How to Diagnose Gastrointestinal Stromal Tumor (GIST)

Diagnosing gastrointestinal stromal tumor (GIST) involves two main approaches, depending on the patient's condition and the tumor's characteristics. This article outlines the primary diagnostic methods used in identifying GIST and understanding its severity.

1. Post-Surgical Diagnosis: The Most Common Method

Currently, pre-surgical diagnosis of GIST typically involves imaging techniques such as abdominal and pelvic scans and endoscopic ultrasound. These methods include CT scans and MRI, which help determine the tumor's size, location, and growth pattern. Endoscopic ultrasound is particularly useful for identifying the layer of the stomach wall where the tumor originates and for differentiating GIST from gastric cancer.

However, neither imaging nor endoscopic ultrasound can provide definitive pathological confirmation. As a result, many patients are not diagnosed with GIST before surgery. In most cases, the tumor is completely removed through surgery, and the final diagnosis is made based on post-operative pathological examination. This analysis helps determine whether the tumor is a GIST and classifies it into a low-risk, intermediate-risk, or high-risk category based on specific criteria.

2. Pre-Surgical Biopsy for Inoperable Cases

In some situations, initial evaluations indicate that surgery may not be the best option. This might be due to the tumor's location, the need for complex multi-organ resection, or high surgical risk. In such cases, doctors may recommend a biopsy before proceeding with surgery.

A biopsy can be performed using endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) or through an abdominal approach. These procedures allow doctors to obtain tissue samples for pathological analysis, which confirms the presence of GIST. Once diagnosed, patients may begin targeted drug therapy, such as tyrosine kinase inhibitors, to shrink the tumor. If the tumor responds well to treatment and becomes operable, surgery can be reconsidered at a later stage.

In summary, accurate diagnosis of GIST is crucial for determining the most appropriate treatment plan. While post-surgery pathology remains the gold standard, advances in biopsy techniques and targeted therapies offer valuable options for patients with inoperable tumors.