Purpose: We investigated the incidence of lymph node metastasis in gastrointestinal stromal tumor (GIST) patients in our PET/CT database. The demographic data and characteristics of the primary tumor were evaluated in GIST patients with or without lymph node metastasis.
Materials and methods: We reviewed our PET/CT database from January 1, 2007 to November 30, 2010 by using keyword search, and identified GIST with lymph node metastasis according to our standard of reference. Statistical analysis was conducted between GIST group with or without lymph node metastasis based on the age, sex, primary tumor size, and primary tumor location.
Results: A total of 29 GIST patients were found in our database. Six of them had lymph node metastasis, corresponding to 20.7%. When considering only the adult patients, the incidence was 17% (5 out of 28). There were 4 males and 1 female, with the mean age of 66.8 years old, which was 8 years older than the group without lymph node metastasis. Of the 5 adult metastasis patients, 4 had their primary tumor located at very rare sites other than stomach or small bowel. Statistical analysis using Fisher exact test of rare location showed significance between the 2 groups with P = 0.004. The mean size of the primary tumor in the group with lymph node metastasis was 5.2 cm, which was 2.9 cm less than the group without metastasis. No statistical significance was found in age, sex, or size of primary tumor between the 2 groups.
Conclusion: The incidence of lymph node metastasis in GISTs in our database is 20.7%, which is surprisingly higher than we thought from other previous studies. In contrast to the group without lymph node metastasis, these patients tend to be of older ages and had rare location of the primary tumor. This result supports further study with larger sample size.