Chemotherapy is one of the important treatments in the standardized comprehensive treatment of gastric cancer, and some early-stage patients and almost all intermediate- and late-stage patients need to receive chemotherapy. So, why do so many tests need to be performed before the first chemotherapy treatment? What tests are usually ordered by doctors? Why do the tests vary from patient to patient? What is the basis for deciding what tests a patient needs to have?
Patients with different stages need different chemotherapy, chemotherapy goals, and end results. In addition to the usual pre-chemotherapy tests, the focus of the tests is different for patients receiving different chemotherapy.
Routine tests
Every drug has toxic side effects, and this is especially true for chemotherapy drugs. The primary purpose of pre-chemotherapy testing is to determine whether the patient is physically able to tolerate chemotherapy, and to ensure that life safety is paramount. Therefore, the routine examination before chemotherapy is mainly to detect the function of organs, including blood routine (to judge the bone marrow hematopoietic function), urine routine (to judge the function of urinary tract and whether there is infection), stool routine (to judge whether there is gastrointestinal bleeding and other lesions), blood biochemistry (to judge the function of liver and kidney), nutritional deficiency status (vitamin B12 and iron content), tumor markers (to judge the efficacy and monitor recurrence after treatment) The patient’s physical status needs to be thoroughly evaluated, as well as ECG and echocardiography (to determine cardiac function).
Preoperative chemotherapy-related tests
Preoperative chemotherapy can be divided into neoadjuvant chemotherapy and translational therapy. Neoadjuvant chemotherapy for gastric cancer refers to systemic chemotherapy done before radical surgery for gastric cancer, which aims to bring down the tumor stage, shrink the mass, and kill invisible metastatic cells early to facilitate subsequent surgery. The purpose of chemotherapy is to make the tumor shrink through chemotherapy so that inoperable patients can regain the opportunity for radical surgery, and then combine it with chemoradiotherapy after surgery to achieve the purpose of curing the tumor.
These patients undergo a routine examination along with an evaluation of the local lesion, including ultrasound endoscopy (EUS), abdominal enhancement CT, etc. EUS is important in the initial clinical staging of gastric cancer. Careful interpretation of ultrasound images provides evidence of depth of tumor invasion (T staging), the presence of abnormal or enlarged lymph nodes resembling tumor implants (N evaluation), and incidental findings of distant dissemination, such as peri-organic lesions (M staging) or the presence of ascites.
Patients also require comprehensive, detailed, and accurate whole-body imaging, including chest-enhanced CT, abdominal-enhanced CT, pelvic-enhanced CT, abdominal magnetic resonance imaging (MRI) to evaluate metastases to the lungs and liver, bone radionuclide scan (ECT) to evaluate bone metastases, cranial-enhanced CT or MRI to evaluate brain metastases, and whole-body positron emission computed tomography (PET-CT) if necessary. If necessary, whole-body positron emission tomography (PET-CT) examinations may be performed. Laparoscopic exploration improves the diagnosis of abdominal implants and microscopic liver metastases in progressive gastric cancer compared with imaging such as abdominal enhancement CT, and allows simultaneous cytologic examination of abdominal lavage fluid; therefore, laparoscopic exploration for staging is recommended before chemotherapy.
Postoperative chemotherapy-related tests
The purpose of postoperative adjuvant chemotherapy is to remove tumor cells that may enter or have entered the circulation and to reduce the risk of cancer recurrence and metastasis. Patients undergoing postoperative chemotherapy, even if they have been thoroughly examined before surgery, still need a careful, comprehensive examination of the tumor for reassessment and staging before the first postoperative chemotherapy.
In addition to these routine examinations, enhanced CT of the chest, abdomen, and pelvis should be considered, as well as bone ECT to rule out bone metastases if the patient has symptoms such as bone pain. This not only ensures that the patient can receive standardized chemotherapy, but also provides comprehensive and accurate baseline information for clinical outcome evaluation.
Tests related to palliative chemotherapy
Some gastric cancer patients already have distant metastases at the time of initial diagnosis. There is no chance of surgery for such advanced gastric cancer, and the treatment aims at prolonging survival and improving quality of life, and the treatment is systemic therapy with chemotherapy as the mainstay. In addition to routine examinations and enhanced CT of the chest, abdomen, pelvis and abdominal MRI, enhanced CT or MRI of the head is needed to exclude brain metastases and ECT of the whole body to exclude bone metastases, and if economic conditions allow, whole-body PET-CT should be performed to accurately assess the metastatic sites and size of the tumor throughout the body, so as to provide reference for evaluating the efficacy of treatment.
In conclusion, in addition to the above, the doctor will take into account the patient’s own economic situation and local medical conditions to select a scientific, reasonable and cost-effective chemotherapy test for each gastric cancer patient before chemotherapy, in accordance with the principle of “standardization and individualization”. In order to achieve accurate assessment and precise treatment, we will select scientific, reasonable and cost-effective chemotherapy treatment according to the patient’s specific situation. (Written by Xiaoyu Guo, Department of Gastrointestinal Oncology, The First Hospital of China Medical University)