Gastric Cancer: Staging and Treatment

What is staging for cancer?

Staging is the process of learning how much cancer is in your body and where it is. Tests like upper endoscopy, barium swallow, ultrasound, CT scans, MRI, PET scan, laparoscopy, biopsy, and blood tests are done to help stage your cancer. Your providers need to know about your cancer and your health so that they can plan the best treatment for you.

Staging looks at the size of the tumor and where it is, and if it has spread to other organs. The staging system for gastric cancer is called the “TNM system,” as described by the American Joint Committee on Cancer. It has three parts:

• T-describes the size/location/extent of the "primary" tumor in the stomach, how far it has grown in the layers of the stomach wall, and if it is in any nearby organs or tissues.
• N-describes if the cancer has spread to the lymph nodes.
• M-describes if the cancer has spread to other organs (metastases).

Your healthcare provider will use the results of the tests you had to determine your TNM result and combine these to get a stage from 0 to IV.

How is gastric cancer staged?

Staging of gastric cancer is based on:

• The size of your tumor.
• If the cancer has spread to the lymph nodes, and if it has, how many lymph nodes are affected.
• If the cancer has spread to other organs. This is called metastasis.

Staging may be done at different times during treatment. A clinical stage is given based on any testing you have had done and can be used to decide on a treatment plan. A pathological stage is done after cancer has been removed during surgery. If you have chemotherapy or radiation before having surgery, you may be given another stage to see how well the treatment worked. Staging is important because it helps to guide your treatment plan and to see how your treatment is working. The staging system is very complex. It is helpful to understand the layers that make up the stomach first:

• Mucosa: First layer of the inside of the stomach. It is made of glands that release fluid that helps you digest.
• Submucosa: The second layer. It supports the mucosa and is made of blood and lymphatic vessels, and nerves.
• Muscularis: Third layer that is made of thick muscles that help mix food with digestive juices.
• Subserosa: Fourth layer that is made of supporting tissue for the serosa.
• Serosa: Outermost layer that is the lining that wraps around the stomach.

Below is a summary staging system. Be sure to talk to your provider about the stage of your cancer.

• Stage 0 (Tis, N0, M0): Also called carcinoma in situ, there are very abnormal-looking cells in the stomach lining OR there are cancer cells only in the top layers of the innermost layer of the stomach. The cancer has not spread to lymph nodes or organs.
• Stage IA (T1, N0, M0): The tumor has grown from the top layer of cells of the mucosa into the next layers of the stomach like the lamina propria, muscularis mucosa, or submucosa. It has not spread to the lymph nodes or organs.
• Stage IB (T1, N1, M0): The main tumor has grown from the mucosa into the lamina propria, muscularis mucosa, or submucosa and it has spread to 1 to 2 lymph nodes, but not to other organs.
• Stage IB (T2, N0, M0): The tumor has grown into the muscularis propria but not to the lymph nodes or other parts of the body.
• Stage IIA (T1, N2, M0): The tumor has grown from the mucosa into other layers and has spread to 3 to 6 lymph nodes but not to other parts of the body.
• Stage IIA (T2, N1, M0): The cancer has grown into the muscularis propria, and spread to 1 to 2 lymph nodes, but has not spread to other parts of the body.
• Stage IIA (T3, N0, M0): The tumor is growing into the subserosa layer but has not spread to lymph nodes or other parts of the body.
• Stage IIB (T1, N3a, M0): Cancer has grown from the top layers into other layers like the lamina propria, muscularis mucosa, or submucosa and has spread to 7 to 15 lymph nodes but not to other parts of the body.
• Stage IIB (T2, N2, M0): The main tumor is growing into the muscularis propria, to 3 to 6 lymph nodes, but not to other parts of the body.
• Stage IIB (T3, N1, M0): The main tumor is growing into the subserosa layer, has spread to 1 to 2 lymph nodes, and has not spread to other parts of the body.
• Stage IIB (T4a, N0, M0): The main tumor has grown through the stomach wall into the serosa, but has not spread to nearby lymph nodes or organs.
• Stage IIIA (T2, N3a, M0): The tumor is growing into the muscularis propria, and has spread to 7 to 15 lymph nodes, but not to other parts of the body.
• Stage IIIA (T3, N2, M0): The main tumor is in the subserosa layer, and has spread to 3 to 6 lymph nodes, but not to distant parts of the body.
• Stage IIIA (T4a, N1, M0): The tumor has grown into the serosa, and has spread to 1 to 2 lymph nodes, but not to distant parts of the body.
• Stage IIIA (T4a, N2, M0): The tumor has grown from the stomach wall into the serosa, and has spread to 3 to 6 lymph nodes, but has not spread to distant parts of the body.
• Stage IIIA (T4b, N0, M0): The tumor has grown through the stomach wall into nearby organs or tissues but has not spread to nearby lymph nodes or distant parts of the body.
• Stage IIIB (T1, N3b, M0): The tumor has grown from the mucosa to other layers, and has spread to 16 or more lymph nodes, but has not spread to other parts of the body.
• Stage IIIB (T2, N3b, M0): The main layer is growing into the muscularis propria layer and has spread to 16 or more nearby lymph nodes. It has not spread to distant parts of the body.
• Stage IIIB (T3, N3a, M0): The tumor has grown into the subserosa layer and to 7 to 15 lymph nodes. It has not spread to other parts of the body.
• Stage IIIB (T4a, N3a, M0): The main tumor has grown into the serosa but not into nearby organs or structures, it has spread to 7 to 15 nearby lymph nodes but has not spread to other parts of the body.
• Stage IIIB (T4b, N1, M0): The tumor has grown through the stomach wall into nearby tissues and has spread to 1 to 2 lymph nodes. It has not spread to other parts of the body.
• Stage IIIB (T4b, N2, M0): The tumor has grown into nearby tissues and into 3 to 6 lymph nodes. It has not spread to other parts of the body.
• Stage IIIC (T3, N3b, M0): The main tumor is growing into the subserosa layer, and has spread to 16 or more lymph nodes, but has not spread to other parts of the body.
• Stage IIIC: (T4a, N3b, M0): The tumor has grown into the serosa but not into nearby tissues. It has spread to 16 or more lymph nodes but not into other parts of the body.
• Stage IIIC: (T4b, N3a, M0): The tumor has grown into the stomach wall and nearby tissues. It is in 7 to 15 lymph nodes but not other parts of the body.
• Stage IIIC (T4b, N3b, M0): The tumor has grown through the stomach wall into nearby tissues and is in 16 or more lymph nodes. It has not spread to other parts of the body.
• Stage IV (Any T, Any N, M1): The cancer has or has not grown into any layers of the stomach wall and may or may not be in the lymph nodes. It has spread to other parts of the body like the liver, lungs, brain, or peritoneum.

How is gastric cancer treated?

Treatment for gastric cancer is based on your health, your goals, the size of the tumor, and if it has spread to the lymph nodes or other organs. There can be more than one type of treatment used to treat gastric cancer. Some of the treatments used include:

• Surgery.
• Chemotherapy.
• Radiation.
• Targeted Therapy.
• Immunotherapy.
• Clinical Trials.

Surgery

Surgery can be used to treat gastric cancer in some cases. There are a number of surgeries and procedures that can be used depending on your situation. Some of these are:

• Endoscopic Resection: An endoscope (thin, lighted tube) is placed down the throat and into the stomach. Tools at the tip of the endoscope can be used to cut out cancerous tissue for biopsy or to treat early-stage cancer.
• Partial Gastrectomy: Part of the stomach is removed. In some cases, the lower part of the esophagus, the fatty tissue that covers organs in the belly (omentum), the spleen, lymph nodes, or any other cancerous tissue may also need to be removed.
• Total Gastrectomy: The whole stomach is removed along with nearby tissues, lymph nodes, the spleen, and parts of the esophagus and small intestine. The small intestine and the esophagus are then connected together so you can eat and swallow.

Surgery can be done to treat your cancer or to help with side effects (also called palliative surgery). A feeding tube may be placed if you are having trouble eating or getting nutrients, or a stent can be placed to help make openings bigger so that food can move through. An ablation may also be done, which uses a laser to kill cancer cells that are causing bleeding or blockages.

Ask your provider if surgery should be used to treat your gastric cancer, what the potential side effects are, and what other treatments you may need.

Radiation

Radiation is the use of high-energy x-rays to kill cancer cells. Radiation can be used with chemotherapy before surgery to shrink the tumor, after surgery to kill any cancer cells left behind, or if you can’t have surgery. Three-dimensional conformal radiation therapy and intensity-modulated radiation therapy are most often used. You will need to go to a radiation treatment center 5 days a week for several weeks for your treatment. The treatments are painless and take just a few minutes. Radiation can cause side effects like skin issues, fatigue, nausea and vomiting, and diarrhea. Ask your provider how to best manage these side effects if radiation is part of your treatment.

Chemotherapy

Chemotherapy is the use of anti-cancer medicines that go through your whole body to treat cancer cells. These medicines may be given through a vein (IV, intravenously) or by mouth. Chemotherapy may be given before surgery (called neoadjuvant treatment), with radiation (called chemoradiation), after surgery (called adjuvant treatment), or as the main treatment if your cancer has spread to other parts of the body or if you can’t have surgery.

The chemotherapy medications used to treat gastric cancer include 5-FU, capecitabine, cisplatin, paclitaxel, oxaliplatin,carboplatin, epirubicin, irinotecan, trifluridine/tipiracil, and docetaxel. These may be used in combination you may be given more than one medication, which is called a regimen.

Chemotherapy can cause side effects like hair loss, fatigue, mucositis, nausea and vomiting, changes in how you eat, diarrhea, constipation, and changes in your blood counts. Talk to your provider about any side effects you are having and how to manage them.

Targeted Therapy

Targeted therapies are medications that target something specific to cancer cells, stopping them from growing and dividing. In gastric cancer, there are three types of targeted therapy used:

• Medications that target HER2 on the surface of some cancer cells that helps them to grow. These medications are trastuzumab and fam-trastuzumab deruxtecan.
• VEGF targeted medications stop new blood vessels from growing that give blood and nutrients to tumors. Ramucirumab is a targeted therapy that treats gastric cancer.
• TRK proteins can cause abnormal cell growth and cancer. Larotrectinib and entrectinib target TRK proteins.

Immunotherapy

Immunotherapy is the use of medications to help the immune system kill cancer cells. Some immune therapy medications are called immune checkpoint inhibitors and work to target checkpoints on immune cells to help the body attack cancer cells. Immunotherapy medications used to treat gastric cancer are nivolumab and pembrolizumab. They are PD-1 inhibitors that stop PD-1 from working and can help shrink tumors or stop them from growing. They can be given with or without chemotherapy.

Clinical Trials

You may be offered a clinical trial as part of your treatment plan. To find out more about current clinical trials, visit the OncoLink Clinical Trials Matching Service.

Making Treatment Decisions

Your care team will make sure you are included in choosing your treatment plan. This can be overwhelming as you may be given a few options to choose from. It feels like an emergency, but you can take a few weeks to meet with different providers and think about your options and what is best for you. This is a personal decision. Friends and family can help you talk through the options and the pros and cons of each, but they cannot make the decision for you. You need to be comfortable with your decision – this will help you move on to the next steps. If you ever have any questions or concerns, be sure to call your team.

You can learn more about gastric cancer at OncoLink.org.