Gastric cancer: Clinical sciences

Gastric cancer is a malignant tumor of the stomach that is typically diagnosed in advanced stages due to the lack of symptoms. Even with early diagnosis and treatment, the rates of morbidity and mortality remain high for these patients. Unfortunately, about half of patients present with distant metastasis, making curative treatment very difficult. The majority of gastric cancers are adenocarcinomas, as the tumor often starts in the mucosal lining of the stomach. The treatment of gastric cancer is based on the staging of the disease.

Alright, when a patient presents with chief concern suggesting gastric cancer, the first step is to obtain a focused history and physical exam, as well as labs including CBC, CMP, and H. Pylori testing. Patients with gastric cancer are often asymptomatic, but some may report symptoms like dyspepsia, dysphagia, epigastric pain, nausea, or anorexia.

They might also report a recent history of associated anemia or weight loss, which should get you to think about malignancy. There are several risk factors you should look for, including a history of H. pylori and Epstein-Barr virus infections, pernicious anemia, chronic gastritis, smoking,diet of smoked or pickled foods, high-salt diet, or a family history of gastric cancer. The patient’s race might also be a risk factor, especially if they are of Eastern Asian, Eastern European, and South American descent.

When it comes to the physical exam, it’s usually unremarkable. However, in some cases, you might find a palpable epigastric mass or a distended stomach. Other findings may include hepatomegaly, or a Sister Mary Joseph nodule, which represents periumbilical metastatic disease.

Make sure to examine other lymph nodes to check for lymphadenopathy, such as Virchow Nodes, located in the left supraclavicular region, and Irish Nodes around the anterior axillary area. Keep in mind that these physical exam findings usually indicate advanced disease. Finally, labs typically show anemia, electrolyte abnormalities, or elevated liver enzymes. Additionally, H. pylori testing might be positive. If you see these findings, suspect gastric cancer.

Now that you suspect gastric cancer, it’s time to confirm your diagnosis. Your next step is to obtain an upper endoscopy with biopsy, also known as esophagogastroduodenoscopy, or EGD for short, along with an endoscopic ultrasound. This will provide direct visualization of the tumor and its anatomic location, as well as confirmatory tissue diagnosis.

On endoscopy, the tumor might appear as a polypoid, fungating, ulcerated mass, or diffusely infiltrative lesions. The biopsy results may show invasive adenocarcinoma, and histologic features like signet ring cells, which are filled with mucin and have peripheral nuclei. On the other hand, endoscopic ultrasound will give you an idea about the depth of tissue invasion.

Remember that the stomach wall is composed of 5 layers: mucosa, submucosa, muscularis propria, subserosa, and serosa. On the ultrasound, you’ll be able to see to which tissue level the tumor has invaded, which is very important for staging.

Interestingly, invasion of the mucosa and or the submucosa are very common. In addition, the ultrasound might also show perigastric lymphadenopathy. With all these findings on endoscopy, biopsy, and ultrasound, you can confirm the diagnosis of gastric cancer.

Alright, once you have confirmed your diagnosis, your next step is to stage the cancer using the TNM system. Generally, staging gastric cancer is based on the depth of tumor invasion, locoregional lymph node involvement, and the presence of metastatic disease.

Since you already got an idea of how deep the tumor goes based on the endoscopic ultrasound, at this step you’ll need to determine lymph node involvement and look for metastatic disease. To do this, first obtain a CT chest, abdomen, and pelvis. Sometimes, you might need additional tests like a PET scan or a fine-needle aspiration of any suspicious perigastric lymph node.

Okay, let’s start with early disease. In this case, endoscopic ultrasound is showing the tumor that is limited to the mucosal layer. Here, you might find a tumor that hasn’t invaded lamina propria, which is referred to as “in situ” and that’s stage 0. If it invaded lamina propria, but hasn’t invaded submucosa, then it’s stage 1A. In both cases, there’s no evidence of lymphadenopathy or metastasis. If you see these findings, diagnose Stage 0 or I gastric cancer.

To decide on a treatment, you’ll need to assess endoscopy findings. If the tumor is 2 cm or less without ulceration, proceed with endoscopic resection. You should also start the patient on antibiotics for H. Pylori infection.

Now, if the endoscopic resection was complete, meaning that margins are free of cancer cells, the treatment is considered curative and only surveillance is recommended. Surveillance includes a history and physical every 3 to 6 months for 1 to 2 years, then 6 to 12 months for 3 to 5 years, and annually thereafter. EGD should also be performed every 6 months for the first year, and then annually up to 5 years.