubber industries may have a higher risk due to exposure to certain substances.

Symptoms of Stomach Cancer

Early-stage stomach cancer often doesn't cause symptoms, which can make it challenging to detect. As the cancer progresses, symptoms may include:

1. Persistent abdominal pain or discomfort: Often a vague pain in the upper abdomen.

2. Early satiety: Feeling full after eating small amounts of food.

3. Dysphagia: Difficulty swallowing, which may indicate a tumor near the esophagus.

4. Nausea and vomiting: Sometimes with blood, which may appear red or look like coffee grounds.

5. Unintentional weight loss: Often significant and unexplained.

6. Loss of appetite: A general disinterest in food or feeling of fullness.

7. Fatigue or weakness: Often due to anemia caused by chronic blood loss.

8. Blood in the stool: Which may appear black and tarry (melena).

9. Indigestion or heartburn: Persistent symptoms that don't improve with treatment.

10. Swelling or fluid build-up in the abdomen: This can occur in advanced stages.

11. Yellowing of the skin and eyes (jaundice): In cases where the cancer spreads to the liver.

12. Difficulty eating: Due to obstruction or pain.

It's important to note that these symptoms can be caused by many other conditions, many of which are less serious than cancer. However, if you experience persistent symptoms, it's crucial to consult a healthcare professional for proper evaluation.

Diagnosis of Stomach Cancer

If stomach cancer is suspected, several diagnostic tests may be performed:

1. Upper endoscopy: A thin, flexible tube with a camera is passed down the throat to examine the stomach lining. Biopsies can be taken during this procedure.

2. Barium swallow: The patient drinks a liquid containing barium, which coats the stomach, making it visible on X-rays.

3. CT scan: Detailed cross-sectional images of the body can show the extent of the cancer.

4. PET scan: This can help detect cancer that has spread beyond the stomach.

5. Endoscopic ultrasound: This combines endoscopy with an ultrasound probe to provide detailed images of the stomach wall and nearby lymph nodes.

6. Laparoscopy: A surgical procedure that allows doctors to look inside the abdomen for signs of cancer spread.

Staging of Stomach Cancer

If stomach cancer is diagnosed, determining its stage is crucial for planning treatment. The TNM system is commonly used:

- T (Tumor): Describes how far the tumor has grown into the stomach wall.

- N (Nodes): Indicates whether the cancer has spread to nearby lymph nodes.

- M (Metastasis): Shows whether the cancer has spread to distant parts of the body.

Stages range from 0 (very early) to IV (advanced), with higher numbers indicating more extensive disease.

Stomach Cancer Treatment

Treatment for stomach cancer depends on several factors, including the stage of the cancer, its location, and the patient's overall health. Common treatment options include:

1. Surgery: This is the primary treatment for many cases of stomach cancer. Options include:

   - Endoscopic mucosal resection: For very early-stage cancers limited to the stomach's inner lining.

   - Partial gastrectomy: Removal of part of the stomach, typically for cancers in the lower part of the stomach.

   - Total gastrectomy: Removal of the entire stomach, necessary for cancers in the upper part of the stomach or those that have spread throughout the stomach.

   - Lymph node removal: Often performed along with stomach surgery to check for cancer spread.

   After a total gastrectomy, the esophagus is typically connected directly to the small intestine. Patients may need to make significant dietary changes and take vitamin supplements.

2. Chemotherapy: The use of drugs to kill cancer cells. It may be used:

   - Before surgery (neoadjuvant chemotherapy) to shrink tumors and make them easier to remove.

   - After surgery (adjuvant chemotherapy) to kill any remaining cancer cells and reduce the risk of recurrence.

   - As the primary treatment for advanced cancer that can't be surgically removed.

   Common chemotherapy drugs for stomach cancer include 5-fluorouracil, capecitabine, oxaliplatin, and cisplatin.

3. Radiation therapy: The use of high-energy beams to kill cancer cells. It's often used in combination with chemotherapy (chemoradiation). This approach may be used:

   - Before surgery to shrink tumors.

   - After surgery to kill any remaining cancer cells.

   - To relieve symptoms in advanced cancer.

4. Targeted therapy: These drugs target specific abnormalities in cancer cells. Examples include:

   - Trastuzumab (Herceptin) for HER2-positive stomach cancers.

   - Ramucirumab (Cyramza) to inhibit blood vessel growth in tumors.

   - Entrectinib (Rozlytrek) for cancers with NTRK gene changes.

5. Immunotherapy: This treatment helps the body's immune system fight cancer. Drugs like pembrolizumab (Keytruda) and nivolumab (Opdivo) have shown promise in treating certain types of stomach cancer, particularly those with high microsatellite instability (MSI-H) or deficient mismatch repair (dMMR).

6. Palliative care: This focuses on providing relief from symptoms and improving quality of life, regardless of the stage of cancer. It may include treatments to relieve pain, nausea, or blockages in the stomach.

Prevention and Screening

While not all cases of stomach cancer can be prevented, certain steps may help reduce risk:

1. Maintain a healthy diet rich in fruits and vegetables: These foods are high in antioxidants and may help protect against cell damage.

2. Quit smoking: Tobacco use increases the risk of many cancers, including stomach cancer.

3. Maintain a healthy weight: Obesity is a risk factor for several types of cancer.

4. Treat H. pylori infections promptly: If you're diagnosed with an H. pylori infection, complete the full course of treatment prescribed by your doctor.

5. Limit consumption of smoked and heavily salted foods: These may increase the risk of stomach cancer.

6. Consider preventive surgery: For individuals with certain inherited conditions that greatly increase stomach cancer risk.

In countries with high rates of stomach cancer, such as Japan and South Korea, screening programs have been implemented. These typically involve regular endoscopies or tests for H. pylori. However, in countries where stomach cancer is less common, routine screening is not typically recommended for the general population.

Conclusion

Stomach cancer is a serious condition, but advancements in detection and treatment have improved outcomes for many patients. Early detection is crucial, so it's important to be aware of potential symptoms and risk factors. If you have concerns about stomach cancer, consult with a healthcare professional. They can provide personalized advice based on your individual risk factors and symptoms.

Living with a stomach cancer diagnosis can be challenging, both physically and emotionally. Support groups and counseling services can be valuable resources for patients and their families. Additionally, clinical trials may offer access to new and potentially promising treatments.

Remember, while a cancer diagnosis can be overwhelming, there are many treatment options available and ongoing research continues to improve our understanding and management of this disease. With proper care and support, many people with stomach cancer can have positive outcomes and improved quality of life. The field of oncology is continuously evolving, bringing hope for better treatments and potentially even preventive strategies in the future.