Gastric cancer: Clinical sciences

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Introduction0:00–0:36

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.

History & Physical0:36–2:24

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.

Diagnosis2:24–3:46

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.

TNM Staging3:46–4:23

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.

Stage 0 and IA4:23–6:12

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. On the other hand, incomplete resection is considered if the resected tumor showed positive margins, invasion of the submucosa or muscularis propria, poor differentiation, or lymphatic invasion.
In this case, your next step is to obtain a surgical consultation for gastrectomy with lymphadenectomy. Now, if a patient has a tumor that’s more than 2 cm in size, you should directly proceed with gastrectomy with lymphadenectomy, as well as surveillance.
If you see these findings, diagnose Stage IA gastric cancer. Okay, let’s go back to our staging and talk about another option for stage 1A disease.

Stage IA6:12–6:41

If the ultrasound shows that the tumor has invaded the submucosa only, but there’s no lymph node involvement or metastasis on CT, we’re still talking about stage IA gastric cancer, but it has invaded a bit deeper than before.
In this situation, regardless of size or ulceration, the treatment involves gastrectomy with lymphadenectomy, followed by surveillance.
Alright, going back to our staging, let’s look at more advanced cases. If endoscopic ultrasound demonstrates a tumor that invades the submucosa or muscularis propria; with or without lymphadenopathy, but no metastasis on imaging, the patient has stage IB, II, or III gastric cancer.

Stage IB-III - No Metastasis6:41–8:48

IB indicates invasion to the submucosa; II invades the muscularis propria; while III means it invaded subserosal tissue; and all of these may show spreading to nearby lymph nodes.
The next step is to proceed with a staging laparoscopy and peritoneal cytology washings to assess for peritoneal dissemination of disease.
This is very important because peritoneal metastasis cannot be adequately visualized on CT or PET scans. If there’s no evidence of metastatic disease on laparoscopy, peritoneal cytology, or imaging, then the tumor is localized to the gastric tissue only.
For stage IB gastric cancer…Treatment involves gastrectomy with lymphadenectomy, adjuvant chemotherapy or chemoradiation for node-positive disease, followed by surveillance if the treatment was successful.
For stage II or III disease, neoadjuvant chemotherapy or chemoradiation might be needed to shrink the tumor before the gastrectomy and lymphadenectomy.
Similarly, adjuvant chemotherapy or chemoradiation might be needed for nodal disease; followed by surveillance if these treatments were successful.
For these patients, surveillance includes close follow-up every 3 to 12 months, as well as an EGD if clinically indicated, and CT chest, abdomen, and pelvis every 6 months for 1 to 2 years and then annually up to 5 years.Now, let's go back and discuss patients who have locoregional metastasis and stage IV cancer…This means that malignancy was identified on laparoscopy and peritoneal cytology.
If this is the case, they are upstaged to stage IV gastric cancer. Speaking of stage 4 disease, let’s go back to TNM staging.

Stage IV with distant metastasis8:48–9:41

If you see a tumor invading adjacent structures, or there are distant metastases on imaging, you can diagnose stage IV gastric cancer.
This is typically incurable and has a very poor prognosis. When it comes to treatment, you can offer chemotherapy with or without radiation for local disease control.
Surgical consultation for palliative gastrectomy is reserved for patients with symptoms like upper gastrointestinal bleeding or obstruction.
You can also test for genetic mutations like HER-2, PDL1, mismatch repair, or microsatellite instability to see if the patient will be a candidate for immunotherapy.
Unfortunately, these treatments are not curative, so be sure to offer palliative and supportive care.Alright, as a quick recap… Gastric cancer can be diagnosed with endoscopy with biopsy and endoscopic ultrasound.

Review9:41–10:40

Once the diagnosis is pathologically confirmed, stage the cancer using the T, N, M system. Early gastric cancers stage 0 or IA can be treated with endoscopic resection with H.
pylori treatment. For Stage IA that’s invading submucosa, proceed with gastrectomy and lymphadenectomy.
Stage IB cancers are managed surgically with adjuvant chemo and radiation therapy if lymph nodes are involved. Stages II and IV are managed with neoadjuvant chemotherapy for deep tumors followed by surgical resection, and adjuvant therapy for node-positive patients.
Lastly, patients with metastasis of any kind are considered to have stage IV disease. These patients can be considered for chemoradiation, palliative gastrectomy, immunotherapy, and palliative and supportive care.