Hubungan antara Imunoekspresi Ki-67 dan Risiko Agresivitas Tumor pada Gastrointestinal Stromal Tumor - Yulianti, Herry; Hernowo, Bethy S. (Faculty of Medicine, Universitas Padjadjaran, 2015)
Gastrointestinal stromal tumor (GIST) merupakan tumor mesenkimal yang paling sering terjadi pada traktus gastrointestinal dan berasal dari intestinal cells of Cajal yang terdapat pada lapisan muskularis traktus gastrointestinal yang berfungsi sebagai pacemaker cell dalam mengatur motilitas intestinal. Diperkirakan insidensi GIST 3−5% dari seluruh soft tissue sarcoma. Gastrointestinal stromal tumor dapat terjadi sepanjang traktus gastrointestinal, terbanyak pada usia pertengahan dan lebih tua, dengan usia rata-rata 50−60 tahun. Secara histologi, terdapat tiga kategori morfologi GIST, yaitu spindle cell, epitheloid, dan mixed type. Marker spesifik GIST adalah cluster of differentiation (CD117) yang mempunyai sensitivitas baik dan imunoreaktif pada 95% GIST. Ekspresi Ki-67 berhubungan dengan aktivitas proliferasi dan dapat dideteksi pada fase G1, S, G2, dan M dari siklus sel, kecuali pada fase G0. Tujuan penelitian ini adalah mengetahui hubungan risiko agresivitas dengan aktivitas proliferasi yang diukur dengan Ki-67 pada tumor yang telah dikonfirmasi sebagai GIST dengan CD117. Penelitian ini merupakan penelitian analitik potong lintang terhadap 29 kasus GIST dari Departemen Patologi Anatomi Rumah Sakit Dr. Hasan Sadikin/Fakultas Kedokteran Universitas Padjadjaran, Rumah Sakit Santo Borromeus, Rumah Sakit Immanuel, dan Rumah Sakit Santosa Bandung pada tahun 2007−2012. Potongan blok parafin dari 55 kasus GIST diwarnai dengan hematoksilin eosin untuk evaluasi histologi dan evaluasi imunohistokimia menggunakan monoclonal CD117 antibody untuk konfirmasi diagnosis GIST. Terdapat 29 kasus positif dengan CD117, kemudian diwarnai dengan monoclonal Ki-67 antibody. Sel yang dikategorikan positif CD117 memperlihatkan partikel coklat di dalam sitoplasma dan imunoekspresi Ki-67 dinilai dengan warna coklat pada inti sel tumor. Hasil penelitian menunjukkan hubungan bermakna antara risiko agresivitas tumor dan imunoekspresi Ki-67 (p<0,001). Simpulan, semakin tinggi nilai ekspresi Ki-67 semakin tinggi skor risiko agresivitas sehingga pada GIST, pemeriksaan imunohistokimia Ki-67 dapat membantu menentukan apakah pasien akan mempunyai prognosis yang buruk. [MKB. 2015;47(4):231–7]Kata kunci: CD117, gastrointestinal stromal tumor, Ki-67Correlation between Ki-67 Immunoexpression and the Tumor Aggressivity Risk in Gastrointestinal Stromal TumorAbstractGastrointestinal stromal tumor (GIST) is the most common mesenchymal tumor of the gastrointestinal tract, and arises from intestinal cells of Cajal localized in the muscular layer of the digestive tract, which functions as pacemaker cells in regulating intestinal motility. The incidence of GIST is about 3−5% of all soft tissue sarcomas. Gastrointestinal stromal tumor can occur along the gastrointestinal tract and predominantly in middle-aged and older persons, with a median age between 50 and 60 years. Histologically, there are three categories of GIST morphology such as spindle cells, epitheloid, and mixed type. A spesific marker of GIST is cluster of differentiation (CD117), which has good sensitivity and immunoreactive in 95% of GIST. The expression of Ki-67 correlates with proliferative activities and can be detected in G1, S, G2, and M phases of cell cycle but not in G0 phase. The aim of this study was to assessthe correlation between the risk of aggressive behaviors and proliferative activities as measured by Ki-67 in tumors confirmed as GIST by CD117. The method of this study was cross-sectional, performed on 29 cases of GIST from the Department of Pathology Anatomy Dr. Hasan Sadikin General Hospital/Faculty of Medicine Universitas Padjadjaran, Santo Borromeus Hospital, Immanuel Hospital, and Santosa Hospital between 2007−2012. A section from paraffin embedded tissue of 55 cases of GIST was stained with hematoxylin eosin for histological and immunohistochemical evaluations using monoclonal antibody CD117 to confirm the diagnosis of GIST. There were 29 positive cases for CD117. Further staining was performed using monoclonal antibody Ki-67. The categorized positive cells of immunoexpression of CD117 showed brown particles inside cytoplasma and the immunoexpression of Ki-67 was assessed by identification of nuclear brown staining of neoplastic cells. The result showed that there were significant correlations between the risk of tumor aggressive behaviors and immunoexpression of Ki-67 (p<0.001). In conclusion, as the immunoexpression of Ki-67 value increases, the aggressivity risk score becomes higher. Therefore, in GIST, the Ki-67 immunohistochemical analysis may help to decide which patients will have the worst prognosis. [MKB. 2015;47(4):231–7]Key words: CD117, gastrointestinal stromal tumor, Ki-67 DOI: 10.15395/mkb.v47n4.617