Prostate cancer patients overall face a 27 percent probability of developing metastatic disease within seven years of initial diagnosis, according to new research by investigators at UC Davis Cancer Center and five other institutions nationwide. In addition, men with metastatic cancer have a tenfold greater risk of death compared to those whose cancer is confined to the prostate gland. The research was presented at the 2003 meeting of the American Urological Association.
"Even in the contemporary PSA-era, with most patients presenting with low-stage, low-PSA disease, there is a significant rate of metastatic progression," said Christopher Evans, assistant professor of urology at UC Davis School of Medicine and Medical Center, and an author of the study. "The high probability of metastatic progression we observed underscores the need for improved treatments to reduce the rate of metastases and death from this disease."
In the study, Evans and researchers analyzed the medical charts of 2,056 prostate cancer patients in Detroit between 1995 and 2000.
The overall death rate was 9 percent. Patients with metastatic disease had ten times the death rate of those with localized disease.
The investigators also looked for correlations between progression rates and choice of first-line treatment - hormone therapy, surgery, external radiation, watchful waiting or internal radiation. After controlling for stage of cancer at diagnosis, the researchers found initial treatment did not statistically influence the rate of metastasis.
In a separate analysis, the researchers examined the 2,056 charts to determine the economic burden of metastatic prostate disease. They found that compared to patients with localized prostate cancer, patients with metastatic disease incur $13,650 more in health care expenses per year.
Patients with metastatic prostate cancer had $30,626 in medical bills, compared with $16,676 for patients with localized disease. The analysis compared charges incurred during initial care, continuing care and terminal care, after controlling for patient age and baseline stage of disease.
"For prostate cancer patients, metastatic progression poses a significant economic burden, irrespective of baseline stage, grade and treatment," Evans said. "Effective treatments that avoid or delay progression to metastasis may reduce overall costs."
Prostate cancer begins as a tumor within the prostate gland itself. For reasons that remain poorly understood, some prostate tumors grow slowly and remain within the prostate gland for many years, while others escape the gland and spread to other parts of the body, a process known as metastasis.
