Prognostic Value of Ki-67 Proliferative Index in Diffuse Malignant Mesothelioma.
Wanghai Zhang, Maria McIntire, Raphael Bueno, John Godleski, Lucian Chirieac. Brigham and Women's Hospital, Boston, MA; Caris Life Science, Newton, MA
Background: The rate of cell proliferation as assessed by Ki-67 immunohistochemistry has been studied as a prognostic indicator in numerous malignant neoplasms and shown to correlate with tumour grade and patient outcome. The clinical significance of Ki-67 expression in diffuse malignant mesotheliomas has not been described in detail. In this study, we investigated the proliferative index by Ki-67 immunohistochemistry in a large cohort of patients and correlated the findings with the clinicopathologic characteristics.
Design: We studied 204 patients with diffuse malignant mesotheliomas (125 epithelioid, 8 sarcomatoid, 71 biphasic type) and surgical resection performed at Brigham and Women's Hospital between 2001 and 2008. Paraffin embedded tumor samples were used to construct tissue microarrays. We evaluated the Ki-67 proliferative index by immunohistochemistry as a percentage of Ki-67 positive tumor cells in each tumor. Patient age, sex, tumor type, TNM stage, lymphovascular invasion and number of positive lymph nodes were recorded and correlated with Ki-67 proliferative index.
Results: In our study, 166 patients (81%) were men and 38 (19%) were women with mean age 63.2 (range 34-84). T category was 1 in 4% of patients, 2 in 24%, 3 in 43% and 4 in 29%. The median Ki-67 proliferative index was 25% (range 0-95%). A high Ki-67 proliferative index was significantly correlated with positive metastatic lymph nodes (p=0.02), lymphovascular invasion (p=0.02) and number of positive lymph nodes (p=0.0005).
Conclusions: Ki-67 is a useful marker of cell proliferation in diffuse malignant mesotheliomas. A high Ki-67 proliferative index predicts a poor prognosis and correlates with positive lymph nodes, lymphovascular invasion and high number of positive lymph nodes in patients with diffuse malignant mesothelioma.
Tuesday, March 1, 2011 9:30 AM
Poster Session III # 281, Tuesday Morning