Screening Guidelines for Prostate Cancer Challenged
Researchers from the Netherlands evaluated differences in the incidence of prostate cancer diagnosis, comparing two different screening protocols implemented in the European Randomized Study of Screening for Prostate Cancer (ERSPC). The group published their findings in the Journal of the National Cancer Institute.
The ERSPC is an ongoing project that commenced almost 15 years ago with the goal of evaluating the relationship between PSA screening and mortality from prostate cancer. Patients screened in Rotterdam underwent PSA evaluation every four years, whereas those in Gothenburg were screened every two years. There were a total of 4,202 Gothenburg patients screened and over 13,300 evaluated in Rotterdam.
The study also assessed the incidence of prostate cancer diagnosed in the period between screenings that were not identified by the screening activity. The group also evaluated the incidence of aggressive cancers among those that were diagnosed in those intervals.
Overall, more cancers were diagnosed among the patients who were screened more frequently, the Gothenburg cohort, according to the rate calculated across ten years. The rate was 13.14 percent in the Gothenburg patients and 8.41 percent in Rotterdam. Considering only cancers diagnosed during the interval between screenings, the incidence rates were 0.74 percent and 0.43 percent in Gothenburg versus Rotterdam, respectively. There was no statistically significant difference in the rate of aggressive cancers found during the interval between screening.
The team noted that more cancers were detected when the interval between screenings was abbreviated. However, this did not decrease the rate of cancers detected during intervals or the incidence of interval aggressive tumors found.
An extensive critique, in the form of an editorial, was published in the same issue of the journal. One of the questions raised in that commentary is whether or not the two different patient groups were appropriate for comparison. One such factor is the difference in ages among the two comparison groups. Matching patients, on at least one criteria associated with disease, is a standard methodology employed in comparison studies. Dr. David Crawford, author of the editorial, further suggests that little, if any, evidence validates use of screening for prostate cancer as a tool to decrease mortality from disease.
These publications bring to light some interesting controversies, particularly issues surrounding screening. For example, in the United State, the recommendations for prostate cancer screening is PSA evaluation every year. However, a trial is currently underway in the United States to determine the ideal interval between screenings, the Prostate, Lung, Colorectal, and Ovarian Cancer Trial (PLCO).
One controversy surrounding screening for prostate cancer consider the activity of screening in and of itself. Some would argue that screening is the best approach in the absence of means to prevent disease that is widely accepted and utilized. Screening aids in the identification of disease at its earliest stage when it is most amenable to treatment.
One component of validating the use of screening approaches entails some semblance of cost analysis, considering the costs to screen patients in comparison with costs for treatment and lost wages for ill patients. The entire equation for prostate cancer, yet to be fully iterated, may become even more complicated if new modalities for mass screening are introduced. A number of investigations into alternatives to PSA assessment have been previously described on Hospital Buyer. Methods to screen that are less expensive are particularly appealing.
August 29, 2007 Related topics: Monitoring, Diagnostic, Renal & Urology