Increasing knowledge of the molecular characteristics of the tumors from gastric cancer patients has led to an increasingly individualized approach to the treatment of this disease. While surgical resection of the primary tumor followed by adjuvant chemotherapy and/or radiation therapy is considered to be the standard of care for patients with locally advanced gastric cancer, the presence of biomarkers expressed by the tumors of some patients with gastric cancer can lead to consideration of additional systemic therapies for selected patients.
In summary, information from precision oncology is used in concert with clinical information to make the appropriate treatment approach decisions for individual patients. All patients with similar tumors are not necessarily treated with different treatments.
What Precision Oncology Means
Precision oncology is a term of art. Information about a person’s cancer is used to guide decisions about their treatment. The information can come from a tumor obtained by a biopsy. It can also come from elsewhere in the body.
When speaking of gastric cancer, specific biomarkers are analyzed in the tumor tissue. For gastric cancer of the stomach, biomarkers such as HER2, PD-L1, mismatch repair or the status of microsatellite instability (MSI) as well as the biomarker CLDN18.2 are analyzed in the tumor tissue. Biomarker results may help inform treatment planning for individual patients.
Decisions regarding the use of systemic therapy for gastric cancer take into account the information gained from biomarker testing as well as other clinical features (e.g. stage of cancer, location of primary tumor, prior therapy, overall patient health including specific organ function, patient preferences).
Understanding Biomarker Testing
Biomarker testing for precision cancer medicine of gastric cancer involves examination of tumor tissue for specific molecular or biological characteristics to determine whether the cancer will respond to particular treatments. In selected cases, information from biomarker testing can identify a treatment that is directed at a specific feature of the cancer.
Cancers that are HER2-positive can be treated with a number of HER2-targeted therapies including trastuzumab, lapatinib, and pertuzumab among others in specific situations.
Studies of the PD-L1 protein in tumors from patients with advanced gastric cancer have identified subgroups of patients that These cancers have been evaluated in clinical studies involving immune checkpoint inhibitors. These studies use specific algorithms or scoring systems to determine the level of expression of PD-L1 in tumor tissue and to provide the clinical team with information that can be used to determine whether treatment with an immunotherapy may benefit a particular patient.
Tumors with deficient MMR (mismatch repair) and/or high levels of MSI (microsatellite instability) are considered to be a unique subset of cancer for which treatment decisions are being considered. These cancers have been studied in association with immune checkpoint inhibitor therapy.
The Emergence of CLDN18.2
Biomarkers in Gastric Cancer: The Emerging Role of CLDN18.2 in Cancer Diagnosis and Treatment. Zolbetuximab (Zolbetuximab), in combination with fluoropyrimidine- and platinum-containing chemotherapy, is approved for the treatment of adults with locally advanced unresectable or metastatic HER2-negative gastric or gastroesophageal junction adenocarcinoma whose tumors are CLDN18.2-positive by an FDA-approved test.
New treatments such as zolbetuximab are being developed for the gastric cancer patient. These are designed for patients with specific tumor characteristics. The consideration of these for treatment of the gastric cancer patient requires appropriate pathology and biomarker testing.
Combining Precision with Established Treatments
“Precision oncology” is the term used for what is also called “precision cancer medicine” or “PMCM”. This form of treatment does not replace existing forms of cancer treatment such as surgery, chemotherapy, and radiation. it may contribute to treatment planning and disease management in selected patients or control advanced disease and relieve symptoms in patients with cancer.
In many cases patients are treated systemically before or after surgery with the aim of enabling the surgery or to prevent a relapse of cancer after the surgery. There are also patients with advanced cancer who are treated with the goal of controlling the cancer and to alleviate symptoms.
A precision cancer treatment plan can consist of more than one type of treatment, for example a combination of targeted therapies, or of immunotherapy.
Treatment Decisions Can Change
A treatment plan is not set in stone for a cancer patient. Often more information will surface during a patient’s cancer journey and therefore treatment plans will change from time to time.
Imaging during treatment, such as X-rays, CT or PET scans, can tell us whether a tumor is responding to a particular treatment. Information from pathology and biomarker testing, for example testing for CLDN18.2, can also be used to make a decision about treatment. A patient’s symptoms, general health, organ function and even the side effects from a particular treatment can all impact on a treatment decision.
Decisions about the treatment of gastric cancer are made on a case by case basis, and can change as new information becomes available. Therefore, it is very important for patients to understand why a particular treatment has been recommended and whether further testing is required to make the best treatment decision. The reasons behind a particular treatment decision can change from time to time, so it is perfectly reasonable for patients to seek further explanation for their treatment from their doctors, especially when further tests have provided more information about the nature of a patient’s individual cancer.
Considering Quality of Life
In addition to focusing on the characteristics of a cancer, precision oncology should also take into consideration the overall wellbeing of the patient with gastric cancer and their treatment. This is in addition to other factors that affect the wellbeing of patients with gastric cancer and their treatment.
Supporting patients with gastric cancer and their families through the diagnosis and treatment of gastric cancer requires more than just the appropriate treatment approach. Patients with gastric cancer and their families also require support to enable them to deal with the symptoms and side effects of treatment and to cope with the disease.
Important Considerations When Deciding on the best Gastric Cancer Treatment. Patients and their healthcare team must make the informed decision based on the individual circumstances of the patient, taking into account the expected benefits of the treatment in comparison with the potential risks and side effects. It is also essential to consider the impact on the patient’s quality of life and on their daily activities.
The Role of the Healthcare Team
There is a growing team of health care professionals involved in the care of a patient with gastric cancer. These include medical oncologists, surgeons, radiation oncologists, pathologists, radiologists, specialist nurses and dietitians. Multidisciplinary meetings of medical and surgical oncologists, radiation oncologists, pathologists, radiologists and other health care professionals, including specialist nurses and dietitians are often used to integrate information from all of the above tests and to discuss the treatment options for individual patients.
Can we get a second opinion or even consider enrolling in a clinical trial?
Looking Ahead
Increasing numbers of biomarkers are being identified for gastric cancer, leading to the development of an increasing number of targeted treatments. These include a number of immunotherapies as well as other cancer treatments, such as antibody-drug conjugates, and treatments that are given in combination.
In summary, information on the tumor of a patient with a particular type of cancer, in this case gastric cancer, is obtained by the tool of precision oncology. Established clinical factors, on the other hand, provide information for making decisions for the individual patient with a cancer of a particular type and at a particular stage of development.
Ongoing research continues to improve understanding of gastric cancer and its treatment. Precision oncology is becoming a standard of care in the treatment of various cancers, including gastric cancer, with each cancer being treated individually based on the specific tumor characteristics as well as the patient’s individual clinical circumstances.
Disclaimer: The information provided in this article is intended for educational purposes only and should not be interpreted as medical advice, a clinical guideline, or a recommendation for any specific treatment.
