Ki-67 Biomarker Predicts Outcome For Prostate Cancer Patients Treated with Androgen Deprivation plus Radiotherapy
Salt Lake City, UT. (ASTRO; Fox Chase Cancer Center) Oct. 23, 2003 – The presence of a protein biomarker called Ki-67 may be a significant predictor of patient outcome for men with prostate cancer treated with both radiation and hormones.
Results of the largest known biomarker study for prostate cancer patients treated with radiation therapy were presented today by Alan Pollack, M.D., Ph.D., chairman of radiation oncology at Fox Chase Cancer Center, at the 45th annual meeting of the American Society for Therapeutic Radiology and Oncology (ASTRO) in Salt Lake City, Utah
The Ki-67 biomarker is a proliferation antigen that is detected by a process called immunohistochemical staining. When a tumor cell tests positive for Ki-67, the tumor is actively growing.
Most prostate cancers typically have very low percentages of growing cells and they grow slowly. Pollack and others have previously shown that the greater the proportion of prostate tumor cells with Ki-67, the more aggressive the cancer. Prior studies involved small patient numbers and did not definitively establish the usefulness of the Ki-67 biomarker.
"Our study conclusively shows that Ki-67 was the most significant determinant of distant metastasis and death in prostate cancer patients," explained Pollack. "The relationship of Ki-67 to patient outcome is a continuous function, wherein the higher the percent of Ki-67, the greater the risk of an adverse result. In addition, Ki-67, along with PSA, Gleason score and stage, appears to be valuable in determining whether high-risk patients may be spared long-term androgen deprivation."
Pollack says that a consistent threshold for the application of Ki-67 on a routine basis has not been previously established. In this study, when greater than 7.1% of the tumor cells stained for Ki-67, there was a significantly increased risk of distant metastasis and death due to prostate cancer.
Ki-67 should be very useful, Pollack adds, in stratifying patients in future clinical trials.
Ki-67 is one of a group pf genetic factors over-expressed in aggressive, high-Gleason tumors with low PSA. Austrian research published this year found that "expression of Ki-67, p53, Bcl-2 and chromogranin A were expressed significantly higher, and alpha-catenin and PSA significantly lower in HG tumors."
Other authors in the study include Michelle DeSilvio, American College Of Radiology, Philadelphia, Pa.; Li-Yan Khor, Fox Chase Cancer Center, Philadelphia, Pa.; Rile Li, Baylor School of Medicine, Houston, Tex.; Tahseen Al-Saleem, Fox Chase Cancer Center; M. Elizabeth Hammond, University of Utah School of Medicine, Salt Lake City; Varagur Venkatesan, Medical College of Wisconsin, Milwaukee; Roger Byhardt, University of California San Francisco, Calif.; Gerald E. Hanks, retired from Fox Chase Cancer Center; Mack Roach, University of Western Ontario, London, Ontario; William Shipley, Massachusetts General Hospital, Boston; and Howard Sandler, University of Michigan Medical Center, Ann Arbor.
Fox Chase Cancer Center, one of the nation's first comprehensive cancer centers designated by the National Cancer Institute in 1974, conducts basic, clinical, population and translational research; programs of prevention, detection and treatment of cancer; and community outreach. For more information about Fox Chase activities, visit the Center's web site www.fccc.edu.
Source, Fox Chase Cancer Center. This story edited by J. Strax. Page updated Oct 23, 2003.
Ki-67 staining is a strong predictor of patient outcome for prostate cancer patients treated with androgen deprivation plus radiotherapy: an analysis of RTOG 92-02.Pollack A and team. Radiation Oncology, Fox Chase Cancer Center, Philadlephia, PA. Int J Radiat Oncol Biol Phys. 2003 Oct 1;57(2 Suppl):S200-1.
Characterisation of biomolecular profiles in primary high-grade prostate cancer treated by radical prostatectomy.Augustin H and team. Department of Urology, Karl-Franzens-University Graz, Graz, Austria. J Cancer Res Clin Oncol. 2003, Sep 26
Suppression of advanced human prostate tumor growth in athymic mice by silibinin feeding is associated with reduced cell proliferation, increased apoptosis, and inhibition of angiogenesis.
Singh RP and team. Department of Pharmaceutical Sciences, School of Pharmacy, University of Colorado Health Sciences Center, Denver, Colorado Cancer Epidemiol Biomarkers Prev. 2003 Sep;12(9):933-9.