CHICAGO—Researchers have developed a model using readily available clinical parameters that may enable convenient prediction of overall survival (OS) among patients with metastatic castration-resistant prostate cancer (mCRPC) previously treated with abiraterone acetate.
“This allows us to look at patients and to see what is really working,” said Kim N. Chi, MD, Associate Professor of Medicine at the University of British Columbia in Vancouver. “We didn’t go with a nomogram approach because we wanted a simple method for categorizing prognosis quickly.” He presented details of the model at the 2013 American Society of Clinical Oncology annual meeting.
Dr. Chi and his colleagues used data from a multinational, randomized, controlled, phase 3 trial comparing 797 patients treated with abiraterone acetate plus prednisone and 398 patients who received placebo plus prednisone. They analyzed data from 729 patients for whom relevant baseline data were available, and found factors associated with survival.
These factors included an ECOG performance status of 2 and the presence of liver metastases, each of which was associated with a significant twofold increased risk of death. In addition, an interval of 36 months or less from the start of initial luteinizing hormone-releasing hormone agonist therapy to the start of abiraterone acetate treatment was associated with a significant 30% increased risk. Low albumin levels, high alkaline phosphatase, and high lactate dehydrogenase also were associated with significantly increased risk.
“There is a need for a prognostic model like this. There have been so many changes in the treatment of prostate cancer that the current nomograms under-predict patient survival,” Dr. Chi said.
Dr. Chi and his team divided patients into three risk-group categories based on their total number of risk factors (good prognosis [369 patients], intermediate prognosis [321 patients], and poor prognosis  ). The mean OS rate was 21.3 months, 13.9 months, and 6.1 months in the good, intermediate, and poor prognosis groups, respectively.
“External validation is required, but [the model] could be adopted at any institution,” Dr. Chi told Renal & Urology News. “This model can be used to stratify patients and give you a better idea of the timeline when patients are going to run into difficulties. If you had a patient with a very poor prognosis, then you may want to do closer follow-up and the patients with a better prognosis could be more reassured.”