Routine screening for prostate cancer resulted in fewer cases of metastatic disease over the past 10 years even after controlling for disease severity, a new retrospective study suggests.
Men who developed prostate cancer before prostate specific antigen (PSA) testing became routine were 3.5 times more likely to progress to metastatic disease than were men diagnosed after PSA testing became the standard of care, Chandana Reddy, M.S., reported Oct. 25 during a press briefing sponsored by the American Society for Radiation Oncology in advance of its annual meeting.
“Our study showed that routine screening not only improves the patient’s quality of life by stopping metastatic disease but also decreases the burden of care for this advanced disease that must be provided by the health care system,” Ms. Reddy said. “This demonstrates that the prostate specific antigen [PSA] test is extremely valuable in catching the disease earlier and allowing men to live more productive lives after treatment.”
The impact of routine prostate cancer screening has been widely debated for years, Ms. Reddy said. “Because prostate cancer is generally a slow-growing disease, often diagnosed in older men with other medical conditions, the question has been [whether] they [should] be treated, since the treatment itself can have complications.”
Routine screening using the PSA was first implemented in 1992, and, she said, “Skeptics have argued that it has not resulted in any meaningful increase in survival. In fact, two recent trials showed no benefit.”
She cautioned that trial design could have skewed those results. “Those trials looked at overall survival as the primary end point, and since many of these men had other medical conditions, any prostate cancer–specific survival could have been masked by the likelihood of death from other illness.”
Ms. Reddy, a senior biostatistician at the Cleveland Clinic, Ohio, and her colleagues reported a retrospective study of 1,721 men with prostate cancer who were treated at the facility from 1986-1996. All men underwent radical prostatectomy or radiotherapy.
The investigators divided the group into two eras: a prescreening era (1986-1992; 575 patients) and a post-screening era (1993-1996; 1,146 patients). The median follow-up time for both groups was 10 years.
At baseline, according to the National Comprehensive Cancer Network risk classification, 44% of the prescreening era group were high risk, 21% were intermediate risk, and 28% low risk; no classification data were available for the remaining patients. For the post- screening era group, 36% were considered high risk, 27% intermediate risk, and 37% low risk. These differences between screening groups were statistically significant.
Within the 10 year post-treatment follow-up period, 13% (224) of all study patients developed metastatic disease. Significant differences (P less than .0001) in the rate of metastasis-free survival emerged when each risk level was compared between the prescreening and post-screening era groups: high risk (58% vs. 82%), intermediate risk (79% vs. 93%), and low risk (90% vs. 98%)
In a univariate analysis, screening era, age, T stage, pretreatment PSA value, and Gleason score on biopsy were significantly associated with the development of metastatic disease (P less than .05). In the multivariate analysis, screening era, T stage, and biopsy Gleason score remained statistically significant predictors of metastatic disease.
Neither Ms. Reddy nor any of her coauthors had any relevant financial disclosures.