Orlando, FL--American and British scientists have developed a statistical tool for predicting whether a man will survive his prostate cancer for up to 120 months if it is not treated immediately. Michael W. Kattan, PhD, of The Cleveland Clinic Foundation, said the tool should be helpful in patient counseling and clinical trial design.
Dr. Kattan reported on 1,680 men who were diagnosed by transurethral resection of the prostate or needle biopsy in the PSA era between 1990 and 1996 and who received no early aggressive therapy for clinically localized prostate cancer. The patients were chosen from six cancer registries in the United Kingdom. All were under 76 years of age and had a PSA of less than 100.0 ng/mL measured at baseline, no prior cancer diagnosis, no surgery or radiation, and did not metastasize or die within 6 months of diagnosis.
The Cox model used the following predictors: biopsy Gleason grade, clinical stage, method of diagnosis, baseline PSA, age at diagnosis, and year of diagnosis.
"We have recently begun to model those data to try to develop prediction tools that would be helpful to future patients who are considering watchful waiting as a treatment option. For each individual patient, we give a probability from 0 to 1 that he will die of prostate cancer within 96 months if he does not receive immediate, aggressive therapy. That would be an individual prediction for an individual patient based on his features," Dr. Kattan explained.
Because radical prostatectomy and radiation therapy are considered aggressive therapy, patients who had undergone such treatments within 6 months of their diagnosis were excluded from the study.
"We don't necessarily recommend aggressive therapy for all patients. [Patients] are free to choose what they want, but we wanted to predict what would happen to the individual patient if he chooses watchful waiting," he said.
Anthony D'Amico, MD, PhD, chief of genitourinary radiation oncology at the Dana-Farber Cancer Institute in Boston, said the main message of Dr. Kattan's study was that the PSA level, Gleason score, and age of the patient at the time of treatment act significantly in predicting the endpoint and yield more information about which patients can be observed and which ones require immediate treatment.
In an interview, Dr. D'Amico noted that roughly two-thirds of the patients in the study were detected through TURP and questioned whether the study truly represents contemporarily managed patients.