PDGFRA and gastrointestinal stromal tumor: Prognostic factors for GIST are classified into tumor related (anatomic site, histologic type, size of tumor, depth of invasion, grade, M category, mitotic rate, presence of KIT mutation, mutation site in KIT or PDGFRA gene, surgical resection margins, presentation status, tumor hypoxia, Ki-67, TP53), host related (NF1, age) and environment related (quality of surgery) (8).