Stomach Cancer: Symptoms, Causes & Treatment

Stomach cancer is a malignant tumor that can develop in any part of the stomach and may cause symptoms like heartburn, stomach pain, anemia, and loss of appetite. In many cases, stomach cancer does not cause early symptoms, allowing it to progress and be diagnosed at more advanced stages.

Stomach cancer is often linked to factors such as H. pylori infection, chronic gastritis, diet, and genetic predisposition. Diagnosis typically involves tests like endoscopy with biopsy, as well as imaging exams to assess the stage and spread of the tumor.

Treatment for stomach cancer depends on the stage of the disease and may include surgery, chemotherapy, radiation, or immunotherapy. These approaches aim to remove or control cancer growth and improve outcomes, especially when the condition is identified early.

Main symptoms

Most cancers do not cause noticeable symptoms in their early stages. However, you should see your doctor if you experience any of the following symptoms that may be associated with stomach cancer:

• Persistent heartburn

• Ongoing stomach pain

• Nausea or vomiting

• Diarrhea or constipation

• Feeling full after eating small amounts

• Unintentional weight loss

• Weakness or fatigue

• Vomiting blood or noticing blood in the stool

These symptoms are not specific to stomach cancer and can occur with other conditions, such as a stomach infection or gastric ulcer.

Because of this, it is important to consult a doctor to determine the underlying cause. Your doctor may recommend tests such as an endoscopy or imaging studies (for example, an MRI) to investigate further.

Read more about stomach cancer symptoms you should not ignore.

Confirming a diagnosis

A gastroenterologist typically evaluates suspected stomach cancer. Diagnosis usually involves blood tests and an endoscopy with a biopsy.

Additional tests, such as a CT scan, PET scan, or ultrasound, may also be ordered to confirm the diagnosis and assess how far the cancer has progressed. These results help guide treatment decisions and next steps.

Possible causes

The exact cause of stomach cancer is not fully understood, but several risk factors are strongly associated with its development:

• Infection with Helicobacter pylori (H. pylori)

• High intake of smoked or pickled foods

• History of stomach ulcers or untreated chronic gastritis

• Previous stomach surgery

• Conditions such as pernicious anemia, hypochlorhydria, or gastric atrophy

• Genetic predisposition, including a family history of stomach or other cancers

According to the American Cancer Society, the risk of stomach cancer increases with age and is higher in men.

Treatment options

Treatment options for stomach cancer depend on the stage of the disease and the person’s overall health. According to the National Cancer Institute, these may include surgery, chemotherapy, radiation therapy, targeted therapy, and immunotherapy.

1. Surgery

Surgery is a common treatment for stomach cancer and often offers the best outcomes, especially when the cancer is detected early. Depending on the case, surgery may remove only the tumor or include part of the stomach along with nearby lymph nodes.

Some surgical options include:

• Endoscopic mucosal resection: This procedure is used in the early stages of the disease. The tumor is removed using an endoscope, without the need for open surgery.
• Partial gastrectomy: This involves removing only the part of the stomach affected by cancer, while preserving as much healthy tissue as possible.
• Total gastrectomy: This involves removing the entire stomach. It is typically recommended when cancer affects most of the stomach or is located in the upper portion.

During gastrectomy (partial or total), the surgeon may also remove nearby lymph nodes for laboratory analysis. Examining these lymph nodes helps determine whether cancer has spread and how advanced it is, which is important for guiding further treatment.

In addition, organs around the stomach, like the pancreas or spleen, may also be assessed for cancer and removed as necessary. 

2. Chemotherapy

Chemotherapy for stomach cancer uses medications to kill cancer cells. These drugs may be taken by mouth or given intravenously (through an IV). Doctors often prescribe a combination of drugs to improve effectiveness.

Chemotherapy can be used before surgery to shrink the tumor, or after surgery to help eliminate any remaining cancer cells.

Chemotherapy can cause side effects such as:

• Nausea and vomiting
• Loss of appetite
• Hair loss
• Diarrhea
• Mouth sores
• Anemia

Because it affects the whole body, it can weaken your immune system and increase the risk of infections. These side effects usually improve a few days after the last treatment.

3. Radiation therapy

Radiation therapy for stomach cancer uses targeted radiation to destroy cancer cells or slow their growth. It may be given after surgery to eliminate any remaining cancer cells that were not removed. It can also be combined with chemotherapy to help reduce the risk of the cancer coming back. 

Radiation therapy can cause side effects such as:

• Skin burns in the treated area
• Nausea and vomiting
• Diarrhea
• Body aches
• Anemia

Side effects may be more intense when radiation therapy is combined with chemotherapy.

4. Immunotherapy 

Immunotherapy uses medications that help the immune system recognize and attack cancer cells. It may be used together with chemotherapy to slow cancer growth and spread.

Possible side effects include fever, weakness, nausea and vomiting, cough, and diarrhea.