Detecting & Diagnosing Gastric Cancer
- For gastric cancer, high-definition upper endoscopy, where doctors visually examine the upper digestive system using a long, flexible tube with a tiny camera attached, is still the standard choice for screening and precise diagnosis.
- With this technology, small changes in the mucosa that suggest neoplasia (abnormal growth of cells or tissues) can be detected and biopsied.
- While this is considered an invasive method of screening, it is the best approach currently available. As research progresses, non-invasive diagnostic methods (such as blood tests) are becoming more accurate for certain cancers, but research is still underway when it comes to detecting gastric cancer.
- Patients with a family history of gastric cancer should consider speaking to their doctors about genetic testing to assess their risk.
A cancer diagnosis is typically driven by the symptoms a patient is experiencing and a doctor’s suspicions based on those symptoms. Often, to get to the point of diagnosis, several sophisticated testing approaches are used — like biopsies, colonoscopies, scans, etc. However, as research progresses, non-invasive diagnostic methods are becoming more accurate and feasible.
Read MoreWhat is a Tumor Marker?
A tumor marker is anything present in or produced by cancer cells or other cells of the body in response to cancer or certain benign (noncancerous) conditions that can be detected in the blood. These markers provide important information about the cancer. Not all cancers of a specific type secrete biomarkers, sometimes a patient’s cancer can be considered a non-secreter which means that their tumor does not produce a specific biomarker. In these cases, biomarker testing does not give helpful informationBiomarker testing is only a single piece of data and treatment changes are not usually made based on biomarkers alone.
Commonly used examples of tumor markers include:
- Carbohydrate Antigen (CA) 19.9: This may be in addition to scans and other tests to tell if treatment for gastrointestinal cancers is working.
- CA-125: This can be used to help diagnose ovarian cancer, as well as assess response to treatment and evaluate recurrence.
- Carcinoembryonic antigen (CEA): This can be used for colorectal cancer and some other cancers to check the effect of treatment and detect recurrence.
In cases of gastric cancer, tumor markers are of limited use. Specifically, for adenocarcinoma (the most frequent type of gastric cancer), there is no tumor marker that accurately predicts early diagnosis, response to treatment, or recurrence. So, doctors do not routinely test for them unless a patient is undergoing neoadjuvant therapy (treatment before surgery).
Front-line Researchers: What’s New?
Recent technological advances have helped doctors better understand the causes of gastric cancer. This has led to the discovery of new ways to detect gastric cancer early. When cancer cells grow, they can release pieces of their DNA or RNA into the bloodstream. These pieces, known as circulating tumor DNA (ctDNA) and circulating RNA (circRNA), are being studied as potential noninvasive (no surgery or biopsy required) ways to detect gastric cancer early.
These new biomarkers may be more accurate compared to older protein-based tumor markers like CEA and CA 19-9. Some early studies have shown that ctDNA can better tell the difference between people with gastric cancer and those without, with improved accuracy.
Interestingly, patients with early-stage stomach cancer (which can be treated with surgery) tend to have lower levels of ctDNA in their blood.
MiRNAs are another promising marker. These are small molecules that have been found to change in certain conditions that can lead to gastric cancer, like gastritis or stomach lining damage. Specific miRNAs, like miRNA-21 and miR-376c, have been found in the blood of people with early-stage gastric cancer and may help predict the disease with up to 90% accuracy.
However, more extensive studies are needed to confirm these findings. Developing reliable ways to detect gastric cancer early could improve survival rates, especially in countries where the disease is rare and large-scale screening is not cost-effective.
Dr. Sofya Pintova, a Gastrointestinal Medical Oncologist at Mount Sinai Hospital in New York City, tells SurvivorNet that patients who have a family history of gastric cancer may also need to be tested — to assess risk of developing cancer and also look for mutations after a diagnosis. Answering questions about genetic mutations is an important part of the diagnostic process.
“Are there any mutations in your DNA that you were born with? Whether you were born with it as the first person in your family or something you inherited from one of you parents,” Dr. Pintova explains. “…That’s an important aspect of an evaluation of somebody who has either a family history of stomach [gastric] cancer, has other potential concerns for stomach cancer, or already has a diagnosis of stomach cancer.”
To note, an increase in serum pepsinogen II, a particular substance produced and released by gastric cells, has been used for screening purposes to identify patients with increased risk for gastric cancer, but it also lacks the sensitivity and specificity to provide diagnostic value, making this a less useful tool.
Upper Endoscopy: Advances & New Strategies
Despite all the studies and discoveries in tumor markers, the advancements reached by endoscopies (a procedure where a thin, tube-like instrument with a lens is inserted into the body so doctors can view tissues) stand out. Although it is an invasive procedure, it remains the standard approach for both screening and diagnosis of gastric cancer.
High-definition endoscopy with enhanced imaging is superior for detecting dysplasia (abnormal cells) and early cancer. With this technology, small changes in the mucosa that suggest neoplasia (abnormal growth of cells or tissues) can be detected and biopsied.
Furthermore, new endoscopy tools allow for assertive tactics to evaluate particular types of alterations, such as the pattern of vessel distribution and depressed lesions.
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