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Medically reviewed by Dr. C.H. Weaver M.D. Medical Editor updated 6/2019

Stage 0 cancer is referred to as carcinoma in situ, which is cancer that involves only the superficial layer of cells lining the stomach.

Stage I gastric cancer is cancer that invades beneath the surface layer of cells lining the stomach. The cancer is referred to as Stage IA if the cancer does not involve the bladder muscle and has not spread to lymph nodes or distant sites in the body. The cancer is referred to as Stage IB if the cancer involves either the bladder muscle or 1 to 2 lymph nodes.

Surgery as Primary Treatment

Surgery is the primary treatment for early-stage gastric cancer. Depending on the extent and location of the cancer, surgery may involve endoscopic mucosal resection (use of an endoscope to view and remove only the cancerous area), removal of part of the stomach (subtotal gastrectomy), or removal of the entire stomach (total gastrectomy). Patients often have several surrounding lymph nodes removed as well, although there continues to be debate about how extensive this lymph node removal should be.

Patients with Stage I gastric cancer should consider treatment at a medical center with a surgical team that has experience and treats a large number of patients with gastric cancer each year. To learn more about surgical treatment, go to Surgery for Gastric Cancer.

Patients who cannot undergo the usual surgical resection of cancer can have small superficial gastric cancers removed through an endoscope passed through the esophagus. However, this approach precludes lymph node sampling or removal. To learn more go to Surgery and Gastric Cancer.

Strategies to Improve Treatment

Photodynamic Ablation: An alternative approach in patients who cannot undergo surgery is endoscopic photodynamic ablation. During photodynamic ablation, a photosensitizer is injected into a vein and the cancer is then treated with a red light laser through an endoscope, which kills the cells absorbing the photosensitiser. One clinical study designed to evaluate photodynamic ablation involved 22 patients. The results indicated that 73% had a complete response. An average of 2 treatment sessions was required and no severe side effects were experienced. Photodynamic treatment has also been used to treat recurrences after endoscopic surgery.

Adjuvant Therapy (Treatment after Surgery)

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It is important to understand that some patients with gastric cancer already have small amounts of cancer that have spread beyond the stomach and cannot be detected with any of the currently available tests. Undetectable areas of cancer are referred to as micrometastases.

It is the presence of micrometastases that causes cancer recurrence following treatment with surgery alone. For some patients, additional treatment aimed at these micrometastases can improve duration of survival and potential for a cure. The delivery of cancer treatment following local treatment with surgery is referred to as adjuvant therapy. Although some patients with Stage I gastric cancer may not need adjuvant therapy, those who do often receive a combination of chemotherapy and radiation therapy.

Strategies to Improve Treatment

The progress that has been made in the treatment of gastric cancer has resulted from the use of multi-modality treatment and improved patient and physician participation in clinical studies. Currently, there are several areas of active exploration aimed at improving the treatment of gastric cancer.

New Adjuvant Regimens: Development of new multi-drug chemotherapy treatment regimens that incorporate new or additional anti-cancer therapies is an active area of clinical research carried out in clinical trials. Adjuvant therapy may consist of chemotherapy alone or in combination with radiation therapy or targeted therapy.

Targeted therapies interfere with specific biological pathways involved in cancer growth or survival. A type of targeted therapy that improves outcomes for selected patients with advanced gastric cancer is Herceptin® (trastuzumab). Herceptin targets a protein known as HER2 that can stimulate cancer growth. Roughly 20% of patients with gastric cancer have cancer that overexpresses (makes too much of) this protein; these cancers are referred to as HER2-positive. For patients with HER2-positive, metastatic gastric cancer, treatment with Herceptin can improve overall survival.[1] Based on these results, studies are also evaluating the role of Herceptin and other targeted therapies for earlier-stage gastric cancer.

Neoadjuvant Therapy: The practice of administering chemotherapy before surgery is referred to as neoadjuvant. In theory, neoadjuvant chemotherapy can decrease the size of the cancer, thereby making it easier to remove with surgery. With the development of new chemotherapy regimens, new clinical trials of neoadjuvant therapy performed in patients with gastric cancer are currently ongoing.


  1. Bang Y-J, Van Cutsem E, Feyereislova A et al. Trastuzumab in combination with chemotherapy versus chemotherapy alone for treatment of HER2-positive advanced gastric or gastro-oesophageal junction cancer (ToGA): a phase 3, open-label, randomised controlled trial. Lancet. 2010; 376:687-697.