Diagnosis & Staging

Diagnosis

The most common procedure used to diagnose gastric cancer is upper endoscopy. Using this method, a doctor can visualize the gastrointestinal tract, obtain a biopsy of the tumor, and diagnose up to 95% of gastric cancer cases. This is often combined with ultrasound to identify how deeply the cancer has penetrated the wall of the stomach and whether the tumor has spread to adjoining lymph nodes, both very important factors in determining the stage of the disease and deciding on appropriate treatment. Other tests used to establish the stage of the disease are CAT scans of the abdomen and chest, PET scans, MRIs, and laparoscopy, which is a surgical procedure that uses a fiber optic camera to view the organs and tissues directly.

Staging

Staging is the process by which doctors determine the extent to which a cancer has spread. This is critical in deciding on the appropriate course of treatment. Staging is generally done by classifying the cancer in three ways: the nature and extent of the tumor, the T in staging; its spread to lymph nodes, the N in staging; and its spread to other parts or organs in the body, the M in staging. Staging for gastric cancers is complex and includes many factors, but overall, cancers are described on a scale of I-IV based on the combination of the T N and M, stage I being the earliest or most limited form of the disease and IV the most advanced.

Stage IA: The cancer is confined to the stomach and may have invaded the inner layer of the stomach wall but has not spread to any lymph nodes or other organs.

Stage IB: The cancer has grown into the inner layers of the stomach wall and has spread to one or two lymph nodes but not anywhere else, or the cancer has grown into the outer muscular layers of the stomach but has not spread to the lymph nodes or other organs.

Stage IIA: The cancer has invaded the inner layer of the stomach and has spread to three to six lymph nodes; or the cancer has invaded the outer layers of the wall and has spread to one to two lymph nodes; or the cancer has grown through all the layers of muscle into the connective tissue outside the stomach but has not penetrated the peritoneal lining or spread to any lymph nodes or to surrounding organs.

Stage IIB: The cancer has invaded the inner layers of the wall of the stomach and spread to six or seven lymph nodes; or has invaded the outer layers and spread to three to six lymph nodes; or has spread to the connective tissue outside the stomach but has not penetrated the peritoneum and has spread to one or two lymph nodes; or has penetrated the peritoneum but not spread to any lymph nodes.

Stage IIIA: The cancer has invaded the outer muscular layers of the stomach and has spread to six or more lymph nodes; or has grown through all the muscular layers of the stomach, has not penetrated the peritoneum, but has spread to three to six lymph nodes; or the cancer has penetrated the peritoneum and has spread to one to two lymph nodes but not to other organs.

Stage IIIB: The cancer has grown through all the layers of the muscle into the connective tissue outside the stomach, has not penetrated the peritoneal lining, but has spread to seven or more lymph nodes; or the cancer has grown through all the layers of muscle, has penetrated the peritoneal lining and has spread to three to six lymph nodes; or the cancer has grown through all the layers of muscle into the connective tissue outside the stomach, has invaded nearby organs or structures and may or may not have spread to one to two lymph nodes.

Stage IV: The cancer has spread to distant parts of the body besides the area around the stomach.

When a cancer returns or recurs after initial treatment, the staging usually changes to reflect the extent of the disease. Recurrences can be local, meaning that they occur at or near the site of the original tumor or may be a distant metastasis, meaning that the cancer appears in another part of the body.