What are the commonly utilized study designs

As with any clinical question, the randomized clinical trial would be the ideal method of determining the magnitude of differences in QOL between surgery versus radiation techniques. Such a trial would utilize validated general and disease-specific quality of life surveys, and would measure QOL at baseline, and post-treatment at 3, 12, and 24 months (intervals could certainly be changed if acute toxicity vs. longer toxicity were the primary question). While any of the abovementioned surveys could be appropriate, in our opinion, the UCLA PCI has the advantage of having several published studies with which to compare. However, if brachytherapy is involved in the study, the EPIC may be a more appropriate for the reasons listed above. Unfortunately, no such randomized trials exist for survival end-points, much less quality of life.

However, the American College of Surgeons has recently approved a trial comparing prostatectomy to brachytherapy for low-risk disease - the SPIRIT Trial (Surgical Prostatectomy Interstitial Radiation Trial) - and this protocol will include QOL assessment using the EPIC survey.

In the absence of randomized data, the two most common methods utilized are the cross-sectional study and the longitudinal study. A cross-section study has the advantage of being an inexpensive and quick method of collecting data. Scores are often compared to published, age-matched values of men without prostate cancer. A longitudinal study (with pretreatment values, if possible) is a more sensitive method, however, as trends in recovery or deterioration can be identified. With pretreatment values, patients serve as their own controls.

On this note, we should point out two recently published large observational studies that will be referred to in the following discussions.

1. Prostate Cancer Outcomes Study (PCOS). The PCOS is an National Cancer Institute-initiated study that was launched in 1994 as a longitudinal, community-based study of prostate cancer.45 After patients were diagnosed and entered into the study, patients were asked to recall their pretreatment QOL, and were then studied at 6, 12 and 24 months after treatment, using the SF-36 and validated disease-specific instruments. The study primarily included men treated with RP or XRT, but also included and separately reported men treated with hormonal therapy. The study's strength lies in its large size, longitudinal design and multicenter community-based design, which makes the results more generalizable to the population at large, in contrast to data from single academic medical centers. Its potential con-founders include the low response rate of 62% (with further loss to follow-up over time), and the use of recall bias. The use of recall for pretreatment assessment has been criticized,46 and Litwin47 found poor accuracy in recall among men treated for prostate cancer (JCO'99). However, the PCOS authors performed their own validation study and found no significant recall bias.48

2. Cancer of the Prostate Strategic Urological Research Endeavor (CaPSURE). CaPSURE is a large national observational database of prostate cancer patients treated by academic and community urologists, starting in 1995, totally 27 sites and 4061 patients.28 It includes all stages and a variety of treatments. Follow-up is completed at 3-month intervals using the SF-36 and UCLA PCI.

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